Biodegradable thermoplastic poly(ortho ester)-based multiblock copolymers

Abstract

The present invention relates to a biodegradable thermoplastic multiblock copolymer, a method for preparing the biodegradable thermoplastic multiblock copolymer, a use of the biodegradable thermoplastic multiblock copolymer, a composition for delivering at least one biologically active compound to a host, and a medical device comprising the biodegradable thermoplastic multiblock copolymer. The biodegradable thermoplastic multiblock copolymer of the present invention comprises at least one prepolymer (A) segment and at least one hydrolyzable amorphous prepolymer (B) segment, both segments being linked by a multifunctional chain extender, the prepolymer (A) segment a) comprises one or more hydrolyzable bonds, and / or b) comprises a water-soluble polymer, and the hydrolyzable amorphous prepolymer (B) segment comprises a specific poly(orthoester) block.

Description

[Technical field]

[0001] The present invention relates to biodegradable thermoplastic multiblock copolymers, to methods for preparing biodegradable thermoplastic multiblock copolymers, to uses of the biodegradable thermoplastic multiblock copolymers, to compositions for delivering at least one biologically active compound to a host, and to medical devices comprising the biodegradable thermoplastic multiblock copolymers. [Background technology]

[0002] Peptides and proteins, collectively known as polypeptides, play important roles in all biological processes and have attracted increasing attention in recent years as potential pharmaceutical drugs. Rapid advances in peptide and protein pharmacology and the mass production of these compounds by recombinant DNA technology, among other techniques, have increased interest in these compounds. Unfortunately, the development of peptides and proteins has far outpaced the ability to deliver these compounds systemically or locally using convenient and effective delivery systems.

[0003] Biodegradable polymers have received increasing attention in the past decade for use in long-acting parenteral controlled release systems for systemic or site-specific drug delivery. Biodegradable controlled release formulations can significantly improve the pharmacokinetics of therapeutic compounds. This is especially true for the treatment of chronic diseases or for compounds with narrow therapeutic windows, as they can lower systemic plasma concentrations while simultaneously reducing undesirable side effects. Furthermore, many new biologically active compounds have short half-lives, necessitating frequent injections to achieve therapeutically effective plasma levels. Increased patient compliance and the high costs associated with frequent dosing regimens for biologically active compounds administered parenterally have led to increased interest in biodegradable sustained release dosage forms.

[0004] Poly(D,L-lactic acid) (PDLLA) and copolymers of lactic and glycolic acid (PLGA) are the most widely used biodegradable polymers for use in parenteral sustained release depot formulations. The advantage of these polymers is that they have a proven track record of clinical use, are generally considered to be highly biocompatible, and are degraded into non-toxic degradation products that are metabolized and / or excreted from the body by known pathways. As a result, PLGA, PDLLA, and related (co)polymers have been adopted and used effectively by pharmaceutical companies for the development of long-acting injectable and implantable depot formulations of small molecules such as risperidone (Risperdal® Consta), dexamethasone (Ozurdex®), triamcinolone acetonide (Zilretta®), and therapeutic peptides such as leuprolide (Lupron® Depot), goserelin (Zoladex®), and octreotide (Sandostatin® LAR). However, PLGA polymers exhibit certain physicochemical and degradation properties that limit their use and make them less suitable for sustained release delivery of polypeptides. First, PLGA copolymers are relatively hydrophobic and therefore do not provide an optimal environment for hydrophilic or amphiphilic polypeptides. The polypeptides may adsorb to the polymer resulting in slow or incomplete release, disorganization, and / or aggregation. Second, the ability to engineer the release of encapsulated polypeptides, especially larger polypeptides such as (recombinant) proteins, growth factors, or (monoclonal) antibodies, is limited by the negligible diffusion of such polypeptides through the relatively rigid, hydrophobic, non-swelling PLGA matrix. Thus, release of polypeptides from PLGA copolymers depends on diffusion through pores present in the matrix and degradation of the polymer matrix. Typically, the encapsulated polypeptides remain trapped in the PLGA matrix until the PLGA matrix degrades and loses its integrity or dissolves. This results in the biphasic or triphasic degradation-dependent release typically observed with PLGA-based sustained release polypeptide formulations.Finally, acidic components are formed during the degradation of PLGA copolymers, which accumulate in the rigid, non-swelling PLGA matrix, resulting in the formation of an acidic microenvironment within the polymer matrix with an in situ pH of 1-2. Such acidic conditions can have detrimental effects on the structural integrity and biological activity of encapsulated polypeptides, leading to reduced therapeutic efficacy and side effects. Encapsulated polypeptides may form aggregates, leading to incomplete release and enhanced immunogenicity. Furthermore, polypeptides may be chemically modified. Peptide acylation and adduct formation have been reported for PLGA-based sustained release polypeptide formulations, e.g., Sandostatin® LAR sustained release octreotide microparticles (Ghassemi et al., Pharm. Res. 2012, 29(1), 110-20).

[0005] The limitations of PLGA-based amorphous polymers for polypeptide delivery can be overcome by using biodegradable polyester-based polymers that contain hydrophilic water-swellable polymeric moieties in their structure. WO2005 / 068533 describes amorphous polyetherester multiblock copolymers that contain water-soluble polyethylene glycol (PEG) units. These amorphous multiblock copolymers have a low glass transition temperature Tg of less than 37°C under physiological conditions, and are therefore permeable not only to low molecular weight polypeptides such as leuprolide, but also to acidic degradation products generated during hydrolysis of the polymer. As a result, a slow release of such polypeptides and the (acidic) degradation products formed can be achieved, thereby preventing the accumulation of acidic degradation products in the polymer matrix and the formation of an acidic microenvironment.

[0006] Although the amorphous multiblock copolymers disclosed in WO2005 / 068533 are useful for sustained release of small molecule drugs and low molecular weight peptides, they are not suitable for sustained release of larger polypeptides such as recombinant proteins and monoclonal antibodies. This is due to the fact that small high molecular weight segments of water-soluble PEG need to be introduced into the amorphous multiblock copolymers in order to form a polymer matrix with sufficient swelling to allow diffusion-controlled release of the encapsulated large polypeptides. However, the introduction of small high molecular weight segments of PEG into the structure of such amorphous multiblock copolymers significantly reduces the Tg value below room temperature, even below 0°C. Amorphous multiblock copolymers with such low Tg usually have processability problems (sticky polymers) and cannot be processed into solid drug delivery formulations such as microspheres or implants. Furthermore, sustained release drug delivery products obtained from such low Tg amorphous multiblock copolymers are likely to have stability problems and insufficient shelf life when stored under room temperature or refrigerated conditions.

[0007] To overcome the shortcomings of amorphous multiblock copolymers, the present inventors have developed biodegradable phase-separated thermoplastic segmented multiblock copolymers that combine crystalline poly(ε-caprolactone) blocks (described in WO2012 / 005594) or crystalline poly(L-lactide) blocks (described in WO2013 / 015685) with PEG-containing hydrophilic blocks. Such multiblock copolymers allow the preparation of depot formulations that provide sustained release of structurally intact biologically active polypeptides over long periods of time.

[0008] Hydrophilic phase-separated segmented multiblock copolymers containing hydrophobic poly(ε-caprolactone)-based crystalline blocks, as disclosed in WO2012 / 005594, were found to be well processable into implants by hot melt extrusion, allowing for long-term sustained release of peptides and proteins (Stankovic et al., Eur. J. Pharm. Sci. 2013, 49(4), 578587). Hydrophilic phase-separated segmented multiblock copolymers containing hydrophobic poly(L-lactide)-based crystalline blocks, as disclosed in WO2013 / 015685, were shown to have highly beneficial characteristics for protein delivery. In particular, multiblock copolymers composed of a combination of poly(ε-caprolactone)-PEG-poly(ε-caprolactone)-based hydrophilic blocks and poly(L-lactide)-based crystalline blocks (PCL multiblock copolymers) have been found to exhibit promising characteristics that enable long-term sustained release of structurally intact biologics when formulated into microparticles (Teekamp et al., Int. J. Pharm. 2017, 534(12), 229236;Teekamp et al., J. Control Release 2018, 269, 258265;Scheiner et al., ACS Omega 2019, 4(7), 1148111492).

[0009] Furthermore, the authors found that the degradation time of biodegradable phase-separated thermoplastic multiblock copolymers containing poly(L-lactide) crystalline blocks was 3-4 years. Multiblock copolymers containing poly(ε-caprolactone) crystalline blocks are expected to have longer degradation times. Most sustained release drug delivery formulations have such unacceptably long degradation times that repeated injections may lead to polymer accumulation and long-term tolerability issues. Depending on the release period, multiblock copolymers with shorter degradation times, such as degradation times of about 0.5-1.5 years, are desirable. Furthermore, most of the semi-crystalline poly(L-lactide)-based multiblock copolymers disclosed in WO2013 / 015685 have high melting points (120-140 °C), which require high temperatures for processing into implants by hot melt extrusion, injection molding, or 3D printing, which may lead to thermal stress-induced degradation of the introduced drugs. Finally, the hardening of microspheres prepared from semicrystalline poly(L-lactide)-based multiblock copolymers by solvent extraction / evaporation-based emulsion process or spray drying is highly dependent on the crystallization rate of the semicrystalline block. Multiple factors such as polymer concentration, solvent removal rate, type of active pharmaceutical ingredient, and temperature greatly affect the crystallization rate of the polymer during microsphere production, so small changes in these parameters can dramatically affect the hardening of the microspheres. As a result, the production of microspheres using these polymers is accompanied by challenges in terms of reproducibility, scale-up, and storage stability. At the same time, it would be beneficial to maintain the excellent tunability of drug release kinetics reported for poly(L-lactide) and poly(ε-caprolactone)-based multiblock copolymers disclosed in WO2013 / 015685 and WO2012 / 005594.

[0010] The above-mentioned disadvantages of using semi-crystalline polymers can be overcome by using amorphous polymers to prepare long-acting injectable formulations. However, as mentioned above, typical amorphous biodegradable polyesters, including the amorphous multiblock copolymers disclosed in WO2005 / 068533 that allow sustained release of polypeptides, do not have the necessary thermomechanical properties to obtain a solid, stable, long-acting injectable formulation.

[0011] The redesign of SynBiosys® PCL multiblock copolymers was carried out in an attempt to avoid polymer accumulation upon repeated administration and to shorten the polymer erosion time to improve long-term local tolerability. To overcome the reproducibility and stability issues associated with polymer crystallization, amorphous prepolymers (B) were designed to replace the crystalline poly(L-lactide) and poly(ε-caprolactone)-based prepolymer (B) segments disclosed in WO2013 / 015685 and WO2012 / 005594.

[0012] However, in order to obtain a multiblock copolymer with a Tg high enough to be processed into a stable solid drug delivery formulation under ambient storage conditions, the amorphous prepolymer (B) segment, which is considered to replace the crystalline prepolymer (B) segment such as poly(L-lactide), must exhibit a sufficiently high Tg to compensate for the low Tg prepolymer segment (A), e.g., the prepolymer (A) segment containing a relatively large amount of ε-caprolactone or polyethylene glycol, and if phase mixing of the amorphous prepolymer (A) segment with the amorphous prepolymer (B) segment occurs as reported in the amorphous multiblock copolymer disclosed in WO2005 / 068533. The prepolymer blocks used in the amorphous multiblock copolymers of WO2005 / 068533 have a relatively low Tg, so that the resulting amorphous multiblock copolymers exhibit Tg values ​​in the range of -24°C to 21.4°C. This Tg is usually too low to obtain a stable pharmaceutical product during storage at room temperature or under refrigerated conditions. Preferably, amorphous polymers used in drug delivery products should have a Tg significantly above the intended storage conditions to minimize relaxation of the polymer chains and thereby prevent migration of the active compound incorporated within the polymer matrix. Preferably, the Tg of such amorphous polymers should be about 40° C. or higher.

[0013] Thus, there remains a need for biodegradable polymers that overcome one or more of the shortcomings of prior art polymers and are more suitable for delivery of polypeptides. More specifically, such polymers should preferably be (i) amorphous and have a glass transition temperature high enough to ensure product stability under desired storage conditions, (ii) compatible with polypeptides and allow sustained release of intact and biologically functional polypeptides, and (iii) have an acceptable erosion rate. Furthermore, it is desirable that such new biodegradable delivery systems for polypeptides be designed from prepolymers composed of well-known, biologically safe, and clinically acceptable monomers.

[0014] Poly(orthoesters) are used as biodegradable polymeric excipients in injectable and implantable sustained release drug delivery products. In contrast to poly(L-lactide)-based polymers, poly(orthoesters) are amorphous. They are usually prepared by the reaction of 3,9-diethylidene-2,4,8,10-tetraoxaspiro[5.5]undecane (DETOSU) with diols. Due to their hydrophobic properties, they degrade very slowly under physiological conditions. To hasten their degradation and make them suitable for human and animal drug delivery applications, short latent acid segments based on glycolic acid or lactic acid were incorporated into the structure of DETOSU-based poly(orthoesters) (Ng et al., Macromolecules 1997, 30(4), 770772; US5968543). When the latent acid segments are hydrolyzed, glycolic acid or lactic acid is formed, which catalyzes the hydrolysis of the orthoester units in the polymer chain. The degradation rate of the poly(orthoester) can be tuned by adjusting the latent acid content in the polymer backbone. Besides the degradation rate, the thermal and mechanical properties of the poly(orthoester) can be altered by varying the type and content of diol in the structure of the poly(orthoester) (US5968543). By replacing the rigid diols with more flexible analogues, materials with lower Tg and wax-like properties are obtained. The structure of the poly(orthoester) can be further diversified by adding hydrophilic diols (triethylene glycol and PEG) to the reaction mixture. The more hydrophilic the diol, the higher the water absorption. As a result, the polymers whose degradation is faster (US5968543, WO2006 / 105148; Ng et al., J. Controlled Release 2000, 65(3), 367374) become suitable matrices for the preparation of sustained release formulations in the form of microspheres, implants, films, ointments, or in situ forming implants for the delivery of low molecular weight drugs and large molecules such as proteins and DNA molecules.Ng et al. (J. Controlled Release 2000, 65(3), 367-374) demonstrated that the release of 5-fluorouracil from poly(orthoester) films could be tuned by varying the content of hydrophilic triethylene glycol and glycolide units in the poly(orthoester) backbone. Similarly, the incorporation of small amounts of PEG into poly(orthoester) accelerated the release of bovine serum albumin and shortened the lag phase of its release (Rothen-Weinholod et al., J. Controlled Release 2001, 71(1), 3137). Wang et al. (Nature Materials 2004, 4(3), 190-196) demonstrated that the incorporation of small amounts of tertiary amine units (methyldiethanolamine) into the polymer backbone allowed for pH-tunable release of DNA plasmids from polymer microspheres. Thus, the release of DNA at low pH was extended compared to polymers without tertiary amine units.

[0015] Their tunable degradation and excellent biocompatibility have led this group of materials to achieve successful results in clinical trials, resulting in the launch of several products (Sustol® and Zynrelef) into the market. Currently, commercially available poly(orthoester)-based drug delivery products are primarily used in the form of low molecular weight semi-solid materials with or without the addition of biocompatible solvents (WO2014 / 143635; Heller et al., J. Controlled Release 2002, 78(13), 133141).

[0016] US2014 / 0113975 discloses relatively low molecular weight biodegradable AB diblock and BAB or ABA triblock copolymers for application as flowable liquid drug delivery systems to improve drug delivery. The copolymers in US2014 / 0113975 are composed of biodegradable ABA, BAB, and AB block copolymers based on PEG, PEG derivatives, or mixtures of PEG and PEG derivatives, and biodegradable hydrophobic polyester or poly(orthoester) A blocks and PEG B blocks. According to US2014 / 0113975, high molecular weight polyesters of the ABA, BAB, and AB block copolymers can be synthesized by ring-opening polymerization, but high molecular weight poly(orthoester) A blocks cannot be obtained by following the addition reaction-based synthetic route used in Examples 12 and 13 of US2014 / 0113975. Due to the nature of the addition reaction used to synthesize the poly(ortho ester) A blocks, it is difficult to reproducibly prepare well-controlled high molecular weight polymers with tunable hydrophobic / hydrophilic block composition, which is a significant limitation. In particular, the triblock copolymers of US2014 / 0113975 are limited to those with central (ABA) or peripheral (BAB) hydrophilic blocks.

[0017] The main advantage of poly(orthoesters) over other amorphous polymer systems is the ability to produce materials with Tg as high as 90° C. However, the incorporation of acidic moieties, hydrophilic aliphatic diols, or PEG units, which are critical to obtain polymers with acceptable degradation kinetics, can significantly reduce the Tg to values ​​below room temperature. For example, the swellable and / or fast degrading poly(orthoesters) described in US5968543, WO2006 / 105148, and US2014 / 0113975 lack a high enough Tg to allow long-term storage of preformed drug delivery products, such as microparticle or solid implant-based drug delivery products, under ambient conditions.

[0018] The physicochemical properties of a polymer can be greatly influenced by the monomer distribution within the copolymer. Poly(orthoesters) described in US5968543 and WO2006 / 105148 are prepared by reacting diketene acetals with diols. This reaction mechanism results in a random distribution of diol units in the polymer backbone. Due to the random distribution of diol units, the polymer properties cannot be controlled, which is a major drawback when further optimization of drug delivery formulations prepared from this polymer is required. It is highly desirable to control the distribution of acidic and / or hydrophilic moieties in the polymer backbone, for example to allow for more block-like incorporation of the moieties. This provides a broader and more versatile tool kit for customizing polymer properties and improving drug release and degradation kinetics.

[0019] Furthermore, the synthesis of poly(ortho esters) involves a step-growth reaction, which requires the presence of a diol in the reaction mixture. The nature of the step-growth reaction limits the types of functional groups that can be incorporated into the backbone. For example, the incorporation of poly(amino acid)-based segments into the poly(ortho ester) backbone can add additional functionality to the polymer to improve its interaction with proteins and peptides, but this is a difficult task to achieve. The production of poly(amino acid) diols that meet the requirements for the synthesis of poly(ortho esters) described in US5968543 and WO2006 / 105148 requires multiple synthesis steps, which can increase the number and level of impurities in the final poly(ortho esters).

[0020] The present invention relates to a multiblock copolymer comprising at least two prepolymer segments, one of which comprises a short poly(orthoester) block. The multiblock copolymer of the present invention is preferably amorphous in the dry state. More particularly, the copolymer of the present invention is a biodegradable multiblock copolymer in which at least two prepolymer segments are linked with a multifunctional chain extender. The multifunctional chain extender is preferably an aliphatic chain extender.

[0021] Compared to the semi-crystalline polymers of the prior art, the polymers of the present invention degrade faster and their degradation can be easily tuned by varying the composition of the blocks used in combination with the poly(ortho ester) blocks in the multiblock copolymers. Moreover, because they are composed of amorphous poly(ortho ester) blocks, they avoid the processability, reproducibility, and storage stability problems associated with crystallization.

[0022] In contrast to PLGA and PDLLA polymers, which degrade by bulk erosion, or the multiblock copolymers disclosed in WO2005 / 068533, the polymers of the present invention degrade primarily by surface erosion. This has the advantage that a slower mass loss occurs, resulting in a more constant drug release rate. Furthermore, the polymers disclosed in WO2005 / 068533 undergo hydrolysis under both basic and acidic conditions. This poses a major challenge when the encapsulated drug, such as risperidone, is highly basic. Basic nucleophilic (drug) molecules can catalyze the hydrolysis of ester bonds in the hydrated or dissolved state, causing degradation of the polymer during processing or storage (Wang et al., Adv. Drug Deliv. Rev. 2021, 178, 113912). As a result, important properties such as drug release kinetics can be affected. Unlike the polymers disclosed in WO2005 / 068533 or commonly used PLGA polymers, the poly(orthoester) blocks are stable to hydrolysis under basic conditions, and when basic (drug) molecules are encapsulated in poly(orthoester)-based polymer matrices, the degradation of the polymer is prevented. Furthermore, the high hydrophobicity of the poly(orthoester) blocks slows and limits the penetration of water into the polymer matrix, thus preventing bulk hydrolysis of the polymer matrix. Instead, the poly(orthoester)-based polymer matrix may exhibit surface erosion behavior, thereby enabling a slower surface erosion controlled release of the encapsulated drug molecules. Thus, the incorporation of poly(orthoester) blocks improves the stability of the biodegradable thermoplastic multiblock copolymer in the presence of highly basic drug molecules, making it easier to achieve a longer and more constant release of such drug molecules.

[0023] In the polymers disclosed in US5968543 and WO2006 / 105148, the acidic or hydrophilic moieties are randomly distributed in the polymer backbone, whereas in the polymers of the present invention, the acidic or hydrophilic moieties are introduced as blocks containing multiple acidic and / or hydrophilic moieties, resulting in a more block-like distribution. Multiblock copolymers consisting of (pre-prepared) blocks with different compositions and different physicochemical properties are more likely to phase separate. Such structures can achieve biphasic release patterns. For example, if one of the segments has low permeability and / or degrades slowly and the other segment has high permeability and / or degrades quickly, the encapsulated drug molecules will be released primarily from the highly permeable and / or rapidly degrading phase first, and then release of the encapsulated drug molecules in the phase with the lower permeability / degradation rate will begin to occur. By modifying the permeability and / or degradation rate of the two phases, the release rate of the drug from a particular phase can be controlled. Furthermore, phase separation is more likely with a more block-like structure as opposed to a random orientation of the monomer units within the polymer. It is known that above a certain block length, block copolymers undergo phase separation, with each block maintaining its own properties such as Tg, degradation rate, etc. Thus, the relatively high Tg of the poly(ortho ester) block is not significantly diminished by phase separation between the high Tg poly(ortho ester) block and other low Tg polymer blocks, so that the polymers of the present invention still exhibit good structural integrity.

[0024] Furthermore, the polymer of the present invention is prepared by chain extension reaction. In contrast to the synthesis procedures required for preparing the polymers disclosed in US5968543 and WO2006 / 105148, this chain extension reaction is not limited to the use of diol in the reaction mixture. In addition to the short polymer block terminated with diol, other types of difunctional blocks such as diacids and diamines can also be used, as long as they meet the requirement of being able to react with multifunctional chain extenders. Summary of the Invention [Means for solving the problem]

[0025] In a first aspect, the present invention provides a biodegradable thermoplastic multiblock copolymer comprising at least one prepolymer (A) segment and at least one hydrolyzable amorphous prepolymer (B) segment, Both segments are connected by a multifunctional chain extender, The prepolymer (A) segment is a) contains one or more hydrolyzable bonds; and / or b) a water-soluble polymer; The hydrolyzable amorphous prepolymer (B) segment relates to a biodegradable thermoplastic multiblock copolymer comprising the following structure: JPEG2025509813000001.jpg27144 (wherein n is 4 to 100, for example, 5 to 50, x is 0.25 to 1, and x + y is 1; p is 0 or 1; R1 and R2 are independently selected from hydrogen and C1-C4 alkyl; Q1 is Selected from JPEG2025509813000002.jpg33153, Q2 is Selected from JPEG2025509813000003.jpg26153, r is 1 to 100; s is 1 to 12, t is 1 to 10; R3 is selected from hydrogen and C1-C6 alkyl; R4 is selected from hydrogen and C1-C4 alkyl; R5 is Selected from JPEG2025509813000004.jpg52153, v is 1 to 100; w is 1 to 12; R6 is selected from hydrogen and C1-C6 alkyl.

[0026] In a further aspect, the present invention relates to a process for the preparation of the biodegradable thermoplastic multiblock copolymers of the present invention, comprising a chain extension reaction of prepolymer (A) with prepolymer (B) in the presence of a multifunctional chain extender.

[0027] In yet another aspect, the present invention relates to a composition for delivering at least one biologically active compound to a host, the composition comprising at least one biologically active compound encapsulated within a matrix, the matrix comprising at least one biodegradable thermoplastic multiblock copolymer of the present invention.

[0028] In yet another aspect, the present invention relates to a medical device in the form of a microsphere, microparticle, nanoparticle, nanosphere, rod, solid implant, gel, in situ forming implant, coating, film, sheet, spray, tube, membrane, mesh, fiber, scaffold or plug, said medical device comprising the biodegradable thermoplastic multiblock copolymer of the present invention. [Brief description of the drawings]

[0029] [Figure 1] In vitro erosion of polymer-only microspheres composed of 50CP10C20-LL40: Experimental data up to 12 months and extrapolation of experimental data to complete erosion. [Diagram 2] Molecular structure of diol-functional poly(ortho ester) prepolymers derived from DVTOSU and CHDM. [Diagram 3] Reaction scheme for the preparation of 20CP10C20-POE40. [Figure 4] SEM image of polymer-only microspheres prepared from 20CP10C20-POE40 (RCP 1679). [Diagram 5] In vitro erosion of polymer-only microspheres composed of 50CP10C20-LL40, 20CP10C20-POE40, and 50CP10C20-POE40. [Figure 6]Cumulative in vitro release of protein ICP002 from microspheres prepared from mixtures of 20CP10C20-POE40 and 50CP10C20-POE40 in the following ratios: 0 / 100 (PBD17-008), 33 / 67 (PBD17-027), 50 / 50 (PBD17-025), 67 / 33 (PBD17-024) and 100 / 0 (PBD17-011). The amount released is expressed as μg of ICP002 released in time. [Figure 7] Reaction scheme for the preparation of 20LP6L12-POE40. [Figure 8] Reaction scheme for the preparation of 10L40-POE40. [Figure 9] Reaction scheme for the preparation of 20GL40-POE40. [Figure 10] In vitro erosion of polymer-only microspheres composed of 100POE40, 10L40-POE40, 50L40-POE40, 25GL40-POE40, and 50LP10L20-POE40. [Figure 11] SEM images of ropivacaine-loaded microspheres prepared from 20L40-POE40 (210554), 20GL40-POE40 (210555), 50L40-POE40 (210556) and 20LP6L12-POE40 (210557). [Figure 12] Cumulative in vitro release of ropivacaine from microspheres prepared from 20L40-POE40, 20GL40-POE40, 50L40-POE40, and 20LP6L12-POE40. [Figure 13] Cumulative in vitro release of ropivacaine from NMP-based in situ forming implants composed of 20L40-POE40, 20GL40-POE40, 50L40-POE40, and 20LP6L12-POE40. [Figure 14] Cumulative in vitro release of levonorgestrel from NMP-based in situ forming implants composed of 10L40-POE40, 20L40-POE40, 20GL40-POE40, 50L40-POE40, and 20LP6L12-POE40. [Figure 15] Cumulative in vitro release of leuprolide from NMP / BB 90 / 10 w / w based in situ forming implants composed of 50L40-POE40, 20L40-POE40, and 20GL40-POE40. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] The term "prepolymer" as used herein means a polymer segment linked by a polyfunctional chain extender and which together constitutes the multiblock copolymer of the present invention. Each prepolymer is obtained by polymerization of a suitable monomer, which thus becomes the chemical unit of each prepolymer. The properties of the prepolymer, and therefore the properties of the multiblock copolymer of the present invention, can be controlled by, inter alia, selecting a prepolymer of appropriate composition and molecular weight.

[0031] As used herein, the terms "block" and "segment" refer to different regions in a multiblock copolymer. The terms "block" and "segment" are used interchangeably. As used herein, the term "multiblock" means that there are at least two different prepolymer segments in the polymer chain. The term "thermoplastic" as used herein refers to the non-crosslinked nature of the multiblock copolymer. Thermoplastic polymers become liquid when heated and solidify when (re)cooled. Thermoplastic polymers are soluble in suitable solvents.

[0032] The term "hydrolyzable" as used herein means the ability of a molecule to react with water to be cleaved. For example, hydrolyzable segments include esters, carbonates, anhydrides, amides, phosphates, phosphazenes, urethanes, and ureas. The multiblock copolymers of the present invention may include, for example, one or more hydrolyzable bonds selected from the group consisting of enol ethers, acyclic acetals, anhydrides, carbonates, phosphazenes, N-substituted amides, N-substituted urethanes, N-substituted iminos, imides, substituted imides, N,N-disubstituted hydrazos, thioesters, phosphonates, sulfonates, orthoesters, ethers, thios, and siloxyl bonds.

[0033] As used herein, the term "multifunctional chain extender" refers to the presence of at least two reactive groups on the chain extender that allow reactive prepolymers to be chemically linked to form a multiblock copolymer.

[0034] The term "water-soluble polymer" as used herein means a polymer that has good solubility in an aqueous medium such as water under physiological conditions. This polymer can be copolymerized with a more hydrophobic moiety to obtain a copolymer that is swellable in water. The water-soluble polymer can be a diol, a diamine, or a diacid. The diol or diacid is suitable for use to initiate the ring-opening polymerization of cyclic monomers. Typically, the water-soluble polymer transmits at least 75%, more preferably at least 95%, of the light transmitted by the same solution after filtering. On a weight basis, the water-soluble polymer is preferably at least 35%, more preferably at least 50%, even more preferably 70%, and even more preferably 85% soluble in water. However, it is most preferred that the water-soluble polymer is 95% soluble in water or completely soluble in water on a weight basis.

[0035] The term "swellable" as used herein means the absorption of water by a polymer. The swelling ratio can be calculated by dividing the mass of the water-swollen copolymer by the mass of the dry copolymer.

[0036] The term "biologically active compound" as used herein is intended to be broadly construed as any drug that provides a therapeutic or prophylactic effect, including, but not limited to, antibiotics (including antibacterial and antifungal agents), antiviral agents, antitumor agents, hormones, immunogenic drugs, and the like. As used herein, the term "biologically active polypeptide" refers to peptides and proteins that are biologically active in a mammalian body, more particularly in the human body.

[0037] The inventors have surprisingly found that the multiblock copolymers of the present invention, comprising prepolymer (A) segments with hydrolyzable bonds and / or water-soluble polymers and amorphous prepolymer (B) segments with specific poly(orthoester) prepolymer blocks, have desirable properties suitable for sustained release of, for example, active pharmaceutical ingredients (including biologically active compounds such as small molecule, peptide, or protein-based therapeutics). Without wishing to be bound by any theory, the inventors believe that the polymers of the present invention degrade primarily by a surface erosion mechanism, leading to a slower degradation and release profile. The prepolymer (B) segments ensure the relatively high Tg and hydrophobicity of the multiblock copolymer, which slows the penetration of water into the polymer matrix and limits or restricts the diffusion of the active pharmaceutical ingredient from the interior (non-hydrated) parts of the material. At the surface, the polymer is in contact with the surrounding water. Water can cause the degradation of the polymer at the surface by hydrolysis of the hydrolyzable bonds in the prepolymer (A) and prepolymer (B) segments, thereby releasing the active pharmaceutical ingredient from the surface region. Alternatively or in addition, water may cause swelling of the polymer at the surface via the water soluble polymer present in the prepolymer (A) segments, thereby allowing the active pharmaceutical ingredient contained within the polymer to diffuse and release more quickly from the surface region.

[0038] The multiblock copolymers of the present invention comprise at least one hydrolyzable prepolymer (A) segment and at least one hydrolyzable prepolymer (B) segment linked by a multifunctional chain extender. The prepolymer (A) segment has one or more hydrolyzable bonds and / or water-soluble polymers.

[0039] Examples of hydrolyzable bonds include ester bonds, carbonate bonds, anhydride bonds, amide bonds, phosphate bonds, phosphazene bonds, urethane bonds, and urea bonds. The multiblock copolymer of the present invention may include, for example, one or more hydrolyzable bonds selected from the group consisting of enol ether, acyclic acetal, anhydride, carbonate, phosphazene, N-substituted amide, N-substituted urethane, N-substituted imino, imide, substituted imide, N,N-disubstituted hydrazo, thioester, phosphonate ester, sulfonate ester, orthoester, ether, thio, and siloxyl bonds. From the viewpoint of time scale, ester, carbonate, and / or phosphazene bonds are preferred.

[0040] Preferably, the prepolymer (A) comprises the reaction product of one or more cyclic monomers and / or one or more acyclic monomers. The cyclic monomer may be selected, for example, from the group consisting of glycolide, L-lactide, D-lactide, D,L-lactide, ε-caprolactone, δ-valerolactone, trimethylene carbonate, tetramethylene carbonate, 1,5-dioxepan-2-one, 1,4-dioxan-2-one (p-dioxanone), cyclic anhydrides (such as oxepane-2,7-dione), N-carboxyanhydrides of natural amino acids and their derivatives (such as N-carboxyalanine anhydride), and morpholine-2,5-dione-based cyclic depsipeptides (such as 6-methylmorpholine-2,5-dione). The acyclic monomer may be selected, for example, from the group consisting of succinic acid, glutaric acid, adipic acid, sebacic acid, lactic acid, glycolic acid, hydroxybutyric acid, natural amino acids and their derivatives (such as alanine), ethylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-butanediamine and 1,6-hexanediamine.

[0041] When the prepolymer (A) contains poly(D,L-lactide), the L / D ratio of the lactide may be far from 1 (other than 50 / 50). For example, an L / D ratio between 85 / 15 and 15 / 85 will result in a completely amorphous homopolymer. Furthermore, it is known that the Tg of poly(D,L-lactide) increases when one isomer (L or D) is in excess of the other isomer. When the prepolymer (A) comprises poly(D,L-lactide-co-glycolide), the molar ratio of D,L-lactide / glycolide may be far from 1 (other than 50 / 50). For example, poly(D,L-lactide-co-glycolide) with a molar ratio of D,L-lactide / glycolide >1 or <1, ​​e.g., poly(D,L-lactide-co-glycolide) with a molar ratio of D,L-lactide / glycolide of 85 / 15 or 15 / 85, degrades slower than poly(D,L-lactide-co-glycolide) with a molar ratio of D,L-lactide / glycolide of 50 / 50. Furthermore, the Tg of poly(D,L-lactide-co-glycolide) increases when one monomer (D,L-lactide or glycolide) is in excess of the other.

[0042] Furthermore, the prepolymer (A) can also be based on (mixtures of) condensation (non-cyclic) type monomers of hydroxy acids (e.g. lactic acid, glycolic acid, hydroxybutyric acid), diacids (e.g. glutaric acid, adipic acid or succinic acid, sebacic acid) and diols such as ethylene glycol, diethylene glycol, 1,4-butanediol or 1,6-hexanediol, forming hydrolyzable moieties of esters and / or anhydrides.

[0043] The prepolymer (A) segment may comprise a water-soluble polymer. The water-soluble polymer may comprise one or more polyethers (such as polyethylene glycol (PEG), polytetramethylene oxide (PTMO), polypropylene glycol (PPG), and polytetramethylene ether glycol (PTMG)), or one or more other water-soluble polymers (such as polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyvinylcaprolactam, poly(hydroxyethyl methacrylate) (poly(HEMA)), or polyphosphazene). The prepolymer (A) segment may also comprise a mixture and / or copolymer of two or more of these polymers. Preferably, the prepolymer (A) segment comprises a water-soluble polymer derived from poly(ethylene glycol) (PEG). The poly(ethylene glycol) may have, for example, a number average molecular weight Mn of 150 to 10,000 g / mol, preferably 300 to 5,000 g / mol, and more preferably 600 to 3,000 g / mol.

[0044] Non-limiting examples of suitable prepolymer (A) segments include poly(D,L-lactide-co-glycolide), poly(D,L-lactide), poly(ε-caprolactone), poly(p-dioxanone), poly(D,L-lactide)-co-PEG-co-poly(D,L-lactide), poly(glycolide)-co-PEG-co-poly(glycolide), poly(ε-caprolactone)-co-PEG-co-poly(ε-caprolactone), and poly(p-dioxanone)-co-PEG-co-poly(p-dioxanone). The prepolymer (A) segment does not have hydrolyzable bonds, but can be composed of one or more water-soluble polymers such as PEG, PTMO, PPG, PTMG, PVA, PVP, polyvinylcaprolactam, poly(HEMA), polyphosphazene, or combinations thereof.

[0045] In any case, the prepolymer (A) segment includes a water-soluble polymer and can have any copolymer of the above monomers on both sides of the water-soluble polymer. Non-limiting examples of such prepolymer (A) segments include [poly(ε-caprolactone-co-D,L-lactide)]-co-PEG-co-[poly(ε-caprolactone-co-D,L-lactide)], [poly(ε-caprolactone-co-glycolide)]-co-PEG-co-[poly(ε-caprolactone-co-glycolide)], [poly(ε-caprolactone-co-p-dioxanone)]-co-PEG-co-[poly(ε-caprolactone [poly(D,L-lactide-co-glycolide)]-co-PEG-co-[poly(D,L-lactide-co-glycolide)], [poly(D,L-lactide-co-p-dioxanone)]-co-PEG-co-[poly(D,L-lactide-co-p-dioxanone)], and [poly(glycolide-co-p-dioxanone)]-co-PEG-co-[poly(glycolide-co-p-dioxanone)].

[0046] When the prepolymer (A) segment contains a water-soluble polymer, 10% or more of the total weight of the prepolymer (A), for example 15% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, or 70% or more, may be composed of the water-soluble polymer. Suitably, 95% or less, for example 90% or less, 85% or less of the total weight of the prepolymer (A) may be composed of the water-soluble polymer.

[0047] The prepolymer (A) may have a number average molecular weight (Mn) of 300 g / mol or more, for example 500 g / mol or more, 1000 g / mol or more, 1500 g / mol or more, or 2000 g / mol or more. The prepolymer (A) may have a Mn of 30000 g / mol or less, for example 20000 g / mol or less, 10000 g / mol or less, 8000 g / mol or less, 7000 g / mol or less, 5000 g / mol or less, 4000 g / mol or less, 3000 g / mol or less, or 2500 g / mol or less. The length of the prepolymer is preferably such that the resulting multiblock copolymer exhibits the desired mechanical and thermal properties. The content of the prepolymer (A) in the multiblock copolymer of the present invention can be 1 to 99%, for example, 5 to 95%, 10 to 90%, 20 to 80%, 30 to 70%, or 40 to 60%, based on the total weight of the multiblock copolymer.

[0048] The prepolymer (A) can be prepared, for example, by ring-opening polymerization. Thus, in one embodiment with random monomer distribution, the prepolymer (A) can be a hydrolyzable copolymer prepared by ring-opening polymerization initiated by a diol or diacid compound. The diol compound can be an aliphatic diol or a low molecular weight polyether such as PEG. In one embodiment, the synthesis of the prepolymer (A) by ring-opening polymerization is carried out in the presence of a catalyst. A suitable catalyst is Sn(Oct)2 with an M / I of 5000 to 30000 (M / I is the ratio of monomer / initiator).

[0049] The prepolymer (A) may be a hydrolyzable polyester, polyetherester, polycarbonate, polyestercarbonate, polyanhydride, or copolymer thereof. Conditions for preparing such polymers are known in the art. For example, the prepolymer (A) comprises the reaction product of ester-forming monomers selected from diols, dicarboxylic acids, and hydroxycarboxylic acids.

[0050] The hydrolyzable prepolymer (B) segment comprises the following structure: JPEG2025509813000005.jpg27144 (wherein n is 4 to 100, x is 0.25 to 1, and x + y is 1; p is 0 or 1; R1 and R2 are independently selected from hydrogen and C1-C4 alkyl;

[0051] Q1 is Selected from JPEG2025509813000006.jpg33153,

[0052] Q2 is Selected from JPEG2025509813000007.jpg26153, r is 1 to 100; s is 1 to 12, t is 1 to 10; R3 is selected from hydrogen and C1-C6 alkyl; R4 is selected from hydrogen and C1-C4 alkyl; R5 is Selected from JPEG2025509813000008.jpg52153, v is 1 to 100; w is 1 to 12; R6 is selected from hydrogen and C1-C6 alkyl.

[0053] Preferably, n is between 5 and 50, for example between 8 and 45, between 10 and 40, or between 12 and 35. The index x may be between 0.3 and 0.95, for example between 0.4 and 0.9, or between 0.5 and 0.8. In a preferred embodiment, x is 1. R1 and R2 are preferably independently selected from C1-C4 alkyl, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, etc. More preferably, R1 and R2 are both methyl.

[0054] Q1 is preferably JPEG2025509813000009.jpg19153. More preferably, Q1 is selected from The file is TIFF2025509813000010.tif1958.

[0055] Q2 is preferably Selected from JPEG2025509813000011.jpg26153. Preferably, r is an integer of 2 to 90, for example, 5 to 80, or 10 to 70. Preferably, s is an integer of 2 to 10, for example, 3 to 9, or 4 to 8. Preferably, t is an integer of 2 to 9, for example, 3 to 8, or 4 to 7. R3 is preferably selected from hydrogen and C1-C4 alkyl, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl. More preferably, R3 is hydrogen or methyl. R4 is preferably selected from hydrogen and methyl.

[0056] R5 is preferably JPEG2025509813000012.jpg52153 is selected. Preferably, v is an integer of 2 to 90, for example, 5 to 80, or 10 to 70. Preferably, w is an integer of 2 to 10, for example, 3 to 9, or 4 to 8. R6 is preferably selected from hydrogen and C1-C4 alkyl, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl. More preferably, R6 is hydrogen or methyl.

[0057] Preferably, the hydrolyzable prepolymer (B) segment comprises or consists of the following structure: JPEG2025509813000013.jpg5796 (wherein n is 4 to 100, preferably 5 to 50, for example, 8 to 45, 10 to 40, or 12 to 35).

[0058] Optional additional monomers that may be present in the prepolymer (B) segment may be selected from lactic acid, glycolic acid, and combinations thereof. The glass transition temperature Tg of the hydrolyzable prepolymer (B) segment is 40° C. or higher, preferably 50° C. or higher, for example, in the range of 60 to 100° C. Tg can be measured by modulated differential scanning calorimetry (mDSC) as described in Example 2.

[0059] The prepolymer (B) may have a number average molecular weight (Mn) of 1000 g / mol or more, for example 2000 g / mol or more, 2500 g / mol or more, or 3000 g / mol or more. The prepolymer (B) may have a Mn of 10000 g / mol or less, for example 9000 g / mol or less, or 8000 g / mol or less. The length of the prepolymer is preferably such that the resulting multiblock copolymer exhibits the desired mechanical and thermal properties. The content of the prepolymer (B) in the multiblock copolymer of the present invention can be 1 to 99%, for example, 5 to 95%, 10 to 90%, 20 to 80%, 30 to 70%, or 40 to 60%, based on the total weight of the multiblock copolymer.

[0060] Prepolymer (B) can be synthesized by polyaddition reaction of diols with acetals, more specifically, cyclohexanedimethanol (CHDM) and 3,9-divinyl-2,4,8,10-tetraoxaspiro[5.5]undecane (DVTOSU) to obtain CHDM-based poly(ortho ester) prepolymer (B). To obtain difunctional diol-functionalized poly(ortho ester), preferably an excess of CHDM should be used relative to DVTOSU. The polyaddition reaction can be monitored using NMR spectroscopy. Since poly(ortho ester)-based polymers are known to hydrolyze rapidly under acidic conditions, a weak base amine such as triethylamine may be added to the reaction medium to prevent hydrolysis of poly(ortho ester) and loss of molecular weight.

[0061] Optionally, there may be an additional prepolymer segment (in addition to the prepolymer segments (A) and (B)) derived from a water-soluble polymer. The water-soluble polymer may be selected from the group consisting of one or more polyethers (such as polyethylene glycol (PEG), polytetramethylene oxide (PTMO), polypropylene glycol (PPG), and polytetramethylene ether glycol (PTMG)), or one or more other water-soluble polymers (such as polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyvinylcaprolactam, poly(hydroxyethyl methacrylate) (poly(HEMA)), or polyphosphazene). The additional prepolymer segment may also include copolymers of two or more of these polymers. For example, the additional water-soluble polymer segment may be derived from PEG having an Mn of 150 to 5000 g / mol. The additional prepolymer segments derived from water-soluble polymers can be suitably present in the multiblock copolymer in an amount of 60% or less, for example 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less of the total weight of the multiblock copolymer. The amount of the additional water-soluble polymer segments can be 0.1% or more, for example 1% or more, 2% or more, 3% or more, 4% or more, or 5% or more of the total weight of the multiblock copolymer.

[0062] In one embodiment, the prepolymers are linear and random (co)polyesters, polyestercarbonates, polyetheresters, or polyanhydrides with reactive end groups. These end groups may be hydroxyl or carboxyl. Dihydroxy-terminated copolymers are preferred, but hydroxycarboxyl- or dicarboxyl-terminated polymers can also be used. If the polymer must be linear, it can be prepared using difunctional components (diols) as initiators, but branched polyesters can be obtained if trifunctional or higher polyols are used.

[0063] The prepolymer segments of the multiblock copolymer are linked by a multifunctional chain extender. The multifunctional chain extender is preferably a difunctional aliphatic chain extender. More preferably, the chain extender is a difunctional diisocyanate such as 1,4-butane diisocyanate. However, it is also possible to use trifunctional (or higher) chain extenders such as triisocyanates. If the conversion is sufficiently low, a branched multiblock copolymer is produced. Branched copolymers can exhibit improved creep properties. If at least one of the prepolymers has two or more functional groups, it is also possible to obtain a branched multiblock copolymer by using a difunctional chain extender.

[0064] The number of prepolymer blocks in the multiblock copolymer of the present invention is preferably in the range of 2 to 1000, preferably 3 to 1000, for example 5 to 900, 10 to 800, 20 to 700, 30 to 600, or 40 to 500. This number of prepolymer blocks is preferably combined with a typical prepolymer block length in the range of 500 to 10000 g / mol, for example 1000 to 7500 g / mol, more preferably 1200 to 5000 g / mol.

[0065] The multiblock copolymer of the present invention may have an intrinsic viscosity of 0.1 dl / g or more, preferably 0.1 to 3 dl / g, more preferably 0.2 to 2 dl / g, for example 0.3 to 1 dl / g. The intrinsic viscosity can be measured, for example, by a single-point method using an Ubbelohde viscometer (DIN), type 0C, in chloroform at 25°C. These intrinsic viscosities roughly correspond to number average molecular weights (Mn) of 10000 g / mol or more, preferably 10000 g / mol to 300000 g / mol, more preferably 20000 g / mol to 200000 g / mol, for example 30000 g / mol to 100000 g / mol.

[0066] Preferably, the multiblock copolymers of the present invention have a random distribution of the individual blocks, a number average molecular weight in the range of 10,000 g / mol to 300,000 g / mol, and are solid under ambient and physiological conditions.

[0067] In a further aspect, the present invention relates to a method for preparing the biodegradable thermoplastic multiblock copolymer of the present invention, comprising a chain extension reaction of prepolymer (A) with prepolymer (B) in the presence of a multifunctional chain extender, which involves chain extension of the prepolymer blocks using a multifunctional chain extender. This preparation method results in a multiblock copolymer in which the prepolymers are randomly distributed throughout the multiblock copolymer. This copolymer is not obtained by a synthetic method utilizing an addition reaction. In the multiblock copolymer of the present invention, for example, PEG may be randomly distributed throughout the polymer chain.

[0068] In the present process, prepolymer (A), prepolymer (B) and the polyfunctional chain extender may be as described herein. Segmented multiblock copolymers can be prepared by chain extending a mixture of prepolymers in the desired ratio with an equal amount of a multifunctional chain extender, in one embodiment an aliphatic molecule such as 1,4-butane diisocyanate (BDI) or other diisocyanates. The segmented copolymers can be prepared in solution. Suitably, the prepolymers are dissolved in an inert organic solvent and the chain extender is added either pure or in solution.

[0069] Low polymerization temperatures and short polymerization times prevent transesterification and ensure that the monomer distribution is the same as that of the prepolymers that make up the copolymer. Conversely, longer reaction times can lead to transesterification reactions and a more random (i.e., nonblocky) monomer distribution. The resulting bulk chain extended material can also be produced in situ in an extruder. The multiblock copolymer of the present invention preferably has at least one glass transition temperature Tg of 30° C. or higher, preferably 40° C. or higher, for example, 40 to 100° C. The multiblock copolymer may have, for example, two or more Tgs. In one embodiment, the multiblock copolymer has two Tgs, the lower Tg being in the range of −60° C. to 50° C., and the higher Tg being in the range of 40° C. to 100° C.

[0070] The multiblock segmented copolymers can be formed into formulations of various shapes and dimensions using known techniques such as, for example, solvent extraction / evaporation-based emulsion processes, extrusion, molding, solvent casting, spray drying, spray freeze drying, electrospinning, or freeze drying. The latter techniques are used to form porous materials. Porosity can be adjusted by the addition of co-solvents, non-solvents, and / or leachants. The copolymers can be processed into microspheres (either solid or porous), microparticles, nanospheres, rods, films, sheets, sprays, tubes, membranes, meshes, fibers, plugs, coatings, and other products. The products can be either solid, hollow, or (micro)porous. For example, a wide range of biomedical implants can be produced for applications in wound care, skin repair, nerve regeneration, vascular grafts, drug delivery, meniscus reconstruction, tissue engineering, coatings for surgical instruments, ligament and tendon regeneration, dental and orthopedic repair. The copolymers can be used alone or mixed and / or co-extruded with other absorbable or non-absorbable polymers.

[0071] In particular, the biodegradable multiblock copolymers of the present invention are suitable as delivery vehicles for polypeptides, allowing for the controlled release of the polypeptide from the matrix into its environment, for example, into the body of a subject.

[0072] In yet another aspect, the present invention relates to a composition for delivering at least one biologically active compound (e.g., a biologically active small molecule, protein, or peptide) to a host, comprising at least one biologically active compound encapsulated within a matrix, said matrix comprising at least one biodegradable thermoplastic multiblock copolymer as defined herein.

[0073] The composition may be in one or more shapes selected from the group consisting of microspheres, microparticles, nanoparticles, nanospheres, rods, solid implants, gels, in situ forming implants, coatings, films, sheets, sprays, tubes, membranes, meshes, fibers, plugs, and other configurations. For example, the composition may be in the form of microspheres and / or microparticles. The average diameter of the microspheres and / or microparticles is preferably in the range of 0.1 to 1000 μm, more preferably in the range of 1 to 100 μm, and even more preferably in the range of 10 to 70 μm.

[0074] The composition may be in the form of an in situ forming implant in which the biologically active compound is dissolved or suspended in a solution of the biodegradable thermoplastic multiblock copolymer in an acceptable organic solvent, such as n-methylpyrrolidone (NMP), dimethylsulfoxide (DMSO), benzyl benzoate (BB), benzyl alcohol, triacetin, glycofurol, low molecular weight polyethylene glycol, etc. After administration into the body, the solution forms a depot in situ as the organic solvent displaces aqueous body fluids, thereby trapping the biologically active compound within the biodegradable thermoplastic multiblock copolymer depot. The biologically active compound is then gradually released from the biodegradable thermoplastic multiblock copolymer depot.

[0075] The composition may be in the form of a solid implant that can be produced, for example, by hot melt extrusion or injection molding. The biologically active compound can be incorporated into the biodegradable thermoplastic multiblock copolymer as a molecular mixture or as a dispersion of solid particles. The at least one biologically active compound in the composition preferably comprises a non-peptide, non-protein, small drug, and / or biologically active polypeptide.

[0076] The multiblock copolymers of the present invention provide many options for tailoring the release profile of the delivery composition for a particular application. The release rate of the biologically active compound can be increased, for example, by: Increasing the molecular weight of the water-soluble polymer in the prepolymer (A) while keeping the molecular weight of the prepolymer (A) constant; Increasing the molar ratio of prepolymer (A) to prepolymer (B); increasing the content of monomers in the prepolymer (A) which give rise to faster degrading polymers, for example by replacing ε-caprolactone with D,L-lactide or glycolide or by replacing D,L-lactide with glycolide; reducing the molecular weight of prepolymer (A) while keeping constant the molecular weight of the water-soluble polymer and the molar ratio of prepolymer (A) to prepolymer (B); and / or Increasing the water-soluble polymer content by using an additional third segment derived from a water-soluble polymer.

[0077] The opposite change can be made to decrease the release rate. Biologically active compounds that can be included in the multiblock copolymer matrix include, but are not limited to, non-peptide, non-protein, small drugs, generally having a molecular weight of 1000 Da or less, and biologically active polypeptides.

[0078] The at least one small drug molecule may be present in the matrix in an amount of 0.1-80%, in one embodiment 1.0-40%, in another embodiment 5-20% of the combined weight of the matrix and the at least one small drug molecule. If it is desired to increase the hydrophilicity of the multiblock copolymer, thereby increasing the degradation rate of the copolymer and the release rate of the incorporated biologically active compound, the copolymer can be modified by partially or completely replacing the D,L-lactide of the hydrophilic prepolymer (A) segment with glycolide and / or by using a higher molecular weight PEG component or by increasing the weight fraction of the PEG component in the prepolymer (A) segment. If it is desired to decrease the hydrophilicity of the polymer, thereby decreasing the degradation rate of the copolymer and the release rate of the incorporated biologically active compound, the copolymer can be modified by partially or completely replacing the D,L-lactide of the hydrophilic prepolymer (A) segment with ε-caprolactone and / or by using a lower molecular weight PEG component or by decreasing the weight fraction of the PEG component in the prepolymer (A) segment.

[0079] Polypeptides consist of amino acids linked by peptide bonds. Short polypeptides are also called peptides, while longer polypeptides are usually called proteins. By convention, polypeptide chains short enough to be synthesized from the constituent amino acids are called peptides rather than proteins. However, with the advent of better synthesis techniques, polypeptides up to several hundred amino acids in length can be made, including complete proteins such as ubiquitin. Another convention places an informal dividing line at about 50 amino acids in length. This definition is somewhat arbitrary. Longer polypeptides, such as the amyloid beta peptide associated with Alzheimer's disease, can be considered proteins, while smaller proteins, such as insulin, can be considered peptides. In any event, one of skill in the art will appreciate that essentially any type of polypeptide can be encapsulated and subsequently released from the copolymer matrix.

[0080] In one embodiment, the composition of the invention comprises a biologically active peptide or protein. The size of the polypeptide can vary. In one embodiment, the molecular weight of the polypeptide is less than or equal to 10,000 Da. Polypeptides of this size are particularly suitable for encapsulation in a copolymer matrix comprising PEG as a segment of the prepolymer (A) and / or as an additional prepolymer. The number average molecular weight of the PEG is between 400 and 3,000 g / mol, or in another embodiment between 600 and 1,500 g / mol. Alternatively or additionally, the PEG can be present in an amount of 5 to 60%, or in another embodiment between 5 to 40%, of the total weight of the copolymer.

[0081] In another embodiment, the polypeptide is a biologically active protein with a molecular weight of 10,000 Da or more. In one embodiment, this larger polypeptide is encapsulated in a copolymer matrix comprising PEG as a segment of prepolymer (A) and / or as an additional prepolymer, the PEG having a number average molecular weight of 600-5000 g / mol, or in another embodiment 1000-3000 g / mol. Alternatively, or in addition, the PEG can be present in an amount of 5-70%, or in an amount of 10-50% of the total weight of the copolymer.

[0082] The compositions of the present invention can have any desired appearance or shape. In one embodiment, the multiblock copolymers of the present invention are processed in the form of microspheres, microparticles, sprays, implants, coatings, gels, films, foils, sheets, membranes, or rods.

[0083] One specific aspect relates to the composition in the form of a microsphere. Generally, a microsphere is a fine spherical particle with a diameter of less than 1000 μm, which contains a biologically active compound. The microsphere can be a homogeneous or monolithic microsphere in which the biologically active compound is dissolved or dispersed throughout the polymer matrix. The microsphere can also be a reservoir type in which the biologically active compound is surrounded by a polymer in a mononuclear or polynuclear state. When the biologically active compound is a water-soluble drug with a small size, the drug is first dispersed in a hydrophobic or lipophilic excipient, and then the combination is dispersed in the form of particles, droplets, or microsuspensions in the polymer matrix. The microsphere can then be formed from the emulsion.

[0084] Microspheres can be prepared by techniques known to those skilled in the art, including, but not limited to, coacervation, solvent extraction / evaporation, spray drying, or spray freeze drying techniques. In one embodiment, the microspheres are prepared by a solvent extraction / evaporation technique which involves dissolving the multiblock copolymer in an organic solvent such as dichloromethane and emulsifying the multiblock copolymer solution in an aqueous phase containing an emulsifier such as polyvinyl alcohol (e.g., as described in Okada, Adv. Drug Deliver. Rev. 1997, 28(1), 4370).

[0085] The properties of the microspheres thus formed, such as particle size, porosity, drug loading, etc., depend on process parameters such as, for example, the viscosity or concentration of the aqueous polyvinyl alcohol phase, the concentration of the multiblock copolymer solution, the ratio of dichloromethane to the aqueous active solution, the ratio of the primary emulsion to the polyvinyl alcohol phase, and the stirring speed.

[0086] To form microspheres by spray drying, a low concentration of the multiblock copolymer is used in an organic solvent such as dichloromethane, 0.5-5%, in one embodiment about 2%, of the total weight of the solution. Spray drying generally produces porous, irregularly shaped particles.

[0087] When the microspheres are formed, the biologically active compound is encapsulated within the microspheres or microparticles. In general, when using the solvent extraction / evaporation technique to encapsulate lipophilic compounds, the compound is first dissolved in a solution of the multiblock copolymer in an organic solvent, such as dichloromethane and ethyl acetate. The organic solution is then emulsified in an aqueous polyvinyl alcohol solution to obtain an oil-in-water (O / W) emulsion. The organic solvent is then extracted into the aqueous phase and evaporated to solidify the microspheres.

[0088] Generally, when the solvent evaporation technique is used to encapsulate water-soluble compounds, an aqueous solution of the compound is first emulsified in a solution of a multiblock copolymer in an organic solvent such as dichloromethane. This primary emulsion is then emulsified in an aqueous polyvinyl alcohol solution to produce a water-in-oil-in-water (W / O / W) emulsion. Organic solvents such as dichloromethane and ethyl acetate are then extracted to solidify the microspheres, similar to the O / W process route. Alternatively, the water-soluble drug may be directly dispersed in a solution of the multiblock copolymer in an organic solvent. The resulting dispersion is then emulsified in an aqueous solution containing a surfactant such as polyvinyl alcohol to obtain a solid-in-oil-in-water (S / O / W) emulsion. The organic solution is then extracted to solidify the microspheres, similar to the O / W process route.

[0089] When using W / O / W and S / O / W emulsification routes to encapsulate water-soluble compounds, it can be difficult to obtain microspheres with sufficient encapsulation efficiency. Depending on the water-soluble properties of the compound, some of the compound may be lost to the aqueous extraction medium, such as an aqueous polyvinyl alcohol solution. To reduce the diffusion of the compound in the internal aqueous phase to the external aqueous phase, a thickener, such as gelatin, can be used in the internal aqueous phase. Also, additives can be added to the external aqueous phase to reduce the solubility of the compound in the external aqueous phase. For this purpose, salts can be used or the pH can be adjusted.

[0090] Water-in-oil-in-oil (W / O / O) or solid-in-oil-in-oil (S / O / O) emulsification routes offer interesting alternatives to obtain microspheres with sufficient encapsulation efficiency. In the W / O / O process, similar to the W / O / W process, the biologically active compound is dissolved in an aqueous solution and emulsified with a solution of the polymer in an organic solvent, usually dichloromethane and ethyl acetate. A polymeric precipitant, such as silicone oil, is then added slowly with stirring to form initial microparticles, which are poured into heptane or hexane and extracted with silicone oil and an organic solvent to solidify the microspheres. The microparticles are collected by vacuum filtration, washed with additional solvent, and dried under vacuum. In the S / O / O emulsification route, similar to the S / O / W process, the biologically active compound is dispersed as a solid powder in a solution of the polymer in an organic solvent, such as dichloromethane and ethyl acetate. A polymeric precipitant, such as silicone oil, is then added slowly with stirring to form initial microparticles, which are poured into heptane or hexane and extracted with silicone oil and an organic solvent to solidify the microspheres.

[0091] To prevent loss of protein activity during processing into microspheres, stabilizers can be added to the aqueous protein solutions, examples of which include polyvinyl alcohol (PVA), Tween® / Polysorbatum, human serum albumin, gelatin, and carbohydrates such as trehalose, inulin, and sucrose. When using the spray drying technique, an aqueous solution of the compound is emulsified in a solution of the copolymer in an organic solvent, such as methylene chloride, as described above. The water-in-oil emulsion is then spray dried using a spray dryer.

[0092] In further embodiments, the compositions of the invention are in the form of a coating, an injectable gel, an implant (such as an injectable implant), or a coated implant. The compositions in the form of a coating can be applied as a drug-eluting coating on medical implants, such as, for example, vascular or ureteral stents, orthopedic prostheses, or ocular implants.

[0093] Biologically active compounds can be formulated into injectable solid implants by hot melt extrusion. Typically, the compound is physically mixed with the multiblock copolymer powder, and then the resulting powder mixture is introduced into an extruder, heated and processed to produce a formulation of the desired shape and size, such as a small diameter cylindrical rod. Instead of physically mixing the compound with the multiblock copolymer powder, the compound and the polymer can be co-dissolved in a suitable solvent, or a dispersion of the compound in a polymer solution in a suitable solvent can be prepared, followed by lyophilization and extrusion of the lyophilized powder. The latter generally improves the homogeneity of the mixture and the homogeneity of the content of the implant.

[0094] In yet another aspect, the present invention relates to a method of delivering a biologically active compound to a subject in need thereof, comprising administering to said subject an effective amount of a composition as defined herein.

[0095] The subject is typically a mammal, preferably a human. However, the present invention also includes veterinary use. The method can have therapeutic, prophylactic, and / or cosmetic purposes. Depending on the situation, an appropriate administration method can be selected. For example, administration can include parenteral, oral, intra-arterial, intra-articular, intravenous, intraocular, epidural, intrathecal, intramuscular, intraperitoneal, intravenous, intravaginal, rectal, topical, or subcutaneous administration of the composition. In one embodiment, the present invention provides a method for delivering a biologically active polypeptide of interest to a subject in need thereof, comprising administering to said subject an effective amount of a composition of the present invention, wherein the composition is in the form of a microsphere, an injectable implant, or an in situ forming gel, and wherein the composition is administered intraocularly, intra-arterially, intramuscularly, or subcutaneously.

[0096] For topical administration, the microspheres can be included in a gel, cream, or ointment, optionally covered with a barrier, and can thus contain one or more biologically active compounds used to treat skin disorders such as psoriasis, eczema, seborrhea, and dermatitis. In another embodiment, the microspheres may be contained in a gel, such as a hyaluronic acid gel or a polymeric polysaccharide gel, this embodiment being particularly applicable for parenteral use, such as during and after surgery.

[0097] When administered by injection, the microspheres may be contained in a pharmaceutical carrier such as water, saline (e.g., 0.9%), or a solution containing a surfactant in an amount of 0.1-0.5% w / v. Examples of surfactants that can be used include, but are not limited to, Tween 80 surfactant. The pharmaceutical carrier may further include a thickening agent such as sodium carboxymethylcellulose. The microspheres, when administered in combination with an acceptable pharmaceutical carrier, can be used to treat a variety of diseases or disorders depending on the biologically active compound encapsulated.

[0098] In one aspect, an injectable delivery system is provided that includes the multiblock copolymer described herein. The multiblock copolymer can be in the form of an implant. The implant can be a microsphere, a rod, a film, a multiblock copolymer depot, or a plurality thereof. The multiblock copolymer can be in the form of a plurality of polymeric microspheres, each having a diameter of 20 μm or more, the polymeric microspheres comprising the multiblock copolymer described herein. The diameter of the polymeric microspheres can be 20 μm to 80 μm, for example, 30 μm to 70 μm. The polymeric microspheres can be monodisperse with a coefficient of variation of about 25%. The injectable delivery system can further comprise a therapeutic agent, or a pharma- ceutically acceptable salt thereof. The therapeutic agent can be a small chemical, a protein, an antibody, a peptide, an oligonucleotide, or a combination thereof. Additionally, the injectable delivery system can further comprise a pharma- ceutically acceptable excipient.

[0099] The present invention further relates to a medical device comprising the biodegradable thermoplastic multiblock copolymer of the present invention. The medical device can take the form of a microsphere, microparticle, nanoparticle, nanosphere, rod, solid implant, gel, in situ forming implant, coating, film, sheet, spray, tube, membrane, mesh, fiber, scaffold, or plug. Preferably, the medical device further comprises at least one biologically active compound encapsulated within the matrix of the biodegradable thermoplastic multiblock copolymer, which biologically active compound can be controllably released after insertion into a human or animal.

[0100] The present invention has been described with reference to various embodiments, compositions, and methods. Those skilled in the art will appreciate that features of the various embodiments, compositions, and methods can be combined with each other. All references cited herein are fully incorporated by reference into this specification to the same extent as if each reference was individually and specifically indicated to be incorporated by reference and was set forth in its entirety herein.

[0101] Use of the terms "a," "an," and "the," and similar referents in the context of describing the present invention (particularly in the context of the claims) are to be construed as including both the singular and the plural, unless otherwise stated herein or clearly contradicted by context. The terms "comprise," "have," "include," and "contain" are to be construed as open-ended terms (i.e., meaning "including, but not limited to"), unless otherwise stated. The recitation of ranges of values ​​herein is intended to serve as a shorthand method of individually referring to each individual value falling within the range, unless otherwise stated herein. Each individual value is incorporated herein as if it were individually set forth herein. The use of any and all examples or exemplary language (e.g., "etc.") described herein is intended only to better illustrate the present invention and does not limit the scope of the present invention, unless specifically stated otherwise. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. For purposes of this specification and the appended claims, unless otherwise indicated, all numbers expressing amounts, quantities, percentages, and the like, are to be understood in all instances to be modified by the term "about." Also, all ranges include any combination of the maximum and minimum points disclosed. All ranges also include intermediate ranges, whether specifically recited herein or not, within that range.

[0102] For clarity and conciseness of description, features are described herein as part of the same or separate embodiments, but it will be understood that the scope of the invention may include embodiments combining all or some of the described features. EXAMPLES

[0103] The invention is further illustrated by the following non-limiting examples. In the following examples, various biodegradable thermoplastic amorphous poly(ortho ester)-based multiblock copolymers were synthesized and evaluated for processability into long-acting injectable drug delivery formulations, drug release characteristics, and erosion properties. The polymers are composed of amorphous poly(ortho ester)-based prepolymer (B) segments with high Tg and prepolymer (A) segments containing polyester or polyether ester polymer blocks.

[0104] Example 1 PLGA polymers are the most commonly used for sustained release of drugs and have been clinically proven to be safe in the body. Although PLGA polymers are very versatile and their physicochemical properties can be tailored to different drug delivery needs, their suitability for protein delivery has been shown to be limited. Protein stability remains a major obstacle in protein delivery using PLGA. The reasons are (1) the hydrophobic character of the polymer, (2) the generation of acidic degradation products, their accumulation in the polymer matrix, which leads to a decrease in pH in situ, and the possibility of degradation of the encapsulated protein and loss of biological activity due to the decrease in pH. Proteins have also been shown to be chemically modified by (3) deamination or acylation within the PLGA matrix. As a result, delivery systems made with PLGA are associated with all the above problems, including (4) protein aggregation, and (5) undesirable release kinetics.

[0105] PCL (a combination of poly(ε-caprolactone)-PEG-poly(ε-caprolactone)-based hydrophilic blocks and poly(L-lactide)-based crystalline blocks) multiblock copolymers (block ratios ranging from 20 / 80 (20CP10C20-LL40) to 50 / 50 (50 PCL multiblock copolymers consisting of a combination of LL40 and hydrophilic poly(ε-caprolactone)-PEG3000-poly(ε-caprolactone) blocks (Mn: 4000 g / mol, 75 wt% PEG (molecular weight: 3000 g / mol, PEG3000) (abbreviated as CP30C40) in a weight ratio of 30 / 70 (30CP30C40-LL40) or 50 / 50 (50CP30C40-LL40)) were used to express goserelin, lysozyme, bovine serum albumin, insulin-like growth factor-1 (WO2012 / 005594), hepatocyte growth factor, and vascular endothelial growth factor (Scheiner We found that this method is suitable for sustained release delivery of biologics of different molecular sizes, such as erythropoietin (E. et al., J. Pharm Sci. 2020, 109, 863-870).

[0106] Unfortunately, 50CP10C20-LL40 based microspheres were found to degrade very slowly. Based on extrapolation of experimental data, the in vitro erosion time of 50CP10C20-LL40 microspheres was predicted to be 3-4 years (Figure 1) and at least 14-16 months in vivo. The slow erosion of PCL multiblock copolymers was also observed with other PCL multiblock copolymers such as 20CP10C20-LL40 and 30CP30C40-LL40 and was attributed to the slow hydrolysis of the crystalline poly(L-lactide) blocks. Furthermore, the melting enthalpy (and crystallinity) of multiblock copolymers containing crystalline blocks was found to be highly dependent on processing conditions. Changes in the crystallinity of the polymer matrix can lead to (unacceptable) variations in important product properties such as release kinetics, thus causing reproducibility problems and unacceptable batch-to-batch variability. Furthermore, the same important product properties may change over time due to progressive crystallization of the incompletely crystallized polymer matrix during extended product storage, leading to drug stability issues.

[0107] According to the present invention, the crystalline poly(L-lactide) block is replaced by an amorphous poly(ortho ester) block having a high Tg. By carefully selecting the diol used in the poly(ortho ester) polymer synthesis, a prepolymer segment (B) having a Tg of 60° C. or higher can be obtained. In the case of phase separation of this high Tg prepolymer segment (B) and low Tg prepolymer segment (A), a multiblock copolymer with two Tg is obtained, one Tg representing the domain formed by the high Tg prepolymer segment (B) and the other Tg representing the domain formed by the low Tg prepolymer segment (A). The mechanical properties of the multiblock copolymer are determined to a large extent by the high Tg domains, similar to those observed in the semi-crystalline phase separated multiblock copolymers of WO2012 / 005594 and WO2013 / 015685. Furthermore, the high Tg domains act as physical crosslinks, thus providing further control over the drug release rate. In the case of phase mixing of the high Tg prepolymer segment (B) and the low Tg prepolymer segment (A), a multiblock copolymer having a single Tg value between the individual Tgs of the high Tg prepolymer segment (B) and the low Tg prepolymer segment (A) is obtained. Therefore, the Tg of the resulting multiblock copolymer can be sufficiently high, such as about 40° C. or higher.

[0108] High Tg poly(ortho ester) prepolymer blocks were synthesized by polyaddition reaction of cyclohexanedimethanol (CHDM) with 3,9-divinyl-2,4,8,10-tetraoxaspiro[5.5]undecane (DVTOSU) to obtain CHDM-based poly(ortho ester) prepolymer blocks (abbreviated as POE). To obtain difunctional POE blocks, up to 10 wt% excess of CHDM relative to DVTOSU was used, and the polyaddition reaction was monitored using NMR spectroscopy. The molecular weight of the POE prepolymer segment (B) was determined using GPC against polystyrene standards and NMR spectroscopy using an internal standard. The Mn of the diol-functionalized CHDM-based POE prepolymers (Figure 2) was 3.8-4.1 kg / mol (hereafter abbreviated as POE40) and Tg was 65-69 °C. POE-based polymers are known to hydrolyze rapidly under acidic conditions, so the weak base triethylamine was added to the precipitation medium to prevent hydrolysis, and the dry yellow powder was stored below −10 °C in the absence of moisture.

[0109] Poly(ε-caprolactone)-co-PEG1000-co-poly(ε-caprolactone) prepolymer (abbreviated as ppCP10C20) with a target Mn of 2000 g / mol was prepared by ring-opening polymerization of ε-caprolactone using polyethylene glycol (PEG1000) with a molecular weight of 1000 g / mol as initiator. Briefly, ε-caprolactone (Acros Organics) was dried and distilled under reduced pressure with CaH2, and stannous octoate (Sigma Corp.) was purified by vacuum distillation. Approximately 497.7 g (0.49 mol) of PEG1000 (Merck, Emprove® Essential Ph Eur) was weighed into a three-necked bottle under nitrogen atmosphere and dried at 90° C. under reduced pressure for at least 16 hours, after which 503.3 g (4.34 mol) of distilled ε-caprolactone was added to the PEG under nitrogen atmosphere, and the mixture was heated to 160° C. Subsequently, 101 mg of distilled stannous octoate (monomer / catalyst ratio: 17,600 mol / mol) was added, and the mixture was magnetically stirred and heated at 160 °C, resulting in a conversion of over 98% as confirmed by 1H-NMR. The molecular weight measured by 1H-NMR was about 2000 g / mol. Similarly, ppCP30C40, i.e., poly(ε-caprolactone)-co-PEG3000-co-poly(ε-caprolactone) prepolymer with a target Mn of 4000 g / mol, was prepared by using PEG3000 as initiator.

[0110] Poly(ε-caprolactone)-co-PEG-co-poly(ε-caprolactone)]-b-[poly(orthoester)] multiblock copolymers (block ratio: 20 / 80 w / w (hereafter abbreviated as 20CP10C20-POE40) (Figure 3) and block ratio: 50 / 50 (hereafter abbreviated as 50CP10C20-POE40)) were synthesized by chain extending diol-functionalized POE40 together with CP10C20 using 1,4-butane diisocyanate as a chain extender. Briefly, both prepolymers were dried overnight under reduced pressure. After in situ drying of ppPOE40 in a flange glass reactor, the required amount of ppCP10C20 or ppCP30C40 prepolymer was added. Anhydrous distilled p-dioxane was added to the reactor until the polymer concentration reached 30 wt%. The reactor was heated to 80 °C to dissolve the prepolymer, resulting in a homogeneous solution, and 1,4-butane diisocyanate (BDI) (Actu-All Chemicals) was added. Additional stannous octoate was added to increase its total content to 50-120 ppm, and the reaction mixture was mechanically stirred until the desired viscosity was obtained. Then, distilled p-dioxane containing 20 wt% water was added. Stirring was continued for another 30 min. The reaction mixture was further diluted with p-dioxane to a polymer concentration of 10 wt%, cooled to room temperature, poured into a tray, and frozen at -20 °C, after which the p-dioxane was removed from the frozen solution under reduced pressure to obtain a dry polymer. Using a similar procedure, 50CP30C40-POE40 multiblock copolymers were prepared by chain extending ppCP30C40 prepolymer with POE40 prepolymer in a 50 / 50 w / w ratio using BDI as a chain extender. Table 1 shows the experimental details of various [poly(ε-caprolactone)-co-PEG-co-poly(ε-caprolactone)]-b-[poly(orthoester)] multiblock copolymers.

[0111] The polymers were analyzed for polymer composition (1H-NMR), intrinsic viscosity, and thermal properties (mDSC) as described in Example 2. Table 2 shows the results of the characterization of the prepared multiblock copolymers. [Table 1]

[0112] [Table 2]

[0113] The [poly(ε-caprolactone)-co-PEG-co-poly(ε-caprolactone)]-b-[poly(ortho ester)] multiblock copolymers exhibited two glass transitions. The presence of two glass transitions is due to the microphase separation of incompatible low Tg poly(ε-caprolactone)-co-PEG-co-poly(ε-caprolactone)-based and high Tg poly(ortho ester)-based domains. In this way, the poly(ortho ester) prepolymer segments (B) provide good structural integrity to the multiblock copolymers, even when combined with the low Tg prepolymer segments (A).

[0114] The synthesized poly(ortho ester) multiblock copolymers (POE-MBCPs) were evaluated for their processability into polymer-only microspheres (particle size distribution, microscopic appearance, stickiness, absence of aggregation). For polymers that were amenable to process into microspheres, in vitro erosion kinetics were further evaluated.

[0115] Polymer-only microspheres were prepared by a solvent extraction / evaporation-based oil-in-water emulsification process. Approximately 5.8 g of polymer (10.0 wt%) dissolved in 52.4 g of dichloromethane was emulsified in 3.08 kg of ultrapure water containing 4.0 wt% polyvinyl alcohol (PVA) and 5 wt% NaCl by membrane emulsification using a 20 μm pore size membrane. The resulting microspheres were collected on a 5 μm membrane filter and washed three times with 250 ml of ultrapure water containing 0.05 wt% Tween® 80, and then washed three times with 250 g of ultrapure water. Finally, the microspheres were freeze-dried.

[0116] The mean diameter and particle size distribution including coefficient of variation of the polymer-only microspheres were measured by laser diffraction (Horiba® LA-960 Laser Particle Size Analyzer). The microspheres were suspended in water until the transmittance was 70-90%, and the particle size distribution of the suspension was measured in the range of 10 nm to 5000 μm. The surface morphology of the microspheres was evaluated by scanning electron microscopy using a JEOL JCM-5000 Neoscope. A small amount of the microspheres was attached to carbon conductive tape and coated with a gold layer. The samples were imaged using an electron beam at 10 kV.

[0117] In vitro erosion of polymer-only microspheres was measured in 100 mM phosphate buffer pH 7.4 (90-100 mg microspheres in 10 ml). Samples were incubated at 37° C. At each sampling point, microspheres were collected, lyophilized, and weighed.

[0118] POE-MBCP, which consists of a combination of POE40-based prepolymer (B) segments and hydrophilic poly(ε-caprolactone)-PEG-poly(ε-caprolactone) prepolymer (A) segments, was highly processable and could produce spherical microspheres with smooth surfaces as shown in the SEM images in Figure 4. The volume average particle size (D50(vol)) of the 20CP10C20-POE40-based microspheres was 60.9 μm, while the 50CP10C20-POE40-based microspheres were slightly larger, with a D50(vol) of 64.5 μm.

[0119] The in vitro erosion kinetics of polymer-only POE-MBCP-based microspheres are shown in Figure 5. The POE-MBCP-based microspheres were found to erode significantly faster in vitro compared to PCL multiblock copolymers consisting of a combination of crystalline poly(L-lactide) prepolymer (B) segments and hydrophilic poly(ε-caprolactone)-PEG-poly(ε-caprolactone) prepolymer (A) segments. By replacing the poly(L-lactide) prepolymer (B) segments in 50CPC10C20-LL40 with poly(orthoester) prepolymer (B) segments, the resulting 50CP10C20-POE40 was found to completely erode in approximately 300 days.

[0120] 20CP10C20-PQE40, 50CP10C20-POE40, and their mixtures were used to prepare sustained release microspheres of ICP002, a recombinant protein with a molecular weight of approximately 35 kDa. Microspheres carrying the target ICP002 protein at approximately 4 wt% were prepared by solvent extraction / evaporation using a W1 / O / W2 water-in-oil-in-water double emulsion-based membrane emulsification process. Approximately 1-2 g of polymer was dissolved in dichloromethane (O) to a concentration of 15 wt% and filtered through a 0.2 μm PTFE filter. Aqueous protein solution (Wl) with a concentration of approximately 100 mg / ml was added to an O / Wl ratio of 14-15 vol / vol, followed by emulsification using a rotor-stator mixer (21,600 rpm, 40 s) to obtain a primary emulsion. The primary emulsion was then emulsified with an aqueous solution (4.0 wt% PVA, 5 wt% NaCl in ultrapure water) (W2) by membrane emulsification using a membrane with 20 μm pores and a CP / DP ratio of approximately 50 vol / vol to form a secondary emulsion. The secondary emulsion was stirred at room temperature for 4 h and dichloromethane was removed by solvent extraction / evaporation. The resulting microspheres were collected on a 5 μm membrane filter and washed three times with 0.05 w / v% Tween® 80 aqueous solution and three times with ultrapure water, after which the hardened microspheres were dried by lyophilization.

[0121] The mean diameter and particle size distribution including coefficient of variation of the microspheres were measured with a Coulter Counter Multisizer III using 200 or 400 μm aperture and 20,000 counts. The volume average particle size (D50 (volume)) and coefficient of variation (CV) were measured in the range of 4 to 200 μm. The D50 (volume) of ICP002-loaded microspheres varied in the range of 50 to 80 μm, and the CV showed a narrow particle size distribution of 15 to 20%.

[0122] The surface morphology of the microspheres evaluated by scanning electron microscopy showed that the 50CP10C20-POE40-based ICP002-loaded microspheres had a rough surface morphology and extensive aggregation. Increasing the weight fraction of 20CP10C20-POE40 in the 50CP10C20-POE40 / 20CP10C20-POE40 mixture used to prepare the ICP002-loaded microspheres decreased the surface roughness of the microspheres. ICP002-loaded microspheres prepared with 100% 20CP10C20-POE40 had a very smooth surface morphology. The ICP002 loading of the microspheres, determined indirectly from the maximum amount of ICP002 released in vitro, varied between 1.2 and 2.2 wt% as shown in Table 3.

[0123] [Table 3]

[0124] In vitro release (IVR) studies of ICP002-loaded microspheres were carried out in triplicate in 2 ml of 100 mM phosphate buffer, pH 7.4, containing 0.02 w / v% NaN3, thermostated at 37°C. Samples were taken at pre-determined time points and analyzed by RP-UPLC to establish cumulative protein release versus sampling time. Most of the ICP002-loaded microspheres exhibited sigmoidal release kinetics (Figure 6) with lag time, release rate, and release duration dependent on the 20CP10C20-POE40 / 50CP10C20-POE40 polymer blend ratio. Increasing the weight fraction of 20CP10C20-POE40 in the polymer blend decreased the release rate.

[0125] Example 2 In this example, the analytical methods used for the characterization of prepolymers and multiblock copolymers are described. 1H-NMR was performed on a Bruker Avance DRX 500 MHz NMR spectrometer (B AV-500) equipped with a Bruker Automatic Sample Changer (BAGS 60) (Varian) operating at 500 MHz. The d1 wait time was set to 20 s and the number of scans was 16. Spectra were recorded from 0 to 14 ppm. The conversion of the prepolymer and the block ratio in MBCP were determined by 1H-NMR. The Mn of the prepolymer segment (A) was determined both by weight and 1H-NMR. 1H-NMR samples were prepared by adding 1.3 g of deuterated chloroform to 25 mg of polymer.

[0126] The intrinsic viscosity of MBCP was measured using an Ubbelohde Viscosimeter (DIN), type 0C, Si Analytics, equipped with a Si Analytics Viscosimeter containing a water bath. Measurements were performed in chloroform at 25°C. The polymer concentration in chloroform was set to give a relative viscosity in the range of 0.28–2.0 dl / g.

[0127] Modulated differential scanning calorimetry (mDSC) was used to measure the thermal behavior of the multiblock copolymers using a Q2000 MDSC (TA instruments, Ghent, Belgium). Approximately 4–8 mg of dry material was accurately weighed and heated from −85°C to 100°C every 80 s at a heating rate of 2°C / min and a modulation amplitude of ±0.42°C under nitrogen atmosphere. The glass transition temperature (Tg, midpoint) was determined from the reverse heat flow. Temperature and enthalpy were calibrated with an indium standard.

[0128] Example 3 In this example, a method for the preparation of a prepolymer comprising poly(D,L-lactide)-co-PEG-co-poly(D,L-lactide) is provided. A poly(D,L-lactide)-co-PEG600-co-poly(D,L-lactide) prepolymer (abbreviated as ppLP6L12) with a target Mn of 1200 g / mol was prepared by ring-opening polymerization of D,L-lactide using PEG (PEG600) with a molecular weight of 600 g / mol as the initiator. 252.4 g (1.75 mol) of D,L-lactide (Purac) was weighed into a three-necked bottle under nitrogen and dried at 50° C. under reduced pressure for at least 16 hours. 249.5 g (0.42 mol) of pre-dried PEG600 (Merck, Emprove® Essential Ph Eur) was added under nitrogen. The mixture was heated to 140° C. 51 mg of stannous octoate was added and the mixture was stirred magnetically and reacted at 140° C. for 22 hours. 1H-NMR showed 96.0% monomer conversion. The molecular weight determined by 1H-NMR was 1201 g / mol.

[0129] Example 4 In this example, a method for the preparation of prepolymers including poly(D,L-lactide) and poly(D,L-lactide-co-glycolide) is provided. Poly(D,L-lactide) prepolymer (abbreviated as ppL40) with a target Mn of 4000 g / mol was bulk synthesized by 1,4-butanediol (BDO) initiated ring-opening polymerization. BDO (Acros Organics) was distilled with CaH2 under reduced pressure and stored until further use. Under nitrogen atmosphere, 509.6 g (3.53 mol) of D,L-lactide (Purac) was weighed into a three-neck flask and dried at 50°C under reduced pressure for at least 16 hours. Subsequently, 11.4 g (0.13 mol) of BDO was added to the monomers under nitrogen atmosphere. The mixture was heated to 140°C to obtain a clear melt. 62 mg of stannous octoate was added as a 1.0 wt % solution in p-dioxane (Acros, dried and distilled) to initiate the ring-opening polymerization. After 20 h, the reaction was cooled to room temperature. 1H-NMR showed a monomer conversion of 97.0%. The molecular weight determined by 1H-NMR was 4120 g / mol.

[0130] Poly(D,L-lactide-co-glycolide) prepolymer (abbreviated as ppGL40) with a target Mn of 4000 g / mol was prepared by ring-opening copolymerization of D,L-lactide and glycolide using BDO as initiator. 66.6 g (0.46 mol) of D,L-lactide (Purac) and 53.7 g (0.46 mol) of glycolide (Purac) were added to a three-neck flask under nitrogen and dried at 50 °C under reduced pressure for at least 16 hours. After drying, 2.7 g (0.03 mol) of distilled BDO was added to the monomers under nitrogen atmosphere. The reaction mixture was heated to 130 °C. When a clear melt was obtained, 14.1 mg of distilled stannous octoate was added as a solution of 1 wt % in distilled p-dioxane. The reaction was stirred for an additional 27 hours and cooled when the conversion reached 97.2%. The molecular weight determined by 1H-NMR was 4150 g / mol.

[0131] Example 5 This example describes the synthesis and characterization of [poly(D,L-lactide)-co-PEG600-co-poly(D,L-lactide)]-b-[polyorthoester] multiblock copolymer (20LP6L12-POE40) with a block ratio of 20 / 80 w / w. Figure 7 shows its synthesis and molecular structure. 20LP6L12-POE40 (RCP2131) was prepared by chain extending 64.0 g of Mn 4100 g / mol ppPOE40 prepolymer with 16.0 g of Mn 1200 g / mol ppLP6L12 prepolymer using 1.21 g of BDI as chain extender. After drying the prepolymer, the required amount was added to a flange glass reactor and dissolved in distilled p-dioxane at a concentration of 30 wt%, followed by the addition of BDI. Chain extension, post-treatment and drying of 20LP6L12-POE40 was carried out according to the procedure described in Example 1.

[0132] The polymer was analyzed for polymer composition (1H-NMR), intrinsic viscosity, and thermal properties (mDSC) as described above. The block ratio determined from 1H-NMR was 20.0 / 80.0 w / w. The intrinsic viscosity (IV) of this polymer was 0.28 dl / g, and the Tg was 57°C.

[0133] Example 6 In this example, the synthesis and characterization of [poly(D,L-lactide)]-b-[poly(ortho ester)] or [poly(D,L-lactide-co-glycolide)]-b-[poly(ortho ester)] multiblock copolymers are described (Figures 8 and 9). [Poly(D,L-lactide)]-b-[poly(ortho ester)] and [poly(D,L-lactide-co-glycolide)]-b-[poly(ortho ester)] multiblock copolymers with various block ratios were prepared by chain extending ppPOE40 prepolymer with ppL40 or ppGL40 prepolymer using BDI as a chain extender. Both prepolymers were directly dried in a flange glass reactor in the desired amount overnight. Subsequently, distilled p-dioxane was added to obtain a clear polymer solution with a concentration of 30 wt%, followed by the addition of BDI. Chain extension, post-treatment and drying of [poly(D,L-lactide)]-b-[poly(ortho ester)] and [poly(D,L-lactide-co-glycolide)]-b-[poly(ortho ester)] multiblock copolymers were carried out according to the procedures described in Example 1. Table 4 shows the experimental details of various [poly(D,L-lactide)]-b-[poly(ortho ester)] and [poly(D,L-lactide-co-glycolide)]-b-[poly(ortho ester)] multiblock copolymers.

[0134] [Table 4]

[0135] The chemical composition (1H-NMR), intrinsic viscosity, and thermal properties (mDSC) of the polymers were analyzed as described above. Table 5 shows the collected analytical results of the prepared multiblock copolymers. As expected, the Tg of the multiblock copolymer consisting of only POE40-based blocks (100POE40) is very high (90°C). The introduction of small amounts (10-25 wt%) of poly(D,L-lactide) blocks slightly reduced the Tg of the resulting multiblock copolymer to 75-85°C. The chain extension of the POE40 prepolymer blocks together with the poly(D,L-lactide-co-glycolide) prepolymer blocks reduced the Tg of the resulting multiblock copolymers even more.

[0136] [Table 5]

[0137] Example 7 To study the erosion kinetics of POE-based multiblock copolymers, polymer-only microspheres were prepared by solvent extraction / evaporation-based oil-in-water emulsification. 5.8 g of polymer (10.0 wt%) dissolved in 52.4 g of dichloromethane was emulsified in 3.08 kg of ultrapure water containing 4.0 wt% PVA and 5 wt% NaCl by membrane emulsification using a 20 μm pore size membrane. The resulting microspheres were collected on a 5 μm membrane filter and washed three times with 250 ml of ultrapure water containing 0.05 wt% Tween® 80, and then washed three times with 250 g of ultrapure water. Finally, the microspheres were freeze-dried.

[0138] The particle size distribution of the microspheres was measured by laser diffraction (Horiba® LA-960 Laser Particle Size Analyzer). The microspheres were suspended in water until the transmittance was 70-90%, and the particle size distribution of the suspension was measured in the range of 10 nm to 5000 μm. The surface morphology of the microspheres was evaluated by scanning electron microscopy using a JEOL JCM-5000 Neoscope. A small amount of the microspheres was attached to carbon conductive tape and coated with gold for 3 min. The samples were imaged using a 10 kV electron beam.

[0139] In vitro erosion of unsupported polymer-only microspheres was measured in 100 mM phosphate buffer pH 7.4 (90-100 mg microspheres in 10 ml). Samples were incubated at 37° C. At each sampling point, microspheres were collected, lyophilized, and weighed. All POE-based multiblock copolymers could be processed into polymer-only microspheres, resulting in non-porous particles with smooth surfaces. No agglomeration was observed. The volume average particle size distribution (D50(vol)) of the microspheres is shown in Table 6.

[0140] [Table 6]

[0141] FIG. 10 shows the in vitro erosion of polymer-only microspheres composed of 100POE40, 10L40-POE40-10L40, 50POE40-50L40, 25GL40-5POE40, and 50LP10L20-POE40. The 100POE40-based microspheres eroded slowly, with about 35% of the polymer still remaining after 12 months. The introduction of about 10 wt% poly(D,L-lactide) block (10L40-POE40) did not affect the erosion kinetics. However, increasing the poly(D,L-lactide) block content to about 50 wt% (50L40-POE40) resulted in complete polymer erosion within 300 days. The erosion of the multiblock copolymer was significantly accelerated when the poly(D,L-lactide) block was replaced with a poly(D,L-lactide-co-glycolide) block (25GL40-POE40) or when PEG was introduced into the poly(D,L-lactide) block (50LP10L20-POE40).

[0142] Example 8 Ropivacaine-loaded microspheres with a target loading of 50 wt% were prepared by oil-in-water (O / W) membrane emulsification followed by solvent extraction / evaporation. 1.0 g of polymer and 1.0 g of ropivacaine base were dissolved in dichloromethane (DCM) to form the dispersed phase (DP) with a final polymer concentration of 15 wt%. After filtration through a 0.2 μm polytetrafluoroethylene (PTFE) filter, the DP was emulsified with an aqueous solution containing 0.4 wt% PVA and 5 wt% NaCl (continuous phase (CP)) through a membrane with 20 μm pores. The formed O / W emulsion was stirred at room temperature for 2 h, followed by stirring at 40°C under 5 L / min air flow for 1 h to extract and evaporate the DCM and harden the microspheres. After complete evaporation of the solvent and cooling to room temperature, the hardened microspheres were collected by filtration, washed three times with 250 ml of 0.05 wt% Tween® 80 in water, washed three times with 250 ml of WFI (water for injection), and then the microspheres were lyophilized.

[0143] Characterization of the microspheres by scanning electron microscopy showed that the O / W microencapsulation process produced spherical microspheres with smooth surfaces without pores (Figure 11). Crystalline ropivacaine particles were observed in the SEM images of 20LP6L12-POE40-based ropivacaine microspheres, indicating that not all of the ropivacaine was encapsulated in the microspheres (Figure 11). The mean particle size D50 (by volume) of the ropivacaine-loaded microspheres analyzed by laser diffraction ranged from 39 to 50 μm (Table 7).

[0144] The residual DCM content of the microspheres was measured by gas chromatography with headspace injection and flame ionization detection. Briefly, 100 mg of sample was dissolved in 5.0 ml of dimethyl sulfoxide (DMSO) with octane as an internal standard. Samples were analyzed by GC-Headspace using an Agilent 6850 gas chromatograph equipped with a Combi-Pal headspace sampler. The calibration range of the method was 55-5500 ppm of DCM in 100 mg sample using first-order linear regression (weighting factor = 1 / X). The residual DCM content of ropivacaine microparticles composed of 20L40-POE40, 50L40-POE40, and 20GL40-POE40 was relatively high (750-1000 ppm). It was significantly lower (55 ppm) for 20LP6L12-POE40-based ropivacaine-loaded microparticles.

[0145] The ropivacaine content of the microspheres, as determined by elemental analysis (Elementar® Micro Cube), varied from 30.5% by weight for the 20LP6L12-POE40-based ropivacaine microspheres to 41.2% by weight for the 20L40-POE40-based ropivacaine microspheres (Table 7).

[0146] [Table 7]

[0147] In vitro release of ropivacaine from microspheres was determined by incubating 10 mg of ropivacaine microspheres in 45 ml of in vitro release buffer (100 mM PO4 buffer, 0.025% Tween®-20, 0.02% NaN3, 290 mOsm / kg, pH 6.5) at 37°C. At pre-determined time points, the vials were centrifuged and 100 μl aliquots of release buffer were collected. Ropivacaine concentration in the release buffer was measured by reversed-phase ultra-performance liquid chromatography (UPLC) with UV detection using a Waters Acquity H-Class UPLC system equipped with a PDA or UV detector, an Acquity BEH C18 column (50×2.1 mm, 1.7 μm) maintained at 40°C. Mobile phase A consisted of 20 mM phosphate buffer pH 6.5 and acetonitrile in a ratio of 90:10 v / v, and mobile phase B was 100% acetonitrile. The composition of the mobile phase started with 30% B and increased to 70% B within 2 min at a constant flow rate of 0.600 ml / min. Detection was performed at 235 nm. Figure 12 shows the cumulative release of ropivacaine from the microspheres. The 20L40-POE40 and 50L40-POE40 based ropivacaine microspheres released only 5–14% of the encapsulated ropivacaine in the first 14 days. However, the 20GL40-POE40 and 20LP6L12-POE40 based ropivacaine microspheres showed complete release of ropivacaine within 14 days.

[0148] Example 9 Ropivacaine-loaded in situ forming implant formulations using various poly(orthoester)-based multiblock copolymers were prepared by dissolving 1.5 g of polymer in 2.3 g of N-methyl-2-pyrrolidone (NMP) and adding 0.5 g of ropivacaine. The viscosity of the resulting liquid formulations, determined by rheology (TA Instruments AR 2000 rheometer, cone-plate geometry, constant shear at a shear rate of 6 1 / s), ranged from 6 to 21 Pa·s (see Table 8 for details). The injectability of liquid ropivacaine POE-MBCP-based formulations was measured in triplicate using an injectability testing apparatus. 0.2 ml of liquid formulation was drawn into a 1 ml syringe using a 14 G needle. After removing air bubbles, the 14 G needle was replaced with a 20 G × 1 inch (0.9 mm × 25 mm) needle, and then the syringe with the needle was placed vertically in the tensile tester. Force-displacement curves were recorded for the liquid formulations at a displacement rate of 100 mm / min through the needle. Most of the liquid formulations were successfully injectable through a 20G × 1 inch (0.9 mm × 25 mm) needle with an injection force of 11–24 N. However, significantly higher injection forces (24–41 N) were required for the 20GL40-POE40-based formulations.

[0149] Ropivacaine-containing POE-MBC depots were formed in situ by slowly adding 45 ml of buffer (100 mM PO4 buffer, 0.025% Tween®-20, 0.02% NaN3, 290 mOsm / kg, pH 6.5, 37°C) to 100 μl of liquid ropivacaine / polymer / NMP formulation. All formulations showed in situ depot formation without significant swelling. In vitro release of ropivacaine from the in situ formed depots was determined by collecting 100 μl aliquots of release buffer at pre-determined time points. Ropivacaine concentration in the release buffer was determined by UPLC as described in Example 8. Figure 13 shows that the release of ropivacaine from POE-MBCP-based in situ forming implant formulations can be controlled by varying the composition of POE-MBCP. Following an initial burst of approximately 10%, ropivacaine was released gradually from the 50L40-POE40-based depot over a period of 2 months. As expected, release from the 20GL40-POE40-based depot was significantly faster due to the faster erosion of this polymer compared to 50L40-POE40, and was complete within 3 weeks. The other two polymers showed intermediate release rates.

[0150] [Table 8]

[0151] Example 10 Levonorgestrel-loaded in situ forming implant formulations were prepared using different poly(ortho ester)-based multiblock copolymers by dissolving 1.2 g of polymer and 0.05 g of levonorgestrel in 2.2 g of NMP. The viscosity and injectability of the levonorgestrel-containing liquid formulations were characterized as described in Example 9.

[0152] The viscosity of the liquid levonorgestrel formulations varied from approximately 1.6 Pa s to 4.4 Pa s (Table 9), which was significantly lower compared to the liquid ropivacaine formulation of Example 9. All formulations were successfully injectable through a 21 G x 1 inch (0.81 mm x 25 mm) needle (maximum force: 17 N).

[0153] Levonorgestrel-containing POE-MBCP depots were formed in situ by slowly adding 14 ml of buffer (100 mM PO4 buffer, 0.5% SDS, 0.02% NaN3, 290 mOsm / kg, pH 7.4, 37°C) to 500 μl of the liquid levonorgestrel / polymer / NMP formulation. All formulations showed in situ depot formation, with some swelling of the depot observed after 1 day. The tubes were placed in a climate chamber thermostated at 37°C. The in vitro release of levonorgestrel from the in situ formed depots was determined by replacing 13 ml of release buffer at pre-determined time points and analyzing the levonorgestrel concentration in the release buffer by reversed-phase UPLC with UV detection using a Waters Acquity H-Class UPLC system equipped with a PDA or UV detector and an Acquity BEH C18 column (50 x 2.1 mm, 1.7 μm, maintained at 40 °C). The mobile phase was a mixture of water and acetonitrile (isocratic ratio = 50:50 v / v). The flow rate was set at 0.55 ml / min. Detection was performed at 243 nm. Figure 14 shows the release of levonorgestrel from the POE-based levonorgestrel depots. The release of levonorgestrel from the depot was very slow, with only about 15–20% released after 11 weeks, whereas the 20LP6L12-POE40-based in situ forming implant released nearly 35% of the levonorgestrel.

[0154] [Table 9]

[0155] Example 11 Different poly(ortho ester)-based multiblock copolymers were used to prepare leuprolide-loaded in situ forming implant formulations by dissolving 0.66 g of polymer in 1.1 g of a 90 / 10 weight ratio mixture of NMP and benzyl benzoate (BB) and adding 0.12 g of leuprolide. The viscosity and injectability of the leuprolide-containing liquid formulations were characterized as described in Example 9. The viscosity of the formulations varied in the range of 1-7 Pa s. All formulations were successfully injectable through a 20G × 1 inch (0.9 mm × 25 mm) needle with injection forces as low as 8-11 N.

[0156] Leuprolide-containing POE-MBCP depots were formed in situ by slowly adding 2 ml of buffer (100 mM PO4 buffer, 0.025% Tween®-20, 0.02% NaN3, 290 mOsm / kg, pH 7.4, 37°C, 0.02% NaN3, 290 mOsm / kg, pH 7.4) to 100 μl of liquid leuprolide / polymer / NMP / BB formulation. In vitro release of leuprolide from the in situ formed depots was determined by refreshing 1.4 ml of release buffer at pre-determined time points. Leuprolide concentration in the release buffer was measured by reversed-phase UPLC with fluorescence detection using a Waters Acquity H-Class UPLC system equipped with a fluorescence detector and an Acquity CSH C18 column (50 × 2.1 mm, 1.7 μm, maintained at 45°C). Mobile phase A consisted of 37 mM ammonium acetate buffer pH 9.5, and mobile phase B was 100% acetonitrile. The mobile phase composition started at 25% B and was increased to 40% B within 1.5 min at a constant flow rate of 0.75 ml / min. Detection was performed at an excitation wavelength of 280 nm and an emission wavelength of 345 nm. Figure 15 shows the release of leuprolide from POE-MBCP-based in situ forming depots. The release of leuprolide from the liquid formulation was characterized by an initial burst release of 5-20%, a lag period during which no or little leuprolide was released, followed by an accelerated release of leuprolide. The duration of the lag period and the onset of the accelerated release depended on the composition of the POE-MBCP used and occurred earlier for the faster degrading 20GL40-POE40 than for the slower degrading 50L40-POE40 and the slowest degrading 20L40-POE40.

[0157] [Table 10]

Claims

1. A biodegradable thermoplastic multiblock copolymer comprising at least one prepolymer (A) segment and at least one hydrolyzable amorphous prepolymer (B) segment, Both segments are linked by a polyfunctional chain extender. The prepolymer (A) segment is a) comprising one or more hydrolyzable bonds, and / or b) Containing a water-soluble polymer, The hydrolyzable amorphous prepolymer (B) segment is a biodegradable thermoplastic multiblock copolymer containing the following structure. 【Chemistry 1】 [In the formula, n is between 4 and 100, for example, between 5 and 50.] x is between 0.25 and 1, and x + y is 1. p is either 0 or 1, R １ and R ２ is hydrogen and C １ ~C ４ Selected independently of alkyl, Q １ teeth, 【Chemistry 2】 Selected from, Q ２ teeth, 【Transformation 3】 Selected from, r is between 1 and 100. s is between 1 and 12. t is between 1 and 10. R ３ is selected from hydrogen and C １ ~C ６ alkyl, and R ４ is hydrogen and C １ ~C ４ Selected from alkyl groups, R ５ teeth, 【Chemistry 4】 Selected from, v is between 1 and 100. w is between 1 and 12. R ６ is hydrogen and C １ ~C ６ Selected from alkyl groups.

2. R １ and R ２ C １ ~C ４ It is alkyl, preferably R １ and R ２ Both CH ３ The biodegradable thermoplastic multiblock copolymer according to claim 1.

3. R １ and R ２ Both CH ３ And x is 1, Q １ but 【Transformation 5】 The biodegradable thermoplastic multiblock copolymer according to claim 2.

4. The biodegradable thermoplastic multiblock copolymer according to claim 1, wherein the glass transition temperature Tg of the hydrolyzable amorphous prepolymer (B) segment is 40°C or higher, preferably 50°C or higher, for example, 60 to 100°C.

5. The biodegradable thermoplastic multiblock copolymer according to claim 1, wherein the prepolymer (A) segment comprises a water-soluble polymer.

6. The biodegradable thermoplastic multiblock copolymer according to claim 1, wherein the water-soluble polymer comprises one or more selected from the group consisting of polyethers such as polyethylene glycol (PEG), polytetramethylene oxide (PTMO), polypropylene glycol (PPG), and polytetramethylene ether glycol (PTMG); and other water-soluble polymers such as polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyvinyl caprolactam, poly(hydroxyethyl methacrylate) (poly(HEMA)), polyphosphazene, or copolymers of these polymers, and preferably the water-soluble polymer is derived from poly(ethylene glycol) (PEG) having Mn in an amount of 150 to 10,000 g / mol, more preferably 300 to 5,000 g / mol, and most preferably 600 to 3,000 g / mol.

7. The biodegradable thermoplastic multiblock copolymer according to claim 1, wherein the polyfunctional chain extender is a bifunctional aliphatic chain extender, preferably the bifunctional aliphatic chain extender is a diisocyanate, for example, 1,4-butanediisocyanate.

8. The biodegradable thermoplastic multiblock copolymer according to claim 1, wherein the prepolymer (A) comprises a reaction product of one or more cyclic monomers and / or acyclic monomers.

9. The biodegradable thermoplastic multiblock copolymer according to claim 8, wherein the cyclic monomer is selected from the group consisting of glycolides, lactides, ε-caprolactone, δ-valerolactone, trimethylene carbonate, tetramethylene carbonate, 1,5-dioxepan-2-one, 1,4-dioxan-2-one (p-dioxanone), cyclic anhydrides (such as oxepan-2,7-dione), N-carboxyanhydrides of natural amino acids and their derivatives (such as N-carboxyalanine anhydride), and morpholine-2,5-dione-based cyclic depsipeptides (such as 6-methylmorpholine-2,5-dione).

10. The biodegradable thermoplastic multiblock copolymer according to claim 8, wherein the acyclic monomer is selected from the group consisting of succinic acid, glutaric acid, adipic acid, sebacic acid, lactic acid, glycolic acid, hydroxybutyric acid, natural amino acids and their derivatives (such as alanine), ethylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-butanediamine, and 1,6-hexanediamine.

11. The biodegradable thermoplastic multiblock copolymer according to claim 1, wherein the number-average molecular weight (Mn) of the prepolymer (A) is 300 to 30,000 g / mol, preferably 500 to 10,000 g / mol, more preferably 1,000 to 8,000 g / mol, for example, 1,500 to 8,000 g / mol, or 2,000 to 7,000 g / mol.

12. The biodegradable thermoplastic multiblock copolymer according to claim 1, wherein the number-average molecular weight (Mn) of the prepolymer (B) is 1,000 g / mol or more, preferably 2,000 to 10,000 g / mol, or 3,000 to 8,000 g / mol.

13. The biodegradable thermoplastic multiblock copolymer according to claim 1, wherein the prepolymer (A) is present in an amount of 1 to 99%, for example, 5 to 95%, 10 to 90%, 20 to 80%, 30 to 70%, or 40 to 60%, based on the total weight of the multiblock copolymer.

14. The biodegradable thermoplastic multiblock copolymer according to claim 1, wherein the prepolymer (B) is present in an amount of 1 to 99%, for example, 5 to 95%, 10 to 90%, 20 to 80%, 30 to 70%, or 40 to 60%, based on the total weight of the multiblock copolymer.

15. The biodegradable thermoplastic multiblock copolymer according to claim 1, having an intrinsic viscosity of 0.1 dl / g or more, preferably 0.1 to 3 dl / g, more preferably 0.2 to 2 dl / g, for example 0.3 to 1 dl / g.

16. The biodegradable thermoplastic multiblock copolymer according to claim 1, wherein prepolymer segments are randomly distributed within the multiblock copolymer.

17. A method for preparing a biodegradable thermoplastic multiblock copolymer according to any one of claims 1 to 16, comprising a chain extension reaction between prepolymer (A) and prepolymer (B) in the presence of a polyfunctional chain extender.

18. A composition for delivering at least one biologically active compound to a host, The composition comprises at least one biologically active compound encapsulated within a matrix. The matrix is ​​a composition comprising at least one biodegradable thermoplastic multiblock copolymer as described in any one of claims 1 to 16.

19. The composition according to claim 18, wherein the composition is in one or more shapes selected from the group consisting of microspheres, microparticles, nanoparticles, nanospheres, rods, solid implants, gels, in situ-forming implants, coatings, films, sheets, sprays, tubes, membranes, meshes, fibers, and plugs.

20. The composition according to claim 18, wherein the composition is in the form of microspheres and / or microparticles, The composition wherein the average diameter of the microspheres and / or microparticles is preferably in the range of 0.1 to 1000 μm, more preferably in the range of 1 to 100 μm, and even more preferably in the range of 10 to 70 μm.

21. The composition according to claim 18, wherein the composition is in the shape of an in situ-forming implant, The aforementioned biologically active compound is dissolved or suspended in a solution of a biodegradable thermoplastic multiblock copolymer in an acceptable organic solvent such as n-methylpyrrolidone, dimethyl sulfoxide, benzyl benzoate, benzyl alcohol, triacetin, glycoflore, or polyethylene glycol. The composition wherein, after the solution is administered into the body, the organic solvent is replaced with an aqueous body fluid, thereby forming a depot in situ, which traps the biologically active compound within the biodegradable thermoplastic multiblock copolymer depot, and the biologically active compound is then gradually released.

22. The composition according to claim 18, wherein the composition is in the shape of a solid implant manufactured by hot melt extrusion molding or injection molding, The composition wherein the biologically active compound is incorporated into a biodegradable thermoplastic multiblock copolymer as a molecular mixture or as a dispersion of solid particles.

23. The composition according to claim 18, wherein the at least one biologically active compound comprises a non-peptide, a non-protein, a small drug, and / or a biologically active polypeptide.

24. Medical devices in the form of microspheres, microparticles, nanoparticles, nanospheres, rods, solid implants, gels, in situ formation implants, coatings, films, sheets, sprays, tubes, membranes, meshes, fibers, scaffolds or plugs, The medical device comprising a biodegradable thermoplastic multiblock copolymer according to any one of claims 1 to 16.

25. The medical device according to claim 24, further comprising at least one biologically active compound encapsulated within the matrix of the biodegradable thermoplastic multiblock copolymer and released in a controlled manner after insertion into a human or animal.

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