Drug Delivery from Hydrogels

Abstract

A novel delivery method is provided that enables poorly water-soluble therapeutic drugs administered intraocularly to exhibit excellent sustained release and persistence in the drug treatment of ocular fundus diseases. [Solution] Drug delivery involves hydrogels used for various medical conditions and includes hydrogels formed within the eye with extended drug release times. One embodiment of the present invention is a method for delivering a therapeutic agent to tissue, comprising forming a hydrogel in situ within the eye with a therapeutic agent dispersed within the hydrogel, where the agent has low water solubility. The agent can be substantially water-insoluble. The hydrogel can be fabricated such that 50% to 100% w / w of the agent is released when the hydrogel is 100% to 50% sustained, where sustained release is a measure of the dry weight of the hydrogel relative to the initial dry weight of the hydrogel.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 62 / 160,394, filed May 12, 2015, which is incorporated herein by reference.

[0002] The technical field relates generally to drug delivery involving hydrogels used for a variety of medical conditions, and includes hydrogels formed within the eye that have extended drug release times. [Background technology]

[0003] Age-related macular degeneration (AMD), diabetic retinopathy, diabetic macular edema (DME), posterior uveitis, choroidal neovascularization (CNV) and cystoid macular edema (CME) are eye diseases that can lead to blindness. Age-related macular degeneration and diabetic retinopathy are important causes of vision impairment in the United States and other countries, and these conditions are generally caused by angiogenesis (unwanted blood vessel growth in the eye), which can damage the retina and ultimately lead to blindness. Posterior uveitis is a chronic inflammatory condition that is responsible for approximately 10% of blindness in the United States. Summary of the Invention [Means for solving the problem]

[0004] One invention disclosed herein is a crosslinked hydrogel formed in situ that releases a therapeutic drug that can be used, for example, to treat ocular diseases. In this embodiment, an aqueous polymer precursor is combined with a drug at a flowable concentration / viscosity and injected into the eye through a small gauge needle, where the precursor forms a crosslinked in situ hydrogel that releases the drug over time. The hydrogel can be formulated to adhere to itself or to tissues in or around the eye to enhance drug release efficiency and stability, degrade into biodegradable components without causing inflammation, and crosslink in place. The shape-stable hydrogel thus formed effectively delivers the drug and advantageously has a well-controlled size, shape, and surface area. The hydrogel can be manufactured to degrade after the drug is released. [Brief description of the drawings]

[0005] [Figure 1] Depict the anatomical features of the eye from the front. [Diagram 2] FIG. 1 is a perspective view of a partially cut-away eye. [Diagram 3] FIG. 1 is a cross-sectional view of an eye. [Figure 4] Various delivery alternatives for ocular implants are depicted. [Diagram 5] Depict the placement of material on the choroid. [Figure 6] 1 depicts the release of a drug from a hydrogel formed in situ in the intraocular chamber or intravitreal space. [Figure 7] 1 is a plot of hydrogel volume swelling as the hydrogel degrades without external constraints. [Figure 8] 8 is a plot of the dimensions of the hydrogel depot of FIG. 7. [Figure 9] Photograph montages of in situ formed drug-releasing hydrogels shown immediately after placement in vivo (panel a), after 40 hours in physiological buffered saline (PBS) (panel b), after 1 week (panel c) or after 12 days (panel d). [Figure 10] Photograph of hydrogel implants in PBS with drug entrapped within the implant for release. [Figure 11A] 1 is a plot of the release profile in PBS of drug entrapped within a hydrogel depot or directly introduced into PBS. [Figure 11B] The plot of FIG. 11A displayed as a Higuchi plot. [Figure 11C] FIG. 11B is a graph of the data from FIG. 11A showing the Higuchi coefficient, K, as having a linear relationship with drug solubility for poorly or very poorly soluble drugs released from hydrogels. [Figure 12] FIG. 13 is a photographic montage of controlled release of drug from hydrogel depots showing clearance of drug over time. [Figure 13] 1 is an example of zonal clearance of lotepredenol etabonate from a hydrogel depot in PBS. [Figure 14] FIG. 13 is an example of zonal clearance of prednisolone from a hydrogel depot in PBS. [Figure 15] Photograph montages of controlled release of dexamethasone from hydrogel depots showing clearance of the drug over time. [Figure 16] Photograph montage of various drugs released from hydrogels at the indicated time points, an example showing that zonal clearance of drugs from hydrogel depots in release media such as PBS visually correlates with drug solubility in the release media over time. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] One embodiment of the present invention is a method for drug delivery to tissue, particularly the eye, which includes forming a hydrogel implant in situ that includes a therapeutic agent in the hydrogel (e.g., dissolved, suspended, dispersed throughout), where the therapeutic agent has low water solubility.

[0007] Ocular drug delivery is an active field. Improvements in drugs for the treatment of eye diseases have led to new options for patients, including controlled release devices. One approach for sustained release in the eye has been to load drugs into degradable particles, which are then injected into the eye. However, in some cases, particles that settle on the retina have been problematic and can cause contact toxicity. Other approaches have created miniature drug delivery devices that are biodegradable rods of polylactide / glycolic acid copolymer (PLA / PGA) that are impregnated with drugs and inserted into the eye. As they erode, the drug can migrate out of the PLA / PGA, and degradation thus controls the release rate. These devices provide sustained release as they erode with aqueous solutions in the eye. Another approach has involved the use of certain hydrogels that form in situ, as described in US Patent Application Publication No. 2009 / 0252781. While these are useful in certain circumstances, there are still other techniques that can be used to improve biodegradability and expand the range of clinical treatments that can be performed with controlled release devices.

[0008] In particular, there is an opportunity to use the properties of the drug itself in combination with certain properties of the hydrogel to produce depots (also called implants) that release drugs in a controlled manner over time to achieve effective concentrations without reaching toxic levels. Poorly soluble drugs can go into solution particularly slowly in hydrogels. Hydrogels can be produced to allow easy diffusion without requiring degradation (bioerosion) of the hydrogel for the drug to be released. The properties of the hydrogel can be designed to exploit the solubility of the drug to control the release. Such properties include matrix structures that achieve drug diffusion without relying on bioerosion, hydrogel preparations that allow drug dispersion within the hydrogel, and achieving drugs suspended as, for example, micro- and / or nanoparticles or droplets. Drugs do not have to be encapsulated in particles or otherwise combined with materials that require bioerosion to release them. Furthermore, hydrogels can be produced to last longer than the drugs they reach, so that delivery is controlled and the release of the final burst of drug is kept within a range that avoids potential toxic effects.

[0009] Some embodiments achieve encapsulation of drugs within particles, either instead of or in addition to non-encapsulated drugs, particularly outside the eye. These particles can be mixed with one or more precursors that form a hydrogel around them. Particle encapsulation is discussed in more detail below.

[0010] In general, the eye presents an environment with competing design requirements. On the one hand, the eye has a limited volume, so a large volume depot is not preferred. On the other hand, placement of a depot in the eye, for example by injection, involves some discomfort and trauma, so a large depot helps minimize the frequency of placement. Furthermore, the eye is generally sensitive, and fabricating a small depot is a goal when placing the depot in a location that interferes with the requirements for effective vision. Furthermore, therapeutic agents require a minimum concentration to be effective, but too high a concentration can have toxic effects. Thus, the agent must be released quickly and consistently enough to be effective without being released too quickly throughout the life of the implant. The use of hydrogels around the agent presents the challenge of adding volume to the implant. For hydrogels with internal spaces that allow diffusion of the agent, there is a mechanical challenge in fabricating an implant that can withstand the mechanical forces applied to the eye, such as rubbing or accidental force on the eye, or the high intraocular pressure present in certain diseases that the agent is targeted to. Open, lightly crosslinked hydrogel structures tend to have high flexibility but lower mechanical strength compared to more closed hydrogels with more closely spaced crosslinks.

[0011] However, it is possible to use the small volume of the eye as an advantage rather than a disadvantage. Hydrogels that allow for drug diffusion are not only influenced by the concentration of drug within the hydrogel, but also the concentration of drug within the limited volume of the eye. Thus, hydrogel depots using relatively open matrices can utilize the small volume of the eye as a parameter to control release, since the amount of drug released may further limit release. Thus, hydrogel structure, size, shape, loading, and material selection can be balanced in combination with drug properties to provide an effective controlled release implant device. In effect, these various competing design features can be reconciled to achieve delivery of effective concentrations of drug over a period of time while avoiding toxic over-release of drug.

[0012] In contrast to hydrogels that allow drug diffusion, erodible hydrogels prevent diffusion until the matrix erodes. Such designs have the advantage of directly controlling the release rate of the drug. Such designs have a relatively densely crosslinked matrix, making them mechanically robust to withstand mechanical forces during or after their insertion, for example, due to the patient rubbing the eye or accidental force, or internal eye stress in the case of certain diseases that are the target of the drug.

[0013] Topically forming hydrogels made in situ from precursors in aqueous solution can serve as depots of drugs or other therapeutic agents for ocular drug delivery or other sites. Described herein are hydrogels that can be formed in situ on tissues or organs to deliver drugs. The term on tissue is broad and includes contact with tissue, in tissue, around tissue, in tissue voids or defects, in potential spaces of the body, and the like. An organ is a tissue. The term on an organ is broad and includes in organ, on organ, around organ, and the like. In situ refers to forming a material at the site where it is intended to be placed. Thus, hydrogels can be formed in situ in a patient at the site where it is intended to use the hydrogel as a drug depot for controlled release, for example. Certain drugs, such as some tyrosine kinase inhibitors (TKIs), have been shown to have corneal toxicity even in the form of eye drops due to direct contact with ocular tissue. An advantage of hydrogels is that they protect tissues from contact with drugs, for example, in solid particle or suspended form. The drug is slowly released from the hydrogel in a diffuse form.

[0014] Another embodiment includes hydrogels that are formed outside the body and inserted into the body, for example, intravitreally. Example 1 describes the swelling and persistence of two hydrogels made with polyethylene glycol (PEG) matrices at solids concentrations of 5% or 10% w / w PEG (see Table 3). The hydrogels were made from a first PEG precursor with electrophilic end groups (succinimidyl azelate, SAZ) and a second PEG precursor with nucleophilic end groups (amines). The PEGs had 4 or 8 arms, each with a nominal molecular weight of 20k. These were combined in a buffer solution in the presence of a polysaccharide (1% w / w hyaluronic acid, HA). This combination was found to have a low viscosity suitable for injection through a small bore needle, and the resulting hydrogel matrix provided a structure that maintained its shape and mechanical integrity during spatial gelation, for example, in the eye chamber, in the vitreous, or other locations. The precursors have good syringeability and good cohesion. HA is a high molecular weight non-Newtonian linear molecule; it increases the viscosity of the precursor solution and also performs well under high shear conditions (passage through a fine gauge needle). Various dilutions of 850 kDa HA at approximately 1% w / w were tested, which in this case gave excellent results. The buffers used to dissolve each precursor produced a neutral pH when mixed, and the buffer containing the SAZ precursor was at a low pH to maintain the stability of the polymer in solution (avoiding prehydrolysis). Each of these components, when mixed together, formed a hydrogel that maintained shape and volume stability, retaining its shape and position in space until the hydrogel formed in 2-3 minutes. Figures 7 and 8 depict swelling and dimensional change plots, respectively, for these hydrogel depots introduced in vitro in physiological buffer (PBS). It was further observed that as the hydrogel degraded, it continued to swell with an upward linear trend toward 1000% of its pre-liquefaction volume. "Most of the dimensional changes occur within the first hour. As the hydrogels degrade, they become mechanically weaker and swell. Although these tests were performed in unconstrained areas, if formed in vivo, they would swell minimally in vivo under conditions where surrounding mechanical forces limit swelling."

[0015] In Example 2, the hydrogel of the composition of Example 1 further contained a small amount of fluorescein for visualization, and a volume of about 25 μL of the drug dexamethasone was formed in situ within the eye. The depot was explanted and placed in an excess of PBS to observe the release of the drug and the persistence of the hydrogel. The drug was observed to be discharged from the hydrogel in a medial direction, with the edge of the implant having the lowest concentration of drug and the hydrogel interior having the highest concentration (FIG. 9). The hydrogel was substantially persistent over the 12 day observation period, and the visual observations were consistent with the release amount and persistence data shown in the plots herein. The hydrogel had a stable shape and consistent mechanical properties based on the manipulation of the hydrogel. Examples 3-8 provide detailed examples of the preparation and use of various hydrogels and drugs. Example 9 is an example of a method of preparation of a kit for in vivo preparation of hydrogels for drug release. One of ordinary skill in the art can readily understand how to adapt these examples, and all of the examples more broadly, to make and use hydrogels with any of the types of precursors, agents, and application sites described elsewhere in this disclosure.

[0016] Example 10 shows the release profiles of various exemplary drugs, flunisolide (solubility 90 μg / mL), betamethasone sodium phosphate (freely soluble in water), budesonide (30 μg / mL), and triamcinolone acetonide (20 μg / mL). These drugs were either incorporated in PBS or dispersed within hydrogels incorporated in PBS (FIG. 10), and hydrogels were made from a hydrophilic precursor with electrophilic groups (4-arm PEG) and a small hydrophilic precursor with nucleophilic groups (trilysine). The release rates from the drug-containing hydrogel depots were compared to the dissolution profile of the same amount of drug in the undiluted formulation (FIG. 11A).

[0017] Figures 11B and 11C are plots of the data from Example 10. Figure 11B is a Higuchi plot showing that drug release versus the square root of time is a linear relationship with a slope (slope equal to the Higuchi coefficient, K) proportional to drug solubility, drug diffusivity, initial drug concentration, depot surface area, and other depot design factors. Figure 11C shows a linear function of solubility versus K for the same initial drug concentration and other depot design factors. A visual representation of drug release from the depot over time for an exemplary drug (flunisolide) is shown in Figure 12. Results reveal that entrapment of an equal mass of drug within the enclosed space of the hydrogel significantly slows the release rate of the drug compared to drug readily dispersed in an equal volume of dissolution medium, and that the tapered drug release profile correlates with drug solubility.

[0018] These data further establish the sustained release rate from the in situ depots and model the in vivo conditions. Injection of the prehydrogel material containing a suspension of an exemplary drug (steroid) into the closed space of the viscous vitreous was observed to produce a spherical hydrogel depot at the injection site. These example depots formed in vitro produced similar spherical hydrogel depots (e.g., FIG. 10). Drug release data from these in vitro formed depots allows prediction of in vivo drug release rates. The Higuchi equation for release from this type of construct is as follows (Siepmann, J.; Peppas, N.A. Modeling of Drug Release from Delivery Systems Based on Hydroxypropyl Methylcellulose (HPMC). Adv. Drug Deliv. Rev. 2012, 64, Supplement, 163-174):

number

[0019] M t is the mass of drug dissolved at time t, A is the surface area, C0 is the initial drug concentration, and Cs is the drug solubility and D is the diffusion coefficient. This equation is expressed as C>>C s , it is assumed that edge effects can be neglected, swelling or dissolution of the hydrogel depot can be neglected, diffusivity is constant, temperature and pH are constant, and perfect sink conditions are maintained. More generally, this equation can be expressed as:

number

[0020] Where M is the cumulative drug released in infinite time, k is a constant (Higuchi coefficient) that represents the depot design variable. Thus, the drug or drug fraction release profile is tapered when plotted against time, but linear when plotted against the square root of time.

[0021] Thus, the release of the poorly soluble drug is regulated by the drug's limited solubility in the physiological environment within the hydrogel and by the concentration gradient (equal to the drug solubility under full sink conditions) at the hydrogel interface with the physiological environment. As the concentration gradient front moves away from the interface, a tapering drug release profile is formed. This receding front can be seen as an increasing clear zone around the depot. Thus, the duration of drug release can be regulated by adjusting the amount of poorly soluble drug in the depot. The rate of drug release from the intravitreal depot is extended compared to injection of unconstrained undiluted steroids into the vitreous, which is expected to increase the duration of action of the drug in the eye. Another advantage is that the drug particles are trapped within the hydrogel, whereas insoluble drug particles migrating within the eye can cause adverse tissue reactions or visual impairment if the particles enter the visual axis. Factors expected to affect the rate of drug release from hydrogel depots formed in situ include: drug solubility, drug particle (liquid or solid) size, general solubility factors (pH, temperature, salts, etc.), amount of drug within the depot creating various concentrations and gradients, homogeneity of drug within the depot, depot surface area, fluid turnover or exchange rate at the depot interface, hydrogel degradation and dissolution, depot additives (such as surfactants), and possibly other factors known to alter drug solubility.

[0022] In a similar construct described in Example 11, various drugs were suspended in a hydrophilic hydrogel precursor solution that was crosslinked and formed into a cylindrical depot. The drug suspension gel was removed from the tube and ex vivo release was initiated in a dissolution medium. Zonal clearance (released steroid) from the depot interface to the interior was observed and visually recorded. See Figures 13-16. Similar observations are expected to occur over time during in vivo drug release.

[0023] Examples 12-14 detail the results of experiments testing the potential toxicity of burst-released drugs. The hydrogel depot consistently releases effective concentrations of drug over a period of time. After this period, the hydrogel loses mechanical integrity and the matrix structure becomes loosely textured. Any drug remaining during this degradation phase may be released at a faster rate or in bursts, resulting in higher drug concentrations than necessary for efficacy or perhaps amounts that are toxic to local tissue. In order to understand how much persistence is needed in terms of total and residual amounts of drug, in vivo ocular studies were performed to measure the potential effect of burst release. Given the many design variables involved in the delivery process, several experiments were required to prove that the delivery method described herein is appropriate for the ocular space. The results show that depots can be designed with suitable persistence, loading, and other factors to effectively deliver drugs over a sustained period of time while satisfying various design variables.

[0024] The hydrogel depot is designed to provide an effective concentration of the drug at the intended site of use. The term effective amount or effective concentration or therapeutically effective / concentration refers to an amount of drug sufficient to produce a beneficial or desired result. The effective amount may vary depending on one or more of the subject and condition to be treated, the subject's weight and age, the severity of the condition, the method of administration, etc., which can be readily determined by one of skill in the art. The effective concentration can be indicated by a pharmacokinetic effect. Alternatively, a calculated effective amount may be provided, which means an amount 50-100 times the IC50 of the drug for the substrate; one of skill in the art will immediately recognize that all ranges and values ​​between the boundaries specified are contemplated, e.g., 50, 60, 70, 80, 90, or 100 can be used as upper or lower limits. IC50 refers to the half maximal inhibitory concentration (the concentration that reduces an effect by 50%), e.g., inhibition of an unwanted pathological effect.

[0025] Eye Anatomy The structure of the mammalian eye can be divided into three main layers or envelopes: the fibrous membrane, the vascular membrane, and the neural membrane. The fibrous membrane, also known as the ocular sclera, is the outer layer of the eyeball, consisting of the cornea and the sclera. The sclera is the supporting membrane of the eyeball and gives the eye most of its white color. It extends from the cornea (the clear, front part of the eye) to the optic nerve at the back of the eye. The sclera is a fibrous, elastic, protective tissue with a water content of about 70% that is composed of densely packed collagen fibers.

[0026] Above the fibrous membrane is the conjunctiva. The conjunctiva is a membrane that covers the sclera (the white part of the eye) and lines the inside of the eyelid. The conjunctiva effectively surrounds, covers, and attaches to the sclera. It has cellular and connective tissue, is somewhat elastic, and can be removed, shredded, or otherwise removed to expose the surface portions of the sclera. The tunica vascularis, also known as the tunica vasculosa, is the middle vascularized layer that includes the iris, ciliary body, and choroid. The choroid contains blood vessels that provide oxygen to the retinal cells and remove respiratory waste products.

[0027] The optic nerve, also known as the optic nerve, is the inner sensory organ that includes the retina. The retina contains the light-sensitive rod and cone cells and associated neurons. The retina is a relatively smooth (but curved) layer. It has two distinct points; the fovea and the optic disc. The fovea is a depression in the retina just opposite the lens, densely packed with cone cells. The fovea is part of the macula. The fovea is primarily responsible for human color vision and allows for the fine visual acuity needed for reading. The optic disc is the point on the retina where the optic nerve penetrates the retina and connects with nerve cells on its inner side.

[0028] The mammalian eye can also be divided into two main segments: anterior and posterior. The anterior segment consists of the anterior and posterior chambers. The anterior chamber is located in front of the iris and behind the corneal endothelium and contains the pupil, iris, ciliary body and aqueous humor. The posterior chamber is located behind the iris and in front of the vitreous surface, where the crystalline lens and zonular fibers are located between the anterior and posterior lens capsules in an aqueous environment.

[0029] Light enters the eye through the cornea and into the first of two humors, the aqueous humor. Approximately two-thirds of the eye's total refractive power comes from the cornea, which has a constant curvature. Aqueous humor is a clear mass that connects the cornea to the lens of the eye, helps maintain the convex shape of the cornea (necessary for focusing light at the lens) and provides nutrition to the corneal endothelium.

[0030] The posterior portion is located behind the lens and in front of the retina. It occupies about 2 / 3 of the eye, including the anterior hyaloid membrane and all the structures behind it, including the vitreous humor, retina, and optic nerve. Opposite the lens is the second humor, the vitreous humor, which is bounded in all directions by the lens, ciliary body, suspensory ligaments, and retina. It passes light without refraction and helps maintain the shape of the eye, keeping the fragile lens floating.

[0031] FIG. 1 depicts an eye 10 having a sclera 12, an iris 14, a pupil 16, and an eyelid 18. FIG. 2 depicts a perspective view of the eye 10 and includes a partial cross-section depicting the lens 20, the inferior oblique muscle 21, the inferior rectus muscle 23, and the optic nerve 25. FIG. 3 is a cross-section of the eye 10 depicting the cornea 22, which is optically transparent and passes light through the iris 14 and through the lens 20. The anterior chamber 24 is below the cornea 22, and the posterior chamber 26 is between the iris 14 and the lens 20. The ciliary body 28 connects to the lens 20. FIG. 3 depicts a portion of the conjunctiva 30, which overlies the sclera 12. The vitreous body 32 contains a gelatinous vitreous humor, and the vitreous tubule 34 resides within it. The fovea 36 resides in the macula, and the retina 38 resides on the choroid 37. The zonula 42 is depicted.

[0032] FIG. 4 depicts schematics of various intravitreal configurations. Multiple depots may be formed or there may be only one. The depot may have a variety of shapes, for example, elongated, elliptical, spherical, substantially spherical, oval, cylindrical, substantially cylindrical, discoid, or substantially discoid. The term substantially spherical means that the hydrogel occupies at least 70% of the volume of a sphere drawn around the hydrogel. The term spherical means that the hydrogel occupies at least 85% of the volume of a sphere drawn around the hydrogel. The term substantially discoid means that the hydrogel occupies at least 70% of the volume of a cylinder drawn around the hydrogel, the height of the cylinder being less than the diameter of the cylinder. The term substantially discoid means that the hydrogel occupies at least 85% of the volume of a cylinder drawn around the hydrogel, the height of the cylinder being less than the diameter of the cylinder. The term substantially cylindrical means that the hydrogel occupies at least 70% of the volume of a cylinder drawn around the hydrogel, and the height of the cylinder is greater than the diameter of the cylinder. The term substantially cylindrical means that the hydrogel occupies at least 85% of the volume of a cylinder drawn around the hydrogel, and the height of the cylinder is greater than the diameter of the cylinder. Other shapes and sizes can be selected to suit the site and application, and irregular shapes are also contemplated. Volumes described elsewhere herein, such as less than 1 ml, 0.005 to 5 ml, etc., are also applicable; one of skill in the art will readily recognize that all ranges and values ​​between the boundaries specified are contemplated, and 10, 20, 25, 50, 100, 150, 200, 250 μL; 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2, 3, 4, 5 ml can all be used as upper or lower limits. One or more such depots can be formed. 5 shows placement on the choroid. As described in more detail below, other organs may also be sites for hydrogel placement. For example, the hydrogel may be formed within a natural or surgical cavity or a potential cavity, such as another site where a cancer has been removed or is located. Sites include placement of hydrogel material at the site of a cancer, such as, for example, a prostate or breast cancer for the treatment of prostate cancer.

[0033] Application of precursors to form hydrogels in situ Ocular diseases can be treated with drugs using, for example, topical, systemic, intraocular and subconjunctival delivery routes. Systemic and topical drug delivery methods may not achieve therapeutic drug level delivery to treat posterior segment diseases. These drug delivery methods face diffusion and drug dilution problems due to inherent anatomical barriers in the intraocular and systemic systems, leading to significant patient side effects (due to multiple doses per day), poor bioavailability and compliance issues. The delivery location for placing intraocular drug delivery implants generally depends on the disease and type of drug therapy that require treatment.

[0034] The delivery of therapeutic amounts of drugs to the retina in posterior ocular diseases remains a challenge. Intravitreal injection of anti-VEGF agents into the vitreous cavity has shown promise in halting and possibly reversing chronic age-related diseases such as macular degeneration, but these techniques and procedures are not without risks and side effects. Intravitreal administration of therapeutic agents into the vitreous cavity can cause cataracts, endophthalmitis, and retinal detachment. This form of therapy requires many patients to receive monthly intravitreal injections of anti-VEGF agents over a 12-month period, increasing the risk of infection, vitreous incarceration, and retinal detachment. Embodiments directed to in situ hydrogel biodegradable drug implants are expected to provide an effective alternative treatment for ocular diseases and reduce common side effects associated with repeated intravitreal injections. Embodiments of intravitreal, intraanterior chamber, or other ocular biodegradable drug delivery implant systems are summarized below.

[0035] 4 and 5 show several delivery points at or near the eye 10. Locations include within the anterior chamber, intravitreous, or at or near the retina. The hydrogel can rest on the retina, but it is useful to have some spacing from the retina. The spacing can be, for example, 0.1-10 mm; one of skill in the art will readily recognize that all ranges and values ​​between the boundaries specified are contemplated and any of 0.2, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 can be used as upper or lower limits.

[0036] As described in more detail in other sections, the drug depot of the in situ hydrogel drug delivery implant can be designed for controlled long-term drug delivery, ranging, for example, from about 1 to about 12 or 36 months; optionally, can be targeted to treat ocular diseases, including, for example, age-related macular degeneration, diabetic retinopathy, diabetic macular edema, retinal vein occlusion, and cystoid macular edema. The device can carry a drug payload of multiple therapeutic agents for a variety of medical conditions.

[0037] One mode of application is to pass a mixture of precursors and other materials (e.g., therapeutic agents, thickeners, accelerators, initiators) through a needle, cannula, catheter, or hollow wire to a site in or near the eye. The mixture can be delivered, for example, using a manually controlled syringe or a mechanically controlled syringe, for example, a syringe pump. Alternatively, a dual syringe or a multi-barrel syringe or a multi-lumen system can be used to mix the precursors at or near the site. Syringe-syringe mixing can be used if necessary.

[0038] Sites where drug delivery depots may be formed include, among others, the eye, anterior chamber, vitreous, episclera, posterior sub-Tenon space (inferior fornix), subconjunctival, sub-Tenon, retina, subretinal, intracanalicular, intracameral, intravitreal, intrascleral, choroid, suprachoroidal, retina, subretinal, or the surface of the lens, cornea or conjunctiva. Thus, embodiments include providing an effective amount or a calculated effective amount to such sites, for example, the eye, anterior chamber, vitreous, episclera, posterior sub-Tenon space (inferior fornix), subconjunctival, sub-Tenon, retina, subretinal, intracanalicular, intracameral, intravitreal, intrascleral, choroid, suprachoroidal, retina, subretinal, or the surface of the lens, cornea or conjunctiva.

[0039] Sites for formation of hydrogel depots further include tissues, lumens, cavities, potential cavities, within an animal (human or otherwise), or on the surface of an animal. The term tissue is broad. Sites include iatrogenic sites, sites where tissue has been removed, and surgical sites. Sites include at or near cancerous tissue, dental tissue, gingiva, periodontium, paranasal sinuses, brain, intravascular, aneurysmal, and diseased sites.

[0040] Thickener Viscosifiers can be useful for hydrogels formed in or on the eye with drugs, helping the solution to adhere to its placement site or maintain a cohesive mass while the hydrogel is forming. The choice of thickener must be made with consideration of the type of crosslinking that occurs. Viscosifiers can be used with precursors. Generally, thickeners do not react with precursors to form covalent bonds. It is generally recognized that precursors that do not have such bonds may occasionally be involved in unwanted side reactions, but these are "free" of such reactions in the precursors because they have little effect on the hydrogel. For example, if the precursor reacts by electrophile-nucleophile reactions, the thickener will not contain electrophilic or nucleophilic groups that can form covalent bonds with the precursor functional groups, even if there are some low levels of unwanted side reactions. The thickener is generally a hydrophilic polymer with a molecular weight of at least 20,000, 100,000, or about 100,000 to about 2,000,000 Daltons; one of skill in the art will readily recognize that all values ​​and ranges between these stated values ​​are described, such as at least about 100,000, 200,000, more than 500,000, more than 550,000, more than 600,000. For example, concentrations of about 5% to about 25% may be used. For example, PEG (e.g., MW 100,000 to 250,000) is useful. The thickener may not include electrophilic / nucleophilic groups. The thickener may not include one or more functional groups such as hydroxyl, carboxyl, amine, or thiol. The thickener may include one or more biodegradable linkages as described herein for the precursors. The viscosity increasing agent can be useful in preventing the precursor from running off the tissue site until it has crosslinked to form a gel.

[0041] Another consideration is whether the drug must pass through a small diameter syringe or catheter, a property called injectability. Thixotropic thickeners can be used, whereby the thickener offers little resistance during movement but forms a thick gel at rest. Hyaluronic acid (HA) has been found to be a useful thixotropic thickener. Molecular weights (average w / w) from 100,000 to 2,500,000 have been tested. The results indicate that higher MW (e.g., 5000k) can also be used. One of ordinary skill in the art will readily recognize that all ranges and values ​​between the boundaries specified are contemplated, for example, 100k, 200k, 300k, 400k, 500k, 600k, 700k, 800k, 900k, 1000k, 1500k, 1800k, 2000k, 2500k, 3000k, 4000k, 5000k can all be used as upper or lower limits. Other thixotropic thickeners include high molecular weight polysaccharides, or hydrophilic polymers, or PEG. Percentages from 0.3 to 2.5% w / w have been tested, with the optimum percentage depending on the MW being tested. Generally, a range of 0.2-5% polysaccharide may be added to the hydrogel / hydrogel precursor, although one of skill in the art will readily recognize that all ranges and values ​​between the stated boundaries are contemplated and any of 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 1, 2, 2.5, 3, 3.5, 4, 4.5, 5 w / w percent can be used as upper or lower limits.

[0042] Hydrogel Characteristics and Properties The hydrogel is formed, in one embodiment, from precursors that have functional groups that form crosslinks to crosslink the hydrogel, thereby forming a hydrogel. The crosslinks can be covalent and / or physical in nature. The hydrogel delivers drugs to the eye or other sites. In some embodiments, highly fluid precursors are used that gel slowly enough to pass through a very small bore cannula or needle, crosslinking substantially only after injection, but gel quickly enough so as not to migrate back through the incision track. The gel is biodegradable and breaks down in physiological fluids in or around the eye without causing irritation by breaking down into non-acidic components. In some embodiments, the gel adheres to tissue.

[0043] A hydrogel can release its therapeutic drug content or can sustain or sustain until it substantially releases its content. The hydrogel is preferably manufactured to allow the drug to diffuse out of the hydrogel. On the other hand, allowing the drug to diffuse out of the gel leaves no option for controlling the rate of drug delivery. Thus, the implementation of drug delivery from degradable materials typically requires that the material degrade so that the drug can be released. For hydrogels, the distance between crosslinks can be small enough that the drug cannot migrate through the hydrogel until it erodes. It is the bioerosion rate that controls the release. Nevertheless, abandoning approaches based on bioerosion can be useful. Thus, embodiments of the present invention can be implemented with hydrogels that allow diffusion of therapeutic drugs through the hydrogel. Matrices can be manufactured with spacing between crosslinks that allows diffusion.

[0044] The term substantially released means, unless otherwise specified, about 97% w / w i This means that the drug is released when the initial weight of the drug in the hydrogel is w iand weight, w. Other endpoints may be selected, e.g., 50-100 percent persistence; one of skill in the art will readily recognize that all ranges and values ​​between the boundaries expressly stated are contemplated, and any of 50, 60, 70, 80, 85, 90, 95, 96, 97, 98, 99, 99.5, 99.9, 99.99 percent may be used as upper or lower limits. The term range means that the numerical value can be any value within the range, unless otherwise stated. The term substantially persistence means that the numerical value can be any value within the range, unless otherwise stated. i This means that the hydrogel retains its initial weight w i and dry weight, w. Other endpoints may be selected, e.g., 50-100 percent; one of skill in the art will readily recognize that all ranges and values ​​between the boundaries specified are contemplated, and any of 50, 60, 70, 80, 85, 90, 95, 96, 97, 98, 99, 99.5, 99.9, 99.99 percent may be used as upper or lower limits. Persistence is the dry weight of the hydrogel relative to the initial dry weight of the hydrogel; this can be measured, for example, by weighing the content of the hydrogel matrix after digesting the depot and removing the tissue infiltrate immediately after washing the explanted hydrogel and accounting for the weight of the tissue infiltrate. Additionally, persistence / release ranges / values ​​can be mixed and combined. For example, when 99% of the drug is released, the hydrogel persistence is 95%. As will be apparent, all of these percentage values ​​are w / w unless otherwise stated.

[0045] It is also useful to describe the hydrogel / drug combinations in terms of duration and release at various times. For example, it may be desirable to have a particular duration when the drug release is 50%. Thus, in addition to the duration / release combinations already shown, there may be ranges of duration from 0% to 100% and ranges of release from 0% to 100%; one of skill in the art will readily recognize that all ranges and values ​​between the boundaries specified are contemplated and any of 0, 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 49.9, 50, 50.1, 55, 65, 70, 75, 80, 85, 90, 95, 100 (all of which are w / w percentages) may be used as upper or lower limits. Drug is a broad term and is used interchangeably herein with the term therapeutic agent.

[0046] Stability and mechanical integrity are two further factors involved in the control of hydrogels. In this regard, stability is the stability of shape. A hydrogel may be stable at the time of formation, but later lose mechanical integrity, change its shape, become deformed, stretch or shrink, and lose stability. One measure of stability is the change in volume (volume stability). When a hydrogel is hydrated in situ, it will have its initial volume. The volume 24 hours after placement is usually a good measure of the initial volume, since the hydrogel is in sufficient equilibrium with the local fluid, and for gels that degrade over a period of 2 weeks or more, there is essentially no degradation occurring. Thus, a hydrogel can be manufactured with 100% of its initial volume, and will eventually reach 0% volume when fully biodegraded. Another stability metric is the rate of change in the position of the initial shape. The overlap of the shapes at a given time is compared to the initial shape (shape stability). The amount of volume of the initial shape that has not moved or disappeared is calculated, with complete stability being 100% and complete end of stability being 0%. Stability can be expressed in terms of time, such as days, weeks, or months. And / or stability can be expressed in terms of drug release. When a hydrogel designed to be placed as a cohesive mass is used in vivo, forces acting on the hydrogel will typically not cause the hydrogel to deform from its initial shape as long as the hydrogel retains its initial mechanical integrity. Thus, stability can often be used instead of mechanical integrity. Substantially stable means greater than about 97% by shape or volume measure. Shape or volume stability can be set with considerations of duration or release and thus selected to be a value of, for example, 80-100 percent when release is 0-100 percent; one of skill in the art will immediately recognize that all ranges and values ​​between the stated boundaries are contemplated and any of 0, 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 49.9, 50, 50.1, 55, 65, 70, 75, 80, 85, 90, 95, 100 (all of which are shape or volume percentages or w / w release percentages) can be used as upper or lower limits.

[0047] Stability and mechanical integrity can also be used to refer to an injection solution that contains a precursor and maintains its shape and mechanical integrity within a space (whether in the vitreous or elsewhere) from injection to gelation. Examples of other spaces include puncta (canaliculi, superior / inferior canaliculi), conjunctival fornix, superior / inferior conjunctival fornix, sub-Tenon space, choroid, suprachoroid, Tenon's capsule, cornea, cancerous tissue, organ, prostate, breast, void or injury caused by surgery, void, and potential void. Some embodiments include in situ formation of punctal plugs, where precursors are introduced into the canaliculus to form punctal plugs therein. Thus, the shape and volume stability discussed above are considered for the solution.

[0048] Generally, by combining the precursors in or near the eye or other tissue as described herein, a crosslinked hydrogel containing a therapeutic agent may be produced, which is released into the eye for a suitable period of time to treat the disease. The hydrogel may be low swelling, as measured by the hydrogel having a weight increase of about 10% or about 50% or less after 24 hours of exposure to physiological fluids, compared to the weight of the hydrogel at the time of formation; one of skill in the art will readily recognize that all ranges and values ​​within the ranges set forth are contemplated. The hydrogel may also be water degradable, as measured by the hydrogel being dissolvable in vitro in excess water by decomposition of water degradable groups in the hydrogel. The composition containing the mixed precursors may then be introduced through a small gauge needle, where the composition has a suitable viscosity, which depends on the properties, concentration, and chemistry of the precursors. Furthermore, the mechanical strength and reaction time of the hydrogel may be adjusted by controlling the precursors and functional groups. The precursors and hydrogels can have a variety of characteristics that can be mixed and combined as guided by considerations to produce an effective device, some of which are described in the following sections.

[0049] precursor material Hydrogels are made from precursors. The precursors are selected with consideration of the desired properties of the resulting hydrogel. There are a variety of suitable precursors for use in making hydrogels. The term precursor refers to molecules that are crosslinked to form the hydrogel matrix. Other materials, such as therapeutic agents or fillers, may be present in the hydrogel, but they are not precursors. The term matrix can be applied to hydrogels. Some such matrices have a water content of more than about 20% w / w; one of skill in the art will readily recognize that all ranges and values ​​between the boundaries specified, with percentages w / w and the hydrogel solvent being water, are contemplated and any of 20%, 99%, 80%, 95%, at least 50%, etc. can be used as upper or lower limits. Hydrogels can be formed by crosslinking water-soluble molecules to form networks of virtually infinite molecular weight. Hydrogels with high water content are typically soft and flexible materials. The hydrogels and drug delivery systems described in U.S. Patent Application Publication Nos. 2009 / 0017097, 2011 / 0142936, and 2012 / 0071865 can be modified for use with the materials and methods herein by following the guidance provided herein, which references are incorporated by reference for all purposes, with the present specification taking precedence in the event of any conflict.

[0050] Hydrogels can be formed from natural, synthetic, or biosynthetic polymers. Natural polymers can include glycosaminoglycans, polysaccharides, and proteins. Some examples of glycosaminoglycans include dermatan sulfate, hyaluronic acid, chondroitin sulfate, chitin, heparin, keratan sulfate, keratosulfate, and derivatives thereof. Generally, glycosaminoglycans are extracted from natural sources, purified, and derivatized. However, they can also be produced synthetically or synthesized by modified microorganisms, such as bacteria. These materials can be synthetically modified from a naturally soluble state to a partially soluble or water-swellable, or hydrogel state. This modification can be achieved by a variety of well-known techniques, such as linkage or replacement of ionizable or hydrogen-bondable functional groups, such as carboxyl and / or hydroxyl or amine groups, with other, more hydrophobic groups.

[0051] For example, the carboxyl groups on hyaluronic acid are esterified with alcohols to reduce the solubility of hyaluronic acid. Such a process is used by various manufacturers of hyaluronic acid products (such as Genzyme Corp., Cambridge, MA) to form hyaluronic acid-based sheets, fibers, and fabrics that form hydrogels. Other natural polysaccharides, such as carboxymethylcellulose or oxidized regenerated cellulose, natural gum, agar, agarose, sodium alginate, carrageenan, fucoidan, furcellaran, laminaran, euterpe rhizae, gum arabic, gum ghatti, gum karaya, gum tragacanth, locust bean gum, arabinogalactan, pectin, amylopectin, gelatin, hydrocolloids such as carboxymethylcellulose gum or alginate gum crosslinked with polyols such as propylene glycol, also form hydrogels when in contact with an aqueous environment.

[0052] Hydrogels can be biostable or biodegradable. Examples of biostable hydrophilic polymeric materials are poly(hydroxyalkyl methacrylates), poly(electrolyte complexes), poly(vinyl acetates) crosslinked with hydrolytically or otherwise degradable bonds, and water-swellable N-vinyl lactams. Other hydrogels include the hydrophilic hydrogel known as Carbopol®, acidic carboxy polymers (carbomer resins are high molecular weight, allylpentaerythritol crosslinked acrylic acid-based polymers modified with C10-C30 alkyl acrylates), polyacrylamides, polyacrylic acids, starch graft copolymers, acrylate polymers, and ester crosslinked polyglucans. Such hydrogels are described, for example, in U.S. Pat. No. 3,640,741 to Etes, U.S. Pat. No. 3,865,108 to Hartop, U.S. Pat. No. 3,992,562 to Denzinger et al., U.S. Pat. No. 4,002,173 to Manning et al., U.S. Pat. No. 4,014,335 to Arnold, and U.S. Pat. No. 4,207,893 to Michaels, all of which are incorporated herein by reference, with the present specification taking precedence in the event of any conflict.

[0053] Hydrogels can be made from precursors. The precursors are crosslinked to each other. The crosslinks can be formed by covalent bonds or physical bonds. Examples of physical bonds are ionic bonds, hydrophobic association of precursor molecular segments, and crystallization of precursor molecular segments. The precursors can be induced to react to form crosslinked hydrogels. The precursors can be polymerizable and contain a crosslinker that is often, but not always, a polymerizable precursor. Thus, a polymerizable precursor is one that has functional groups that react with each other to form a matrix and / or polymer made of repeating units. The precursor can be a polymer.

[0054] Some of the precursors, for example, react by chain growth polymerization, also called addition polymerization, and include linkages of monomers incorporating double or triple chemical bonds. These unsaturated monomers have extra internal bonds that can break down and combine with other monomers to form repeating chains. A monomer is a polymerizable molecule that has at least one group that reacts with other groups to form a polymer. A macromonomer (or macromer) is a polymer or oligomer that often has at least one reactive group at its end that allows it to act as a monomer. Each macromonomer molecule is bonded to the polymer by reaction of the reactive group. Thus, macromonomers with two or more monomers or other functional groups tend to form covalent crosslinks. Addition polymerization is involved in the production of, for example, polypropylene or polyvinyl chloride. One type of addition polymerization is living polymerization.

[0055] Some of the precursors react by condensation polymerization, which occurs, for example, when monomers are bonded by a condensation reaction. Typically, these reactions can be accomplished by reacting molecules incorporating alcohol, amine, or carboxylic acid (or other carboxyl derivative) functional groups. When an amine reacts with a carboxylic acid, an amide or peptide bond is formed and water is released. Some of the condensation reactions follow nucleophilic acyl substitution, as in, for example, U.S. Pat. No. 6,958,212, which is incorporated by reference in its entirety to the extent that it does not contradict what is expressly disclosed herein. Some of the precursors react by chain growth mechanisms. Chain growth polymers are defined as polymers formed by the reaction of monomers or macromonomers that have a reactive center. A reactive center is a specific location within a chemical compound that is the initiator of a reaction involving that compound. In chain growth polymer chemistry, it is the growth point of the growing chain. Reactive centers are usually radicals that are anionic or cationic in nature, but can take other forms. Chain growth systems include free radical polymerization, which includes the processes of initiation, propagation, and termination. Initiation is the production of free radicals necessary for propagation, made from radical initiators, e.g., organic peroxide molecules. Termination occurs when radicals react in a way that prevents further propagation. The most common method of termination is by coupling, where two radical species react with each other to form a single molecule. Some of the precursors react by a step-growth mechanism, resulting in polymers formed by step-growth reactions between functional groups of monomers. Most step-growth polymers are classified as condensation polymers, although not all step-growth polymers release condensates. Monomers can be polymers or small molecules. Polymers are high molecular weight molecules formed by combining many small molecules (monomers) in a regular pattern. Oligomers are polymers with less than about 20 monomeric repeating units. Small molecules generally refer to molecules less than about 2000 daltons.Thus, the precursor can be a small molecule such as acrylic acid or vinyl caprolactam, a larger molecule containing polymerizable groups such as acrylate-capped polyethylene glycol (PEG-diacrylate), or other polymers containing ethylenically unsaturated groups, such as those of U.S. Pat. No. 4,938,763 to Dunn et al., U.S. Pat. No. 5,100,992 to Cohn et al., and U.S. Pat. No. 4,826,945 to DeLuca et al., each of which is incorporated by reference in its entirety to the extent not inconsistent with what is expressly disclosed herein.

[0056] To form a covalently crosslinked hydrogel, the precursors must be covalently crosslinked. Generally, a polymeric precursor is a polymer that connects to other polymeric precursors at two or more points, each point being a link to the same or different polymer. Precursors with at least two reactive centers (e.g., in free radical polymerization) can act as crosslinkers, since each reactive group can participate in the formation of a different growing polymer chain. In the case of functional groups that do not have reactive centers, in particular, crosslinking requires three or more such functional groups on at least one of the precursor types. For example, many electrophilic-nucleophilic reactions consume an electrophilic functional group and a nucleophilic functional group, so a third functional group is required for the precursor to form a crosslink. Thus, such precursors may have three or more functional groups and may be crosslinked by precursors with two or more functional groups. Crosslinked molecules may be crosslinked by ionic or covalent bonds, physical forces, or other attractive forces. However, covalent crosslinks typically provide stability and predictability in reactant product design.

[0057] In some embodiments, each precursor is multifunctional, meaning that it contains two or more electrophilic or nucleophilic functional groups such that a nucleophilic functional group on one precursor can react with an electrophilic functional group on another precursor to form a covalent bond. At least one of the precursors contains three or more functional groups, so that as a result of an electrophilic-nucleophilic reaction, the precursors combine to form a crosslinked polymeric product.

[0058] The precursor may have a biologically inert, hydrophilic portion, e.g., the core. In the case of a branched polymer, the core refers to the adjacent portion of the molecule that is attached to the arms extending from the core, the arms having functional groups, which are often at the ends of the branches. The hydrophilic molecule, e.g., the precursor or precursor portion, has a solubility of at least 1 g / 100 mL in aqueous solution. The hydrophilic portion may be, for example, a polyether, e.g., a polyalkylene oxide, such as polyethylene glycol (PEG), polyethylene oxide (PEO), polyethylene oxide-co-polypropylene oxide (PPO), co-polyethylene oxide block or random copolymer, and polyvinyl alcohol (PVA), poly(vinylpyrrolidinone) (PVP), poly(amino acids), dextran, or a protein. The precursor may have a polyalkylene glycol portion and may be polyethylene glycol-based, with at least about 80% or 90% by weight of the polymer comprising polyethylene oxide repeats. Polyethers and more particularly poly(oxyalkylenes) or poly(ethylene glycol) or polyethylene glycol are generally hydrophilic. As is conventional in the art, the term PEG is used to refer to PEO with or without hydroxyl end groups.

[0059] The precursor may also be a polymer (or macromer), which is a molecule having a molecular weight ranging from thousands to millions. The hydrogel may be produced with at least one of the precursors as a small molecule of about 1000 Da or less (or 2000 Da or less). When reacted in combination with a small molecule (about 1000 Da or less / 200 Da or less), the polymer is preferably at least 5-50 times larger in molecular weight than the small molecule, and preferably less than about 60,000 Da. One of ordinary skill in the art will readily recognize that all ranges and values ​​within the ranges explicitly stated are contemplated. A more preferred range is about 7 to about 30 times the molecular weight of the polymer than the crosslinker, with the most preferred range being about 10-20 times the difference in weight. Additionally, a molecular weight of the polymer of 5,000 to 50,000 is useful, as are molecular weights of 7,000 to 40,000 or molecular weights of 10,000 to 20,000. There are certain advantages to having small molecules, such as the diffusion rate for the reaction to go to completion.

[0060] Particular macromeric precursors are the crosslinkable, biodegradable, water-soluble macromers described in U.S. Patent No. 5,410,016 to Hubbell et al., which is incorporated herein by reference in its entirety to the extent not inconsistent with the disclosure herein. These macromers are characterized by having at least two polymerizable groups separated by at least one degradable region.

[0061] Synthetic precursors can be used. Synthetic refers to molecules that are not found in nature, and usually not found in humans. Some synthetic precursors do not contain amino acids and do not contain naturally occurring amino acid sequences. Some synthetic precursors are polypeptides that are not found in nature, and usually not found in the human body, such as di-, tri-, or tetra-lysine. Some synthetic molecules have amino acid residues, but only 1, 2, or 3 in a row, and the amino acids or clusters thereof are separated by non-natural polymers or groups. Therefore, polysaccharides or their derivatives are not synthetic.

[0062] Alternatively, natural proteins or polysaccharides, such as collagen, fibrin (fibrinogen), albumin, alginate, hyaluronic acid, and heparin, can be modified for use with these methods. These natural molecules can further include chemical derivatization, such as synthetic polymer decoration. Natural molecules can be crosslinked by their natural nucleophiles, or even after they have been derivatized with functional groups, as in, for example, U.S. Pat. Nos. 5,304,595, 5,324,775, 6,371,975, and 7,129,210, each of which is incorporated herein by reference to the extent not inconsistent with what is expressly disclosed herein. Natural refers to molecules found in nature. Natural polymers, such as proteins or glycosaminoglycans, such as collagen, fibrinogen, albumin, and fibrin, can be crosslinked using reactive precursor species that have electrophilic functional groups. Natural polymers found in the body are usually proteolytically degraded by proteases present in the body. Such polymers can be reacted through functional groups such as amines, thiols, or carboxyls present on their amino acids or can be derivatized to have activatable functional groups. Natural polymers can be used in hydrogels, but their gelation time and final mechanical properties must be controlled by appropriate introduction of additional functional groups and selection of suitable reaction conditions, such as pH.

[0063] Precursors can be produced with hydrophobic moieties if the resulting hydrogel retains the required amount of water, e.g., at least about 20%. In some cases, the precursors are still water soluble because they also have hydrophilic moieties. In other cases, the precursors are dispersed in water (suspensions) but are still able to react and form crosslinked materials. Some hydrophobic moieties can contain multiple alkyl, polypropylene, alkyl chains, or other groups. Some precursors with hydrophobic moieties are sold under the trade names PLURONIC F68, JEFFAMINE, or TECTRONIC. The hydrophobic moiety, such as a hydrophobic molecule or copolymer, is one that is sufficiently hydrophobic to aggregate its molecules (e.g., polymers or copolymers) to form micelles or microphases in which the hydrophobic domains are in the aqueous continuous phase, or one that is sufficiently hydrophobic to precipitate or otherwise change phase in an aqueous solution of water at a pH of about 7 to about 7.5 and a temperature of about 30 to about 50 degrees Celsius when tested alone.

[0064] Some embodiments of the invention include selecting a poorly soluble drug or other soluble drug as described herein and selecting a precursor that includes hydrophobic and hydrophilic moieties. The hydrophobic / hydrophilic precursor may include one or more functional groups: nucleophilic or electrophilic groups. The hydrophilic moiety, the hydrophobic moiety, or both may be selected to receive such functional groups.

[0065] Keeping in mind that some of the precursors may be dendrimers or other highly branched materials, the precursors may have, for example, 2-100 arms, each arm having an end. An arm on a hydrogel precursor refers to a linear chemical group that connects a crosslinkable functional group to a polymer core. Some embodiments are precursors with 3-300 arms. One of skill in the art will readily recognize that all ranges and values ​​within the stated ranges are contemplated, for example, 4-16, 8-100, or at least 6 arms.

[0066] Thus, for example, a hydrogel can be made from, for example, a multi-arm precursor having a first set of functional groups and a low molecular weight precursor having a second set of functional groups. For example, a 6-arm or 8-arm precursor can have hydrophilic arms, e.g., polyethylene glycol terminated in a primary amine, with the arms having a molecular weight of about 1,000 to about 40,000. One of skill in the art will immediately recognize that all ranges and values ​​within the explicitly stated ranges are contemplated. Such precursors can be mixed with smaller precursors, e.g., molecules having at least about three functional groups, or about 3 to about 16 functional groups, and having a molecular weight of about 100 to about 5000, or about 800, 1000, 2000, or 5000 or less. One of skill in the art will immediately recognize that all ranges and values ​​between these explicitly stated values ​​are contemplated. Such small molecules can be polymeric or non-polymeric, natural or synthetic.

[0067] Non-dendrimer precursors can be used. Dendritic molecules are highly branched radially symmetric polymers in which atoms are arranged in many arms and subarms radiating from a central core. Dendrimers are characterized by their degree of structural perfection based on an assessment of both symmetry and polydispersity, and require special chemical processes for synthesis. Thus, those skilled in the art can easily distinguish dendrimer precursors from non-dendrimer precursors. Dendrimers typically have shapes that depend on the solubility of their component polymers in a given environment and can be significantly altered by changes in the surrounding solvent or solute, such as temperature, pH, or ionic content.

[0068] The precursor may be a dendrimer, for example, as described in US Patent Application Publication No. 2004 / 0086479 and US Patent Application Publication No. 2004 / 0131582, and PCT Publication No. WO 2007005249, WO 2007001926, and WO 2006031358, or their US counterparts. Dendrimers are useful as multifunctional precursors, for example, as described in US Patent Application Publication No. 2004 / 0131582 and US Patent Application Publication No. 2004 / 0086479, and PCT Publication No. WO 06031388, each of which is incorporated herein by reference in its entirety to the extent that it does not contradict anything expressly disclosed herein. Dendrimers are highly ordered, have a high surface area to volume ratio, and exhibit many terminal groups for possible functionalization. Embodiments include multifunctional precursors that are not dendrimers.

[0069] Some embodiments include precursors consisting essentially of oligopeptide sequences of five or fewer residues, e.g., amino acids containing at least one amine, thiol, carboxyl, or hydroxyl side chain. The residues are natural or derivatized amino acids. The backbones of such oligopeptides can be natural or synthetic. In some embodiments, peptides of two or more amino acids are combined with a synthetic backbone to create the precursor. Particular embodiments of such precursors have molecular weights ranging from about 100 to about 10,000 or from about 300 to about 500. One of skill in the art will immediately recognize that all ranges and values ​​between these explicitly stated ranges are contemplated.

[0070] Precursors can be prepared to be free of amino acid sequences cleavable by enzymes present at the site of introduction, including free of sequences susceptible to attachment by metalloproteinases and / or collagenases. Additionally, precursors can be made to be free of all amino acids or free of amino acid sequences of more than about 50, 30, 20, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid. Precursors can be non-proteinaceous, meaning that they are not naturally occurring proteins and cannot be made by cleaving naturally occurring proteins and cannot be made by adding synthetic materials to proteins. Precursors can be non-collagenous, non-fibrinous, non-fibrinogen, and non-albumin, meaning that they are not one of these proteins or chemical derivatives of one of these proteins. The use of non-proteinaceous precursors and limited use of amino acid sequences can be useful to avoid immune reactions, to avoid unwanted cellular recognition, and to avoid the risks associated with the use of proteins derived from natural sources. Precursors can be non-saccharide (containing no saccharides) or substantially non-saccharide (containing no more than about 5% saccharides w / w of the precursor molecular weight. Thus, precursors can exclude, for example, hyaluronic acid, heparin, or gellan. Precursors can also be both non-protein and non-saccharide.

[0071] Peptides can be used as precursors. Generally, peptides of less than about 10 residues are preferred, although larger sequences (e.g., proteins) can be used. One of skill in the art will immediately recognize that all ranges and values ​​within these explicit ranges are included, e.g., 1-10, 2-9, 3-10, 1, 2, 3, 4, 5, 6, or 7. Some of the amino acids have nucleophilic groups (e.g., primary amines or thiols) or groups that can be derivatized to incorporate nucleophilic or electrophilic groups (e.g., carboxyl or hydroxyl) as appropriate. Synthetically produced polyamino acid polymers are generally considered to be synthetic if they are not naturally occurring and have been engineered to be non-identical to natural biomolecules.

[0072] Some hydrogels are made from polyethylene glycol-containing precursors. Polyethylene glycol (PEG, also called polyethylene oxide when present at higher molecular weights) is a polymer made up of the repeating group (CH2CH2O). n where n is at least 3. Thus, a polymeric precursor having polyethylene glycol has at least three of these repeating groups bonded to each other in linear succession. The polyethylene glycol content of a polymer or arm is calculated by summing all of the polyethylene glycol groups on the polymer or arm, even if there are other groups between the polyethylene glycol groups. Thus, an arm having at least 1000 MW of polyethylene glycol has enough CH2CHO groups for a total of at least 1000 MW. As is common terminology in the art, a polyethylene glycol polymer does not necessarily refer to a molecule terminated with a hydroxyl group. Molecular weights are abbreviated to units of 1000 using the symbol k, e.g., 15K means 15,000 molecular weight, i.e., 15,000 Daltons. Molecular weights expressed herein are number average molecular weights unless otherwise stated. NH2 refers to amine terminus. SG refers to succinimidyl glutarate. SS refers to succinimidyl succinate. SAP refers to succinimidyl adipate. SAZ refers to succinimidyl azelaate. SS, SG, SAP and SAZ are succinimidyl esters with ester groups that degrade by hydrolysis in water. Thus, hydrolyzable or water degradable refers to a material that degrades spontaneously in vitro in the presence of excess water, even in the absence of any enzymes or cells that mediate degradation. The time of degradation refers to the virtual disappearance of the material as judged by the naked eye. Trilysine (also abbreviated as LLL) is a synthetic tripeptide. PEG and / or hydrogels, as well as compositions containing same, can be provided in a pharmaceutically acceptable form, which means that they are highly purified and free of contaminants, such as pyrogens.

[0073] Hydrogel Structure The structure of the hydrogel and the material composition of the precursors of the hydrogel determine its properties. Precursor factors include properties such as biocompatibility, water solubility, hydrophilicity, molecular weight, arm length, number of arms, functional groups, intercrosslink distance, degradability, etc. The choice of reaction conditions, including the choice of solvent, reaction scheme, reactant concentration, solids content, etc., also affect the structure and properties of the hydrogel. There may be various ways to achieve a particular property or combination of properties. On the other hand, some of the properties may be in opposition to each other, for example, brittleness may increase with increasing intercrosslink distance or solids content. Strength may increase with increasing number of crosslinks, but swelling may decrease thereby. Those skilled in the art will recognize that the same materials may be used to produce matrices with a wide range of structures with very different mechanical properties and performance, so that the achievement of a particular property should not be assumed simply based on the general type of precursor involved.

[0074] The space between the molecular strands of the hydrogel (matrix) affects several hydrogel properties, including the rate of diffusion of molecules. Crosslink density can be controlled by selection of the overall molecular weight of the precursor and other precursors used as crosslinkers, as well as the number of functional groups available per precursor molecule. A lower intercrosslink molecular weight, such as 200, will provide a much higher crosslink density than a higher intercrosslink molecular weight, such as 500,000. Those skilled in the art will readily recognize that all ranges and values ​​within this range, such as 200-250,000, 500-400,000, 5,000, 10,000, 20,000, 30,000, 40,000, 50,000, 60,000, 70,000, 80,000, 90,000, 100,000, etc., are contemplated and supported. Crosslink density can also be controlled by the overall percent solids of the solution of the crosslinker and functional polymer. Yet another way to control crosslink density is by adjusting the stoichiometry of nucleophilic functional groups to electrophilic functional groups. A 1:1 ratio results in the highest crosslink density. Precursors with longer distances between crosslinkable sites generally form softer, more pliable, and more elastic gels. Thus, increasing the length of the water-soluble segment, such as polyethylene glycol, tends to increase elasticity and provide desirable physical properties. Thus, certain embodiments are directed to precursors having water-soluble segments with molecular weights ranging from 2,000 to 100,000. One of skill in the art will immediately recognize that all ranges and values ​​within the express ranges are contemplated, e.g., 5,000 to 35,000. The solids content of a hydrogel can affect its mechanical properties and biocompatibility and reflects a balance between competing requirements. Relatively low solids content, e.g., about 2.5% to about 20%, including all ranges and values ​​therebetween, e.g., about 2.5% to about 10%, about 5% to about 15%, or less than about 15%, are useful.

[0075] One way to configure materials so that retardation is controlled or minimized is to design hydrogels with different rates of diffusion of drugs. In many cases, the molecular weight (MW) of the drug is the governing variable. There are several approaches to relating hydrogel properties to diffusion. These include free volume theory, hydrodynamic theory, obstacle theory, combinatorial theory, and parameters such as mesh size, sieving terms, and distribution of inter-chain spaces (Amsden, Macromolecules (1998) 31:8382-8395). In practice, however, hydrogels can be made with various distances between their crosslinks and tested for a particular molecule to create a hydrogel that provides the desired diffusion rate. In general, a crosslink distance larger than the size of the molecule provides a high diffusion rate, a crosslink distance smaller than the size of the molecule provides slow diffusion, and a crosslink distance smaller than the molecule provides virtually no diffusion. The molecular weight of a molecule is generally a useful measure of its size. There are other factors that can be important and can be accounted for when making hydrogels: for example, interactions between the molecules and the hydrogel, such as affinity or charge-to-charge, and solvent effects, such as the hydrophobicity of the molecules.

[0076] The reaction rate is generally controlled by considering the specific functional groups, unless an external initiator or chain transfer agent is required, in which case manipulation of the initiator trigger or transfer agent can be a controlling step. In some embodiments, the molecular weight of the precursor is used to affect the reaction time. Since low molecular weight precursors tend to accelerate the reaction, some embodiments have at least one precursor with a molecular weight of at least 5,000 to 50,000 or 150,000 Daltons. The crosslinking reaction leading to gelation preferably occurs within about 0.1 to about 10 minutes or about 30 minutes; one of skill in the art will immediately recognize that all ranges and values ​​within the ranges specified are contemplated, such as at least 120 seconds, or 5 to 600 seconds, such as 5, 10, 30, 60, 100, 200, 300 seconds. Gel time is measured by applying the precursor to a flat surface, tilting the surface at an angle of about 60 degrees (i.e., a steep slope approaching a right angle), and determining the time at which there is substantially no downward flow on the surface.

[0077] Hydrogels generally have low swelling, as measured by the hydrogel having a weight increase of about 0 to about 10%, or about 50% or less after 24 hours of exposure to physiological fluids, compared to the weight of the hydrogel at the time of formation. In one embodiment to reduce swelling, the number of crosslinks is increased, although it should be noted that crosslinks may increase stiffness or brittleness. In another embodiment, the average chain distance between crosslinks is decreased. In another embodiment, precursors having multiple arms are used, as described below.

[0078] Another embodiment to reduce swelling involves adjusting the degree of hydrophilicity using less hydrophilic materials that are less likely to swell; for example, a highly hydrophilic material such as PEO can be combined with a less hydrophilic material such as PPO, or with a hydrophobic group such as an alkyl.

[0079] Another embodiment to reduce swelling is to select precursors that have a high degree of solvation upon crosslinking, but later become low and have a substantially reduced extent of solvation. In other words, the precursors expand in solution upon crosslinking, but then shrink. Changes to pH, temperature, solids concentration, and solvent environment can cause such changes; furthermore, increasing the number of branches (other factors held substantially constant) also tends to have this effect. It is believed that the number of arms expand before crosslinking due to steric hindrance with each other, but these steric effects are counterbalanced by other factors after polymerization. In some embodiments, the precursors have multiple similar charges, e.g., multiple functional groups with negative charges, multiple arms with positive charges, or each arm has a functional group of similar charge before crosslinking or other reaction, to achieve these effects.

[0080] The hydrogels described herein may include hydrogels that swell minimally after placement. Such low swelling medical hydrogels may have weights that increase by, for example, about 50% by weight, about 10% by weight, about 5% by weight, about 0% by weight or less, or shrink (reduce in weight and volume) by, for example, at least about 5%, at least about 10%, or more, when equilibrium water content is reached upon exposure to physiological fluid. Those skilled in the art will readily recognize that all ranges and values ​​within the ranges expressly set forth or otherwise related to such ranges are disclosed herein. Unless otherwise stated, the swelling of a hydrogel refers to the change in volume (or weight) from the time of its formation, when crosslinking is substantially complete, to the time after it is placed in an unconstrained condition in a physiological fluid in vitro for 24 hours, at which time it may be reasonably assumed that it has reached its equilibrium swelling state. For most embodiments, crosslinking is substantially complete within only about 15 minutes, so the initial weight can generally be recorded about 15 minutes after formation as the initial formed weight. Thus, the following formula is used: % swelling = [(weight at 24 hours - weight at initial formation) / weight at initial formation] * 100. For hydrogels that have substantial degradation over 24 hours, the maximum weight, e.g., as measured by performing continuous measurements, may be used instead of the 24 hour weight. The weight of the hydrogel includes the weight of the solution in the hydrogel. A hydrogel formed in a constrained location does not necessarily have to be a low swelling hydrogel. For example, a swelling hydrogel formed in vivo may be constrained in swelling by its surroundings, but may still be a highly swelling hydrogel, as revealed by measuring its swelling in the absence of constraint and / or the force against the constraint.

[0081] functional group The covalent crosslink precursors have functional groups that react with each other to form covalently bonded materials either outside the patient or in situ. The functional groups are generally polymerizable, a broad classification that includes free radical, addition, and condensation polymerization, as well as electrophilic and nucleophilic reactive groups. Various aspects of the polymerization reaction are discussed in the precursor section herein.

[0082] Thus, in some embodiments, the precursor has a polymerizable group or electrophilic functional group that is activated by photoinitiation or redox systems used in the polymerization art, such as carbodiimidazole, sulfonyl chloride, chlorocarbonate, N-hydroxysuccinimidyl ester, succinimidyl ester, or sulfasuccinimidyl ester, as in U.S. Pat. No. 5,410,016 or U.S. Pat. No. 6,149,931, each of which is incorporated herein by reference in its entirety to the extent that it does not contradict what is expressly disclosed herein. The nucleophilic functional group can be, for example, amine, hydroxyl, carboxyl, and thiol. Another class of electrophiles is acyl, as in, for example, U.S. Pat. No. 6,958,212, which describes, among other things, the Michael addition scheme of reacting polymers.

[0083] Certain functional groups, such as alcohols or carboxylic acids, do not normally react with other functional groups, such as amines, under physiological conditions (e.g., pH 7.2-11.0, 37°C). However, such functional groups can be made more reactive by using activating groups, such as N-hydroxysuccinimide. Specific activating groups include carbonyldiimidazole, sulfonyl chloride, aryl halides, sulfosuccinimidyl esters, N-hydroxysuccinimidyl esters, succinimidyl esters, epoxides, aldehydes, maleimides, imide esters, and the like. N-hydroxysuccinimide esters or N-hydroxysulfosuccinimide (NHS) groups are useful groups for crosslinking proteins or amine-containing polymers, such as amino-terminated polyethylene glycol. The advantage of the NHS-amine reaction is that the reaction rate is favorable, but the gelation rate can be adjusted by pH or concentration. The NHS-amine crosslinking reaction results in the formation of N-hydroxysuccinimide as a by-product. The sulfonated or ethoxylated forms of N-hydroxysuccinimide have relatively high water solubility and therefore rapid clearance from the body. The NHS-amine crosslinking reaction can be carried out in aqueous solutions and in the presence of buffers, such as phosphate buffer (pH 5.0-7.5), triethanolamine buffer (pH 7.5-9.0), or borate buffer (pH 9.0-12), or sodium bicarbonate buffer (pH 9.0-10.0). Aqueous solutions of the NHS-based crosslinker and functional polymer are preferably made just prior to the crosslinking reaction due to the reaction of the NHS groups with water. The reaction rate of these groups can be slowed by keeping these solutions at a lower pH (pH 4-7). A buffer solution may also be included in the hydrogel to be introduced into the body.

[0084] In some embodiments, as long as both nucleophilic and electrophilic precursors are used in the crosslinking reaction, each precursor contains only nucleophilic or only electrophilic functional groups. Thus, for example, when the crosslinker has a nucleophilic functional group such as an amine, the functional polymer can have an electrophilic functional group such as N-hydroxysuccinimide. On the other hand, when the crosslinker has an electrophilic functional group such as sulfosuccinimide, the functional polymer can have a nucleophilic functional group such as an amine or a thiol. For example, functional polymers such as proteins, poly(allylamine), or amine-terminated difunctional or multifunctional poly(ethylene glycol) can be used.

[0085] One embodiment has reactive precursor species having 2 to 16 nucleophilic functional groups each and reactive precursor species having 2 to 16 electrophilic functional groups each. One of skill in the art will immediately recognize that all ranges and values ​​within the stated ranges are contemplated, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16 groups.

[0086] The functional group can be, for example, an electrophile capable of reacting with a nucleophile, a group capable of reacting with a specific nucleophile, such as a primary amine, a group that forms an amide bond with a material in a biological fluid, a group that forms an amide bond with a carboxyl, an activated acid functional group, or a combination thereof. The functional group can be, for example, a strong electrophilic functional group, which means an electrophilic functional group that effectively forms a covalent bond with a primary amine in aqueous solution at room temperature and pressure at pH 9.0 and / or an electrophilic group that reacts by a Michaels type reaction. The strong electrophile can be of the type that does not participate in a Michaels type reaction or of the type that participates in a Michaels type reaction.

[0087] The Michael type reaction refers to the 1,4 addition reaction of nucleophiles to conjugated unsaturated systems. The addition mechanism can be purely polar or can proceed via a radical-like intermediate state. Lewis acids or appropriately designed hydrogen bonding species can act as catalysts. The term conjugation can refer to both alternating carbon-carbon, carbon-heteroatom, or heteroatom-heteroatom multiple and single bonds, and the linking of functional groups to macromolecules such as synthetic polymers or proteins. The Michael type reaction is discussed in detail in U.S. Pat. No. 6,958,212, which is incorporated herein by reference in its entirety for all purposes to the extent not inconsistent with what is expressly disclosed herein.

[0088] Examples of strong electrophiles that do not participate in Michaels-type reactions are succinimides, succinimidyl esters, or NHS-esters. Examples of Michael-type electrophiles are acrylates, methacrylates, methyl methacrylates, and other unsaturated polymerizable groups.

[0089] Starting system Some of the precursors are reacted with an initiator. An initiator group is a chemical group capable of initiating a free radical polymerization reaction. For example, it can be present as a separate component or as a pendant group on the precursor. Initiator groups include thermal initiators, photoactivatable initiators, and oxidation-reduction (redox) systems. Long wave UV and visible light photoactivatable initiators include, for example, ethyl eosin, 2,2-dimethoxy-2-phenylacetophenone, other acetophenone derivatives, thioxanthone, benzophenone, and camphorquinone groups. Examples of thermally reactive initiators include analogs of 4,4' azobis(4-cyanopentanoic acid) and benzoyl peroxide groups. Several commercially available low temperature free radical initiators, such as V-044 available from Wako Chemicals USA, Inc., Richmond, Va., can be used to initiate free radical crosslinking reactions at body temperature to form hydrogel coatings with the monomers mentioned above.

[0090] Metal ions can be used as oxidants or reductants in redox initiation systems. For example, ferrous iron can be used in combination with peroxides or hydroperoxides to initiate polymerization or can be used as part of a polymerization system. In this case, the ferrous iron will act as a reductant. Alternatively, the metal ion can act as an oxidant. For example, cerium ions (cerium's 4+ valence state) interact with various organic groups, including carboxylic acids and urethanes, removing electrons to the metal ion and leaving an initiating radical on the organic group. In such systems, the metal ion acts as an oxidant. Potentially suitable metal ions for either role are any of the transition metal ions, lanthanides, and actinides, which have at least two readily accessible oxidation states. Particularly useful metal ions have at least two states separated by only one charge difference. Of these, the most commonly used are ferric iron / ferrous iron, copper / copper, cerium / cerium, cobalt / cobalt, vanadate V vs. IV, permanganate, and manganese / manganese.Peroxygen-containing compounds such as peroxides and hydroperoxides, including hydrogen peroxide, t-butyl hydroperoxide, t-butyl peroxide, benzoyl peroxide, and cumyl peroxide, can be used.

[0091] An example of an initiator system is a combination of a peroxygen compound in one solution and a reactive ion such as a transition metal in another solution. In this case, no external initiator of the polymerization is required and the polymerization proceeds spontaneously upon interaction of two complementary reactive functional group-containing moieties at the utilization site, without the application of external energy or the use of an external energy source.

[0092] The precursors for producing the hydrogel and / or the hydrogel produced from the precursors may not contain one or more of an initiator, a photoactivatable group, and a visualization agent, an imaging agent.

[0093] Visualization Agent A visualization agent may be present in the hydrogel, which reflects or emits light at wavelengths detectable by the human eye so that a user applying the hydrogel can view the object when it contains an effective amount of the agent. Chemicals that require mechanical assistance for imaging are referred to herein as imaging agents, examples include radiopaque contrast agents and ultrasound contrast agents. Some biocompatible visualization agents include FD&C Blue No. 1, FD&C Blue No. 2, and methylene blue. These agents, if used, are preferably present in the final electrophilic-nucleophilic reactive precursor species mix at a concentration greater than 0.05 mg / ml, preferably in a concentration range of at least 0.1 to about 12 mg / ml, more preferably in the range of 0.1 to 4.0 mg / ml, although higher concentrations up to the solubility limit of the visualization agent could potentially be utilized. The visualization agent may be covalently bound to the molecular network of the xerogel / hydrogel, and therefore remain visible until the hydrogel hydrolyzes and dissolves after use in a patient. The visualization agent can be selected from any of a variety of non-toxic coloring substances suitable for use in medical implantable devices, such as FD&C Blue dyes 3 and 6, eosin, methylene blue, indocyanine green, or colored dyes commonly found in synthetic sutures. A reactive contrast agent, such as NHS-fluorescein, can be incorporated into the molecular network of the xerogel / hydrogel. Fluorescein is typically the imaging agent unless otherwise noted, provided that it is in a concentration sufficient to be visualized without machine assistance. The visualization agent may be present with any reactive precursor species, such as a crosslinker or functional polymer solution. The preferred coloring substances may or may not be chemically bound to the hydrogel.

[0094] biodegradation The hydrogels can be formulated such that upon hydration in physiological solutions, the hydrogel loses its mechanical strength and eventually dissipates in vitro by hydrolysis of the hydrolytic groups in excess water, forming a measurably hydrolytic hydrogel. This test predicts hydrolytically driven dissolution in vivo, a process that contrasts with cell or protease driven degradation. Importantly, however, polyanhydrides or other conventionally used degradable materials that degrade to acidic moieties tend to cause irritation to tissues. However, the hydrogels can be free of polyanhydrides, anhydride linkages, and / or precursors that degrade to acids or diacids, and / or PLA, PLGA, PLA / PLGA, since such materials can be excluded.

[0095] For example, electrophilic groups such as SG (N-hydroxysuccinimidyl glutarate), SS (N-hydroxysuccinimidyl succinate), SC (N-hydroxysuccinimidyl carbonate), SAP (N-hydroxysuccinimidyl adipate) or SAZ (N-hydroxysuccinimidyl azelate) can be used, which have hydrolytically unstable ester bonds. More linear hydrophobic bonds such as pimelate, suberate, azelate, or sebacate bonds can also be used, which are less degradable than succinate, glutarate, or adipate bonds. Branched, cyclic, or other hydrophobic bonds can also be used. Polyethylene glycol and other precursors can be prepared with these groups. Crosslinked hydrogel degradation can proceed by water-driven hydrolysis of the biodegradable segments when water-degradable materials are used. Polymers containing ester bonds may be included to provide a desired degradation rate, with groups being added or subtracted near the ester to increase or decrease the degradation rate. In this way, degradable segments can be used to construct hydrogels with desired degradation profiles of days to months. When polyglycolate is used as the biodegradable segment, for example, crosslinked polymers can be made to degrade in about 1 to about 30 days, depending on the crosslinking density of the network. Similarly, polycaprolactone-based crosslinked networks can be made to degrade in about 1 to about 8 months. The degradation time generally varies depending on the type of degradable segment used, in the following order: polyglycolate<polylactate<polytrimethylenecarbonate<polycaprolactone. In this way, degradable segments can be used to construct hydrogels with desired degradation profiles of days to months. Some embodiments include precursors that do not contain adjacent ester groups and / or have only one ester group per arm in one or more of the precursors. Control of the number and location of esters can aid in the uniform degradation of the hydrogel.

[0096] The biodegradable bonds in the organogel and / or xerogel and / or hydrogel and / or precursors may be hydrolytic or enzymatically degradable. Exemplary hydrolytic biodegradable bonds include glycolide, dl-lactide, l-lactide, dioxanone, esters, carbonates, and trimethylene carbonate polymers, copolymers, and oligomers. Exemplary enzymatically biodegradable bonds include peptide bonds cleavable by metalloproteinases and collagenases. Examples of biodegradable bonds include polymers and copolymers of poly(hydroxy acids), poly(orthocarbonates), poly(anhydrides), poly(lactones), poly(amino acids), poly(carbonates), and poly(phosphonates).

[0097] If it is desired that the biocompatible crosslinked matrix be biodegradable or resorbable, one or more precursors can be used in which there is a biodegradable bond (or only one biodegradable bond, e.g., an ester) between the functional groups. The biodegradable bond can optionally also act as the water-soluble core of the precursor or precursors used to prepare the matrix. In each approach, the biodegradable bond can be selected so that the resulting biodegradable biocompatible crosslinked polymer is degraded or resorbed in a desired period of time.

[0098] The eye is a very sensitive organ. The inventors have found that fragmentation of biodegradable implants in the eye is a particular factor that conflicts with biocompatibility. Besides that sensitivity, the interior of the eye is a small space, so if long-term release is the goal, the drug must be present in high concentrations. Without being bound to a single theory, it is believed that in this environment, the presence of the drug exacerbates the biological response to the material, especially when the implant reaches a stage of fragmentation. Macrophages may begin to recognize the drug as foreign when the fragments reach the size of cells or the size of bacteria. Biologics tend to cause such reactions, but even small molecule agents are believed to have an unwanted augmentation effect. Thus, rather than minimizing the persistence of the implant, some embodiments include hydrogels with long persistence times that enhance biocompatibility. The persistence times can be extended until the drug in the hydrogel is completely released. This approach enhances biocompatibility.

[0099] Drugs or other therapeutic agents for delivery Therapeutic agents include, for example, agents for treating conditions that may result from inflammatory or abnormal vascular conditions, retinal vein occlusion, geographic atrophy, retinitis pigmentosa, retinoblastoma, etc. In the case of cancer, the agent may be, for example, an anti-cancer agent, an anti-VEGF, or a drug known to be used in cancer treatment.

[0100] Examples of therapeutic agents include anti-VEGF agents, VEGFR1 blockers, VEGFR2 blockers, VEGFR3 blockers, anti-PDGF agents, anti-angiogenic agents, sunitinib, E7080, Takeda-6d, tivozanib, regorafenib, sorafenib, pazopanib, axitinib, nintedanib, cediranib, vatalanib, motesanib, macrolides, sirolimus, everolimus, tyrosine kinase inhibitors (T KI), imatinib (Gleevec), gefitinib (Iressa), toceranib (Palladia), erlotinib (Tarceva), lapatinib (Tykerb), nilotinib, bosutinib, neratinib, lapatinib, vatalanib, dasatinib, erlotinib, gefitinib, imatinib, lapatinib, lestaurtinib, nilotinib, semaxanib, toceranib, vandetanib.

[0101] The therapeutic agent may include a macromolecule, such as an antibody or an antibody fragment. Therapeutic macromolecules may include VEGF inhibitors, such as ranibizumab, the active ingredient in the commercially available Lucentis™. VEGF (vascular endothelial growth factor) inhibitors, when released into the vitreous humor of the eye, can cause the regression of abnormal blood vessels and improvement of vision. Examples of VEGF inhibitors include Lucentis™ (ranibizumab), Eylea™ (aflibercept or VEGF trap), Avastin™ (bevacizumab), and Macugen™ (pegaptanib). Platelet-derived growth factor (PDGF) inhibitors, such as Fovista™, anti-PGDF aptamers, can also be delivered.

[0102] The therapeutic agent may also include small molecules such as steroids or corticosteroids and their analogs. For example, the therapeutic corticosteroid may include one or more of triamcinolone, triamcinolone acetonide, dexamethasone, dexamethasone acetate, fluocinolone, fluocinolone acetate, loteprednol etabonate, or analogs thereof. Alternatively or in combination, the therapeutic agent small molecule may include a tyrosine kinase inhibitor.

[0103] The therapeutic agent may include an anti-VEGF therapeutic agent. Anti-VEGF agent therapies and agents can be used in the treatment of certain cancers and in age-related macular degeneration. Examples of anti-VEGF therapeutic agents suitable for use with the embodiments described herein include monoclonal antibodies such as bevacizumab (Avastin™) or antibody derivatives such as ranibizumab (Lucentis™), or one or more small molecules that inhibit VEGF-stimulated tyrosine kinases, such as lapatinib (Tykerb™), sunitinib (Sutent™), sorafenib (Nexavar™), axitinib, or pazopanib.

[0104] The therapeutic agent may include a therapeutic agent suitable for treating dry AMD, such as one or more of Sirolimus™ (rapamycin), Copaxone™ (glatiramer acetate), Othera™, complement C5aR blockers, ciliary neurotrophic factor, fenretinide, or Rheopheresis.

[0105] The therapeutic agent may include a therapeutic agent suitable for treating wet AMD, such as one or more of REDD14NP (Quark), Sirolimus™ (rapamycin), ATG003; Regeneron™ (VEGF trap) or a complement inhibitor (POT-4).

[0106] The therapeutic agent may include a kinase inhibitor such as one or more of BIBW 2992 (a small molecule targeting EGFR / Erb2), imatinib (small molecule), trastuzumab (monoclonal antibody), gefitinib (small molecule), ranibizumab (monoclonal antibody), pegaptanib (small molecule), sorafenib (small molecule), dasatinib (small molecule), sunitinib (small molecule), erlotinib (small molecule), nilotinib (small molecule), lapatinib (small molecule), panitumumab (monoclonal antibody), vandetanib (small molecule), or E7080 (a small molecule commercially available from Esai, Co.).

[0107] The therapeutic agent may include drugs from a variety of classes, including, for example, steroids, nonsteroidal anti-inflammatory drugs (NSAIDS), anti-cancer drugs, antibiotics, anti-inflammatory drugs (e.g., diclofenac), painkillers (e.g., bupivacaine), calcium channel blockers (e.g., nifedipine), antibiotics (e.g., ciprofloxacin), cell cycle inhibitors (e.g., simvastatin), and proteins (e.g., insulin). The therapeutic agent may include drugs from multiple classes, including, for example, steroids, NSAIDS, antibiotics, painkillers, inhibitors of vascular endothelial growth factor (VEGF), chemotherapeutic agents, and antiviral agents. Examples of NSAIDS are ibuprofen, meclofenamate sodium, mefenamic acid, salsalate, sulindac, tolmetin sodium, ketoprofen, diflunisal, piroxicam, naproxen, etodolac, flurbiprofen, fenoprofen calcium, indomethacin, celoxib, ketorolac, and nepafenac. Examples of steroids are flunisolide (solubility 90 μg / mL), betamethasone sodium phosphate (freely water soluble), budesonide (30 μg / mL), and triamcinolone acetonide (20 μg / mL). The drugs themselves can be small molecules, proteins, RNA fragments, proteins, glycosaminoglycans, carbohydrates, nucleic acids, inorganic and organic biologically active compounds; specific biologically active agents include, but are not limited to, enzymes, antibiotics, anti-neoplastic agents, local anesthetics, hormones, angiogenic agents, anti-angiogenic agents, growth factors, antibodies, neurotransmitters, psychotropic drugs, anti-cancer drugs, chemotherapeutic drugs, drugs affecting the reproductive organs, genes, and oligonucleotides, or other constructs.

[0108] The therapeutic agent may include proteins or other water-soluble biologics. These include peptides and proteins. The term protein herein refers to peptides of at least about 5000 daltons. The term peptide herein refers to peptides of any size. The term oligopeptide refers to peptides having a mass up to about 5000 daltons. Peptides include therapeutic proteins and peptides, antibodies, antibody fragments, short chain variable fragments (scFv), growth factors, angiogenic factors, and insulin. Other water-soluble biologics are carbohydrates, polysaccharides, nucleic acids, antisense nucleic acids, RNA, DNA, small interfering RNA (siRNA), and aptamers.

[0109] The therapeutic agent can be used as part of a method for treating the indicated condition or a method for manufacturing a composition for treating the indicated condition. For example, AZOPT (Brinzolamide Ophthalmic Suspension) can be used to treat elevated intraocular pressure in patients with ocular hypertension or open-angle glaucoma. Betadine in povidone-iodine ophthalmic solution can be used for prepping the periocular area and irrigating the ocular surface. Betoptic (Betaxolol HCl) can be used to reduce intraocular pressure or for chronic open-angle glaucoma and / or ocular hypertension. Siloxane (Ciprofloxacin HCl Ophthalmic Solution) can be used to treat infections caused by susceptible strains of microorganisms. Natacin (Natamycin Ophthalmic Suspension) can be used to treat fungal blepharitis, conjunctivitis, and keratitis. Nebanac (Nepanfenac Ophthalmic Suspension) can be used to treat pain and inflammation associated with cataract surgery. Travatan (Travoprost ophthalmic solution) can be used to lower elevated intraocular pressure - open angle glaucoma or high intraocular pressure. FML FORTE (Fluorometholone ophthalmic suspension) can be used to treat corticosteroid responsive inflammation of the eyelid and bulbar conjunctiva, cornea and anterior segment of the eye. Lumigan (Bimatoprost ophthalmic solution) can be used to lower elevated intraocular pressure - open angle glaucoma or high intraocular pressure. Pred Forte (Prednisolone acetate) can be used to treat steroid responsive inflammation of the eyelid and bulbar conjunctiva, cornea and anterior segment of the eye. Propyne (Dipivefrine hydrochloride) can be used to control intraocular pressure in chronic open angle glaucoma. Restasis (Cyclosporine ophthalmic emulsion) can be used to increase tear production in patients, for example, those with ocular inflammation associated with keratoconjunctivitis sicca. ALREX (loteprednol etabonate ophthalmic suspension) can be used for temporary relief of seasonal allergic conjunctivitis. Lotemax (loteprednol etabonate ophthalmic suspension) can be used to treat steroid-responsive inflammation of the eyelids and bulbar conjunctiva, cornea, and anterior segment of the eye. Macugen (pegaptanib sodium injection) can be used to treat neovascular (wet) age-related macular degeneration. Optivar (azelastine hydrochloride) can be used to treat itchy eyes associated with allergic conjunctivitis.Xalatan (Latanoprost ophthalmic solution) can be used to reduce intraocular hypertension in patients with, for example, open-angle glaucoma or high intraocular pressure. Betimol (Timolol ophthalmic solution) can be used to treat intraocular hypertension in patients with high intraocular pressure or open-angle glaucoma. Latanoprost is a prodrug in the free acid form and is a prostanoid selective FP receptor agonist. Latanoprost reduces intraocular pressure in patients with glaucoma and has few side effects. Latanoprost has relatively low solubility in aqueous solutions, but is readily soluble in organic solvents that are typically used to prepare microspheres using solvent evaporation.

[0110] Further embodiments of therapeutic agents for delivery include those that specifically bind to target peptides in vivo and prevent interaction of the target peptide with natural receptors or other ligands. For example, Avastin contains bevacizumab, an antibody that binds to VEGF. Also, Aflibercept is a fusion protein that contains a portion of the VEGF receptor that captures VEGF. IL-1 traps are also known that utilize the extracellular domain of the IL-1 receptor. The traps prevent IL-1 from binding to and activating cell surface receptors. Embodiments of agents for delivery include nucleic acids, e.g., aptamers. Pegaptanib (Macugen), for example, is a pegylated anti-VEGF aptamer. Fovista is a pegylated anti-PDGF aptamer. The advantage of the particle and hydrogel delivery process is that the aptamer is protected from the in vivo environment until it is released. Further embodiments of agents for delivery include macromolecular drugs, a term that refers to drugs that are significantly larger than classical small molecule drugs, i.e., drugs such as oligonucleotides (aptamers, antisense, RNAi), ribozymes, gene therapy nucleic acids, recombinant peptides, and antibodies.

[0111] One embodiment includes extended release of pharmaceutical agents for allergic conjunctivitis. For example, ketotifen, antihistamines and mast cell stabilizers can be provided in particles and released to the eye as described herein in an effective amount to treat allergic conjunctivitis. Seasonal allergic conjunctivitis (SAC) and perennial allergic conjunctivitis (PAC) are allergic conjunctival diseases. Symptoms include itchy and pink to red eyes. These two eye conditions are mediated by mast cells. Non-specific treatments to improve symptoms traditionally include cold compresses, eye irrigation with tear substitutes, and avoidance of allergens. Treatment traditionally consists of antihistamine mast cell stabilizers, dual mechanism antiallergens, or topical antihistamines. Corticosteroids can be effective, but are reserved for more severe forms of allergic conjunctivitis, such as vernal keratoconjunctivitis (VKC) and atopic keratoconjunctivitis (AKC), due to side effects.

[0112] Oxifloxacin is the active ingredient in Vegamox, a fluoroquinolone approved for use in the treatment or prevention of bacterial infections of the eye. The dose is typically one drop of a 0.5% solution, administered three times a day for a period of one week or more. VKC and AKC are chronic allergic diseases in which eosinophils, conjunctival fibroblasts, epithelial cells, mast cells, and / or TH2 lymphocytes deteriorate the biochemical characteristics and tissue structure of the conjunctiva. VKC and AKC can be treated with medications used to suppress allergic conjunctivitis. Penetrating agents are agents that can be included in the gels, hydrogels, organogels, xerogels, and biomaterials also described herein. These are agents that aid in the penetration of drugs into the intended tissue. Penetrating agents can be selected as needed for the tissue, for example, a penetrating agent for the skin, a penetrating agent for the tympanic membrane, or a penetrating agent for the eye.

[0113] Therapeutic Agent Solubility Embodiments of the present invention include a method of drug delivery to a tissue, eye, intraocular space, or other site as described herein, which includes forming a hydrogel in situ containing a drug (e.g., dissolved, suspended, liquid, solid, or dispersed throughout) in the hydrogel, where the drug has low water solubility or other solubility as described herein. Examples of such drugs are generally TKIs. Poorly soluble is a broad term and means soluble in water at 25° C. at 200 μg / ml or less, where the water is pure water and the drug is substantially pure or a salt. Similarly, very poorly soluble is a broad term that means soluble in water at 25° C. at 50 μg / ml or less. Other descriptive terms are shown in Table 1 and have the definitions described therein, and are directed to multiple solubility ranges, except in the case of substantially insoluble or insoluble, which are defined as having upper limits. One of skill in the art will immediately recognize that all ranges and values ​​between the stated boundaries are contemplated and any of the following solubilities can be used as upper or lower limits: 200,000, 100,000, 33,000, 10,000, 1,000, 225, 200, 150, 100, 50, 25, 20, 1, e.g., water solubility less than 100 or less than 50, or less than 20 μg / ml, or water solubility between 0.001-225, 1-200, 2-125 μg / ml.

[0114] The United States Pharmacopeia defines relative solubilities in descriptive terms for various listed substances, which can be converted to quantitative solubilities in units of micrograms per milliliter, as shown in Table 1. Various forms of drugs are suitable for sustained release from the in situ formed hydrogel depots. Suitable drugs include various drugs, such as those described herein, antibacterial agents, antifungal agents, antiviral agents, antiangiogenic agents, antiallergic agents, steroids, immunosuppressants, glaucoma agents, NSAIDs, and the like, of both small and large (if applicable) molecular size.

[0115] The sustained release of small molecules from the depot can be controlled by their limited solubility, and drugs classified as poorly soluble, substantially insoluble, or insoluble are generally preferred candidates, as illustrated in Table 2. Experimental water solubility (when available from the scientific literature) is added to the table to support the descriptive terms. It will be understood that this experimental aqueous solubility and / or water solubility is often dependent on the test conditions (pH, temperature), and variations in these conditions may alter the experimental solubility value. Solubility is controlled by many factors, and it should be understood that, of particular interest, the solubility of various salt forms of the same parent drug molecule differs. For example, dexamethasone sodium phosphate salt form is considered soluble, while dexamethasone alcohol or dexamethasone acetate are considered substantially insoluble or insoluble, as shown in Table 2.

[0116] It should be understood that all drugs can be released from the hydrogel depot using a secondary form of encapsulation to provide a more tailored drug release profile, which is controlled by the degradation of the microparticles rather than the solubility of the drug. For example, drugs classified as poorly to very soluble will most likely require a secondary form of encapsulation (e.g., microcapsules) to provide sustained release.

[0117] The hydrogel forms during crosslinking of the PEG arms, forming a network structure with a defined porosity of a limited molecular size. Therefore, the entrapment of large macromolecules, such as the antiangiogenic drugs shown in Table 2, which exceed the limited molecular size, is physically trapped within the hydrogel network. Therefore, degradation of the gel network is necessary to release the entrapped large macromolecules, even though these macromolecules are considered to be soluble to highly soluble.

[0118] [Table 1]

[0119] [Table 2]

[0120] [Table 3]

[0121] [Table 4]

[0122] [Table 5]

[0123] Eye conditions The materials described herein can be used to deliver drugs or other therapeutic agents (e.g., imaging agents or markers) to the eye or nearby tissues. Some of the pathologies are ocular fundus diseases. The term ocular fundus disease is recognized by those skilled in the art of endeavor and generally refers to any posterior eye disease that affects the vasculature and integrity of the retina, macula, or choroid, resulting in impaired vision, vision loss, or blindness. Posterior pathologies can be caused by age, trauma, surgical intervention, and genetic factors. Disease is a broad term that includes illnesses in general. Some ocular fundus diseases are age-related macular degeneration (AMD), cystoid macular edema (CME), diabetic macular edema (DME), posterior uveitis, and diabetic retinopathy. Some ocular fundus diseases result from unwanted angiogenesis or proliferation of blood vessels, such as macular degeneration or diabetic retinopathy. Drug treatment options for these and other pathologies are further discussed elsewhere in this specification.

[0124] Hydrogel loading of drugs; preparation as particles The hydrogel can be loaded with one or more drugs that are placed directly and / or indirectly within the hydrogel. In some circumstances, encapsulation into the particles is not preferred, but can be particularly useful for introducing drugs into the particles outside the eye. Encapsulation can include mixing the drug with a biodegradable material. Direct refers to placing the drug in direct contact with the matrix, for example, by forming a matrix in the presence of the drug in solid or soluble form. Indirect loading methods include, for example, introducing the drug into the particle and forming a hydrogel around the particle, so that the drug is inside the particle and does not directly contact the matrix when formed. Biodegradable vehicles in which active agents are present include encapsulation vehicles, e.g., microparticles, microspheres, microbeads, micropellets, in which the active agent is encapsulated in a bioerodible or biodegradable polymer, e.g., polymers and copolymers, such as: poly(anhydrides), poly(hydroxy acids), poly(lactones), poly(trimethylene carbonate), poly(glycolic acid), poly(lactic acid), poly(glycolic acid)-co-poly(glycolic acid), poly(orthocarboxylic acids), poly(caprolactones), crosslinked biodegradable hydrogel networks such as fibrin glue or fibrin sealant, caging and trapping molecules such as cyclodextrins, molecular sieves, and the like. Microspheres made from poly(lactones) and poly(hydroxy acids) polymers and copolymers are useful as biodegradable encapsulation vehicles. The therapeutic agent or encapsulated therapeutic agent may be present in solution or suspension form. Additionally, particles may be produced that are free of one or more of binders, non-peptide polymers, surfactants, oils, fats, waxes, hydrophobic polymers, polymers containing alkyl chains longer than four CH2 groups, phospholipids, micelle-forming polymers, micelle-forming compositions, amphiphiles, polysaccharides, polysaccharides consisting of three or more sugars, fatty acids, and lipids. Proteins that are lyophilized, spray-dried, or otherwise processed are often formulated with sugars such as trehalose to stabilize the protein through the lyophilization or other process used to prepare the protein. These sugars may remain in the particles throughout the organogel / xerogel process.The particles can be made to contain from about 10% to about 100% (dry w / w) protein; one of skill in the art will immediately recognize that all ranges and values ​​within the explicit ranges are contemplated, e.g., from about 40% to about 80%, or at least 50%, or at least 80%, or at least 90%, or at least about 99%.

[0125] A gel or organogel or hydrogel may be formed around the drug and then made into an encapsulating particle, which may then be processed to remove the organic or aqueous solvent or solvents to form a xerogel. For injectable forms, the organogel or hydrogel may be macerated, homogenized, extruded, screened, chopped, diced, or otherwise made into a granular form. Alternatively, the organogel or hydrogel may be formed as droplets or as a molded article containing suspended protein particles. One process for making such particles includes producing a material that is degraded to form the particles.

[0126] These particles may be separated into populations with desired size ranges and size distributions by various methods. Very precise sizing control is available, with sizes ranging from 1 micron to several mm, and with controllable mean and range particle sizes with narrow distributions. Those skilled in the art will readily recognize that any range and value within the stated range is contemplated, for example, about 1 to about 10 μm or about 1 to about 30 μm. About 1 to about 500 microns is another such range that is useful, with sizes ranging throughout the range and with an average size of one value within the range, with standard deviations centered around the mean value, for example, about 1% to about 100%. Simple methods of sizing particles include utilizing custom or standardized sieve mesh sizes. The term particle is broad and includes spherical, cylindrical, discoidal, and irregularly shaped particles. Some embodiments include producing a population of particles with different degradation rates in vivo and mixing the population to obtain the desired degradation performance.

[0127] Kit or System A kit or system for producing hydrogels can be prepared. The kit includes precursors manufactured using medically acceptable conditions and having pharma- ceutically acceptable sterility, purity and preparation. The kit may include an applicator and instructions, if necessary. Therapeutic agents may be included premixed or available for mixing. Solvents / solutions may be provided in the kit or separately, or the components may be premixed with the solvent. The kit may include a syringe and / or needle for mixing and / or delivery. In some embodiments, the kit includes at least one precursor and an applicator. A visualization or imaging agent may be incorporated into the material. The kit may include a thickening agent, e.g., hyaluronic acid, premixed or separate from the other components. Embodiments include kits including one or more precursors described herein and one or more agents described herein, optionally with an applicator and a solvent (e.g., water) for preparing a solution of the precursors and / or agents.

[0128] The precursor or precursors may be provided in a dry form (e.g., cake, powder, immobilized pellets). A diluent for the precursor may be included, such as an aqueous diluent. A buffer may be present in either the dry material, the diluent, or both. A method for producing a dry precursor may, for example, produce the precursor in an organic solution or dissolve the precursor in a solution. If the functional group is an electrophilic group, the solvent and / or pH may be selected so that the electrophilic group is non-reactive. If the precursor contains a hydrolytically unstable group, such as an ester in various forms, the solvent may be selected to be non-aqueous, such as a dry organic solvent, dimethyl carbonate (DMC), dimethylformamide (DMF), a polar aprotic solvent. The precursor may be frozen and lyophilized. The lyophile may be ground or otherwise powdered and pressed into a cake, produced into a pellet, or lyophilized in its final use container.

[0129] In some embodiments, kits with precursors and other materials necessary to form hydrogels in situ with therapeutic agents can be provided with components such as those described herein. In some embodiments, hydrogel characteristics can be selected to produce hydrogels that can be delivered through small needles with minimal swelling, incorporated into aqueous low-viscosity preparations, and gel after placement. Forming biodegradable drug depots using flowable aqueous precursors allows for administration through small (e.g., 30 gauge) needles. Hydrogels can also be manufactured to not degrade into acidic byproducts, so that the drug depots are well tolerated by sensitive tissues such as the eye.

[0130] Thus, the implants can be made significantly larger in size (e.g., 1 ml volume for the eye) compared to implants made from conventional biodegradable polymers, which are usually much smaller. On the other hand, smaller depots may also be useful. Thus, some embodiments are hydrogels having a volume of about 0.005 to about 5 ml; one of skill in the art will readily recognize that all ranges and values ​​within the stated ranges are contemplated, e.g., 0.005, 0.01, 0.05, 0.1, 0.5, 1, 2, 3, 4, 5 ml. EXAMPLES

[0131] Some of the precursors are referred to by the nomenclature naxxKpppfff, where n is the number of arms, xx is the molecular weight (MW), ppp is the polymer, and fff is the functional end group. For example, 8a15KPEGSAP refers to an 8-arm polyethylene glycol (PEG) with a MW of 15,000 g / mol = 15KPEG. Succinimidyl adipate is SAP. Succinimidyl glutarate is SG. Succinimidyl azelaate is SAZ.

[0132] Example 1 This example concerns the evaluation of the swelling and persistence of 5% and 10% PEG formulations. This provides an injectable solution that can maintain its shape and mechanical integrity within the space, whether that space is intravitreal or other locations. The precursors have good needle passability and cohesiveness. Hyaluronic acid (HA) is a high molecular weight non-Newtonian linear molecule; it increases the viscosity of the precursor solution and performs well under high shear conditions (passage through a fine gauge needle). A variety of different dilutions of 850 kDa HA were tested, with approximately 1% being suitable in this case. The buffers used to dissolve each precursor should produce a neutral pH when mixed, while the buffer for the SAZ precursor should be low pH to maintain the stability of the polymer in solution (avoiding prehydrolysis). Each of these components maintained its shape and volume stability when mixed together, retaining its shape and position within the space until the hydrogel formed in 2-3 minutes (Table 3).

[0133] procedure: 4.8% PEG formulation Two stock buffers were prepared for use in dissolving each PEG: - 10mL of PEG Amine Buffer (8a20k NH3 + (for use with). - 105 mg of sodium tetraborate decahydrate was introduced into 10.0 mL of WFI and vortexed until a solution was formed. - 200mg of 850kDa HA was introduced into 9.8mL of borate / WFI solution in a TD20 stirrer. Stirred at 6000RPM for 15 minutes (until complete solution was achieved). -Prepare 10mL of PEG ester buffer (for use with 4a20K SAZ). - 70 mg of sodium phosphate monobasic was introduced into 10.0 mL of WFI and vortexed until a solution was formed. - 32mg 8a20k NH3 +The powder was loaded into a 3 mL Becton Dickinson (BD) syringe and luer-connected with 968 μL of PEG amine buffer. The buffer was added to the powder and mixed between the syringes until a solution was formed. - 64mg of 4a20K SAZ was loaded into a 3mL BD syringe and then luer-connected with 946μL of PEG ester buffer. The buffer was added to the powder and mixed between the syringes until it became a solution. - 500mg 8a20k NH3 + The solution was introduced into a 3 mL BD syringe, luer-connected with 500 mg of 4a20K SAZ solution, mixed back and forth for 30 seconds, and then dispersed onto an aluminum weigh boat for gel time testing. A depot is said to gel when it begins to take on a solid state and is no longer liquid. - Gel times were wide, ranging from 2:30 minutes to 3:00 minutes.

[0134] 9.6% PEG formulation Two stock buffers were prepared for use in dissolving each PEG: - 10mL of PEG Amine Buffer (8a20k NH3 + (for use with). - 105 mg of sodium tetraborate decahydrate was introduced into 10.0 mL of WFI and vortexed until a solution was formed. - 200mg of 850kDa HA was introduced into 9.8mL of borate / WFI solution in a TD20 stirrer. Stirred at 6000RPM for 15 minutes (until complete solution was achieved). -Prepare 10mL of PEG ester buffer (for use with 4a20K SAZ). - 70 mg of sodium phosphate monobasic was introduced into 10.0 mL of WFI and vortexed until a solution was formed. - 64mg 8a20k NH3 + was introduced into a 3 mL BD syringe and then luer-connected with 946 μL of PEG amine buffer. The buffer was added to the powder and mixed between the syringes until it became a solution. - 128mg of 4a20K SAZ was loaded into a 3mL BD syringe and then luered together with 872μL of PEG ester buffer. The buffer was added to the powder and the syringes were mixed together until a solution was formed. - 500mg 8a20k NH3 + The solution was introduced into a 3 mL BD syringe, luer-connected with 500 mg of 4a20K SAZ solution, mixed back and forth for 30 seconds, and then dispersed onto an aluminum weigh boat for gel time testing. A depot is said to gel when it begins to take on a solid state and is no longer liquid.

[0135] [Table 6]

[0136] observation: At 4.8% PEG, there is a linear relationship between borate concentration and gel time, allowing for an excellent target range for the syringe: y=-0.2223x+2.6816 (where x=[borate] and y=gel time) 10.7mg / mL (2 min GT) ≧ x 9.35 mg / mL (4 min GT).

[0137] Swelling and Dimensional Analysis: Figures 7 and 8 depict swelling and dimensional change plots, respectively, for hydrogel depots introduced in vitro in physiological buffer (PBS). As the hydrogels degraded, they continued to swell with an upward linear trend toward 1000% of pre-liquefaction. For the swellable preparations, the formulations were cast into 2 mm ID silicone tubing and left to harden in a 37°C, 100% RH environment for 24 hours before being introduced into 1x PBS pH 7.2. The depots aggregated and captured bursts at t=1 hour and 24 hours, followed by a lower frequency.

[0138] For dimensional analysis, Formulation 2 (9.8% PEG) was cast into 2 mm ID silicone tubing and left to harden for 24 hours in a 100% RH environment at 37° C. before being introduced into 1× PBS pH 7.2. Most of the dimensional change occurs within the first hour.

[0139] Example 2 (1 dry syringe, 1 wet syringe) procedure: 20% dexamethasone loaded, 10% PEG formulation (integral formulation).

[0140] Dimethyl carbonate (DMC) 4a20K SAZ / 8a20k NH3 + Preparation of suspension: The following preparations were carried out under dry conditions: - 1.00 g of 4a20K SAZ is introduced into a pre-weighed 10 mL glass vial. - 0.50g of 8a20k NH3 into the same glass vial + Addition of. - Seal the glass vial with a rubber stopper. Using a measuring syringe, add 8.50 mL of DMC. - Vortex the vial until the suspension is homogenous.

[0141] Preparation of syringe containing dexamethasone powder: - 40 mg of dexamethasone powder was measured into a 1 mL Soft-ject syringe. - 133μL of pre-prepared 4a20K SAZ / 8a20k NH3 + of dimethyl carbonate suspension was added through the luer of a Soft-ject syringe using a metered syringe and needle. - The syringes were then capped and immediately frozen on a customized tote (-50°C). - Once frozen, the syringe caps were removed and the tote was placed in the freeze dryer. - The syringe was then dried overnight to remove any remaining solvent.

[0142] Preparation of diluent: - 2.56g sodium phosphate monobasic, 2.56g sodium phosphate dibasic, 8.50g sodium chloride, and 0.50g sodium tetraborate decahydrate were added to a 1 L volumetric flask and made up to volume with WFI. -The pH of the solution was then adjusted to 6.8 using 6N hydrochloric acid. - To prepare the diluent, 400 μL of prepared buffer was mixed with 1600 μL of Provisc (1% HA 2000 kDa) between syringes to obtain 2 mL of stock diluent solution.

[0143] Gel formation: - 40mg dexamethasone and 20mg dry PEG powder (4a20K SAZ / 8a20k NH3 + ) was mixed with 140 μL of the prepared diluent solution for approximately 30 seconds. - The resulting suspension was dispersed onto an aluminum weight boat for gel time testing. - A depot calls itself a gel when it starts to take on a solid state and is no longer liquid. The gel time for these depots is 3-6 minutes.

[0144] In vivo injections: - A 20% Dex formulation (containing fluorescently labeled amines) was used for in vivo injection in PARF. 25 μL was injected using a 50 μL Hamilton syringe with 27G1 / 2" RN. The solution is highly injectable. Some depots were left for in vivo release. One depot was explanted immediately after injection for in vitro release (visually tracking dex clearance). The results are shown in Figure 9. Depots were placed in excess PBS for the indicated times, photographed, and observed for drug release. The matrix was fluorescently labeled and had a yellow appearance. The presence of drug made the matrix appear opaque. As drug was released, the depot became translucent. The depot was darker in the center, and in the images, the coloring of the matrix gives it a more opaque appearance. Drug release is most easily observed at the periphery.

[0145] Example 3: Dexamethasone Intravitreal Depot This example details methods that can be used to make, test, or use hydrogels for drug release.

[0146] A. Mix the following ingredients: 20mg of 4-arm 20K PEG SAZ 10mg 8-arm 20K PEG amine HCl salt 30mg micronized dexamethasone 240 mg dimethyl carbonate The mixture is lyophilized to form a dry lyophilizate.

[0147] B. Prepare an aqueous buffer solution as follows: 8mg / mL Sodium Hyaluronate (850KDa) 0.1 mg / mL sodium tetraborate decahydrate 0.51 mg / mL Sodium Phosphate Monobasic 0.51 mg / mL dibasic sodium phosphate 1.7 mg / mL sodium chloride Adjust the pH to 6.8 using 6N hydrochloric acid solution.

[0148] 10 mg of A and 40 mg of B are combined in a syringe and then injected into the posterior chamber. A substantially spherical shape forms within the eye, which solidifies into a hydrogel in approximately 2-5 minutes. Dexamethasone is slowly released into the vitreous humor and gradually migrates into adjacent tissues, such as the retina, ciliary body, anterior chamber, and choroid, to provide therapeutic benefit.

[0149] Example 4: Lotepredenol etabonate intravitreal deposit This example details methods that can be used to make, test, or use hydrogels for drug release.

[0150] A. Mix the following ingredients: 20mg of 4-arm 20K PEG SAZ 10mg 8-arm 20K PEG amine HCl salt 30mg micronized dexamethasone 240 mg dimethyl carbonate The mixture is lyophilized to form a dry lyophilizate.

[0151] B. Prepare an aqueous buffer solution as follows: 8mg / mL Sodium Hyaluronate (850KDa) 0.1 mg / mL sodium tetraborate decahydrate 0.51 mg / mL Sodium Phosphate Monobasic 0.51 mg / mL dibasic sodium phosphate 1.7 mg / mL sodium chloride Adjust the pH to 6.8 using 6N hydrochloric acid solution.

[0152] 10 mg of A and 40 mg of B are combined in a syringe and then injected into the posterior chamber. A substantially spherical shape forms within the eye, which solidifies into a hydrogel in approximately 2-5 minutes. Lotepredenol etabonate is slowly released into the vitreous humor and gradually migrates into adjacent tissues, such as the retina, ciliary body, anterior chamber, and choroid, to provide therapeutic benefit.

[0153] Example 5: Axitinib Intravitreal Depot This example details methods that can be used to make, test, or use hydrogels for drug release.

[0154] A. Mix the following ingredients: 20mg of 4-arm 20K PEG SAZ 10mg 8-arm 20K PEG amine HCl salt 30mg micronized lotepredenol etabonate 240 mg dimethyl carbonate The mixture is lyophilized to form a dry lyophilizate.

[0155] B. Prepare an aqueous buffer solution as follows: 8mg / mL Sodium Hyaluronate (850KDa) 0.1 mg / mL sodium tetraborate decahydrate 0.51 mg / mL Sodium Phosphate Monobasic 0.51 mg / mL dibasic sodium phosphate 1.7 mg / mL sodium chloride Adjust the pH to 6.8 using 6N hydrochloric acid solution.

[0156] 10 mg of A and 40 mg of B are combined in a syringe and then injected into the posterior chamber. A substantially spherical shape forms within the eye, which solidifies into a hydrogel in approximately 2-5 minutes. Axitinib is slowly released into the vitreous humor and gradually migrates into adjacent tissues, such as the retina, ciliary body, anterior chamber, and choroid, to provide therapeutic benefit.

[0157] Example 6: Axitinib intravitreal deposits with gelation trigger This example details methods that can be used to make, test, or use hydrogels for drug release.

[0158] A. Mix the following ingredients: 20mg of 4-arm 20K PEG SAZ 10mg 8-arm 20K PEG amine HCl salt 30mg micronized lotepredenol etabonate 240 mg dimethyl carbonate The mixture is lyophilized to form a dry lyophilizate.

[0159] B. Prepare an aqueous buffer solution as follows: 8mg / mL Sodium Hyaluronate (850KDa) 1.7 mg / mL sodium chloride

[0160] C. Prepare the aqueous solution as follows: 0.1 mg / mL sodium tetraborate decahydrate 0.51 mg / mL Sodium Phosphate Monobasic 0.51 mg / mL dibasic sodium phosphate 50mg / mL polyethylene glycol (8KDa)

[0161] A 3.25 mm long piece of polyethylene tubing with an outer diameter of 3.02 mm and an inner diameter of 1.26 mm is coated with C and allowed to dry to form a coating over the entire surface. The coated tube is placed into the hub of a Nipro 30 gauge thin wall Luer Lok needle.

[0162] 10 mg of A and 40 mg of B are combined in a syringe and then the needle containing the coating tube is attached. The syringe contents are injected into the posterior chamber with a smooth movement for approximately 2 seconds. A substantially spherical shape is formed within the eye, which solidifies into a hydrogel in approximately 2-5 minutes. Axitinib is slowly released into the vitreous humor and gradually migrates into adjacent tissues, such as the retina, ciliary body, anterior chamber, and choroid, to provide therapeutic benefit.

[0163] Example 7: Axitinib intravitreal deposits with gelation trigger This example details methods that can be used to make, test, or use hydrogels for drug release.

[0164] A. Mix the following ingredients: 20mg of 4-arm 20K PEG SAZ 10mg 8-arm 20K PEG amine HCl salt 30mg micronized lotepredenol etabonate 240 mg dimethyl carbonate The mixture is lyophilized to form a dry lyophilizate.

[0165] B. Prepare an aqueous buffer solution as follows: 11mg / mL Sodium Hyaluronate (850KDa) 2.3 mg / mL sodium chloride

[0166] C. Prepare the aqueous solution as follows: 0.4 mg / mL sodium tetraborate decahydrate 2.0 mg / mL Sodium Phosphate Monobasic 2.0 mg / mL dibasic sodium phosphate

[0167] Combine 10 mg of A and 30 mg of B in the larger lumen of a two-barrel syringe with a 2:1 barrel ratio and a needle equipped with a static mixing element. Inject the syringe contents into the posterior chamber with a smooth movement of approximately 2 seconds. A substantially spherical shape forms within the eye, which solidifies into a hydrogel in approximately 2-5 minutes. Axitinib is slowly released into the vitreous humor and gradually migrates into adjacent tissues, such as the retina, ciliary body, anterior chamber, and choroid, to provide therapeutic benefit.

[0168] Example 8: Axitinib Intravitreal Depot This example details methods that can be used to make, test, or use hydrogels for drug release.

[0169] A. Mix the following ingredients: 20mg of 4-arm 20K PEG SAZ 10mg 8-arm 20K PEG amine HCl salt 30mg micronized axitinib 240 mg dimethyl carbonate The mixture is lyophilized to form a dry lyophilizate.

[0170] B. Prepare an aqueous solution by adjusting the pH of the injection solution to 4.0 using 0.1N hydrochloric acid solution.

[0171] 10 mg of A and 40 mg of B are combined in a syringe and then injected into the posterior chamber. A substantially spherical shape is formed in the eye, which solidifies into a hydrogel as the local pH increases until it is equal to the pH of the vitreous humor, about 7.2. Axitinib is slowly released into the vitreous humor and gradually migrates into adjacent tissues, such as the retina, ciliary body, anterior chamber, and choroid, to provide therapeutic benefit.

[0172] Example 9: Kit preparation and testing Preparation of enveloped PEG and anhydrous dimethyl carbonate suspensions - 500mg of 4-arm 20K SAZ was collected in a pre-weighed vial. - 250mg 8arm 20K NH3 + were collected in the same vial. - 9.25 mL of anhydrous dimethyl carbonate was added to the powder under nitrogen until the suspension was homogenous (this resulted in a 5%:2.5% 4-arm 20K SAZ:8-arm 20K NH3 + preparation was produced). - 2.5 mL of the PEG / DMC suspension was poured into a small aluminum weight boat. - The weight boat, placed under the glove bag, was then placed on a cold aluminum surface (freshly removed from a -40°C freezer) to allow the PEG / DMC to freeze without exposure to the atmosphere. -While still frozen, the weight boat was transferred to the freeze dryer rack and a cycle was run to remove all the solvent.

[0173] Preparation of PEG in needle hub: - A 27G1 / 2" needle was pre-weighed on a balance under dry conditions. -Pre-prepared PEG powder was transferred into the needle hub by using the needle as a biopsy punch (target was 3-6 mg PEG). - 4.96 mg of enveloped PEG was weighed into the needle, which was set aside for future use.

[0174] Preparation of xerogel: - The following ingredients were dissolved in dimethyl carbonate: - 8-arm 20k NH2 at 11.4% in DMC - 8-arm 15k SG at 8.6% DMC - 1600mg of anhydrous microfine lactose from DFE Pharma was suspended in 11.4% 8-arm 20k NH2 (as above). - This syringe was mixed syringe-to-syringe with 4200 μL of 8.6% 8-arm 15k SG until a bulk gel was formed. - The particle size of the bulk gel was then reduced by running the homogenizer. - The particles were then dried using a filter drier to remove DMC and fines. - Final particle size had a d50 of 430um.

[0175] Preparation of diluent: - Sodium phosphate monobasic, sodium phosphate dibasic, sodium tetraborate decahydrate were added to a 1 L volumetric flask and made up to volume with water. - The pH of the solution was adjusted to 7.2 using 6N hydrochloric acid. - To prepare the diluent, 1120 μL of prepared buffer was mixed between syringes with 880 μL of Provisc (1% HA 2000 kDa) to obtain 2 mL of stock diluent solution.

[0176] Preparation of hydrogel slurry: - 212 mg of previously prepared xerogel (described above) was collected in a syringe. - Next, 1.829g of the previously prepared diluent (described above) was mixed between the syringes to mix the hydrogel suspension until it was completely homogenous.

[0177] Injection and gelation: Table 4 shows each formulation containing the kit components and the resulting gel time. Gelling is accomplished by injecting the slurry through a needle onto an aluminum weigh boat.

[0178] [Table 7]

[0179] Example 10 Steroid candidates 1. Flunisolide, Anhydrous, USP 2. Micronized Budesonide 3. Betamethasone Sodium Phosphate, USP 4. Triamcinolone acetonide, powder, USP.

[0180] Steroid Solubility Test The solubility of the steroid candidates was assessed for 68 hours in dissolution medium (PBS, pH 6.3) at room temperature. UV detection of soluble steroids was determined against a standard curve. The maximum solubilities determined are shown below: · Maximum solubility of flunisolide in PBS, pH 6.3 = 90 μg / mL (245 nm). · Maximum solubility of betamethasone sodium phosphate in PBS, pH 6.3 ≥ 100,000 μg / mL (freely soluble in water) (241 nm). · Maximum solubility of budesonide in PBS, pH 6.3 = 30 μg / mL (247 nm). · Maximum solubility of triamcinolone acetonide in PBS, pH 6.3 = 20 μg / mL (241 nm).

[0181] Depot formulation Syringe 1: 10 mg of steroid and 42 mg of 4-arm 20,000 molecular weight PEG succinimidyl glutarate (4a20KSG) were weighed into a syringe and then dissolved in 233 μL of 1 mg / mL monobasic sodium phosphate containing 1 mg trilysine (LLL). The low pH (approximately 4.5) prevents reactivity between the PEG and LLL components.

[0182] Syringe 2: 6 mg of sodium tetraborate was weighed into a syringe and dissolved in 233 μL of water for injection (WFI).

[0183] The two syringes were mixed between the syringes using a Luer connector before being injected into a 10 mm borosilicate tube equipped with a small stirring bar on a stir plate. Mixing prevented the steroid suspension from settling until sufficient viscosity was achieved during hydrogel formation. This resulted in 10 mg of steroid entrapped in a 9% hydrogel (w / v) in a volume of approximately 0.45 mL. A visual representation of the depot shape is shown in Figure 10.

[0184] Release rates from in vitro depots For each steroid candidate, the release rate from 10 mg of steroid containing hydrogel depot in 1 L of PBS, pH 6.3, with gentle agitation at room temperature was performed and compared to the dissolution profile of 10 mg of undiluted drug dispersed in an equal volume of dissolution medium (Figure 11). For the flunisolide steroid candidate, a visual representation of the release from the drug depot over time is observed in Figure 12.

[0185] Example 11 In a similar construct, lotepredenol etabonate, dexamethasone, micronized dexamethasone, prednisolone and prednisolone acetate were suspended in PEG hydrogel precursor solution and then injected into the tube to allow the gel to be covalently crosslinked as a hydrogel and then cut into barrel-shaped depots. The steroid suspension gel was removed from the tube and ex vivo release was initiated in the elution medium. Zonal clearance (released steroid) from the depot interface inwards was observed and visually recorded. See Figures 13-16.

[0186] Example 12: 100 μg micronized axitinib suspension injection Buffer preparation 10x PBS (VWR International) was diluted 1:10 with water and the pH was brought to 7.2 with 0.01 N NaOH and 0.01 N HCl. The solution was then filtered through a 0.2 μm filter at a rate of 2 mL / min to remove any endotoxins or bioburden.

[0187] Preparation of suspension 200 μg of micronized axitinib was weighed into a 50 mL amber vial. It was dried, stoppered, crimped, and then sterilized by gamma irradiation. After irradiation, 9.80 mL of buffer was added to the vial. The suspension was then placed in a sonic bath for 20 minutes to homogenously disperse the micronized particles.

[0188] Injection of materials Next, 50 μL of the 2% axitinib suspension was injected into a 100 μL Luer-lock Hamilton syringe with a 21 G1.5" needle. The needle was replaced with a new 27 G1 / 2" TW needle (Nipro). 50 μL of the suspension was then injected into the vitreous at the 6 o'clock position of male New Zealand White rabbits. After one month, the eyes were explanted and prepared for histology.

[0189] Histology methods Two eyes were fixed (Davidson), blocked, sectioned, mounted, and stained for microscopic examination by a board-certified veterinary pathologist. Eyes were sectioned according to the following scheme: Sutures were placed at the 12 o'clock position in the orientation at the time of harvest. Typically, eyes were sectioned in half along the midline through the lens and optic nerve at the 12 o'clock to 6 o'clock plane. This captures as many ocular structures as possible. The sectioned eyes were grossly examined and abnormalities noted. Each sectioned half globe was embedded in its own cassette. Cassette A was always the nasal portion of the eye and cassette B was always the temporal portion of the eye. For each block, six hematoxylin and eosin (H&E) stained slides were prepared, separated by 1000 microns (1 mm). Each slide contained sections from two consecutive eyes. All slides were evaluated by board-certified veterinary pathologists at Charter Preclinical Services. Tissues were scored for any abnormalities on a semiquantitative scale of 0 to 5.

[0190] The eyes were scored in several categories for signs of inflammation or other adverse findings. The inflammation scores were as follows: 0 - no change; normal 1 - Very little change center; minimal 2 - Mild diffuse changes or more prominent focal changes 3 - Moderate diffuse changes 4 - Marked diffuse changes 5 - severe diffuse changes.

[0191] Histology results: Inflammation in the vitreous chamber: 0.0±0.0 Inflammation around the injected material: 0.04 ± 0.29 Other adverse findings (retina, sclera, lens, etc.): None.

[0192] Example 13: 200 μg micronized axitinib suspension injection Axitinib dissolution 195 mg of axitinib (LGM Pharma, GMP grade) was dissolved in 110 mL of ethanol (Sigma Aldrich) in a glass vial, capped and crimped (1.77 mg of axitinib / mL of ethanol). The vial was then wrapped in aluminum foil to protect the solution from light and sonicated until completely dissolved. The solution was then drawn into two 60 mL polyethylene (PE) Luer-lock syringes (BD) wrapped in aluminum foil.

[0193] Axitinib Precipitation 1800mL of sterile Water For Injection (WFI) was weighed into a 2L beaker and placed on a stir plate with a stir bar stirring at 600 RPM, creating a large WFI vortex in the center of the beaker. One 60mL BD syringe containing axitinib in ethanol was placed on a syringe pump fixed above the WFI beaker. A hypodermic needle (21G, BD) was connected to the syringe and aimed at the center of the vortex for administration of the axitinib solution. The axitinib solution was added dropwise to the WFI to precipitate the micronized axitinib.

[0194] Filtration and collection of axitinib suspension After micronization, axitinib suspended in 5.7% ethanol / 94.3% WFI was filtered through a 0.2 um vacuum filter (Thermo Scientific) and then rinsed three times with 100 mL of WFI. After filtration, the axitinib powder was collected from the filter using a spatula and dried overnight under vacuum in a 10 mL glass vial to remove all excess solvent.

[0195] Particle size analysis Particle size was analyzed using a Beckman Coulter LS 120 Particle Size Analyzer. Samples were sonicated for 15 minutes in deionized water prior to analysis. On average, the particle size distribution is d10=0.773um, d50=2.605um, and d90=6.535um.

[0196] Preparation of suspension 40 μg of micronized axitinib was weighed into a sterile 3 mL BD Luer Lock syringe. 960 μL of Provisc (Alcon, Inc., 1% 2000 kDa hyaluronic acid solution) was added to a new 3 mL BD Luer Lock syringe. The two syringes were mixed using the Luer connector.

[0197] Injection of materials Next, 50 μL of the 4% axitinib suspension was injected into a 100 μL Luer-lock Hamilton syringe with a 21 G1.5" needle. The needle was replaced with a new 27 G1 / 2" TW needle (Nipro). 50 μL of the suspension was then injected into the vitreous at the 6 o'clock position of male New Zealand White rabbits. After one month, the eyes were explanted and prepared for histology.

[0198] Histology methods Two eyes were fixed (Davidson's fixative), blocked, sectioned, mounted, and stained for microscopic examination by a board-certified veterinary pathologist. Eyes were sectioned according to the following scheme: Sutures were placed at the 12 o'clock position in the orientation at the time of collection. Typically, the eye was sectioned in half along the midline through the lens and optic nerve at the 12 o'clock to 6 o'clock plane. This captures as many ocular structures as possible. The sectioned eyes were grossly examined and abnormalities were noted. Each sectioned half globe was embedded in its own cassette. Cassette A was always the nasal portion of the eye and cassette B was always the temporal portion of the eye. For each block, six hematoxylin and eosin (H&E) stained slides were prepared, separated by 1000 microns (1 mm). Each slide contained sections from two consecutive eyes. All slides were evaluated by board-certified veterinary pathologists at Charter Preclinical Services. Tissues were scored for any abnormalities on a semiquantitative scale of 0 to 5.

[0199] As previously described, the eyes were scored in several categories for signs of inflammation or other adverse findings.

[0200] histology results Inflammation in the vitreous chamber: 0.14±0.35 Inflammation around the injected material: 0.08 ± 0.37 Other adverse findings (retina, sclera, lens, etc.): None.

[0201] Example 14: 400 μg micronized axitinib suspension injection Axitinib dissolution 195 mg of axitinib (LGM Pharma, GMP grade) was dissolved in 110 mL of ethanol (Sigma Aldrich) in a glass vial, capped and crimped (1.77 mg of axitinib / mL of ethanol). The vial was then wrapped in aluminum foil to protect the solution from light and sonicated until completely dissolved. The solution was then drawn into two 60 mL polyethylene (PE) Luer-lock syringes (BD) wrapped in aluminum foil.

[0202] Axitinib Precipitation 1800mL of sterile Water For Injection (WFI) was weighed into a 2L beaker and placed on a stir plate with a stir bar stirring at 600RPM, creating a large WFI vortex in the center of the beaker. One 60mL BD syringe containing axitinib in ethanol was placed on a syringe pump fixed above the WFI beaker. A hypodermic needle (21G, BD) was connected to the syringe and aimed at the center of the vortex for administration of the axitinib solution. The syringe pump was then operated at 7.5mL / min to add the axitinib solution drop by drop into the WFI, precipitating the micronized axitinib.

[0203] Filtration and collection of axitinib suspension After micronization, axitinib suspended in 5.7% ethanol / 94.3% WFI was filtered through a 0.2 um vacuum filter (Thermo Scientific) and then rinsed three times with 100 mL of WFI. After filtration, the axitinib powder was collected from the filter using a spatula and dried overnight under vacuum in a 10 mL glass vial to remove all excess solvent.

[0204] Particle size analysis Particle size was analyzed using a Beckman Coulter LS120 particle size analyzer. Samples were sonicated for 15 minutes in deionized water prior to analysis. On average, the particle size distribution is d10=0.773um, d50=2.605um, and d90=6.535um.

[0205] Preparation of suspension 80 μg of micronized axitinib was weighed into a sterile 3 mL BD Luer Lock syringe. 960 μL of Provisc (Alcon, Inc., 1% 2000 kDa hyaluronic acid solution) was added to a new 3 mL BD Luer Lock syringe. The two syringes were mixed using the Luer connector.

[0206] Injection of materials Next, 50 μL of the 8% axitinib suspension was injected into a 100 μL Luer-lock Hamilton syringe with a 21 G1.5" needle. The needle was replaced with a new 27 G1 / 2" TW needle (Nipro). 50 μL of the suspension was then injected intravitreously at the 6 o'clock position in both eyes of male New Zealand White rabbits. After one month, the eyes were explanted and prepared for histology.

[0207] Histology methods Two eyes were fixed (Davidson's fixative), blocked, sectioned, mounted, and stained for microscopic examination by a board-certified veterinary pathologist. Eyes were sectioned according to the following scheme: Sutures were placed at the 12 o'clock position in the orientation at the time of collection. Typically, the eye was sectioned in half along the midline through the lens and optic nerve at the 12 o'clock to 6 o'clock plane. This captures as many ocular structures as possible. The sectioned eyes were grossly examined and abnormalities were noted. Each sectioned half globe was embedded in its own cassette. Cassette A was always the nasal portion of the eye and cassette B was always the temporal portion of the eye. For each block, six hematoxylin and eosin (H&E) stained slides were prepared, separated by 1000 microns (1 mm). Each slide contained sections from two consecutive eyes. All slides were evaluated by board-certified veterinary pathologists at Charter Preclinical Services. Tissues were scored for any abnormalities on a semiquantitative scale of 0 to 5.

[0208] As previously described, the eyes were scored in several categories for signs of inflammation or other adverse findings.

[0209] histology results Inflammation in the vitreous chamber: 0.14±0.35 Inflammation around the injected material: 0.14 ± 0.35 Other adverse findings (retina, sclera, lens, etc.): None.

[0210] Further disclosure 1. A method of drug delivery to a tissue, comprising forming a hydrogel implant in situ with a therapeutic agent (e.g., dissolved, suspended, dispersed throughout) in the hydrogel, where the therapeutic agent has low or poor water solubility. The site may be, for example, intraocular, intraocular tissue, intracameral, or intravitreal.

[0211] 2. The method of 1, wherein the hydrogel is water-degradable as can be measured by the hydrogel being dissolvable in vitro in an excess amount of water by decomposition of the water-degradable groups.

[0212] 3. The method of 1 or 2, wherein the hydrogel remains substantially intact until the drug is substantially released.

[0213] 4. The method of 1 or 2, wherein 50%-100% w / w of the drug is released when the hydrogel is 100%-90% sustained (one of skill in the art will immediately recognize that all ranges and values ​​between the stated boundaries are contemplated, e.g., 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 99%, e.g., 90%-99%, or 55%-99%, can all be used as upper or lower limits). Alternatively, when the hydrogel is 100%-80% sustained.

[0214] 5. The method of any of 1-4, wherein the hydrogel delivers the agent at a therapeutically effective concentration for a period ranging from 1 to 36 months from formation of the hydrogel in situ. One of skill in the art will immediately recognize that all ranges and values ​​between the stated boundaries are contemplated, e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36 months can all be used as upper or lower limits. Shorter periods of time, e.g., 1 to 31 days, can also be used; one of skill in the art will immediately recognize that all ranges and values ​​between the stated boundaries are contemplated, e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 20, 25, 30, or 31 days can all be used as upper or lower limits.

[0215] 6. The method of claim 5, wherein after said period of time, the hydrogel has released all of the drug and is at least 80% sustained.

[0216] 7. The method of claim 5, wherein after that period of time, the hydrogel releases an amount of the drug that is non-toxic.

[0217] 8. The method of 5 or 7, wherein after that period of time, the hydrogel delivers 1%-20% final w / w of drug. One of skill in the art will immediately recognize that all ranges and values ​​between the boundaries stated are contemplated, e.g., 1, 2, 3, 4, 5, 10, 15, 16, 17, 18, 19% w / w can all be used as upper or lower limits.

[0218] 9. The method of any of 1-8, wherein the hydrogel delivers 1%-20% final w / w of drug upon degradation of the hydrogel. One of skill in the art will immediately recognize that all ranges and values ​​between the boundaries stated are contemplated, e.g., 1, 2, 3, 4, 5, 10, 15, 16, 17, 18, 19% w / w can all be used as upper or lower limits.

[0219] 10. The method of any of 1-9, wherein the hydrogel degrades by no more than 10% (alternatively no more than 15%, 20%, or 25%) over a period ranging from 1 to 36 months after formation of the hydrogel in situ. One of skill in the art will immediately recognize that all ranges and values ​​between the stated boundaries are contemplated, e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36 months can all be used as upper or lower limits.

[0220] 11. After in situ hydrogel formation, 50% w / w at time points ranging from 1 to 20 months i The method of any of 1-10, wherein the drug is delivered. One of skill in the art will immediately recognize that all ranges and values ​​between the boundaries stated are contemplated, e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 months can all be used as upper or lower limits.

[0221] 12. After in situ hydrogel formation, 50% w / w at time points ranging from 1 to 20 months i The method of any of 1-11, wherein the hydrogel is degraded. One of skill in the art will immediately recognize that all ranges and values ​​between the stated boundaries are contemplated, and that, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 months can all be used as upper or lower limits.

[0222] 13. The method according to any one of 1 to 12, wherein the tissue and / or site of hydrogel formation is an eye, intracanalicular, sub-Tenon's, intracameral, vitreous, intrascleral, choroid, suprachoroidal, retina, subretinal, lens, tissue, lumen, space, potential space, inside an animal (human or other) or on the surface of an animal, an iatrogenic site, a site where tissue has been removed, a surgical site, cancerous tissue, cancerous tissue or nearby, dental tissue, gums, periodontium, paranasal sinuses, brain, within a blood vessel, an aneurysm, or a diseased site.

[0223] 14. The method according to any one of 1 to 13, wherein the drug is for treating an ocular fundus disease.

[0224] 15. The method according to 14, wherein the ocular fundus disease is age-related macular degeneration (AMD), cystoid macular edema (CME), diabetic macular edema (DME), posterior uveitis, diabetic retinopathy, retinal vascular occlusion, or glaucoma.

[0225] 16. The method according to any one of 1 to 15, wherein the tissue is a retina, a lens, a cornea, or a sclera.

[0226] 17. The method of any one of 1 to 16, wherein the drug comprises an anti-VEGF agent, a VEGFR1 blocker, a VEGFR2 blocker, a VEGFR3 blocker, an anti-PDGF agent, an anti-PDGF-R agent, a PDGFRβ blocker, an anti-angiogenic agent, sunitinib, E7080, Takeda-6d, tivozanib, regorafenib, sorafenib, pazopanib, axitinib, nintedanib, cediranib, vatalanib, motesanib, a macrolide, sirolimus, everolimus, a tyrosine kinase inhibitor (TKI), imatinib (Gleevec), gefitinib (Iressa), toceranib (Palladia), erlotinib (Tarceva), lapatinib (Tykerb), nilotinib, bosutinib, neratinib, lapatinib, or vatalanib. Also herein, the drug is a steroid, a nonsteroidal anti-inflammatory drug, an antibiotic, or an analgesic.

[0227] 18. The method of any of 1-17, wherein the medicament comprises a poorly soluble prostaglandin analogue for glaucoma, nepafenac for uveitis, or a macrolide such as rapamycin, sirolimus, or tacrolimus to block the mTOR receptor for AMD / CNV.

[0228] 19. The method of any of 1-18, wherein the drug is in suspension (liquid or solid) in a hydrogel, e.g., particulate drug or droplet drug, the particles or droplets are microscale (1-500 microns in diameter) and / or nanoscale (less than 1 micron in diameter).

[0229] 20. The method according to any one of 1 to 19, wherein the drug is dispersed throughout the hydrogel.

[0230] 21. The method of any of 1-20, wherein the volume of the hydrogel is 1-1000 μL. One of skill in the art will immediately recognize that all ranges and values ​​between the stated boundaries are contemplated, e.g., 1, 10, 20, 50, 100, 200, 300, 400, 500, 900, 1000 μL can all be used as upper or lower limits.

[0231] 22. The method of any of 1-21, wherein the hydrogel is a first hydrogel and the method further comprises forming a second hydrogel in situ with a second agent in the second hydrogel, the second agent optionally having low water solubility.

[0232] 23. The method of claim 22, wherein the first agent and the second agent have the same active ingredient.

[0233] 24. The method of 22 or 23, wherein the first and second agents have different enantiomers, salts, or free bases.

[0234] 25. The method of 22 or 23, wherein the first agent and the second agent have the same chemical structure.

[0235] 26. The method of any of 22 to 25, wherein the first hydrogel releases the drug more quickly than the second hydrogel.

[0236] 27. The method of any of 22 to 26, wherein the first hydrogel has a larger surface area than the second hydrogel.

[0237] 28. The method of any of 22-27, wherein the first hydrogel provides a faster rate of drug diffusion compared to the second hydrogel.

[0238] 29. The method of any of 22 to 28, wherein the first agent and the second agent are different chemical moieties.

[0239] 30. The method of any of 22-29, wherein the hydrogel is formed by combining a first precursor and a second precursor that react with each other to form the hydrogel.

[0240] 31. The method of claim 30, wherein the hydrogel is formed without covalent crosslinking between the first precursor and the second precursor.

[0241] 32. The method of any of 1-31, wherein the hydrogel is formed by combining a first precursor that includes nucleophilic groups with a second precursor that includes electrophilic groups, and forming covalent crosslinks by reaction between the nucleophilic and electrophilic groups to form the hydrogel.

[0242] 33. The method of any of 30-32, comprising injecting an aqueous mixture of precursors into the site.

[0243] 34. The method according to any one of 30 to 33, wherein the first precursor and the second precursor are hydrophilic.

[0244] 35. The method according to any one of 30 to 34, wherein the first precursor and / or the second precursor comprises a poly(ethylene) glycol repeat sequence.

[0245] 36. The method of any one of 1 to 35, further comprising hyaluronic acid or a hydrophilic polymer that does not form part of the hydrogel matrix.

[0246] 37. A method according to any one of 1 to 36, comprising activating a precursor to form a hydrogel.

[0247] 38. The method of any of 1-37, comprising mixing a plurality of precursors to initiate a chemical reaction between the plurality of precursors, wherein the plurality of precursors react with each other to form a hydrogel.

[0248] 39. The method of any of 32-38, wherein the precursors are activated and / or mixed before, after, or during placement at the site.

[0249] 40. The method according to any one of 1 to 39, further comprising a buffering agent.

[0250] 41. The method of claim 40, wherein the buffer is a solid.

[0251] 42. The method of claim 41, wherein the solid is disposed within an applicator for depositing the hydrogel precursor at the site, and the precursor contacts the solid as it passes through the applicator.

[0252] 43. The method of any of 41 or 42, wherein the solid is disposed within a lumen of an applicator that receives the precursor, within the hub of a needle, within a syringe, or a pellet disposed within the applicator.

[0253] 44. The method according to any one of claims 40 to 43, wherein the buffer solution contains a phosphate, a bicarbonate, or a carbonate.

[0254] 45. The method of any one of 1 to 44, wherein the site and / or tissue is a tumor, damaged tissue, diseased tissue, infected tissue, organ, blood vessel, adventitia, artery, vein, or nerve.

[0255] 46. ​​The method of any of 1 to 45, wherein the hydrogel is elongated, ellipsoidal, spherical, substantially spherical, oval, cylindrical, substantially cylindrical, disc-shaped, or substantially disc-shaped.

[0256] 47. The method of any one of 1 to 46, wherein the agent is delivered in an effective amount or a calculated effective amount.

[0257] 51. A hydrogel implant comprising a therapeutic agent (e.g., dissolved, suspended, or dispersed throughout) in the hydrogel, the agent having low or poor water solubility in water. The site may be, for example, within the eye, within an ocular tissue, within the eye chamber, or within the vitreous.

[0258] 52. The hydrogel according to 51, wherein the hydrogel is water-degradable as can be measured by the hydrogel being dissolvable in vitro in an excess amount of water by decomposition of the water-degradable groups.

[0259] 53. The hydrogel according to 51 or 52, wherein the hydrogel remains substantially intact until the drug is substantially released.

[0260] 54. The hydrogel of 51 or 52, wherein 50%-100% w / w of the drug is released when the hydrogel is 100%-90% sustained (one skilled in the art will immediately recognize that all ranges and values ​​between the stated boundaries are contemplated, e.g., 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 99%, e.g., 90%-99%, or 55%-99%, can all be used as upper or lower limits). Alternatively, when the hydrogel is 100%-80% sustained.

[0261] 55. The hydrogel of any of 51-54, wherein the hydrogel delivers a drug at a therapeutically effective concentration for a period ranging from 1-36 months from formation of the hydrogel in situ. One of skill in the art will readily recognize that all ranges and values ​​between the boundaries specified are contemplated, e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36 months can all be used as upper or lower limits. Shorter periods of time, e.g., 1 to 31 days, can also be used; one of skill in the art will immediately recognize that all ranges and values ​​between the stated boundaries are contemplated, e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 20, 25, 30, or 31 days can all be used as upper or lower limits.

[0262] 56. The hydrogel according to 55, after which period the hydrogel has released all of the drug and is at least 80% sustained.

[0263] 57. The hydrogel according to 55, after which period the hydrogel releases an amount of the drug that is non-toxic.

[0264] 58. The hydrogel of 55 or 57, wherein after that period of time, the hydrogel delivers a final 1%-20% w / w of drug. One of skill in the art will immediately recognize that all ranges and values ​​between the boundaries specified are contemplated, e.g., 1, 2, 3, 4, 5, 10, 15, 16, 17, 18, 19% w / w can all be used as upper or lower limits.

[0265] 59. The hydrogel of any of 1-8, wherein the hydrogel delivers a final 1%-20% w / w of drug upon degradation of the hydrogel. One of skill in the art will immediately recognize that all ranges and values ​​between the boundaries specified are contemplated, e.g., 1, 2, 3, 4, 5, 10, 15, 16, 17, 18, 19% w / w can all be used as upper or lower limits.

[0266] 60. The method of any of 51-59, wherein the hydrogel degrades by no more than 10% (or degrades by no more than 15%, 20%, or 25%) over a period ranging from 1 to 36 months after formation of the hydrogel in situ. One of skill in the art will immediately recognize that all ranges and values ​​between the stated boundaries are contemplated, e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36 months can all be used as upper or lower limits.

[0267] 61. After in situ hydrogel formation, 50% w / w at time points ranging from 1 to 20 months i 61. The hydrogel of any of 51 to 60, wherein the drug is delivered in an amount of 51 to 60. One of skill in the art will readily recognize that all ranges and values ​​between the boundaries set forth are contemplated, and that, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 months can be used as an upper or lower limit.

[0268] 62. After in situ hydrogel formation, 50% w / w at time points ranging from 1 to 20 months i 62. The hydrogel of any of 51-61, wherein the hydrogel degrades after 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 months. One of skill in the art will readily recognize that all ranges and values ​​between the boundaries stated are contemplated, and that any of the following can be used as upper or lower limits, for example: 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 months.

[0269] 63. The hydrogel according to any one of 51 to 62, wherein the tissue and / or site of hydrogel formation is the eye, intracanalicular, sub-Tenon's, intracameral, vitreous, intrascleral, choroid, suprachoroidal, retina, subretinal, lens, tissue, lumen, space, potential space, inside an animal (human or other) or on the surface of an animal, an iatrogenic site, a site where tissue has been removed, a surgical site, cancerous tissue, cancerous tissue or its vicinity, dental tissue, gums, periodontium, paranasal sinuses, brain, within a blood vessel, an aneurysm, or a diseased site.

[0270] 64. The hydrogel described in any one of 51 to 63, wherein the drug is for treating an ocular fundus disease.

[0271] 65. The hydrogel according to 64, wherein the ocular fundus disease is age-related macular degeneration (AMD), cystoid macular edema (CME), diabetic macular edema (DME), posterior uveitis, diabetic retinopathy, retinal vascular occlusion, or glaucoma.

[0272] 66. The hydrogel described in any one of 51 to 65, wherein the tissue is a retina, a lens, a cornea, or a sclera.

[0273] 67. The drug is an anti-VEGF agent, a VEGFR1 blocker, a VEGFR2 blocker, a VEGFR3 blocker, an anti-PDGF agent, an anti-PDGF-R agent, a PDGFRβ blocker, an anti-angiogenic agent, sunitinib, E7080, Takeda-6d, tivozanib, regorafenib, sorafenib, pazopanib, axitinib, nintedanib, cediranib, vatalanib, motesanib, 67. The hydrogel according to any one of 51 to 66, comprising a macrolide, sirolimus, everolimus, a tyrosine kinase inhibitor (TKI), imatinib (Gleevec), gefitinib (Iressa), toceranib (Palladia), erlotinib (Tarceva), lapatinib (Tykerb), nilotinib, bosutinib, neratinib, lapatinib, or vatalanib, wherein the drug is a steroid, a nonsteroidal anti-inflammatory drug, an antibiotic, or an analgesic.

[0274] 68. The hydrogel according to any one of 51 to 67, wherein the drug comprises a poorly soluble prostaglandin analogue for glaucoma, nepafenac for uveitis, or a macrolide such as rapamycin, sirolimus, or tacrolimus for blocking the mTOR receptor for AMD / CNV.

[0275] 69. The hydrogel according to any one of 51 to 68, wherein the drug is in suspension (liquid or solid) in the hydrogel, e.g., the drug in particulate form or in droplet form, the particles or droplets are microscale (1 to 500 microns in diameter) and / or nanoscale (less than 1 micron in diameter).

[0276] 70. The hydrogel described in any one of 1 to 19, wherein the drug is dispersed throughout the hydrogel.

[0277] 71. The hydrogel of any of 1-70, wherein the volume of the hydrogel is 1-1000 μL. One of skill in the art will immediately recognize that all ranges and values ​​between the boundaries specified are contemplated, e.g., 1, 10, 20, 50, 100, 200, 300, 400, 500, 900, 1000 μL can all be used as upper or lower limits.

[0278] 72. The hydrogel of any of 1-71, wherein the hydrogel is a first hydrogel, and the hydrogel further comprises forming a second hydrogel in situ with a second agent in the second hydrogel, the second agent optionally having low water solubility.

[0279] 73. The hydrogel according to 72, wherein the first agent and the second agent have the same active ingredient.

[0280] 74. The hydrogel according to 72, wherein the first and second drugs have different enantiomers, salts, or free bases.

[0281] 75. The hydrogel described in 72 or 73, wherein the first drug and the second drug have the same chemical structure.

[0282] 76. The hydrogel described in any one of 72 to 75, wherein the first hydrogel releases the drug more quickly than the second hydrogel.

[0283] 77. The hydrogel according to any one of 72 to 76, wherein the first hydrogel has a larger surface area than the second hydrogel.

[0284] 78. The hydrogel described in any of 72 to 77, wherein the first hydrogel provides a faster rate of drug diffusion compared to the second hydrogel.

[0285] 79. The hydrogel described in any one of 72 to 78, wherein the first agent and the second agent are different chemical moieties.

[0286] 80. The hydrogel according to any of 72-79, wherein the hydrogel is formed by combining a first precursor and a second precursor that react with each other to form the hydrogel.

[0287] 81. The hydrogel according to 80, wherein the hydrogel is formed without covalent crosslinking between the first precursor and the second precursor.

[0288] 82. The hydrogel according to any one of 1-81, wherein the hydrogel is formed by combining a first precursor containing nucleophilic groups with a second precursor containing electrophilic groups, and forming covalent crosslinks by reaction between the nucleophilic groups and the electrophilic groups to form the hydrogel.

[0289] 83. The hydrogel described in any of 80 to 82, comprising a step of injecting an aqueous mixture of precursors into the site.

[0290] 84. The hydrogel according to any one of 80 to 83, wherein the first precursor and the second precursor are hydrophilic.

[0291] 85. The hydrogel according to any one of 80 to 84, wherein the first precursor and / or the second precursor comprises a poly(ethylene) glycol repeat sequence.

[0292] 86. The hydrogel according to any one of 51 to 85, further comprising hyaluronic acid or a hydrophilic polymer that does not form part of the hydrogel matrix.

[0293] 87. The hydrogel according to any one of 51 to 86, comprising activating a precursor to form a hydrogel.

[0294] 88. The hydrogel according to any one of 51 to 87, comprising mixing a plurality of precursors to initiate a chemical reaction between the plurality of precursors, wherein the plurality of precursors react with each other to form the hydrogel.

[0295] 89. The hydrogel according to any one of 82 to 88, wherein the precursors are activated and / or mixed before, after, or during placement at the site.

[0296] 90. The hydrogel described in any one of 81 to 88, further comprising a buffer agent.

[0297] 91. The hydrogel according to 90, wherein the buffer is a solid.

[0298] 92. The hydrogel according to 91, wherein the solid is disposed within an applicator for disposing the hydrogel precursor at the site, and the precursor contacts the solid as it passes through the applicator.

[0299] 93. The hydrogel of any of 91 or 92, wherein the solid is disposed within a lumen of an applicator that receives the precursor, within the hub of a needle, within a syringe, or a pellet that is disposed within the applicator.

[0300] 94. The hydrogel according to any one of 90 to 93, wherein the buffer solution contains a phosphate, a bicarbonate, or a carbonate.

[0301] 95. The hydrogel according to any one of 1 to 94, wherein the site and / or tissue is a tumor, damaged tissue, diseased tissue, infected tissue, organ, blood vessel, adventitia, artery, vein, or nerve.

[0302] 96. The hydrogel according to any one of 1 to 95, wherein the hydrogel is elongated, elliptical, spherical, substantially spherical, oval, cylindrical, substantially cylindrical, disc-shaped, or substantially disc-shaped.

[0303] 97. A hydrogel described in any one of 1 to 96, wherein the drug is delivered in an effective amount or a calculated effective amount.

[0304] 98. Use of a method or hydrogel according to any one of 1 to 97.

[0305] 99. Use of a method or hydrogel according to any one of 1 to 97 for delivery of an effective amount of a drug, for example for treating a disease, for example for treating an eye disease according to any one of 1 to 97.

[0306] 100. Use of a method or hydrogel according to any of 1-97 for delivery of an effective amount of a drug to a tissue, for example to treat a disease.

[0307] 101. An agent as described in any one of 1 to 97 for the treatment of a condition as described in any one of 1 to 97. Use of an agent as described in any one of 1 to 97 for the treatment of a condition as described in any one of 1 to 97.

[0308] 102. A kit combining a precursor and an agent as described in any one of 1 to 101 or as described herein.

[0309] 103. A kit for any method, use, or agent according to any one of 1 to 101, comprising a combination of a precursor and an agent.

[0310] 104. A process for producing a kit according to any one of 102 to 103.

[0311] A process for producing a hydrogel according to any one of 105.51 to 97.

[0312] The process according to 105, including any of the methods described in 106.1 to 49.

[0313] 107. The process according to 105, comprising the step of preparing a precursor according to any of the present invention or 1-97.

[0314] 108. The process according to 107, further comprising the step of adding a drug to the precursor.

[0315] A process for producing a pharmaceutical product, comprising a step of producing a hydrogel according to any one of 109.51 to 97, or comprising a method according to any one of 1 to 50.

[0316] 110. A process according to 109 for treating a condition, for example a condition described herein or in any of 1-97.

[0317] Many embodiments are described herein. In general, the components of the embodiments can be mixed and matched with each other according to the guidelines of the need to produce a functional embodiment. The patent applications, patents, journal articles, and publications described herein are incorporated by reference. In the event of a conflict, the present specification will control.

Claims

1. 1. A method of manufacturing a medical material for intraocular injection, comprising: forming a solution by combining a first precursor comprising a nucleophilic group, a second precursor comprising an electrophilic group, a therapeutic agent, a buffer, and an aqueous diluent, comprising forming a covalently crosslinked hydrogel having the therapeutic agent dispersed therein; The method of claim 1, wherein the first precursor comprises a plurality of arms having amine-terminated HCl salt polyethylene glycol and the second precursor comprises poly(ethylene glycol) arms terminated with electrophilic groups.

2. 2. The method of claim 1, wherein the first precursor and the second precursor each independently comprise a multi-arm poly(ethylene glycol)-containing precursor.

3. The method of claim 1 or 2, wherein the first precursor has 4-8 arms and a molecular weight of 5,000-50,000 Daltons.

4. The method of any one of claims 1 to 3, wherein the first precursor, the second precursor, the therapeutic agent, and / or the buffering agent are provided as powders.

5. The method of any one of claims 1 to 4, wherein the first precursor, the second precursor, and the therapeutic agent are provided as a lyophilized mixture.

6. The method according to any one of claims 1 to 5, wherein the buffer is a phosphate, bicarbonate or carbonate.

7. The method according to any one of claims 1 to 6, wherein the pH of the solution is from 6.8 to 7.

2.

8. The method of claim 1, further comprising adjusting the pH of the solution to be between 6.8 and 7.

2.

9. The method of any one of claims 1 to 8, wherein the hydrogel is formed in the eye in 2 to 5 minutes.

10. 10. The method of any one of claims 1 to 9, further comprising combining a first precursor comprising a nucleophilic group, a second precursor comprising an electrophilic group, a therapeutic agent, a buffer, and an aqueous diluent to form a solution.

11. The method of any one of claims 1 to 10, further comprising adding hyaluronic acid or a hydrophilic polymer to the solution that does not form part of the matrix of the hydrogel.

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