Pharmaceutical composition based on biodegradable polymers comprising polyoxazoline

Abstract

The invention relates to a pharmaceutical composition comprising: a. 20-75 wt% of a biodegradable polymer according to Formula (1) POZx, y –(B-R)z (1), wherein POZx, y is a polyoxazoline, B = a hydrophobic moiety, R = H, or a C1-C18 alkylgroup, x = the number of chain ends of the POZx, y, and is 2, 3, 4, 5 or 6, y = the number of attachment points for B-R at each chain end of the POZx, y, and is 1 or 2, and z is the number of (B-R) groups per biodegradable polymer, and is 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12; b. 20-79 wt% of a biocompatible organic solvent; and c. 1-40 wt% of an active pharmaceutical ingredient; wherein the weight percentages of (a), (b) and (c) are defined relative to the sum of (a)+(b)+(c); wherein the weight fraction of the POZx, y ranges between 4-40 wt% relative to the total weight of the biodegradable polymer, wherein the weight fraction of the POZx, y is determined by 1H-NMR. The invention also relates to a biodegradable polymer, and to pharmaceutical compositions comprising the biodegradable polymer and an active pharmaceutical ingredient, wherein the pharmaceutical compositions are in the form of microparticles, microgranules, microspheres or an implant.

Description

[0001] PHARMACEUTICAL COMPOSITION BASED ON BIODEGRADABLE POLYMERS COMPRISING POLYOXAZOLINE

[0002] The invention relates to novel biodegradable polymers comprising polyoxazoline, a pharmaceutical composition based on biodegradable polymers comprising polyoxazoline in the form of solutions comprising selected solvents, or in the form of microparticles, microgranules, microspheres or an implant.

[0003] BACKGROUND OF THE INVENTION

[0004] Liquid long-acting injectable (LAI) polymeric drug delivery formulations have gained increasing attention in recent years as an alternative for hot melt extruded implants and microparticles, owing to their ease of administration, simple scale-up and cost-effective manufacturing. Solvent exchange in situ forming depot (ISFD) systems are among the most widely applied liquid LAI polymeric depot technologies Such ISFD systems are based on solutions of water insoluble biodegradable polymers in a pharmaceutically acceptable organic solvent or cosolvent system, further containing an active ingredient. The ISFD system acts as a carrier for active pharmaceutical ingredient(s) (API) that are co-formulated with the polymer solution to generate a homogeneous and syringeable liquid solution or suspension.

[0005] US5324519A describes a solvent exchange in situ formed implant system comprising a liquid formulation of a biodegradable, bioerodable, biocompatible thermoplastic polymer dissolved in a biocompatible organic solvent containing a biologically active substance, either dissolved or dispersed in the solution. Upon injection of the liquid formulation into an aqueous environment or into the body, the solvent is replaced by water leading to precipitation of the water-insoluble polymer, thereby forming a microporous, solid or gelatinous matrix with the biologically active substances entrapped within the precipitated polymer matrix. The entrapped API is then released for a prolonged period of time by the diffusion through the (porous) polymer matrix and by ongoing degradation and erosion of the polymer matrix. US5324519A showed that solvent exchange in situ forming depots based on solutions of poly(DL-lactide) in N-methyl pyrrolidone are useful for sustained release of biologically active substances. ISFD provide an interesting alternative to existing long acting injectables like solid implants and microparticles, owing to their biocompatibility, stability, ease of administration and scale up. ISFD technology has been successfully applied to develop long-acting injectable drug products and numerous products based on ISFD such as Eligard®, Atridox®, Sublocade® and Perseris® are nowadays available on the market. Solvent exchange-based in situ forming depot systems composed of linear polymers disclosed in US5324519A, W02012090070A, WO2021048817A and W02014001905A, however still suffer from multiple drawbacks and limitations such as the high viscosity of the polymers solutions requiring relatively large diameter needles for injection. Furthermore, the initial drug release, also called burst release, from these ISFD is typically high, and erosion of the depots is relatively slow .

[0006] W02012090070A discloses a solvent-exchange in situ forming depot system based on solutions of mixtures of linear PEG-polyester triblock and diblock copolymers in biocompatible organic solvents that provides better control over the release kinetics as compared to the drug delivery system described in US5324519A. W02012090070A defines a drug delivery system that comprises triblock and diblock PEG-polyester linear copolymers formulated with organic solvent in such a way that the ratio between copolymers controls the drug release pattern. By varying the ratio of the PEG-polyester triblock and diblock copolymers, the release kinetics of a co-formulated API can be controlled. PEG-polyester triblock and diblock copolymer based ISFD are described, for instance, in WO2021048817A and WO2022229402A1 and were found to be useful for the sustained release of small molecule drugs such as risperidone and etonogestrel.

[0007] Branched polymers are known to be less viscous as compared to linear polymers with the same molecular weight. The use of branched PEG-polyester copolymers has been found effective to obtain polymer-based drug delivery solutions with lower viscosity and thus better injectability (WO2020144239A1). Furthermore branched PEG-polyester copolymers degrade faster as compared to linear PEG polyesters (WO2020144239A1).

[0008] Despite the improvements enabled by branched PEG-polyester copolymers there remains a high demand for in situ forming depot systems that can overcome some of the above mentioned drawbacks of existing in situ forming depot systems, such as their high viscosity, poor injectability, and poor control over the drug release kinetics .

[0009] So far, poly(ethylene glycol) (PEG) has been exclusively used as a non-ionic hydrophilic polymer in in situ forming depots. Balancing the molecular weight and content of this water-soluble polymer in overall polymer structure is used to modify the drug release characteristics of solvent exchange systems. The main reason for the use of PEG in drug delivery systems next to its biocompatibility and non-fouling properties is due to its availability with many functional end groups which allows simple preparation of block or branched copolymers. However, the use of PEG in preparation of block or branched copolymers is limited to availability of polymer of certain structure at individual suppliers. The monomer ethylene oxide is a flammable gas and tailored synthesis requires use of expensive equipment. Furthermore, PEG can only be further functionalized via end group modification, leading to low potential to add extra functionality inside polymer chain. PEG has a low glass transition temperature (Tg) of approximately - 40 °C, which reduces the overall glass transition temperature of block or branched copolymers. This makes it difficult to obtain a solid product in powder form, that is needed for easy handling and fast dissolution. Despite being generally considered as biologically inert, it can stimulate anti-PEG IgM antibody response that is associated with its immunogenicity and accelerated blood clearance. Furthermore, the growing industry of PEG-based therapeutics is associated with the increasing number of people that are allergic to it.

[0010] The polymer according to the invention comprises water soluble polyoxazoline groups (POZ’s). Due to their peptidomimetic structure (tertiary amide), polyoxazolines exhibit similar biocompatibility as PEG. Furthermore, polyoxazolines exhibit excellent synthetic versatility and structural modularity. They are typically synthesized via cationic ring-opening polymerization of 2-oxazolines which allows preparation of well-defined polymers with different functionalities, either as end groups or in the main chain. In addition, POZ polymers have glass transition temperatures as high as 50 °C, giving solid polymers in powder form. In most drug delivery-related applications, the POZ polymers were applied as oral or trans- mucosal drug delivery systems in the form of powder, tablet, capsule or mucoadhesive sheet (W02002026179A1 , WO1999051209A1, W02011002285A1).

[0011] Hydrogels composed of polyethyl oxazoline-b / oc -poly(e-caprolactone) (PEtOz-b- PCL) diblock and PCL-b-PEtOz-b-PCL triblock copolymers are described by Kim et al. (J. Polym. Sci. Part B 2000, 38, 2400 - 2408). When dissolved in water the polymers arrange into micelles which at lower temperatures (20 to 50 °C) and sufficiently high concentrations form thermoreversible gels with gel-sol transition and precipitation temperatures dependent on the block copolymer composition. Conversely, aqueous solutions of poly(L-lactide)-b- polyethyl oxazoline-b-poly(L-lactide) (PLLA-PEtOz-PLLA) triblock copolymer exhibited a solgel transition upon increasing temperature (Biomacromolecules 2003, 4, 1487-1490). Similar to the PCL-b-PEtOz-b-PCL solutions, the gelation temperature of aqueous solutions of these PLLA-PEtOz-PLLA triblock copolymers can be tailored by adjusting the polymer composition, e.g. by changing the molecular weight of polymer or the ratio between the blocks. Knop et al. (Biomacromolecules 2013, 14, 2536-2548) describes four-arm star-shaped amphiphilic copolymers with a PCL core surrounded by four oligomeric chains of PEtOz and the use of micellar aqueous solutions thereof for encapsulation and delivery of cytotoxic drugs. Doxorubicin-containing micellar aqueous solutions demonstrated lower in vitro cytotoxicity compared to free doxorubicin. Similarly, PLA-b-PEtOz micelles in water were used for encapsulation of the hydrophobic drug paclitaxel with high loading efficiency (Colloids and Surfaces A 2019, 566, 120-127). Such systems allowed sustained release in vitro of the drug for up to 30 days and tailoring of the release rate by changing the hydrophilic-hydrophobic ratio in the block copolymer. None of the prior art describes biodegradable polymer-based solvent exchange systems comprising low viscosity, well injectable linear, branched or star-shaped biodegradable POZ-polyester (POZ-PE) copolymer solutions that form solid or semi-solid depots upon injection in the body, that allow sustained release of co-formulated drug molecules with (in many cases) surprisingly low burst release, and that are well degradable thereafter.

[0012] The drawbacks mentioned above can at least partly be overcome by providing a pharmaceutical composition comprising a biodegradable polymer according to claim 1 of the present invention. of the invention

[0013] The invention relates to a pharmaceutical composition comprising: a. 20-75 wt% of a biodegradable polymer according to Formula (1)

[0014] POZx y-(B-R)z(1), wherein POZx yis a polyoxazoline,

[0015] B = a hydrophobic moiety,

[0016] R = H, or a 01-018 alkylgroup, x = the number of chain ends of the POZX’y, and is 2, 3, 4, 5 or 6, y = the number of attachment points for B-R at each chain end of the POZx y, and is 1 or 2, and z is the number of (B-R) groups per biodegradable polymer, and is 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12; b. 20-79 wt% of a biocompatible organic solvent; and c. 1-40 wt% of an active pharmaceutical ingredient; wherein the weight percentages of (a), (b) and (c) are defined relative to the sum of (a)+(b)+(c); wherein the weight fraction of the POZx yranges between 4-40 wt% relative to the total weight of the biodegradable polymer, wherein the weight fraction of the POZx yis determined by1H-NMR.

[0017] The pharmaceutical composition according to the invention has a number of unique features.

[0018] The viscosity of the composition can be very low, which allows injection with very thin needles, for example needles of 27G, or even 30G. Further, the use of specific biodegradable polymers gives the possibility to tune the release profile of the API from fast to slow and from a continuous release to a release which starts after certain time (delayed release).

[0019] Furthermore, the composition can contain very high amounts of API, making the system very convenient and efficient.

[0020] The pharmaceutical composition can be used to prepare a subcutaneous depot of the biodegradable polymer with the API, for tuneable release of the API. It is believed that the biocompatible organic solvent is exchanged with water or bodily fluids after injection, followed by formation of a depot of the biodegradable polymer with the API. Subsequently the API is released from the depot and the biodegradable polymer in the depot will be degraded. The characteristics of the biodegradable polymer, its concentration in the pharmaceutical composition, the biocompatible organic solvent used determine to a large extent the release properties of the API from the pharmaceutical composition according to claim 1.

[0021] The invention also relates to novel (branched) biodegradable polymers comprising polyoxazoline and polyester blocks, and to solid pharmaceutical compositions (for example microparticles, microgranules, microspheres or implants) comprising biodegradable polymers comprising polyoxazoline and polyester blocks and 1-70 wt% of one or more active pharmaceutical ingredients.

[0022] Detailed description

[0023] As indicated in the summary, the invention relates to a pharmaceutical composition comprising: a. 20-75 wt% of a biodegradable polymer according to Formula (1)

[0024] POZx y-(B-R)z(1), wherein POZx yis a polyoxazoline, B = a hydrophobic moiety, R = H, or a C1-C18 alkylgroup, x = the number of chain ends of the POZX’y, and is 2, 3, 4, 5 or 6, y = the number of attachment points for B-R at each chain end of the POZx y, and is 1 or 2, and z is the number of (B-R) groups per biodegradable polymer, and is 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12; b. 20-79 wt% of a biocompatible organic solvent; and c. 1-40 wt% of an active pharmaceutical ingredient; wherein the weight percentages of (a), (b) and (c) are defined relative to the sum of (a)+(b)+(c); wherein the weight fraction of the POZx yranges between 4-40 wt% relative to the total weight of the biodegradable polymer, wherein the weight fraction of the POZx yis determined by1H-NMR.

[0025] It is an advantage of the biodegradable polymer according to Formula 1 that pharmaceutical compositions comprising said biodegradable polymer, in the form of for example ISFD- forming compositions, microparticles, microgranules, microspheres, or implants, facilitates the preparation of compositions having a more favorable balance between release duration and erosion time. Release duration is herein defined as the time taken for the API to be fully released from for example the ISFD-forming compositions, microparticles, microgranules, microspheres, or implants in the human body. Erosion time is herein defined as the time it takes for the biodegradable polymer in for example the ISFD-forming compositions, microparticles, microgranules, microspheres, or implants to fully degrade in the human body.

[0026] In a preferred embodiment, the biodegradable polymer is a water-insoluble polymer. A polymer according to the present invention is deemed to be water-insoluble when a 2 wt% solution of biodegradable polymer in deionized water does not fully dissolve after stirring the 2 wt% solution at 22 °C and at atmospheric pressure (1 bar) for 24 hours. Water-insoluble polymers have the advantage that they more efficiently form ISFD upon injection.

[0027] In a preferred embodiment, the total amount of ingredients (a), (b) and (c) is at least 75 wt% relative to the total weight of the pharmaceutical composition, preferably at least 90 wt% or 95 wt% relative to the total weight of the pharmaceutical composition.

[0028] In a preferred embodiment, the weight fraction of the POZx yranges between 4-25 wt% relative to the total weight of the biodegradable polymer. This range facilitates advantageous sustained release behavior.

[0029] The pharmaceutical composition of the invention preferably has a low viscosity, for easy injection of the composition with a needle with acceptable diameter, such as 21 gauge or smaller, preferably 23 gauge or smaller, more preferably 25 gauge or smaller, or most preferably 27 gauge or smaller. The dynamic viscosity of the composition measured using a rotational cone-plate rheometer typically ranges between 0.01-5 Pa s, preferably ranges between 0.01-1 Pa s, more preferably ranges between 0.01-0.5 Pa s, most preferably ranges between 0.01-0.1 Pa s. The pharmaceutical composition may have a higher dynamic viscosity, for example a dynamic viscosity higher than 5 Pa s. Although highly viscous, such pharmaceutical compositions may be injected using needles with significantly larger diameter, such as 18 gauge, 16 gauge, or 14 gauge, although this is typically not preferred as the use of these larger needles causes significant pain leading to reduced therapy compliance of patients. New developments in the field of injection devices has resulted in more advanced spring-powered and gas-powered injectors that enable administering of highly viscous liquid formulations by means of more patient friendly smaller needle diameters. For example, Windgap Medical’s LVDC gas powered autoinjector allows injection of pharmaceutical compositions with viscosities higher than 5 Pa s.

[0030] The pharmaceutical composition preferably is biocompatible and / or biodegradable. Biocompatible is herein defined as the pharmaceutical composition typically not being harmful or toxic to living tissue.

[0031] Biodegradable is herein defined as the natural biological processes of the human body typically being capable of breaking down the pharmaceutical composition into harmless substances.

[0032] The biodegradable polymer according to the invention comprises polyoxazoline moieties (POZx yalso abbreviated as POZ). Preferably, these are water soluble POZ moieties. Due to their peptidomimetic structure (tertiary amide), polyoxazolines exhibit similar biocompatibility as PEG. Furthermore, polyoxazolines exhibit excellent synthetic versatility and structural modularity. They are typically synthesized via cationic ring-opening polymerization of 2- oxazolines which allows preparation of well-defined polymers with different functionalities, either as end groups or in the main chain. In addition, POZx ypolymers have glass transition temperatures as high as 50 °C, giving solid biodegradable polymers in powder form.

[0033] POZx y(also abbreviated as POZ) is preferably a poly(2-oxazoline) moiety, more preferably a 2-alkyl-2-oxazoline moiety. POZx yis preferably a poly(alkyl oxazoline) moiety. Examples of suitable POZx ymoieties are poly(2-ethyl-2-oxazoline) moieties, poly(2-methyl-2-oxazoline) moieties and / or water soluble copolymers of 2-ethyl-2-oxazoline or 2-methyl-2-oxazoline with more hydrophobic monomers such as 2-n-propyl-2-oxazoline), (2-n-propyl-2-oxazoline), (2-iso-propyl-2-oxazoline), (2-sec-butyl-2-oxazoline), 2-cyclopropyl-2-oxazoline. Preferably the POZ moieties are poly(2-ethyl-2-oxazoline) moieties.

[0034] The POZx ycan be linear or branched. For linear POZx y, x= 2, therefore the biodegradable polymer has 2 chain ends. For branched POZx y, x is 3, 4, 5, or 6. X is the number of chain ends of the POZx ymoiety, which chain ends are covalently connected to one or more B-moieties. X is at least 2, yielding a triblock copolymer with a central hydrophilic POZx ymoiety having at least one hydrophobic B moiety at each end. X can be an integer from 2 to 6, but is preferably 2, 3 or 4, most preferably 2 or 4.

[0035] Y represents the number of attachment points at each chain end of the POZx ymoiety. Y is at least one, meaning that for every chain end at least one attachment point for a B-moiety is present. When y = 2, 2 B-moieties are coupled to each chain end of POZx y. Preferably y is 1 or 2.

[0036] Z is the total number of B moieties coupled to the POZx ygroup in the biodegradable polymer, and is an integer ranging from 2 to 12. Preferably Z is 2, 4, 6 or 8.

[0037] The POZx ycan also be branched, whereby x is an integer from 3-6, preferably x = 4 or 6, most preferably x=4. A POZx ywith x=4 has 4 arms which can connect to B moieties (at the chain ends of the POZx y).

[0038] At each arm of the POZx y, 1 or 2 B-moieties can be attached, whereby each B moiety has an R end group.

[0039] A POZx ywith x=2 and y=2 is a POZx yhaving two POZx yendgroups, wherein at each end groups 2 B-R moieties are attached. The biodegradable polymer comprises therefore 1 POZx ycore molecule with 4 B-R groups, attached to 2 chain ends of the POZx y(see Formula 2).

[0040] Formula 2

[0041] A POZx ywith x=4 and y=1 is a branched POZx yhaving 4 chain ends and at each chain end 1 B-R moiety (see Formula 3). Subscripts m and n in the formula relate to the number of monomeric units in each depicted chain segment between square brackets: m is the number of monomeric moieties of POZx y, while n is the number of monomeric moieties of a polyester moiety.

[0042] Formula 3

[0043] In an embodiment of the invention, x is 2, 3 or 4, most preferably 2 or 4, and z is 2, 4, 6 or 8.

[0044] The biodegradable polymer may be branched, in this example star-shaped, and x=2, 3 or 4, y=2, and z is 4, 6, or 8.

[0045] Typically, the POZx yis prepared by the ring opening polymerization of a 2-alkyl-2-oxazoline (like for example 2-ethyl-2-oxazoline) using an initiator. The POZx ymoiety according to Formula 1 therefore typically comprises an initiator. Examples of suitable initiators are ethylene glycol bis-p-toluenesulfonate, diethylene glycol di(p-toluenesulfonate), triethylene glycol di(p-toluenesulfonate), ethyleneglycol bistriflate, 1 ,4-dibenzyl bromide, trans-1 ,4- dibromo-2-butene. For example use of 1 , 4-dibromo-2-butene yields a linear POZx y, wherein x=2 and y=1 (POZ2’1). Quenching the reaction with a base (like for example KOH, sodium bicarbonate or tetramethylammonium hydroxide) yields a linear POZx yhaving one OH endgroup at both ends of the POZx ymoiety. Quenching the reaction with an amine having more than one hydroxyl groups (like for example a diethanolamine) yields a linear POZx yhaving more than one OH-endgroups at both ends of the POZx ymoiety. For using diethanolamine, the POZx ywould have x=2 (linear-core) and y=2 (branched at the chain ends of the POZx y), which can be abbreviated to POZ2 2.

[0046] Another suitable initiator is pentaerythritol tetratri fl ate, which yields a branched POZx ywhen reacted with 2-ethyl-2-oxazoline, with x=4. The biodegradable polymer preferably has a number average molecular weight (Mn) between 4000-30000 g / mol, preferably between 4500-20000 g / mol, more preferably between 5000- 15000 g / mol.

[0047] The Mnof the POZx ymoiety preferably ranges between 400-5000 g / mol, more preferably between 450-3000, or between 500-2500 g / mol .

[0048] The Mnof the B moiety generally ranges between 500-10 000 g / mol, preferably between 600-5000 g / mol, more preferably between 750-4000 g / mol.

[0049] In an embodiment of the invention, the biodegradable polymer has a number average molecular weight (Mn) between 4000-30000 g / mol, preferably between 4500-20000 g / mol, more preferably between 5000-15000 g / mol, the Mnof the POZx yranges between 400-5000 g / mol, preferably between 450-3000 g / mol, or between 500-2500 g / mol; and the Mnof each B moiety ranges between 500-10 000 g / mol, preferably between 600-5000 g / mol, more preferably between 750-4000 g / mol.

[0050] The B moiety is a hydrophobic moiety. Preferably, the B moiety is a polymer moiety comprising at least one of the monomers from the group consisting of glycolide, lactide, E- caprolactone, p-dioxanone (1 ,4-dioxan-2-one), trimethylene carbonate (1 ,3-dioxan-2-one),

[0051] 1 .4-dioxepan-2-one (including its dimer 1 ,5, 8, 12-tetraoxacyclotetradecane-7, 14-dione), 1 ,5- dioxepan-2-one, 6,6-dimethyl-1 ,4-dioxan-2-one, 2,5-diketomorpholine, pivalolactone, chi.- diethylpropiolactone, ethylene carbonate, ethylene oxalate, 3-methyl-1 ,4-dioxane-2, 5-dione, 3, 3-diethyl-1 ,4-dioxan-2, 5-dione, 6,8-dioxabicycloctane-7-one, p-propiolactone, y- butyrolactone, b-valerolactone, s-decalactone, 3-methyl-1 ,4-dioxane-2, 5-dione, 1 ,4-dioxane-

[0052] 2.5-dione, 2,5-diketomorpholine, a,a-diethylpropiolactone, y-butyrolactone, 1 ,4-dioxepan-2 - one, 1 ,5-dioxepan-2-one, 6,6-dimethyl-dioxepan-2-one, 6,8-dioxabicycloctane-7-one, 5,5- dimethyl-1 ,3-dioxan-2-one, including mixtures of these monomers.

[0053] Preferably the monomers of the B-moiety are chosen from the group consisting of glycolide, lactide, s-caprolactone, p-dioxanone (1 ,4-dioxan-2-one), trimethylene carbonate (1 ,3-dioxan- 2-one), 1 ,4-dioxepan-2-one (including its dimer 1 ,5, 8,12-tetraoxacyclotetradecane-7, 14- dione) and 1 ,5-dioxepan-2-one, including mixtures of these monomers.

[0054] Most preferably the monomers of the B-moiety are chosen from the group consisting of glycolide, lactide, and s-caprolactone, or the B-moiety is a polylactide.

[0055] The biodegradable polymer comprises an R group at each end of the B moiety, wherein R can be a hydrogen atom (H) or an organic hydrocarbyl group, comprising 1-18 carbon atoms. Preferably R is chosen from a hydrogen atom (H), or C1-C18 alkyl group. Most preferred R group is hydrogen atom. An embodiment of the invention relates to a pharmaceutical composition comprising a biodegradable polymer according to Formula (1), a biocompatible organic solvent and an API, wherein the biodegradable polymer concentration ranges between 30-60 wt% relative to the total weight of (a)+(b)+(c), the Mnof the POZ ranges between 400-2200, the Mnof the B moiety ranges between 750-4000 and x = 2, y=2 and z=4.

[0056] In an embodiment of the invention, the weight fraction of the biodegradable polymer ranges between 20-75 wt% relative to the total weight of the pharmaceutical composition and the weight fraction of the biocompatible organic solvent ranges between 20-75 wt% relative to the total weight of (a)+(b)+(c); preferably the weight fraction of the biodegradable polymer ranges between 30-60 wt% relative to the total weight of (a)+(b)+(c) and the weight fraction of the biocompatible organic solvent ranges between 20-69 wt% relative to the total weight of (a)+(b)+(c).

[0057] In an embodiment of the invention, the pharmaceutical composition comprises a biodegradable polymer according to Formula (1), a biocompatible organic solvent, and an API, wherein the weight fraction of the biodegradable polymer ranges between 30-60 wt% relative to the total weight of (a)+(b)+(c), the Mnof the POZx yranges between 400-2200 g / mol, the Mnof each B moiety ranges between 750-2500 g / mol, and x = 2, y=2, and z=4. The pharmaceutical composition comprises between 1-40 wt% of an active pharmaceutical ingredient (API), relative to the total amount of biodegradable polymer, biocompatible organic solvent and API.

[0058] The composition comprises a biocompatible organic solvent. Biocompatible is herein defined as the organic solvent typically not being harmful or toxic to living tissue.

[0059] The biocompatible organic solvent is preferably chosen from the group consisting of N- methyl-2-pyrolidone (NMP), N-ethyl2-pyrolidone , dimethyl sulfoxide (DMSO), dimethyl isosorbide (DMI), benzyl alcohol, benzyl benzoate, ethyl lactate, ethyl benzoate, ethyl acetate, pyrrolidone-2, tetraglycol, triacetin, tripropionin, tributyrin, glycofurol, polyethyleneglycol dimethyl ether and mixtures thereof.

[0060] Preferred biocompatible organic solvents are selected from NMP, DMSO, triacetin, tripropionin and benzyl benzoate or mixture thereof.

[0061] The amount of biocompatible organic solvent ranges between 20-79 wt%, preferably between 50-69 wt%, relative to the total weight of (a)+(b)+(c). Accordingly, in an embodiment of the invention, the weight fraction of the biodegradable polymer ranges between 29-49 wt% relative to the total weight of (a)+(b)+(c), the weight fraction of the biocompatible organic solvent ranges between 50-69 wt% relative to the total weight of (a)+(b)+(c), and the weight fraction of the API ranges between 1-21 wt% relative to the total weight of (a)+(b)+(c)n.

[0062] The API can be chosen from a small sized drug, a biologically active polypeptide, such as a peptide, a protein, an antibody or an antibody fragment, or a biologically active oligonucleotide.

[0063] Active pharmaceutical ingredients which may be contained in the pharmaceutical composition include but are not limited to small molecules, having a molecular weight which in general is 1000 g / mol or less, polypeptides, polynucleotides, or combinations thereof.

[0064] Polypeptides consists of amino acids linked by peptide bonds. Short polypeptides are also referred to as peptides, whereas longer polypeptides are typically referred to as proteins. One convention is that those polypeptide chains that are short enough to be made synthetically from the constituent amino acids are called peptides rather than proteins. However, with the advent of better synthetic techniques, polypeptides as long as hundreds of amino acids can be made, including full proteins like ubiquitin. Another convention places an informal dividing line at approximately 50 amino acids in length. This definition is somewhat arbitrary. Long polypeptides, such as the amyloid beta peptide linked to Alzheimer’s disease, can be considered proteins; and small proteins, such as insulin, can be considered peptides. At any rate, the skilled person will appreciate that essentially any type of polypeptide can be encapsulated and subsequently released from a polymer matrix. The size of the polypeptide(s) can vary. In one embodiment, the polypeptide has a molecular weight of 10 000 g / mol or less. In another embodiment, said polypeptide is a biologically active protein having a molecular weight of 10 000 g / mol or more.

[0065] Polynucleotides, or nucleic acids, are macromolecules composed of nucleotide monomers that are covalently bonded in a chain. DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) are examples of polynucleotides with distinct biological functions. Nucleotides are composed of a nitrogenous base, a five carbon sugar, and a phosphate group. Oligonucleotides are relatively short polynucleotide fragments (oligomers), usually 13-25 nucleotides long, although the maximum length of synthetic oligonucleotides can go up to 200 nucleotide monomers. Antisense oligonucleotides (ASO) are short, single stranded oligonucleotides that can alter RNA and reduce, restore, or modify protein expression through several distinct mechanisms.

[0066] Active pharmaceutical ingredients can also be combinations of any of the foregoing, which includes but is not limited to the combinations of monoclonal antibodies and cytotoxic small molecule agents in antibody-drug conjugates (ADCs) used as targeted therapy for treating cancer. The active pharmaceutical ingredient in the composition of the present invention may be an active ingredient such as any therapeutically active ingredient and any diagnostic and any contrast agent and includes those therapeutically active ingredients having a prophylactic effect on the animal, including human as well as those therapeutically active ingredients that have an effect of alleviating, reducing or even completely eliminating a symptom, or a cause, or a consequence of a disease, such as pain, swelling or inflammation or a disease from the animal, including human.

[0067] For example, the therapeutically active ingredient may include broad classes of compounds normally delivered into the body. For example, these therapeutically active ingredients include but are not limited to anti-infectives (including antibiotics, antivirals, fungicides, scabicides or pediculicides); antiseptics; analgesics and analgesic combinations; anorexics; antihelminthics, antiarthritics, antiasthmatic agents; anticonvulsants; antidepressants; antidiabetic agents; antidiarrheals; antihistamines; anti-inflammatory agents, antimigraine preparations; antinauseants; antineoplastics; antiparkinsonism drugs; antipuritics; antipsychotics; antipyretics, antispasmodics; anticholinergics; sympathomimetics; xanthine derivatives; cardiovascular preparations including potassium and calcium channel blockers; beta-blockers; alpha-blockers and antiarrhythmics; antihypertensives; diuretics and antidiuretics; vasodilators including general coronary, peripheral and cerebral vasodilators; central nervous system stimulants; vasoconstrictors; cough and cold preparations, including decongestants; hormones and steroids (e.g. estrogens, progestins, androgens, adrenocorticoids, corticosteroids and the like); hypnotics; immunosuppressives; muscle relaxants; parasympatholytics; psychostimulants; sedatives and tranquilizers, narcotics, local anesthetics (e.g. amide- or anilide-type local anesthetics such as bupivacaine and ropivacaine; antiemetic agents; antiangiogenic agents, polysaccharides, immune-modulating, anti-thrombogenic compounds, anti-claudicating drugs, anti-atherosclerotic drugs, antihistamines, anti-cancer drugs and photosensitizers used in photodynamic therapy, vascular drugs, ophthalmic drugs, amino acids, vitamins, neurotransmitters, neurohormones, signaling molecules, psychoactive medicaments, synthetic drugs, semi-synthetic drugs, natural drugs and substances derived from these, or combinations of the above.

[0068] The therapeutically active ingredient may also be a biological including but not limited to peptides, (recombinant) proteins and PEGylated-proteins (e.g. insulin, erythropoietin, exenatide, glucagon-like-peptide-1 , morphogenic proteins (e.g. bone morphogenic proteins, transforming growth factors, fibroblast growth factors, tumor necrosis factors), receptor antagonists (e.g. lnterleukin-1-receptor-antagonist), anticancer proteins (e.g. neocarzinostatin, L-asparaginase, interleukin-2, bevacizumab and other anti-VEGF agents), prophylactic vaccines, therapeutic vaccines, genetic materials (e.g. nucleic acid sequences, polynucleotides, (antisense) oligonucleotides, plasmids, DNA, RNA, siRNA, microRNA), aptamers, enzymes, antigens, antibodies, antibody fragments, viruses, virus-based materials, cells, cellular substructures, etc.).

[0069] Prodrugs, metabolites, derivatives, in-vivo or in in-vitro chemically modified products, in-vivo or in-vitro enzymatic modified products and therapeutically active degradation products of the therapeutically active ingredients described herein are included in the scope of the invention.

[0070] Preferably, the active ingredient is a therapeutically active ingredient chosen from the group of immune-modifying drugs, anti-inflammatory drugs or growth factors.

[0071] Preferably, the active ingredient is a therapeutically active ingredient chosen from the group of immune-modifying drugs.

[0072] Preferably, the active ingredient is a therapeutically active ingredient chosen from the group of steroidal anti-inflammatory drugs.

[0073] Preferably, the active ingredient is a therapeutically active ingredient chosen from the group of non-steroidal anti-inflammatory drugs or a selective COX-2 inhibitor.

[0074] Preferably, the active ingredient is a therapeutically active ingredient chosen from the group of anticancer agents.

[0075] Preferably, the active ingredient is a therapeutically active ingredient chosen from the group of anti-viral agents.

[0076] Preferably, the active ingredient is a therapeutically active ingredient chosen from the group of anti-bacterial agents.

[0077] Preferably, the active ingredient is a therapeutically active ingredient chosen from the group of anti-diabetic agents.

[0078] Preferably, the active ingredient is a therapeutically active ingredient chosen from the group of vaccines.

[0079] Preferably, the active ingredient is a therapeutically active ingredient chosen from the group of ophthalmic agents.

[0080] Preferably, the active ingredient is a therapeutically active ingredient effective against forms of neuro-degenerative diseases .

[0081] Preferably, the active ingredient is a therapeutically active ingredient chosen from the group of biologicals including but not limited to growth factors which are very suitable for application in orthopedics and in particular in the prevention or treatment of diseases of intervertebral discs, or cartilage, or bone. Examples of such growth factors include but are not limited to transforming growth factor 3, fibroblast growth factor 18, osteogenic protein 1, bone morphogenic protein 2, bone morphogenic protein 6, bone morphogenic protein 7, interleukin-1 -receptor-antagonist . Preferably, the active ingredient belongs to the class of human growth hormones and its biosimilar derivatives, which can be applied in both pediatric and adult growth disorders, maintenance of sufficient musculature, and for anti-ageing applications.

[0082] Preferably, the active ingredient is a therapeutically active ingredient effective against inflammation or microbial infections of the inner ear and its connecting tissues, (intratympanic ear diseases).

[0083] Preferably, the active ingredient is a therapeutically active ingredient effective against forms of diabetes.

[0084] For the active ingredient which are water soluble, the drug preferably has a solubility in water of at least 20 pg / ml, for example of at least 100 pg / ml, for example of at least 500 pg / ml, for example of at least 1000 pg / ml, for example of at least 5000 pg / ml in water measured at 20°C and at atmospheric pressure (1 bar).

[0085] Examples of water soluble active ingredients include small molecules (of up to 1000 g / mol), medium sized molecules (of 1000 g / mol up to 10 000 g / mol), but also large molecules (of at least 10 000 g / mol), such as proteins. These water soluble active ingredients may be synthesized chemically, but may also be a biological including but not limited to (recombinant) proteins and peptides (e.g. insulin, erythropoietin, exenatide, glucagon-like- peptide-1 , morphogenic proteins (e.g. bone morphogenic proteins, transforming growth factors, fibroblast growth factors, tumor necrosis factors), receptor antagonists (e.g. lnterleukin-1-receptor-antagonist), anticancer proteins (e.g. neocarzinostatin, L- asparaginase, interleukin-2, bevacizumab and other anti-VEGF agents) prophylactic vaccines, therapeutic vaccines, genetic materials (e.g. nucleic acid sequences, polynucleotides, (antisense) oligonucleotides, plasmids, DNA, RNA, siRNA, microRNA), aptamers, enzymes, antigens, antibodies, antibody fragments, viruses, virus-based materials, cells, cellular substructures, etc.).

[0086] Release properties of the API in compositions according to the invention can be tuned by the choice of a number of parameters.

[0087] In general, a high amount of the hydrophilic POZx y(for example 20-40 wt% of the biodegradable polymer), and / or a high molecular weight of the POZx y(for example 1000- 2000 g / mol) tends to shorten the release time of an API.

[0088] Compositions having a biodegradable polymer having a relatively short POZx ymoiety (for example Mnranges from 500-1300 g / mol) and a low POZx ycontent (for example 5-10 wt% of the biodegradable polymer) tend to form a depot after injection, which gives constant slow or very limited release for a certain time (for example 2-4 weeks) after which delay time the release sets off to a reasonable fast release. Branching of the POZx ycore of the biodegradable polymer also influences the release properties: branching of the core tends to shorten the release times of an API.

[0089] Another factor which influences the release time is the initial concentration of the biodegradable polymer in the pharmaceutical composition: a higher initial concentration of biodegradable polymer in the pharmaceutical composition lowers the initial burst release and prolongs the release duration of an API.

[0090] The composition and chain length of the B moiety also influence the release properties of an API. B moieties composed of poly(lactide) tend to give a slower release and release with an delay time. B moieties composed of poly(lactide-glycolide) tends to give shorter release times and shorter delay time, compared to poly(lactide).

[0091] The choice of solvent also seems to influence the release of the API . Hydrophilic solvents demonstrate faster solvent-water exchange and formation of solid depot, while hydrophobic solvents have lower solubility in water and thus slower exchange with water after injection. Combining solvents of different hydrophilicity can thus be used for tuning the kinetics of the release of the active pharmaceutical ingredient.

[0092] In an embodiment the pharmaceutical composition comprises: a. 30-60 wt% of a biodegradable polymer according to Formula (1)

[0093] POZx y-(B-R)z(1), wherein POZx yis a polyoxazoline, B = a hydrophobic moiety, R = H, x = the number of chain ends of the POZX’y, and is 2, y = the number of attachment points for B-R at each chain end of the POZx y, and is 2, z = the number of (B-R) groups per biodegradable polymer, and is 4; b. 20-68 wt% of a biocompatible organic solvent; and c. 2-20 wt% of an API ; wherein the weight percentages of (a), (b) and (c) are defined relative to the sum of (a)+(b)+(c); wherein the Mnof the POZx yranges between 1000 and 2500 g / mol, the weight fraction of the POZx yranges between 20 and 40 wt% relative to the weight of the biodegradable polymer, and the Mnof each B moiety ranges between 500 and 5000 g / mol. Such pharmaceutical compositions typically yield a relatively fast release of API. The higher the content or molecular weight of POZx y, the faster the release of API. The degradation of pharmaceutical composition comprising such a biodegradable polymer is fast, as well. Some of the biodegradable polymers tend to degrade fully within 100 days in vitro), at high biodegradable polymer concentration such as 50 wt%. The degradation rate is even faster for pharmaceutical composition with lower polymer concentration.

[0094] In a preferred embodiment the pharmaceutical composition comprises: a. 30-60 wt% of a biodegradable polymer according to Formula (1)

[0095] POZx y-(B-R)z(1), wherein POZx yis a polyoxazoline, B = a hydrophobic moiety, R = H, x = the number of chain ends of the POZX’y, and is 2, y = the number of attachment points for B-R at each chain end of the POZx y, and is 2, z is the number of (B-R) groups per biodegradable polymer, and is 4; b. 20-68 wt% of a biocompatible organic solvent; c. 2-20 wt% of an API; and wherein the weight percentages of (a), (b) and (c) are defined relative to the sum of (a)+(b)+(c); wherein Mnof the POZX’yranges between 500 and 1250 g / mol, the weight fraction of the POZx yranges between 4 and 12 wt% relative to the weight of the biodegradable polymer, and the Mnof each B moiety ranges between 500 and 5000 g / mol.

[0096] Such pharmaceutical compositions typically yield long sustained release of API. The release profile of drug can be adjusted by changing the POZx ymolecular weight and content of POZx ywithin the biodegradable polymer. Depending on the structure of the biodegradable polymer, pharmaceutical composition can give constant slow release of API or delayed release of API. Thus, these pharmaceutical compositions can be used if long sustained release of certain drugs is required or if the drug should be released after an exact period of time after injection. The length of the delay can be tuned by changing the composition of the segment. The invention also relates to a biodegradable polymer according to Formula (1), POZx y-(B-R)z(1), wherein POZ is a polyoxazoline

[0097] B = a hydrophobic moiety R = H, or a C1-C18 hydrocarbyl group x = the number of chain ends of POZ, and is 2, 3, 4, 5 or 6; y = the number of attachment points for B-R at each chain end of POZ, and is 1 or 2 when x=3 or 4, and y=2 when x=2; z is the number of (B-R) groups per biodegradable polymer, and is 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12

[0098] The POZx ycan be linear or branched. For linear POZx y, x= 2, and the biodegradable polymer has 2 chain ends. For branched POZx y, x is 3, 4, 5, or 6.

[0099] X is the number of chain ends of the POZx ymoiety, which chain ends are covalently connected to one or more B-moieties. X is at least 2, yielding a triblock copolymer with a central hydrophilic POZx ymoiety having at least one hydrophobic B moiety at each end.

[0100] X can be an integer from 2 to 6, but is preferably 2, 3 or 4, most preferably 2 or 4.

[0101] Y represents the number of attachment points at each chain end of the POZx ymoiety. Y is at least one, meaning that for every chain end at least one attachment point for a B-moiety is present. When y = 2, 2 B-moieties are coupled to each chain end of POZx y. Preferably y is 1 or 2.

[0102] Z is the total number of B moieties coupled to the POZx ygroup in the biodegradable polymer, and is an integer ranging from 3 to 12. Preferably Z is 4, 6 or 8.

[0103] The POZx ycan also be branched, whereby x is an integer from 3-6, preferably x = 4 or 6, most preferably x=4. A POZx ywith x=4 has 4 arms which can connect to B moieties (at the chain ends of the POZx y).

[0104] At each arm of the POZx y, 1 or 2 B-moieties can be attached, whereby each B moiety has an R end group.

[0105] A POZx ywith x=2 and y=2 is a POZx yhaving to POZx yendgroups, wherein at each end groups 2 B-R moieties are attached. The biodegradable polymer comprises therefore 1 POZX’ycore molecule with 4 B-R groups, attached to 2 chain ends of the POZx y(see Formula 2).

[0106]

[0107] Formula 2

[0108] A POZx ywith x=4 and y=1 is a branched POZx yhaving 4 chain ends and at each chain end 1 B-R moiety (see Formula 3). In formula 3, subscripts m and n relate to the number of monomeric units in each chain segment: m is the number of monomeric moieties of POZ, while n is the number of monomeric moieties of a polyester moiety.

[0109] Formula 3

[0110] In an embodiment of the invention the biodegradable polymer is branched, in this example star-shaped, and x=2, 3 or 4, y=2, and z is 4, 6, or 8.

[0111] Typically, the POZx yis prepared by the ring opening polymerization of a 2-alkyl-2-oxazoline (like for example 2-ethyl-2-oxazoline) using an initiator. The POZx ymoiety according to

[0112] Formula 1 therefore typically comprises an initiator. Examples of suitable initiators are ethylene glycol bis-p-toluenesulfonate, diethylene glycol di(p-toluenesulfonate), triethylene glycol di(p-toluenesulfonate), ethyleneglycol bistriflate, 1 ,4-dibenzyl bromide and trans-1 ,4- dibromo-2-butene. For example use of 1 , 4-dibromo-2-butene yields a linear POZx y, wherein x=2 and y=1 (POZ2’1). Quenching the reaction with a base (like for example KOH, sodium bicarbonate or tetramethylammonium hydroxide) yields a linear POZx yhaving one OH endgroup at both ends of the POZx ymoiety. Quenching the reaction with an amine having more than one hydroxyl groups (like for example a diethanolamine) yields a linear POZx yhaving more than one OH-endgroup at both ends of the POZx ymoiety. When using diethanolamine, the POZx ywould have x=2 (linear-core) and y=2 (branched at the chain ends of the POZx y), which can be abbreviated to POZ2 2.

[0113] Another suitable initiator is pentaerythritol tetratri fl ate, which yields a branched POZx ywhen reacted with 2-ethyl-2oxazoline, with x=4.

[0114] The biodegradable polymer preferably has a number average molecular weight (Mn) between 4000-30000 g / mol, preferably between 4500-20000 g / mol, more preferably between 5000- 15000 g / mol.

[0115] The Mnof the POZx ymoiety preferably ranges between 400-5000 g / mol, more preferably between 450-3000 g / mol, or between 500-2500 g / mol .

[0116] The Mnof the B moiety generally ranges between 500-10 000 g / mol, preferably between 600-5000 g / mol, more preferably between 750-4000 g / mol.

[0117] The B moiety is a hydrophobic moiety. Preferably the B moiety is a polymer comprising at least one of the monomers from the group consisting of glycolide, lactide, e-caprolactone, p- dioxanone (1 ,4-dioxan-2-one), trimethylene carbonate (1 ,3-dioxan-2-one), 1 ,4-dioxepan-2- one (including its dimer 1 ,5, 8, 12-tetraoxacyclotetradecane-7, 14-dione), 1 ,5-dioxepan-2-one, 6,6-dimethyl-1 ,4-dioxan-2-one, 2,5-diketomorpholine, pivalolactone, chi.- diethylpropiolactone, ethylene carbonate, ethylene oxalate, 3-methyl-1 ,4-dioxane-2, 5-dione, 3, 3-diethyl-1 ,4-dioxan-2, 5-dione, 6,8-dioxabicycloctane-7-one, p-propiolactone, y- butyrolactone, b-valerolactone, e-decalactone, 3-methyl-1 ,4-dioxane-2, 5-dione, 1 ,4-dioxane- 2, 5-dione, 2,5-diketomorpholine, a,a-diethylpropiolactone, y-butyrolactone, 1 ,4-dioxepan-2 - one, 1 ,5-dioxepan-2-one, 6,6-dimethyl-dioxepan-2-one, 6,8-dioxabicycloctane-7-one, 5,5- dimethyl-1 ,3-dioxan-2-one, including mixtures of these monomers.

[0118] Preferably the monomers of the B-moiety are chosen from the group consisting of glycolide, lactide, e-caprolactone, p-dioxanone (1 ,4-dioxan-2-one), trimethylene carbonate (1 ,3-dioxan- 2-one), 1 ,4-dioxepan-2-one (including its dimer 1 ,5, 8,12-tetraoxacyclotetradecane-7, 14- dione) and 1 ,5-dioxepan-2-one, including mixtures of these monomers.

[0119] Most preferably the monomers of the B-moiety are chosen from the group consisting of glycolide, lactide, and e-caprolactone, or the B-moiety is a polylactide. The biodegradable polymer comprises an R group at each end of the B moiety, wherein R can be a hydrogen atom (H) or a short chain organic hydrocarbyl group, comprising 1-18 carbon atoms.

[0120] Preferably R is chosen from a hydrogen atom (H), or C1-C18 alkyl group. Most preferably, the R group is a hydrogen atom.

[0121] The invention also relates to a pharmaceutical composition in the form of microparticles, microgranules, microspheres, nanoparticles, or nanospheres, solid implants in the form of a rod, film, foil, sheet, membrane, a viscous paste or gel, a spray, or a coating on a medical device, which pharmaceutical composition comprises the biodegradable polymer according to Formula 1 in combination with an active pharmaceutical ingredient, wherein Formula (1) is

[0122] POZx y-(B-R)z(1), wherein POZx yis a polyoxazoline, B = a hydrophobic moiety, R = H, or a C1-C18 alkylgroup, x = the number of chain ends of the POZX’y, and is 2, 3, 4, 5 or 6, y = the number of attachment points for B-R at each chain end of the POZx y, and is 1 or 2, and z is the number of (B-R) groups per biodegradable polymer, and is 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12.

[0123] In one embodiment, the pharmaceutical composition is in the form of a solid implant. The active pharmaceutical ingredient may be formulated into solid implants via processes like for example hot melt extrusion or injection moulding. The active pharmaceutical ingredient can be incorporated in a biodegradable polymer as a molecular blend or as a dispersion of solid particles. Typically, the compound and biodegradable polymer powders are physically mixed where after the resulting powder blend is introduced to the extruder, heated and processed to yield formulations of the desired shape and dimensions, such as a small diameter cylindrical rod or a film. Instead of physical mixing of the compound and biodegradable polymer powders, the active pharmaceutical ingredient and biodegradable polymer may be co-dissolved in a suitable solvent or a dispersion of compound in a solution of biodegradable polymer in a suitable solvent may be prepared, followed by freeze-drying and extrusion of the freeze-dried powder. The latter generally improves the blend homogeneity and the content uniformity of the implants. In further embodiments, the implant may be a monolithic implant or an implant with one or more additional layers applied to a core implant, such as a dual layer implant or a core-sheath implant. The at least one active pharmaceutical ingredient is typically incorporated in the core implant, and the function of the additional layer or layers is typically to control the release kinetics. The at least one active pharmaceutical ingredient can also be incorporated in the additional layer. It is also possible that both the core implant and the additional layer contain at least one active pharmaceutical ingredient. The additional layer or layers may be applied to the core implant via spray-coating, dip-coating or via co-extrusion or over-moulding.

[0124] One specific aspect relates to a pharmaceutical composition in the form of microparticles. In general microparticles are small particles having a diameter of less than 1000 pm, and containing an active pharmaceutical ingredient. Spherical microparticles are also known as microspheres. The microparticle may be a homogeneous or monolithic microparticle in which the active pharmaceutical ingredient is dissolved or dispersed throughout the biodegradable polymer matrix. It is also possible that the microparticle is of a reservoir type in which the active pharmaceutical ingredient is surrounded by a shell of biodegradable polymer. When the active pharmaceutical ingredient is a water-soluble small molecule drug, the drug may first be dispersed in a hydrophobic or lipophilic excipient, which combination then is dispersed in the form of particles, droplets, or micro-suspensions in the biodegradable polymer matrix.

[0125] In one embodiment the microparticles are obtained by grinding of premade formulations of the active pharmaceutical ingredient and biodegradable polymer, such as solid implants prepared by hot melt extrusion or injection moulding. Such microparticles are also known as microgranules.

[0126] Microspheres may be prepared by techniques known to those skilled in the art, including but not limited to coacervation, solvent extraction / evaporation, spray-drying, sprayfreeze drying or spray-congealing. In one embodiment, the microspheres are prepared by a solvent extraction / evaporation technique which comprises dissolving the biodegradable polymer in an organic solvent such as dichloromethane or ethylacetate, and emulsification of the biodegradable polymer solution in an aqueous phase containing an emulsifying agent, such as polyvinyl alcohol (PVA) (as described among others by Okada, Adv. Drug Deliver. Rev. 1997, 28(1), 43-70).

[0127] The characteristics, such as particle size, porosity and drug loading of the so formed microspheres depend on the process parameters, such as viscosity or concentration of the aqueous polyvinyl alcohol phase, concentration of the biodegradable polymer solution, ratio of dichloromethane to aqueous solution of active, ratio of primary emulsion to polyvinyl alcohol phase and the stirring rate. As the microspheres are being formed, the active pharmaceutical ingredient is encapsulated in the microspheres. In general, when the solvent extraction / evaporation technique is employed to encapsulate lipophilic active pharmaceutical ingredient, the active pharmaceutical ingredient is first dissolved in the solution of the biodegradable polymer in the organic solvent, which is subsequently emulsified in an aqueous PVA solution, yielding an oil-in-water (O / W) emulsion. The organic solvent is then extracted into the aqueous phase and evaporated to solidify the microspheres.

[0128] In general, when the solvent evaporation technique is employed to encapsulate water-soluble active pharmaceutical ingredient, an aqueous solution of the compound is first emulsified in a solution of the organic solvent-based biodegradable polymer solution. This primary emulsion is then subsequently emulsified in a PVA solution, which yields a water-in-oil-in-water (W / O / W) emulsion. The organic solvent is then extracted similarly to the O / W process route to solidify the microspheres. Alternatively, active pharmaceutical ingredients that are not or insufficiently soluble in the organic solvent based polymer solution, may be dispersed directly in the organic solvent based biodegradable polymer solution. The obtained dispersion is then subsequently emulsified in a PVA solution, yielding a solid-in-oil-in-water (S / O / W) emulsion. The organic solvent is then extracted similarly to the O / W process route to solidify the microspheres.

[0129] When the microspheres are formed by spray-drying, a solution of biodegradable polymer in an organic solvent, typically a volatile organic solvent such as dichloromethane, is employed. In general, when spray-drying is employed to encapsulate lipophilic active pharmaceutical ingredient, the active pharmaceutical ingredient is directly dissolved in the biodegradable polymer solution, whereafter the solution is spray-dried into microparticles. In general, when spray-drying is employed to encapsulate water-soluble active pharmaceutical ingredient, such as peptides are proteins, the active pharmaceutical ingredient may be dispersed in the organic solvent based biodegradable polymer solution, whereafter the dispersion is spray-dried into microparticles. Alternatively, the water-soluble active pharmaceutical ingredient may be first dissolved in an aqueous solution, followed by emulsification of the aqueous solution with the organic solvent-based biodegradable polymer solution, whereafter the emulsion is spray-dried into microparticles.

[0130] To allow spray-drying of solutions of active pharmaceutical ingredients and standard biodegradable polymers such as poly(DL-lactide) or poly(DL-lactide-co-glycolide) into microparticles without the formation of fiber-like structures, the concentration of the biodegradable polymer in the organic solvent is typically kept low, such as between 0.5 and 2 wt% relative to the total weight of the solution.

[0131] It has been surprisingly found that solutions with high concentration of biodegradable polymer according to Formula 1, can be spray-dried into active pharmaceutical ingredient-loaded microparticles, which can be administered as a suspension and show extended release of the active pharmaceutical ingredient. In one embodiment, the biodegradable polymer concentration is about 5 wt%, in another embodiment about 10 wt%, in another embodiment about 20 wt% with respect to the total weight of biodegradable polymer, solvent, and API.

[0132] The ability to obtain microparticles with the desired release characteristics of the active pharmaceutical ingredient via spray-drying is believed to be due to the low viscosity of the biodegradable polymer solutions, in combination with reasonably high Tgand the hydrophilic nature of the biodegradable polymer comprising polyoxazoline and polyester (POZ-PE copolymers), which allows formation of solid particles when spray-drying is applied, and at the same time allows sustained release of the active pharmaceutical ingredient due to swelling of the biodegradable polymer matrix of the microparticles in an aqueous environment.

[0133] When the microspheres are formed by spray-congealing, the biodegradable polymer is processed in the molten state at sufficiently high temperature. When spraycongealing is employed, the active pharmaceutical ingredient is either dissolved or dispersed in the molten biodegradable polymer, whereafter the liquid mixture is atomized via a nozzle into droplets which are subsequently solidified into microparticles via cooling with air or gas in a chill tower.

[0134] It has been surprisingly found that the biodegradable polymer according to Formula 1 can be spray-congealed dried into active pharmaceutical ingredient-loaded microparticles with the desired loading, and which can be administered as a suspension and show extended release of the active pharmaceutical ingredient. In one embodiment the loading of the active pharmaceutical ingredient in the spray-congealed microparticles is about 10 wt%, in another embodiment about 25 wt%, in another embodiment about 30 wt%, in another embodiment about 40 wt%, in another embodiment about 60 wt% with respect to the total weight of the active pharmaceutical ingredient-loaded microparticles.

[0135] The ability to obtain microparticles with the desired loading and release characteristics of the active pharmaceutical ingredient via spray-congealing is believed to be due to the low viscosity of the biodegradable polymers in the molten state, in combination with their reasonably high Tgand the hydrophilic nature of the biodegradable polymer comprising polyoxazoline and polyester (POZ-PE copolymers), which allows formation of solid particles when spray-congealing is applied, and at the same time allows sustained release of the active pharmaceutical ingredient due to swelling of the biodegradable polymer matrix of the microparticles in an aqueous environment.

[0136] The microparticles, microgranules, microspheres or implants preferably contain between 80 and 100 wt% of the biodegradable polymer and the at least one active pharmaceutical ingredient, relative to the total weight of the microparticles, microgranules, microspheres or implants. The amount of the at least one active pharmaceutical ingredient is preferably between 1 and 70 wt% of the total weight of the microparticles, microgranules, microspheres or implants, more preferably between 10 and 60 wt%, most preferably between 20 and 50 wt% of the total weight of the microparticles, microgranules, microspheres or implants.

[0137] Typically the microparticles, microgranules or microspheres have a volume based average diameter (D50(vol)) between 10 and 150 micrometer, preferably between 20 and 100 micrometer, most preferably between 30 and 70 micrometer. The amount of active pharmaceutical ingredient incorporated in the microparticles, microgranules, or microspheres ranges generally between 1 and 70 wt% relative to the total weight of the composition, preferably between 10-60 wt% relative to the composition, most preferably 20-50 wt% relative to the composition.

[0138] FIGURES

[0139] Figure 1 shows the relationship between the viscosity of solutions of biodegradable POZ-PE polymers listed in Table 3 in NMP, DMSO, triacetin and tripropionin with polymer concentrations of 20, 35 and 50 wt% and the smallest needle size (expressed in Gauge) allowing ejection of the solutions using ejection forces < 20 N. The figure shows that a 21 G needle is the smallest needle size allowing ejection of solutions of biodegradable POZ-PE polymers with a viscosity between -1 Pa s and -4 Pa s using ejection forces < 20 N, and that a 25 G needle is the smallest needle size allowing ejection of biodegradable POZ-PE polymer solutions with a viscosity between -0.07 Pa s and -0.3 Pa s using ejection forces < 20 N.

[0140] Figure 1B shows the effect of polymer topology on the viscosity of 35 and 50 wt% polymer solutions in NMP for biodegradable triblock copolymer 10POZ[PLA]2-OH with a linear topology (black), biodegradable polymer 10POZ[PLA]4-OH polymer with a branched topology (grey), and biodegradable polymer 10POZ(PLA)4-OH_s with a star-shaped topology (white).

[0141] Figure 2 shows the cumulative release of ropivacaine base from NMP-based ISFD formulations prepared of biodegradable POZ-PE polymers with polymer concentrations of 35 wt%. Ropivacaine loading was 2 wt% (20 mg / g).

[0142] Figure 3 shows the effect of the composition of the polyester arm (B) of biodegradable POZ- PE copolymers on cumulative release of ropivacaine from NMP-based ISFD formulations with polymer concentrations of 35 wt% and 50 wt%. Ropivacaine loading was 2 wt% (20 mg / g). Figure 4 shows the effect of polymer concentration on the cumulative release of ropivacaine from NMP-based ISFD formulations prepared of biodegradable POZ-PE polymers with polymer concentration 35 or 50 wt%. Ropivacaine loading was 2 wt% (20 mg / g).

[0143] Figure 5 shows the effect of polymer end groups (R) on the cumulative release of ropivacaine from ISFD formulations prepared of biodegradable polymer 10POZ1400[LA3150]4-R based solutions in NMP with polymer concentration of 35 wt%. Ropivacaine loading was 2 wt% (20 mg / g).

[0144] Figure 6 shows the effect of solvent on the cumulative release of ropivacaine from ISFD prepared of solutions of biodegradable polymer 20POZ2100[LA2280]4-OH in NMP (35 wt% polymer concentration). Ropivacaine loading was 2 wt% (20 mg / g).

[0145] Figure 7 shows the cumulative release of ivermectin (ivermectin loading 1 wt%, 10 mg / g) from NMP-based ISFD formulations prepared of various biodegradable POZ-PE polymers. The polymer concentration was 35 wt%.

[0146] Figure 8 shows the effect of celecoxib loading (20 mg / mL, 50 mg / mL, 100 mg / mL) on the release of celecoxib from NMP-based ISFD formulations prepared of biodegradable polymer 10POZ1300[LA4860]2-OH with a polymer concentration of 35 wt%.

[0147] Figure 9 shows the daily release rate of celecoxib vs. time for NMP-based ISFD formulations prepared of biodegradable polymer 10POZ1300[LA4860]2-OH with a polymer concentration of 35 wt%. and celecoxib concentrations of 20 mg / mL, 50 mg / mL and 100 mg / mL.

[0148] Figure 10 shows the cumulative release of octreotide acetate from NMP-based ISFD formulations prepared of biodegradable polymers 5POZ800[LA4000]4-OH and 10POZ800[LA2070]4-OH with 40 wt% polymer concentration. Octreotide acetate loading was 6 wt% (60 mg / g).

[0149] Figure 11 relates to a cumulative release of ropivacaine from NMP-based ISFD formulations prepared of branched biodegradable polymer 20POZ1400[LA1400]4-OH, linear copolymer PLGA PDLG5004 and linear multiblock copolymer 10LP6L12-L20. The concentrations of the polymer solutions were 50 wt% for the branched biodegradable polymer 20PGZ1400[LA1400]4-OH, and 35 wt% for linear copolymer PLGA PDLG5004 and linear multiblock copolymer 10LP6L12-L20. Ropivacaine loading was 2 wt% (20 mg / g) for all formulations.

[0150] Figure 12 shows a comparison of degradation behavior of NMP based ISFD formulations prepared of branched biodegradable polymer 20PGZ1400[LA1400]4-OH, linear copolymer PLGA PDLG5004, and linear multiblock copolymer 10LP6L12-L20. The concentrations of the polymer solutions was 50 wt% and ropivacaine loading was 2 wt% (20 mg / g).

[0151] Figure 13 shows SEM images showing the morphology of levonorgestrel-loaded microgranules prepared of biodegradable polymer 5PGZ800(LA4000)4-OH. Figure 14 shows SEM images showing the morphology of Celecoxib-loaded microparticles prepared of 5POZ800(LA3924)4-OH by spray-congealing. Celecoxib loadings were 25, 40 and 60 wt%.

[0152] Figure 15 shows the cumulative release of Celecoxib from Celecoxib microparticles prepared by spray congealing using biodegradable polymers 5POZ800(LA3924)4-OH and 5POZ800(LA3924)4-C18. Celecoxib loadings were 25, 40 and 60 wt%.

[0153] Figure 16 shows the cumulative release of CXB from CXB-MP prepared by spray congealing using biodegradable polymers 7.5POZ800(LL2265)4-QH and 7.5POZ800(LL2265)4-C18.

[0154] Celecoxib loadings were 25 and 40 wt%.

[0155] Figure 17 shows SEM images showing the morphology of spray-dried ropivacaine-loaded microparticles prepared of biodegradable polymers 5POZ800(LA4000)4-QH by spray-drying. Ropivacaine loading was 40 wt%.

[0156] NOMENCLATURE

[0157] In the experimental section, abbreviations have been used for the biodegradable polymer. When the biodegradable polymers are polyoxazoline-polyester (POZ-PE) copolymers, the abbreviation is in the form of for example xxPOZyyyy[LAzzzz]4-OH, with xx the wt% of the POZ block, yyyy the Mnof the POZ block, and zzzz the Mnof the B-block (that is, B-R according to Formula 1), wherein for this example the B-block is D,L-lactide.

[0158] For example, biodegradable polymer 10PQZ1000[((LA75GA25)2250)4-QH means a biodegradable polymer having 10 wt% of POZ block having Mnof 1000 g / mol, and on each side of POZ block 2 B-blocks wherein Mnof one B-block is 2250 g / mol for a total of 4 B- blocks. B-block comprises D,L-lactide and glycolide in 75 / 25 (mol) ratio. The end group R according to Formula 1 is H in this case.

[0159] In cases where R is not H, the carbon chain length has been added to the formula.

[0160] For example, 10POZ1000[((LA75GA25)2250)4-C6 indicates biodegradable polymer consisting of 10 wt% of POZ having a number-averaged molecular weight (Mn) of 1000 g / mol, and 4 B-blocks each having number-averaged molecular weight of 2250 g / mol and on each end a C6 R-group.

[0161] In this application, the units Da and g / mol are used interchangeably.

[0162] In this application, when the biodegradable polymer comprises polyoxazoline and polyester, it may also be referred to by the term POZ-PE copolymers.

[0163] In tables, the biodegradable polymer may be referred to as polymer for brevity.

[0164] ANALYTICAL TECHNIQUES The conversion of all monomers (EOz, D,L-lactide, glycolide and e-caprolactone) during polymerization, the block ratio of biodegradable polymers, and the number-averaged molecular weight (Mn) of the biodegradable polymers, POZ, and polyester units ((B-R)zin Formula 1) were determined by1H-NMR.1H-NMR was performed on a Bruker Avance DRX 500 MHz NMR spectrometer (B AV 500) equipped with Bruker Automatic Sample Changer (BAGS 60) (Varian) operating at 500 MHz. The d1 waiting time was set to 20 s, and the number of scans was 16. Spectra were recorded from 0 to 14 ppm.1H-NMR samples were prepared by adding 1 .3 g of deuterated chloroform to 25 mg of biodegradable polymer. 1H-NMR is used to determine the Mnof the POZx y, the biodegradable polymer, and each B moiety, and the weight fraction of the POZx yrelative to the weight of the biodegradable polymer according to the claims.

[0165] The Mnof POZ as obtained by1H-NMR is determined from the ratio between initiator and POZ signals in1H-NMR for synthesized POZ polymers. The molecular weight of the synthesized POZ-PE copolymers as obtained using1H-NMR was determined by finding the weight fraction of POZ from the ratio between POZ and PE signals in1H-NMR. The number averaged molecular weight of the POZ-PE copolymers was calculated using the following equation:

[0166] Mnof POZ as determined by1H-NMR

[0167] Mn(POZ — PE copolymer) Weight fraction of POZ as determined by1H-NMR

[0168] The overall molecular weight of the polyester arms was calculated by subtracting the molecular weight of the POZ polymer from the molecular weight of the POZ-PE copolymer as determined by1H-NMR according to the equation above. The molecular weight of each polyester arm was determined taking in account the number of polyester arms per POZ-PE copolymer.

[0169] Modulated differential scanning calorimetry (mDSC) was used to determine the thermal behaviour of the biodegradable polymers using a Q2000 MDSC (TA instruments). About 4-8 mg of dry material was accurately weighed and heated under a nitrogen atmosphere from -85 °C to 100 °C at a heating rate of 2 °C / min and a modulation amplitude of + / - 0.42 °C every 80 seconds. The glass transition temperature (Tg, midpoint) was determined from the reversing heat flow. Temperature and enthalpy were calibrated with an indium standard.

[0170] The weight-average molecular weight (Mw), the number-average molecular weight (Mn) and the polydispersity (PDI) of the biodegradable polymer were determined by a gel permeation chromatography (GPC) system (PSS Security system), equipped with a refractive index detector. Separation is performed at 35°C on two Linear-M PFG columns, 300 x 8.0 mm with a separation range of 100 - 1 000 000 g / mol (PSS). Chloroform was used as an eluting solvent. The flow rate was set to 1 mL / min. Calibration was performed using PMMA molecular weight standards (PSS). Samples was dissolved in mobile phase and 50 pL is injected. Equipment control, data acquisition and data processing were performed by WinGPC® (PSS). The Mndetermined by GPC is not used to define the Mnof the biodegradable polymers according to the claims.

[0171] The solubility of the biodegradable polymers in water was determined by preparing a 2 wt% solution of biodegradable polymer in deionized water in a 15 mL glass vial. The solution was stirred using a magnetic stirring bead by means of a magnetic stirrer with a stirring speed of 200 rpm at 22 °C for 24 hours. The stirred solutions were visually inspected. If undissolved biodegradable polymer is visible in the solution, the biodegradable polymer is deemed to be a water-insoluble polymer. Undissolved biodegradable polymer may for example be visible as sediment or suspended particles. In case no clear undissolved biodegradable polymer is visible, the solution is filtered through filter paper (pore size 7 - 12 pm, for example Whatman® prepleated qualitative filter paper for technical use, Grade 1574 1 ). The filtration paper is washed twice with 1 mL deionized water. If biodegradable polymer is visibly retained by the filtration paper, the biodegradable polymer is also deemed to be a water-insoluble polymer. Solubility of the POZ polymers may be determined in the same way.

[0172] The viscosity of the solutions -with and without dissolved drug- was measured by cone-and-plate rotational rheology using an AR2000ex rotational rheometer (TA Instruments, New Castle, DE, USA) with a 40 mm cone, an angle of 1° and a Peltier plate. The gap between cone and plate was 29 pm. Samples of ca. 300 pL were equilibrated at 25°C for 180 s whereafter a 300 s time sweep was initiated, during which the samples were sheared at a shear rate of 5 s-1.

[0173] The syringeability of biodegradable polymer solutions was determined by drawing biodegradable polymer solutions into a 1 mL Luer-Lock syringe using an 18 G needle. Air bubbles were removed from the syringe and the needle was replaced by a 21, 23, 25, 27 or 30 G needle. The syringe was positioned in a Mecmesin injectability tester (PPT Group UK Ltd, West Sussex, UK). The glide force needed to eject the solutions at a displacement rate of 100 mm / min was determined using Emperor™ Force software.

[0174] MATERIALS USED.

[0175] Acetonitrile, >99.9% was purchased from Actu-AII Chemicals (Actu-AII Chemicals B.V., Oss, The Netherlands). Sodium sulfate, 99%; Triethylamine, 99% were purchased from Acros Organics (Thermo Fisher Scientific Inc., Waltham, MA, USA). Diethyl ether was purchased from Boom (Boom B.V, Meppel, The Netherlands). Purasorb® DL D,L-lactide and Purasorb® G, glycolide were purchased from Corbion (Purac Biochem B.V., Gorinchem, The Netherlands). Sodium Chloride; Methanol, liquid chromatography grade were purchased from Merck (Merk KGaA, Darmstadt, Germany). 1-methyl-2-pyrrolidone, 99.50%; Calcium hydride; Diethanolamine, >99.0%; Pentaerythritol, 99%; Pyridine, 99.8%; Tin (II) octanoate (Sn(Oct)2), >92.5%; Triflic anhydride, 99% were purchased from Sigma-Aldrich (Merk KGaA, Darmstadt, Germany). n-Hexane, 99+%; 2-ethyl-2-oxazoline, 99+%; Molecular sieves, 4A 8 to 12 mesh; Deuterated chloroform, 99.8 atom% D; Dichloromethane, 99.50% stabilized with ethanol; Celite® 545; Activated charcoal Norit® CN1; 1,4-dioxane, 99+%, extra pure, stabilized; Deuterated acetone, 99.8 atom% D; tetramethylammonium hydroxide, 25wt% in methanol were purchased from Thermo Scientific (Thermo Fisher Scientific Inc., Waltham, MA, USA). Trans-1,4-dibromo-2-butene, >98.0%; Hexanoyl chloride, >98.0%; Tripropionin; Stearoyl chloride, >97.0% were purchased from Tokyo Chemicals Industry Co., Ltd. (Toshima, Kita-Ku, Tokyo, Japan). Hydrochloric acid, 37%; Sodium hydroxide were purchased from VWR Chemicals (VWR International, LLC, Radnor, PA, USA).

[0176] Example 1

[0177] This example describes the preparation of a,a’,w,w’-hydroxyl terminated poly(2-ethyl-2- oxazoline) (POZ(OH)4) and a,w-hydroxyl terminated poly(2-ethyl-2-oxazoline) (POZ(OH)2) by cationic ring-opening polymerization using trans-1 ,4-dibromo-2-butene (tDBB) as initiator. A three-neck flask was dried and placed under N2 atmosphere. Recrystallized trans-1,4- dibromo-2-butene was weighed in the three-neck flask and dried under high vacuum (approximately 1 x 10"2mbar ) for 2h at room temperature. Subsequently, distilled acetonitrile (ACN) and 2-ethyl-2-oxazoline (EOz) were added. The molecular weight of polymer was tuned by adjusting the ratio between initiator and monomer. The reaction mixture was quickly heated to 80 °C and left stirring overnight under N2 atmosphere. After quantitative conversion of the EOz monomer into POZ polymer (determined by1H-NMR as described in Example 8), the reaction mixture was cooled down to 50 °C in case of a,a’,w,w’-hydroxyl terminated poly(2-ethyl-2-oxazoline) and to 0 °C in case of a,w-hydroxyl terminated poly(2-ethyl-2- oxazoline).

[0178] Subsequently, to obtain a,a’,w,w’-hydroxyl terminated poly(2-ethyl-2-oxazoline), a 2-fold excess of diethanolamine relative to the number of end groups of the POZ polymer) was added to the mixture. To obtain a,w-hydroxyl terminated poly(2-ethyl-2-oxazoline) tetramethylammonium hydroxide solution in methanol (25 wt%) was added to the three-neck flask to terminate the reaction. The reaction mixture was further stirred overnight whereafter it was filtered and ACN was removed using a rotavapor. Subsequently, dichloromethane (DCM) was added and the resulting mixture was filtered under vacuum. The filtered polymer solution was washed twice with 15 wt% aqueous NaCI solution. The organic phase was collected and dried over anhydrous Na2SO4 and filtered through a column filled with activated charcoal and Celite. Finally, the solvent was evaporated to yield POZ as a white powder. The molecular weight of the obtained POZ polymers as determined by1H-NMR was slightly higher in all cases compared to the intended molecular weight based on the in-weights. The increase in molecular weight is attributed to the cleaning procedure to remove unreacted quenching agents, salts formed during quenching and short oligomers as to obtain polymers of high purity.

[0179] Reaction scheme for the preparation of a, co-hydroxyl terminated poly(2-ethyl-2-oxazoline) (POZ(OH)2)

[0180] Reaction scheme for the preparation of a, a’, co, co’-hydroxy I terminated poly(2-ethyl-2- oxazoline) (POZ (OH) 4)

[0181] The number-averaged molecular weight (Mn) of the hydroxyl terminated polymers were determined by1H-NMR by comparing the ratio between peaks corresponding to initiator fragments and polymer fragments.

[0182] The characteristics of the so-prepared a,a’,co,co’-hydroxyl terminated POZ (POZ(OH)4) with different molecular weights and the a,co-hydroxyl terminated POZ with a molecular weight of 1300 g / mol (POZ1300(OH)2) are depicted in Table 1. Table 1. Experimental details of prepared poly(2-ethyl-2-oxazoline)s

[0183] Example 2

[0184] This example describes the preparation of branched POZ-polyester (POZ-PE) copolymers with four poly(D.L-lactide) arms by ring-opening polymerization of D,L-lactide using a, a’, co, co’- hydroxyl terminated POZ1400(OH)4, synthesized as described in Example 1 , as initiator. Briefly, 10 g of POZ1400(OH)4 and 90 g of D,L-lactide were weighed into a 250 ml threenecked round bottom flask and dried at 60 °C under vacuum overnight. Water-free distilled p- dioxane was added into the flask until a polymer concentration of 50 wt% was reached and the temperature was set to 95 °C to dissolve the prepolymers. Once homogeneous, stannous octoate (100 ppm) 1 wt% solution in p-dioxane was added and stirring continued at 95 °C until a conversion > 95% as confirmed by1H-NMR. The polymer solution was diluted to 20 wt% and freeze dried yielding an off-white polymer powder. Similarly, POZ-(PLA)4-OH polymers with different POZ content were prepared using POZ800(OH)4, POZ1400(OH)4, POZ1900(OH)4 and POZ2100(OH)4 as initiator. The characteristics of the so prepared POZ(PLA)4-OH biodegradable polymers are listed in Table 2.

[0185] Reaction scheme for the preparation of branched xxPOZyyyy[LAzzzz]4-OH

[0186] Example 3

[0187] This example describes the preparation of branched POZ-PE copolymer with four poly(D,L- lactide-co-glycolide)) arms by ring-opening copolymerization of D,L-lactide and glycolide using a,a’,co,co’-hydroxyl terminated POZ1400(OH)4 as an initiator. Briefly, 10 g of POZ1400(OH)4, 71 g of D,L-lactide and 19 g of glycolide were weighed into a 250 ml threenecked round bottom flask and dried at 60 °C under vacuum overnight. Water-free distilled p- dioxane was added into the flask until a polymer concentration of 50 wt% was reached and the temperature was set to 95 °C to dissolve the prepolymers. Once homogeneous, stannous octoate (100 ppm) 1 wt% solution in p-dioxane was added and stirring continued at 95 °C until conversion was above 95% as confirmed by1H-NMR. The polymer solution was diluted to 20 wt% and freeze dried to obtain off-white polymer powder. The characteristics of the so-prepared 10POZ1400[(LA75GA25)]3310]4-OH biodegradable polymer are given in Table 2.

[0188] Example 4

[0189] This example describes the preparation of branched POZ-PE copolymer with four poly(D,L- lactide-co-£-caprolactone) arms by ring-opening copolymerization of D,L-lactide and e- caprolactone using a,a’,w,w’-hydroxyl terminated POZ1400(OH)4 as an initiator. Briefly, 10 g of POZ1400(OH)4 and 59 g of D,L-lactide were weighed into a 250 ml three-necked round bottom flask and dried at 60 °C under vacuum overnight. The next day, ca. 31 g of distilled e- caprolactone was added to the dried POZ1400(OH)4 and D,L-lactide. The reactants were dissolved in distilled toluene (50 wt% solution) at 120 °C. As soon as the contents of the flask had dissolved, stannous octoate (100 ppm) 1 wt% solution in toluene was added. The reaction was stirred for 3 days to obtain conversion above 95 %. Toluene was removed using rotavapor at 70 °C overnight. The polymer was further dried overnight in vacuum oven at 60 °C and at ca. p = 1 x 10"2mbar to obtain waxy solid polymer. The characteristics of the so- prepared 10POZ1300[(LA75CL25)]2830]4-OH biodegradable polymer are given in Table 2.

[0190] Example 5

[0191] This example describes the preparation of a linear poly(D,L-lactide)-POZ-poly(D,L-lactide) triblock copolymer by ring-opening polymerization of D,L-lactide using linear a, w-hydroxyl terminated POZ1300(OH)2 synthesized in Example 2 as an initiator. The reaction conditions were the same as used for the synthesis of 10POZ1300[LA4860]2-OH in Example 3. The characteristics of the so-prepared 10POZ1300[LA4860]2-OH biodegradable polymer are given in Table 2.

[0192] Reaction scheme for the preparation of linear xxPOZyyyy[LAzzzz]2-OH Example 6

[0193] This example describes the end capping of 10POZ1400[LA3150]4-OH copolymer with C6 and C12 fatty acid chains to obtain 10POZ1400[LA3150]4-C6 and 10POZ1400[LA3150]4- C12. To synthesize 10POZ1400[LA3150]4-C6, 10POZ1400[LA3150]4-OH was weighed in a three-neck flask and left drying under high vacuum at 70 °C overnight. The flask was cooled to room temperature and distilled DCM was added to the flask under N2 flow, to make a 33.3 wt% solution. As soon as the contents of the flask were dissolved, a 2.5x excess of triethylamine (with respect to the OH groups of copolymer) was added to the mixture. Subsequently, a 2x excess, with respect to the OH end groups, of hexanoyl chloride was added as well. The flask was left stirring in an ice bath overnight, whereafter the reaction mixture was filtered under vacuum. The resulting polymer solution was passed through a short silica column, concentrated using a rotavapor and precipitated twice in hexane. Finally, the polymer was dried in a vacuum oven at room temperature for 4 days, followed by additional vacuum-drying overnight at 60 °C to remove any remaining amounts of hexane. 10POZ1400[LA3150]4-C12 was synthesized in a similar way using lauryl chloride instead of hexanoyl chloride. The polymers were analyzed as described in Analytical Techniques. The characteristics of the so-prepared 10POZ1400[LA3150]4-C6 and 10POZ1400[LA3150]4-C12 biodegradable polymers are given in Table 2.

[0194] Example 7

[0195] Synthesis of pentaerythritol tetratriflate Pentaerythritol (1 eq) was added to the 3-neck flask with pyridine (8.4 eq) and ACN (21 eq). The solution was stirred while cooling to 0 °C using an ice bath. Triflic anhydride (4.8 eq) was added dropwise over 1 h at 0 °C and the reaction mixture was left stirring for some time after the addition. 1 M HCI solution (excess) was added dropwise and the solution was left stirring at room temperature overnight. Subsequently, the solution was cooled using an ice bath to complete precipitation. The precipitate was collected by filtration of the solution using a Whatman filter paper and washed several times with cold water. The solid was recrystallized with ACN / H2O, whereafter the crystallized product was washed with water, filtered, and then vacuum-dried at room temperature, resulting in pentaerythritol tetratriflate. Finally, the initiator was dried under vacuum at room temperature.

[0196] Synthesis of 4-arm star-shaped POZ

[0197] To synthesize 4 arm star-shaped POZ polymer with a target molecular weight of 1000 g / mol (POZ1000(OH)4_s), the initiator pentaerythritol tetratriflate (7.53 g) was weighed in a dried flask and dried under vacuum whereafter 300 mL distilled ACN and 10.15 g of EOz were added under N2 using a syringe. The system was heated to 80 °C, under N2 and stirred at 250 rpm overnight. The solution was allowed to cool down to RT whereafter tetramethylammonium hydroxide (TMAH) (25 wt% solution in MeOH) (8 eq to the initiator) was added and the reaction was left overnight, whereafter ACN was removed using a rotary evaporator. The polymer was dissolved in DCM and washed twice with 15 wt% aqueous NaCI solution and then passed through a charcoal plug, dried and stored at 5°C. The molecular weight of the star-shaped POZ could not be measured due to overlap of the signals the1H NMR spectrum. Based on in-weights, the molecular weight of the star-shaped POZ was 1171 g / mol.

[0198] Reaction scheme for the preparation of4-arm star-shaped POZ Example 8

[0199] Synthesis of 4-arm star-shaped POZ-PE copolymer

[0200] Star-shaped POZ-PE copolymers with 4 poly(DL-lactide) arms (POZ(PLA)4-OH_s) was synthesized by ring-opening polymerization of D,L-lactide using 4-arm star-shaped POZ1000(OH)4_s as synthesized in example 7 as initiator. Briefly, 2.0 g of POZ1000(OH)4_s and 18.10 g of D,L-lactide were weighed into a 100 mL three-necked round bottom flask and dried at 50 °C under vacuum overnight. Water-free distilled p-dioxane was added into the flask until a polymer concentration of 50 wt% was reached and the temperature was set to 95 °C to dissolve the prepolymers.

[0201] Once homogeneous, stannous octoate (100 ppm) 1 wt% solution in p-dioxane was added and stirring continued at 95 °C until a conversion > 95% as confirmed by1H-NMR. The polymer solution was diluted to 30 wt% and freeze dried yielding an off-white polymer powder. The star-shaped 10POZ1000(PLA)4_s was analyzed as described in Analytical Techniques. The number averaged molecular weight of each poly(D.L-lactide) arm of the biodegradable polymer as determined by1H-NMR was 3345 g / mol and the total number averaged molecular weight of the biodegradable polymer was 14382 g / mol.

[0202] Table 2 shows the collected analysis results for the synthesized branched and linear POZ-PE copolymers. Table 2 shows that the obtained POZ-PE copolymers have a narrow molecular weight distribution with low dispersity <1.3 due to the use of ring opening polymerization Having biodegradable polymers with a well-defined molecular structure is advantageous, since it directly affects properties such as viscosity, swelling degree and degradation rate.

[0203] The thermal properties of prepared biodegradable polymers were determined by DSC. All biodegradable polymers were amorphous in nature with glass transition temperature ranging from 11 °C to 39 °C. All biodegradable polymers except 10POZ1300[(LA75CL25)]2830]4-OH are solid at room temperature which allows their processing into a powder form that is beneficial for their fast dissolution in organic solvents. The glass transition temperature is mainly influenced by the composition of the polyester arms and the polymer molecular weight. Biodegradable polymers with higher molecular weight have higher glass transition temperature, while the incorporation of flexible caprolactone (CL) units into the polyester block leads to reduction of the overall glass transition due to which such a biodegradable polymer is waxy and difficult to handle.

[0204] Table 2. Structural characteristics of branched and linear POZ-polyester copolymers

[0205] *Value based on in-weight since the molecular weight of the star shaped POZ could not be measured due to overlap of the signals in the1H NMR spectrum

[0206] Example 9

[0207] Viscosity and injectability of solutions of POZ-PE copolymers

[0208] The POZ-PE copolymers described in examples 2-8 were dissolved in DMSO, NMP, triacetin and tripropionin (20, 35 and 50 wt%) and the viscosity of the solutions was measured as described in Analytical Techniques. Table 3 lists the measured viscosity values. For all samples the viscosity increased exponentially with concentration and all solvents showed a similar trend. Solutions of the lower molecular weight biodegradable polymers 10POZ800[LA2070]4-OH and 20POZ1400[LA1400]4-QH had the lowest viscosity, while the biodegradable polymers with the highest molecular weight such as 10POZ1400[(LA75GA25)]3310]4-OH and 5POZ800[LA4000]4-QH had the highest viscosity.

[0209] Next to the viscosity, the biodegradable polymer solutions were evaluated for their injectability using the method described in Analytical Techniques. The obtained results are depicted in Table 3. Surprisingly, solutions of 35% biodegradable polymer in the polar biocompatible organic solvents NMP and DMSO can be ejected via 25G needles using an ejection force of ~ 20 N or even lower, which is a significant improvement compared to marketed ISFD-based drug products which require significantly larger needles, such as 18, 19, or 21 Gauge needles. The injectability is strongly correlated with the viscosity of the biodegradable polymer solutions. Figure 1 plots the smallest needle size that allowed ejection (using an ejection force < 20 N) of solutions of POZ-PE copolymers (listed in Table 3) in NMP, DMSO, triacetin and tripropionin (polymer concentrations of 20, 35 and 50 wt%) as a function of the viscosity of the solutions. Figure 1 teaches that a 21 G needle is the smallest needle size allowing ejection of POZ-PE solutions with a viscosity between ~1 Pa s and -4 Pa s using ejection forces < 20 N, and that a 25 G needle is the smallest needle size allowing ejection of POZ-PE copolymer solutions with a viscosity between -0.07 and -0.3 Pa s using ejection forces < 20 N. Table 3. Effect of biodegradable polymer composition, solvent type and polymer concentration (20, 35 and 50 wt%) of POZ-PE copolymer solutions on viscosity and injection force (glide force) (N).

[0210] In Table 3, Mnis measured in g / mol by1H-NMR, and injection force is measured in N. “y” indicates that the composition will show a glide force < 20 N based on the measured composition for a higher gauge number needle (smaller diameter) having a glide force < 20 N. “n” indicates that the composition will show a glide force > 20 N based on the composition having a glide force > 20 N for a lower gauge number needle (larger diameter). Furthermore, the effect of polymer topology on biodegradable polymer solution viscosity was studied. Biodegradable POZ-PE polymers with linear, branched and starshaped topology and similar POZ block and poly(DL-lactide) arms were dissolved in NMP and tripropionin to concentrations of 20, 35 and 50 wt% and the solutions were analyzed for their viscosity. The results are listed in Table 3B. Table 3B. Effect of polymer topology (linear, branched and star-shaped), solvent type (NMP and tripropionin) and polymer concentration (20, 35 and 50 wt%) of biodegradable POZ-PE copolymer solutions on viscosity.

[0211] The effect of polymer topology on solution viscosity is clearly shown in Table 3B and Figure 1B. The viscosity of biodegradable polymer solutions decreased significantly by replacing the linear biodegradable triblock copolymer 10POZ1300[LA4860]2-OH by the branched biodegradable polymer 10POZ1400[LA3150]4-OH. Surprisingly, the viscosity of solutions of the star-shaped biodegradable polymer 10POZ1117[LA3345]4-OH_s was significantly more reduced as compared to solutions of the branched biodegradable polymer 10POZ(PLA)4- OH.

[0212] Example 10

[0213] Ropivacaine-loaded POZ-PE copolymer-based ISFD formulations

[0214] ISFD formulations containing 2 wt% ropivacaine were prepared by dissolving ropivacaine base in solutions of POZ-PE copolymers in NMP, as to obtain formulations with a biodegradable polymer : solvent : ropivacaine weight ratio of 35:63:2 or 50:48:2. In all cases clear low viscosity solutions were obtained, indicating complete dissolution of ropivacaine.

[0215] The viscosity of the liquid biodegradable polymer-only and ropivacaine-loaded formulations as determined via the cone-and-plate rotational rheology method described in Analytical Techniques are listed in Table 4. The viscosity of the solutions was hardly affected by the addition of ropivacaine. For all ropivacaine-loaded formulations, low viscosities were obtained due to which they were well injectable. 35 wt% biodegradable polymer solutions were typically injectable via 25 G needles, whereas 50 wt% biodegradable polymer solutions were still injectable via 21 G needles. This is a significant improvement compared to currently marketed ISFD-based drug products such as for example Eligard leuprolide acetate suspension for subcutaneous injection, which have to be injected via 20 Gauge needles (Eligard 7.5 mg, 0.25 mL of 33 wt% PLGA polymer solution in NMP) or even 18 Gauge (Eligard 45 mg, 0.375 mL of 44 wt% PLGA solution in NMP).

[0216] All formulations demonstrated fast depot formation upon injection in aqueous medium of 37 °C.

[0217] Table 4. Ropivacaine containing in situ forming depot formulations prepared of branched POZ-PE copolymers and NMP

[0218] *nPoi soi = viscosity of biodegradable polymer solution; r|form = viscosity of formulation

[0219] Ropivacaine content of the ISFD was determined by RP-UPLC. Approximately 100 mg of ISFD formulation was dissolved in 2 mL of DCM. Subsequently, 10 mL of 1% acetic acid solution was added to precipitate the biodegradable polymer and extract ropivacaine. After mixing (roller mixer) for 30 minutes, the sample was centrifuged and the supernatant was analyzed by reversed phase ultra-performance liquid chromatography (RP-UPLC).

[0220] For in vitro release testing, ropivacaine containing POZ-PE copolymer based depots were first formed in situ by slowly adding 45 ml of buffer (100 mM PO4 buffer, 0.025 wt% Tween-20, 0.02 wt% NaNs, 290 mOsm / kg, pH 6.5, 37 °C) to 100 pl of the liquid ropivacaine / biodegradable polymer / solvent formulations, whereafter the vials with the so- formed ISFD were incubated in a shaking water bath thermostated at 37 °C. At predetermined time points, aliquots of 100 pl release buffer were collected. The ropivacaine concentrations in the collected release buffer samples were determined via RP-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 x 2.1 mm, 1.7 pm), maintained at 40 °C. Mobile phase A consisted of a 20 mM phosphate buffer pH 6.5 and acetonitrile at a ratio of 90 : 10 v / v and 100 % of acetonitrile was used as mobile phase B. The mobile phase composition started at 30 vol% B and increased to 70 vol% B in 2 minutes, at a constant flow rate of 0.600 ml / min. Detection was performed at 235 nm.

[0221] The release of ropivacaine from NMP-based ISFD formulations (Figure 2) was affected by POZ-PE copolymer composition (POZ content, POZ molecular weight, number and molecular weight of polyester arms, overall molecular weight of the biodegradable polymers) and concentration of the biodegradable polymer solution.

[0222] POZ-PE copolymers with the highest content of hydrophilic POZ block (40POZ1900[LA815]4-OH (40 wt% POZ1900), 20POZ2100[LA2280]4-OH (20 wt% POZ2100) and 20POZ1400[LA1400]4-QH) (20 wt% POZ1400) demonstrated the fastest release of ropivacaine. With a decrease of content of hydrophilic POZ block from 20 to 10 or 5 wt%, the duration of release was prolonged from a few days to more than a month, which is attributed to the lower swelling degree and slower degradation of the biodegradable polymers containing a lower fraction of hydrophilic POZ block.

[0223] POZ molecular weight, and consequently overall molecular weight of the POZ-PE copolymers, had a strong effect on the release profile of ropivacaine. Interestingly, POZ-PE copolymers 10POZ1400[LA3150]4-OH and 10POZ800[LA2070]4-QH, which both contain 10 wt% POZ, showed similar overall release duration, while their release profiles were very different. Despite the higher molecular weight of POZ of 1400 g / mol as compared to 10POZ800[LA2070]4-QH which contains POZ of 800 g / mol, 10POZ1400[LA3150]4-OH- based ISFD hardly released any ropivacaine for the first 2 weeks, whereas 10POZ800[LA2070]4-OH-based ISFD immediately started to release ropivacaine.

[0224] Effect of composition of polyester arm

[0225] To investigate the effect of composition of the polyester arms of the branched POZ-PE copolymers on release kinetics, the poly(DL-Lactide)-based polyester arms of 10POZ1400(LA3150)4-OH were replaced by poly(DL-Lactide-co-glycolide) (PLGA) arms with a 75 : 25 lactide : glycolide molar ratio. Figure 3 shows that ropivacaine was released from NMP-based ISFD prepared of 10POZ1400(LA3150)4-OH with PLA-based polyester arms according to sigmoidal release kinetics with a lag time of around 18 days. NMP-based ISFD prepared of 10POZ1400[(LA75GA25)]3310]4-OH with PLGA based polyester arms demonstrated a significantly shorter lag phase of only a few days The shorter lag time and earlier onset of release observed for 10PGZ1400[(LA75GA25)]3310]4-OH based ISFD is attributed to the earlier onset of biodegradable polymer degradation of the PLGA-based polyester arms of 10PGZ1400[(LA75GA25)]3310]4-OH as compared to PLA-based polyester arms of 10PGZ1400[LA3150]4-OH. Effect of biodegradable polymer concentration

[0226] Biodegradable polymer molecular weight and biodegradable polymer concentration directly affect the viscosity of the solutions of biodegradable polymers used in ISFD. To investigate the effect of viscosity on the release kinetics, 20 mg / g ropivacaine- loaded ISFD were prepared of biodegradable POZ-PE polymers with different molecular weight using polymer concentrations of 35 and 50 wt%. The viscosities of the formulations varied from 0.050 Pa s (35 wt%) to 0.366 Pa s (50 wt%) for the lower molecular weight 20POZ1400[LA1400]4-QH (Mn7010 g / mol) and 0.099 Pa s (35 wt%) to 0.698 Pa s (50 wt%) for the higher molecular weight 20POZ2100[LA2280]4-OH (Mn11220 g / mol). Figure 4 shows that the release kinetics of ropivacaine were highly dependent on the biodegradable polymer grade and viscosity of the biodegradable polymer solution.

[0227] The overall release duration decreased with increasing POZ molecular weight and increased slightly with increasing biodegradable polymer concentration.

[0228] Furthermore, the higher the viscosity of the ISFD solutions, the lower the burst release. For the 35 wt% solution of 20POZ1400[LA1400]4-OH (Mn 7010 g / mol) with the lowest viscosity of 0.050 Pa s, the highest burst (-57%) was observed, whereas for the 50 wt% solution of 20POZ2100[LA2280]4-OH (Mn11220 g / mol) with the highest viscosity of 0.698 Pa s, the burst was very low (~ 2%) (Figure 4). The higher viscosity of these formulations slows down solvent exchange and as a consequence lowers the initial burst.

[0229] Effect of biodegradable polymer end group

[0230] The branched POZ-PE copolymers synthesized in the examples 2 - 4 contain free hydroxyl groups at the end of the PLA branches. For some POZ-PE copolymers the hydroxyl endgroups were replaced by aliphatic chains to obtain more hydrophobic biodegradable polymers. To study the effect of end groups moiety, 20 mg / g ropivacaine- loaded ISFD were prepared of 35 wt% solutions of 10POZ1400(LA3150)4 copolymers with OH, C6 and C12 endgroups in NMP (Table 4). The viscosities of the formulations varied from 0.121 Pa s (OH end group), 0.171 Pa s (C6 end group) to 0.167 Pa s (C12 end group). Figure 5 shows the effect of endgroups moiety on the in vitro release kinetics of ropivacaine from 10POZ1400[LA3150]4-R-based ISFD.

[0231] Interestingly, the type of end groups did not have any significant effect on release duration. All formulations completely released ropivacaine in 6 - 7 weeks. However, formulations with the more hydrophobic C6 and C12 end groups demonstrated faster ropivacaine release in the first few weeks which might be caused by slower phase inversion resulting from slower replacement of the solvent due to the higher hydrophobicity of the biodegradable polymer matrix. As a consequence of slower phase inversion, the remaining solvent content in the precipitated biodegradable polymer matrix will be higher thereby increasing the diffusion rate of the drug via the biodegradable polymer matrix.

[0232] Effect of solvent type

[0233] The effect of solvent type on the drug release kinetics was studied. NMP and DMSO are relatively hydrophilic solvents and allow fast solvent replacement. In contrast, triacetin, benzyl benzoate and tripropionin have limited miscibility with water due to which phase inversion is significantly slower. To study the effect of solvent type on the release profile of ropivacaine, ropivacaine-loaded ISFD formulations (35 wt% biodegradable polymer concentration, 20 mg / g ropivacaine) were prepared of NMP, DMSO, benzyl benzoate, triacetin and tripropionin according to the procedures described above. The viscosity of the NMP and DMSO based ISFD formulations were significantly lower as compared to the ISFD formulations prepared of triacetin, benzyl benzoate and tripropionin (Table 5). The release kinetics are shown in Figure 6.

[0234] Table 5. Ropivacaine containing in situ forming depot formulations prepared of 20POZ2100[LA2280]4-OH using different solvents

[0235] Qpoi soi = viscosity of biodegradable polymer solution; r|fOrm = viscosity of formulation

[0236] ISFD formulations prepared of hydrophobic solvents (BB, TP, TA) exhibited significantly faster (initial) release as compared to ISFD formulations prepared of the water miscible solvents (NMP and DMSO). Ropivacaine release from BB and TP-based ISFD formulations was completed within a week. TA-based ISFD also showed fast initial (burst) release of ropivacaine, after which it slowed down for up to 2 weeks, whereafter it accelerated releasing its complete payload in approximately 4 weeks. The fast release of ropivacaine from these hydrophobic solvent-based ISFD formulations is attributed to slow water penetration and solidification of the polymer matrix due to which the formulations remain low viscosity liquids for a longer time which allows fast diffusion-based release of ropivacaine. Contrary to BB and TP which are not water-miscible, TA is partially miscible with water due to which faster depot solidification occurs, which slows down the release of ropivacaine. The sudden increase of the release is believed to be related to the degradation of the polymer matrix.

[0237] ISFD formulations prepared of NMP and DMSO demonstrated sustained and close to linear release of ropivacaine. Interestingly, the release of ropivacaine from the 20PGZ2100[LA2280]4-OH-based ISFD formulations prepared of NMP and DMSO based was almost identical and complete within 2 weeks, which is attributed to the relatively fast erosion of the hydrophilic 20POZ2100[LA2280]4-OH polymer matrix.

[0238] Example 11

[0239] Ivermectin-loaded POZ-PE copolymer based ISFD formulations

[0240] Ivermectin-loaded ISFD formulations with a loading of 1 wt% ivermectin were prepared of POZ(PLA)4 based copolymers with different POZ molecular weight and PLA arm length. Ivermectin was dissolved in solutions of POZ(PLA)4 copolymers in NMP in a polymer : solvent : ivermectin weight ratio of 35:64:1 .

[0241] The viscosity of the polymer solutions with and without ivermectin as determined by cone-and-plate rotational rheology varied between 0.052 and 0.193 Pa s (Table 6). The viscosity of the solutions was hardly affected by the addition of ivermectin. For all ivermectin- loaded ISFD formulations low viscosities were obtained due to which they were injectable via 25G needles which is a significant improvement compared to currently marketed ISFD-based drug products which typically have to be injected with significantly larger needles, such as 21 , 19, or even 18 Gauge needles.

[0242] Upon injection in buffered release medium (thermostated at 37 °C) all formulations demonstrated fast depot formation.

[0243] Table 6. Ivermectin containing in situ forming depot formulations prepared of POZ(PLA)4- based copolymers

[0244] Qpoi soi = viscosity of polymer solution; r|fOrm = viscosity of formulation

[0245] For in vitro release testing, ivermectin containing depots were formed in situ by slowly adding 2 ml of buffer (100 mM PO4 buffer, 0.5% SDS, 1.5 mg / mL sodium L ascorbate, 1.5 mg / mL sodium metabisulfite, 0.02% NaN3, pH 7.4, 37 °C, 290 mOsmol / Kg) to 100 pl of the liquid ivermectin / polymer / NMP formulations in 4 mL vials, whereafter the vials were incubated in a shaking water bath thermostated at 37 °C. At predetermined time points aliquots of 1.4 mL pl release buffer were taken and replaced with fresh buffer. Collected release samples were analyzed for ivermectin concentrations by RP-UPLC.

[0246] Chromatographic analysis of ivermectin containing samples was performed on a Waters Acquity™ H-class LIPLC system, equipped with a PDA detector. Separation was performed on an Acquity™ BEH C18 column (50 x 2.1 mm; 1.7 pm), maintained at a temperature of 40°C. Mobile phase A consisted of a 0.1 % H3PO4 in water solution. Mobile phase B consisted of acetonitrile. The gradient went from 80%B to 90%B in 1 minute, at a flow rate of 0.600 mL / min. 3.0 pL of sample was injected. The column effluent was monitored at a detection wavelength of 244 nm. The release kinetics of the ivermectin-loaded NMP-based ISFD formulations are shown in Figure 7.

[0247] The release of ivermectin from NMP-based ISFD formulations was affected by POZ content, POZ molecular weight and overall molecular weight of the POZ(PLA)4 copolymers (and thus by the viscosity of the solutions).

[0248] POZ(PLA)4 copolymers with the highest content of hydrophilic POZ block (20POZ2100[LA2280]4-OH (20% POZ2100) and 20POZ1400[LA1400]4-QH) (20 % POZ1400) demonstrated the fastest release of ivermectin. With a decrease of content of the hydrophilic POZ block from 20 to 10 or 5 wt%, the duration of release was prolonged from approximately 1 month to 4 months, which is attributed to the lower swelling degree and slower degradation of the polymers containing a smaller fraction of hydrophilic POZ block POZ(PLA)4 copolymers with lower POZ content and lower overall molecular weight such as 10POZ800[LA2070]4-QH) with Mn9100 g / mol and (20PQZ1400[LA1400]4- OH with Mn7010 g / mol demonstrated higher initial burst. This is attributed to the low viscosity of ISFD formulations prepared of these copolymers which allows faster solvent exchange and consequently faster initial ivermectin release. Interestingly, initial burst of ivermectin was similar for POZ(PLA)4 copolymers with similar molecular weight such as 20POZ1400[LA1400]4-QH (Mn7010 g / mol) and 10POZ800[LA2070]4-QH (Mn9100 g / mol) which exhibited a burst release of approximately 10% or 10POZ1400[LA3150]4-OH (Mn14010 g / mol) and 5POZ800[LA4000]4-OH (Mn16800 g / mol), which both did not show burst release but a lag time instead, which supports the hypothesis that initial burst release is mainly governed by the viscosity of ISFD formulations.

[0249] Example 12

[0250] Celecoxib-loaded POZ-PE based ISFD formulations In this example, celecoxib-containing sustained release ISFD formulations were prepared using POZ(PLA)4 copolymers, NMP as solvent and different celecoxib concentrations. Celecoxib-loaded ISFD formulations with celecoxib loading of 2, 5 and 10 wt% were prepared by dissolving celecoxib in 10POZ1400[LA3150]4-OH copolymer solutions in NMP overnight. Formulations were prepared in such a way that the resulting polymer concentration in each ISFD formulation was 35 wt%.

[0251] The viscosity of the obtained liquid formulations was determined by cone-and-plate rotational rheology as described in Analytical Techniques.

[0252] For in vitro release testing, celecoxib loaded depots were first formed by transferring 100 mg of celecoxib loaded ISFD formulation into a 50 mL polypropylene conical bottom tube and the addition of 45.0 mL of IVR buffer (100 mM PO4 buffer, 5 wt% Tween-20, 0.02 wt% NaNs, pH 7.4, 290 mOsmol / Kg, 37 °C) to each vial. The tubes were incubated at 37 °C ± 2 °C, while shaking. At predetermined time points 100 pL of the supernatant was removed. The content of celecoxib in the IVR samples was determined by RP-UPLC, and from the measured concentrations, the release curves were constructed.

[0253] The LIPLC method has been set up using a Water Acquity LIPLC with PDA detector. The system was equipped with a Water Acuity BEH C18 column of 50 x 2.1 mm with 1.7pm particles (part no. 186002350). The column temperature was set to 40°C. A gradient was used as listed in Table 7 wherein eluent A consists of 0.1 wt% H3PO4 in water and eluent B of 100% acetonitrile. The run time was 3 minutes and elution of Celecoxib was at 0.8 minutes. An injection volume of 1 pL was used and the compound was detected at 251 nm. All samples were analyzed together with a calibration curve and controls prepared in buffer in a range of 1-500 pg / mL. A weighing factor of 1 / (X*X) was used to construct the calibration curve with a linear fit.

[0254] Table 7. Gradient characteristics for determination of celecoxib

[0255] Table 8 lists the composition and viscosities of 10POZ1400[LA3150]4-GH-based celecoxib-loaded ISFD formulations with different celecoxib concentrations. Table 8. Celecoxib containing in situ forming depot formulations prepared of 10POZ1400[LA3150]4-OH (LP-2301-017A) with different Celecoxib loadings (NMP as solvent).

[0256] Qform = viscosity of formulation

[0257] *N.A.: celecoxib was not fully dissolved

[0258] All celecoxib-loaded ISFD formulations demonstrated fast depot formation upon injection in aqueous medium. For all formulations, distinctly low viscosities were achieved, allowing injection via 25 G needles, which shows the benefit of using branched POZ-PE copolymers to obtain well injectable ISFD formulations.

[0259] The effect of celecoxib loading on celecoxib release from the celecoxib-loaded ISFD formulations is shown in Figure 8. The celecoxib loaded ISFD formulations based on branched POZ-PE copolymers exhibit different release kinetics. By increasing the celecoxib loading from 2 to 5 and 10 wt%, the release rate slowed down and the release duration increased from approximately one month to approximately 3 months. The decrease of release rate with increasing drug loading is attributed to the hydrophobic nature of celecoxib and the increasing viscosity of the ISFD formulations with increasing celecoxib content. The presence of celecoxib inside formulation slows down the penetration of water into the depot, slows down solvent exchange and reduces the swelling degree of the depot. As a consequence a more compact depot is formed, which slows down the release of celecoxib. Figure 9, which shows the daily release of celecoxib from the celecoxib-loaded ISFD formulations, clearly shows that the initial burst release of celecoxib decreased increasing celecoxib loading in the ISFD depots.

[0260] Example 13

[0261] Octreotide acetate-loaded POZ-PE based ISFD formulations

[0262] In this example, octreotide acetate-containing sustained release ISFD formulations were prepared using POZ(PLA)4 copolymers and NMP as solvent. Octreotide acetate-loaded ISFD formulations with a loading of 6 wt% were prepared by dissolving octreotide acetate powder in POZ(PLA)4 copolymer solutions in NMP Formulations were prepared in such a way that the final concentration of biodegradable polymer in each formulation was 40 wt%.

[0263] The viscosity of the obtained liquid formulations was determined by cone-and-plate rotational rheology as described in Analytical Techniques and depicted in Table 8.

[0264] Total content of octreotide base (OCT) in OCT-ISFDs was determined in duplicate by BCA Protein Assay after hydrolysis of OCT-based samples by LIV-VIS spectroscopy. Briefly, 10 pL of OCT-ISFD was dissolved in 1 mL of DMSO at 80 °C. Then, 5.00 mL of 0.5 wt% SDS in 0.05 M NaOH was added. The mixture was stirred overnight on a roller mixer at room temperature. Then, 100 pL of sample was added to 2 mL of BCA reagent followed by incubation at 50 °C for 10 minutes. The absorbance was measured at 562 nm. Calibration curve from absorption of standards against absolute amount of OCT in standards was constructed using a quadratic model and a 1 / X weighting factor. The OCT content in samples was calculated by interpolation on calibration curve.

[0265] For in vitro release testing, octreotide acetate loaded depots were first formed by transferring 100 mg of formulation into a 15 mL polypropylene conical bottom tube whereafter 10 mL of IVR buffer (100 mM PO4buffer, 0.025 wt% Tween-20, 0.02 wt% NaN3, 290 mOsm / Kg, pH 6.5, 37 °C) was added to each vial. The tubes were incubated at 37 °C ± 2 °C, without shaking. At predetermined time points 8 mL of the supernatant was removed and replaced with fresh buffer. Aliquots of 800 pL release buffer were collected and stored at 5 °C until analysis. OCT concentrations in the collected release samples were determined via reversed phase ultra performance liquid chromatography ("UPLC") with FLR-detection using a Waters Acquity H-Class UPLC system, equipped with a FLR detector, and a Waters Acquity CSH C18 column (2.1 x 50 mm, 1.7 pm) maintained at 40°C. Mobile phase A consisted of Water / Acetonitrile / TFA mixed in ratio 90 / 10 / 0.1 v / v / v%, while Water / Acetonitrile / TFA mixed in ratio 10 / 90 / 0.1 v / v / v% was used as mobile phase B. The mobile phase composition started at 10% B and increased to 50% B in 2.5 minutes, at a constant flow rate of 0.600 mL / min. At 2.6 minutes the flow is reverted to 10% B and maintained up to a total run time of 3.5 minutes. FLR detection was used for the quantification with ^excitation of 280 nm, Aemission of 330 nm.

[0266] The list of all prepared octreotide containing in situ forming depot formulations is given in Table 9.

[0267] Table 9. Octreotide containing in situ forming depot formulations prepared of branched POZ(PLA)4 copolymers (NMP as solvent).

[0268] Qpoi soi = viscosity of biodegradable polymer solution; r|fOrm = viscosity of formulation

[0269] It can be seen that the viscosity of the ISFD formulations is highly impacted by the addition of octreotide acetate, which is expected taking into account the high loading of octreotide. For both formulations, distinctly low viscosities were achieved, allowing injection using 23 G and 25 G needles, which proves the benefit of using this family for preparation of easy injectable formulations. All octreotide loaded POZ(PLA)4 based ISFD formulations demonstrated fast depot formation in aqueous release buffer at 37 °C.

[0270] The effect of POZ-PE copolymer composition on the release characteristics of octreotide acetate is shown in Figure 10. The release of octreotide acetate r from the branched POZ(PLA)4 copolymer-based ISFD formulations can be tailored by adjusting the structure of the biodegradable polymer. The biodegradable polymer with higher content of hydrophilic POZ block (10PGZ800[LA2070]4-OH) demonstrated faster release compared to the less swellable 5PGZ800[LA4000]4-OH. Next to the biodegradable polymer swelling degree playing a role in the octreotide release kinetics, the release of octreotide was also affected by the degradation rate of the biodegradable polymer. Due to its higher hydrophilicity and lower molecular weight 10PGZ800[LA2070]4-OH swells more and degrades faster compared to 5PGZ800[LA4000]4-OH, leading to faster release of octreotide from 10PGZ800[LA2070]4-GH-based ISFD.

[0271] Example 14

[0272] Comparison of characteristics of ISFD composed of branched POZ-PE copolymers and linear biodegradable polymer copolymers

[0273] In this example, quality attributes of ISFD formulations based on a branched POZ(PLA)4 copolymer were compared with ISFD formulations prepared of a linear PLGA copolymer (Purasorb PDLG5004, Corbion) and a linear DL-Lactide I polyethylene glycol- based multiblock copolymer (SynBiosys 10LP6L12-L20, InnoCore Pharmaceuticals B.V.). Purasorb PDLG5004 is a linear poly(DL-lactide-co-glycolide) copolymer with intrinsic viscosity of approximately 0.4 dL / g which is comparable (in terms of molecular weight and monomer molar ratio) to the PLGA polymer grade used in Eligard 7.5 mg, a marketed NMP- based ISFD formulation of leuprolide acetate (Eligard 7.5 mg, 0.25 mL of 33 wt% PLGA polymer solution in NMP) which is administered with a 20 Gauge needle. SynBiosys 10LP6L12-L20 represents a multiblock copolymer composed of a poly(D,L-lactide)-co- PEG600-co-poly(D,L-lactide) block with a molecular weight of 1200 g / mol and a poly(D,L- lactide) block with a molecular weight of 2000 g / mol in a 10 / 90 w / w% block ratio and an intrinsic viscosity of 0.3 dL / g.

[0274] ISFD formulations containing 2 wt% ropivacaine were prepared of 35 and 50 wt% polymer solutions as described in Example 10 and analyzed for their viscosity (Table 10).

[0275] Table 10. Viscosity of ropivacaine loaded ISFD formulations prepared of branched POZ(PLA)4, linear PLGA copolymer, and linear LA / PEG-based multiblock copolymer (SynBiosys 10LP6L12-L20) (NMP as solvent).

[0276] Pol = polymer; solv = solvent; qPoi soi = viscosity of polymer solution; r)fOrm = viscosity of formulation

[0277] The viscosity of ropivacaine-loaded ISFD formulations prepared of solutions of branched biodegradable polymer 20PGZ1400[LA1400]4-GH in NMP was 8 to 70 times lower as compared to the viscosity of ropivacaine-loaded NMP-based ISFD formulations of 10LP6L12-L20 and PDLG5004 with the same polymer concentration (35 wt%). The viscosity of the ropivacaine loaded ISFD prepared of a 50 wt% solution of biodegradable polymer 20PGZ1400[LA1400]4-OH (0.366 Pa s, Table 11) was even lower than the viscosity of the ropivacaine loaded ISFD prepared of 35 wt% 10LP6L12-L20 polymer solution (0.430 Pa s, Table 10).

[0278] The cumulative release of ropivacaine from the NMP-based ISFD formulations listed in Table 10 are shown in Figure 11. The ropivacaine loaded ISFD formulations based on a 50 wt% solution of the branched biodegradable polymer 20PGZ1400[LA1400]4-OH in NMP (q = 0.366 Pa s) exhibited a significantly lower burst release of -5 % as compared to the SynBiosys 10LP6L12-L20-based ropivacaine loaded ISFD formulations (35 wt%) with similar viscosity (q = 0.430 Pa s) which showed a burst release of -10%. The Purasorb PDLG5004- based ropivacaine loaded ISFD formulations (35 wt%), despite its significantly higher viscosity (q = 3.501 Pa s) showed an even higher burst release of -20 %.

[0279] In addition to their good injectability and improved release characteristics, the more concentrated branched POZ-PE copolymer-based ISFD formulations contain less biocompatible organic solvent as compared to the less concentrated ISFD solutions prepared of the linear copolymers PDLG5004 and 10LP6L12-L20, which is highly beneficial as to minimize the risk of solvent-related local tolerability issues at or around the injection site.

[0280] Finally, the branched biodegradable polymer 20PGZ1400[LA1400]4-OH based ISFD formulation degraded significantly faster than the ISFD formulations prepared of the linear PDLG5004 and SynBiosys 10LP6L12-L20 multiblock copolymer, as is shown in Figure 12. The 20PGZ1400[LA1400]4-OH based ISFD demonstrated complete erosion in vitro by visual inspection within 90 days with the initially white solid depot turning into a transparent liquid after 45 days. In contrast, the linear PDLG5004 copolymer and 10LP6L12-L20 multiblock copolymer degraded significantly slower and erosion was not yet complete at the last time point (165 days) of the degradation study.

[0281] Table 11. Comparison of viscosity, syringeability, burst release and erosion time of ropivacaine loaded ISFD formulations prepared of branched biodegradable polymer 20POZ1400(LA1400)4-OH, linear 10LP6L12-L20 multiblock copolymer (SynBiosys) and linear PDLG5004 copolymers.

[0282] Pol = polymer; solv = solvent; r)poisoi = viscosity of polymer solution; r)fOrm = viscosity of formulation, d = days *Burst release defined as percentage of drug load released within 24 hours with respect to the initial drug load.

[0283] To summarize, ropivacaine-loaded ISFD formulations prepared of branched biodegradable polymer 20POZ1400[LA1400]4-OH with similar release duration (~ 1 month) as PLGA PDLG5004 and SynBiosys 10LP6L12-L20 based ISFD formulations had lower solvent content and exhibited, lower viscosity, better syringeability, lower burst release, and faster depot erosion. The faster depot erosion allows for a more favourable balance between release duration and depot erosion time, which may prevent polymer accumulation in the body upon repeated injection as typically performed in the treatment of chronic diseases.

[0284] Example 15

[0285] Levonorgestrel-loaded POZ-PE based microgranules

[0286] In this example, branched POZ-PE copolymers are used to prepare levonorgestrel (LNG) loaded microgranules. First, 1 mm-diameter implants with a target LNG loading of 25 and 50 wt% are prepared at a scale of 7 g by hot melt extrusion. In brief, LNG and biodegradable polymer 5POZ800(LA4000)4-OH (Mn16800 g / mol, Tgof 31 °C) are weighed and pre-mixed in a 15-mL tube using a roller bench, whereafter the powder mixture is fed to a Haake Minilab extruder equipped with a 1-mm cylindrical die, preheated at a process temperature of 85 °C. The material is compounded by circulation (open bypass) for 15 min at a screw speed of 15 rpm, whereafter the bypass is switched-off to extrude the compounded material through the die. The extruded strand is collected on a conveyer belt.

[0287] Next, the collected LNG-loaded strands are cut into small pellets using a Varicut pelletizer (ThermoFisher Scientific, Germany) whereafter the pellets are ground cryogenically using a cryomill (RETSCH, Germany) supplied with liquid nitrogen. Milling is performed at max speed of 30 Hz frequency using 2x stainless steel ball diameter of 1.5 cm in a 10-mL stainless steel jar yielding a fine white powder with good flow properties.

[0288] The surface morphology of the microgranules is evaluated by scanning electron microscopy (SEM), using a JEOL JCM-5000 Neoscope. A small amount of microgranules is adhered to carbon conductive tape and coated with gold for 3 min. The sample is imaged using a 10 kV electron beam. Microscopic examination of the obtained LNG-loaded microgranules by SEM shows that microparticles with a narrow particle size distribution are obtained (Figure 13).

[0289] The particle size distribution of the microgranules is measured by laser diffraction (Horiba® LA-960 Laser Particle Size Analyser), in dry mode using 0.1 MPa suction air and transmittance of at least 98%, within the range of 10 nm - 5000 pm. Particle size analysis by laser diffraction confirmed the result from SEM microscopic examination with D10(vol) of 10 pm, D50(vol) of 26 pm, and D90(vol) of 58 pm.

[0290] For LNG content analysis, triplicates of 2.0 mg ± 0.3 mg of LNG-loaded microgranules are dissolved in 3.00 ml of acetonitrile via sonication and heating to 60 °C for 20 min. Dissolved implant samples are diluted with 3.00 ml water and analyzed for LNG concentrations using RP-UPLC. Separation is performed on an Acquity™ BEH C18 column (50 x 2.1 mm; 1.7 pm), maintained at a temperature of 55 °C. Mobile phase consists of a 50 % acetonitrile in water. Sample run time is 3 min (isocratic), flow rate 0.55 ml / min and the sample injection volume is 3.0 pl. The column effluent is monitored at a detection wavelength of 243 nm. The recovered contents of LNG are close to the targeted LNG loadings.

[0291] For in vitro release testing, triplicates of ca. 3 mg of LNG-loaded microgranules are weighed into a 15.0 ml of IVR buffer (100 mM PO4 buffer, 0.5 wt% SDS, 0.02 wt% NaNs, pH 7.4) inside 15 ml tubes. Tubes are placed horizontally in a climate chamber at 37 °C ± 1 °C, with shaking at 130 rpm. Tubes are sampled regularly by replacing 14.0 ml of the buffer with 14.0 ml fresh buffer. Samples are analyzed using the RP-UPLC method described above and cumulative release curves are constructed from all data points. All LNG-loaded implants and microgranules sustained release of LNG for periods ranging from several weeks to several months. Example 16

[0292] Celecoxib-loaded POZ-PE based microparticles prepared by spray-congealing

[0293] In this example, branched POZ-PE copolymers were used to prepare celecoxib (CXB) loaded microparticles (MP) by spray congealing. Different POZ-PE copolymers with poly(DL- Lactide) (LA3924) or poly(L-lactide) (LL2265) based polyester arms with -OH or -C18 endgroups (Table 12) were tested. First, CXB and the biodegradable polymer were mixed to obtain powder mixtures containing 25, 40, or 60 wt% CXB which were subsequently heated in a stainless steel vessel at a temperature of 180 °C. The molten mixture was then atomized with a ProCepT spray congealing unit (Xedev, Belgium) equipped with a bi-fluid nozzle with 1.0 mm orifice, using preheated pressurized air at a flow rate of 6 L / min. The molten droplets were solidified into particles in a chill tower with cyclone gas blown at 400 mL / min to cool and to collect the particles.

[0294] Table 12. Branched POZ-PE copolymers used for preparation of CXB-loaded microparticles via spray-congealing

[0295] Table 13. Characteristics of CXB-loaded microparticles prepared of branched POZ-PE copolymers via spray-congealing Microscopic examination of the obtained CXB-loaded microparticles by scanning electron microscopy (SEM) showed spherical particles with a broad particle size distribution was obtained (Figure 14). Particle size analysis by laser diffraction confirmed the results from SEM with D10(vol) of 2 - 7 pm, D50(vol) of 40 - 80 pm, and D90(vol) of 120 - 200 pm.

[0296] For CXB content analysis, triplicates of 10.0 mg ± 0.3 mg of CXB MP sample were dissolved in 1 .00 ml of DMSO via vortex mix and heating at 60 °C using a heating block. Then, 50 pL dissolved MP samples were diluted with 1.5 mL of buffer (100 mM PO4 buffer, 5% Tween20, 0.02% NaNs, pH 7.4, 290 mOsmol / Kg). The sample was left on a roller mixer for 30 mins at 60 rpm to allow the biodegradable polymer to precipitate. After centrifugation, the supernatant was analysed for CXB concentrations using RP-UPLC. Separation was performed on an Acquity™ BEH C18 column (50 * 2.1 mm; 1.7 mm), maintained at a temperature of 40°C. Mobile phase A consisted of a 0.1 % H3PO4 in water solution. Mobile phase D consisted of acetonitrile. The gradient went from 55%D to 65%D in 2 minutes, at a flow rate of 0.600 mL / min. 1.0 ml of sample was injected. The column effluent was monitored at a detection wavelength of 251 nm. The recovered contents of CXB were close to the targeted 25, 40, and 60 wt% representing complete encapsulation of CXB (Table 13).

[0297] Thermal characteristics of the CXB loaded microparticles were determined by modulated differential scanning calorimetry according to the method described in Analytical Techniques. The Tg of CXB-loaded microparticles increased with CXB loading and varied between 39 and 47 °C.

[0298] Triplicates of ca. 30 mg of CXB-MPs were weighed into a 45.0 mL of IVR buffer (100 mM PO4 buffer, 5% Tween 20, 0.02 % NaNs, pH 7.4) inside a 50.0 mL tube. Tubes were placed horizontally in a climate chamber at 37 °C ± 1 °C, with shaking at 55 rpm. Tubes were sampled regularly by centrifugation and 100 pL of the supernatant was taken. After sampling, the tubes were then homogenized by gently inversion and placed back in the climate chamber. Samples were analysed using RP-UPLC and the release curve of the cumulative release was constructed from all data points. The release of CXB from CXB-MP is shown in Figure 15 and 16. The 7.5POZ800(LLA2265)4-C18 based microparticles with 25 or 40 wt% celecoxib released their complete payload within 2 days whereas 7.5POZ800(LLA2265)4- OH8 based microparticles with 25 or 40 wt% celecoxib showed sustained release of celecoxib for 2 to 3 weeks. Example 17

[0299] Ropivacaine-loaded POZ-PE based microparticles prepared by spray-drying In this example, branched POZ-PE copolymers 5POZ800[LA4000]4-OH, 10POZ1400[LA3150]4-OH and 10POZ1400[(LA75GA25)3310]4-OH are used to prepare ropivacaine (ROP) loaded microparticles (MP) by spray drying. First, the biodegradable polymer is dissolved in dichloromethane (DCM) to concentrations of 2, 5, 10 and 20 wt% whereafter ropivacaine is dissolved to concentrations required to obtain microparticles with a target ROP loading of 40 wt%. The solutions are spray-dried through a 2-fluid nozzle with orifice diameter of 1.0 mm using a Buchi mini spray-drier B290 (Buchi, Switzerland) with the following process parameters: inlet temperature of 40 - 50 °C, feeding rate of 1 or 2 mL / min, atomizing air pressure of 30L / min, and aspirator at 100% capacity.

[0300] The solutions are well sprayable and a white fine powder is obtained without any fiber-like structures.

[0301] The surface morphology of the microspheres is evaluated by scanning electron microscopy (SEM), using a JEOL JCM-5000 Neoscope. A small amount of microparticles is adhered to carbon conductive tape and coated with gold for 3 min. The sample is imaged using a 10 kV electron beam. Microscopic examination of the obtained ROP-loaded microparticles by SEM shows that the spray-dried powder has a broad particle size distribution and consists of spherical particles with a smooth surface without any pores (Figure 17).

[0302] Ropivacaine content of the microparticles is determined by CHN elemental analysis. In brief, 2.5 - 5 mg of ropivacaine microparticles, ropivacaine and biodegradable polymer are accurately weighed in a tin foil and combusted at 1150 °C in an Elementar® Micro Cube with an excess of oxygen to ensure complete sample combustion. The formed N2, CO2, H2O and SO2 gasses are retained by an adsorption column and eluted separately and analysed using a thermal conductivity detector. By comparing the nitrogen content of the ropivacaine microparticles with that of ropivacaine and biodegradable polymer, the ropivacaine content of the ropivacaine microparticles is calculated. Ropivacaine content of the microparticles as determined by CHN elemental analysis is close to the target loading of 40 wt% representing - 100 % encapsulation efficiency.

[0303] The in vitro release of ropivacaine from the microparticles is determined by incubating 10 mg of ropivacaine microspheres in 45 ml in vitro release buffer (100 mM PO4 buffer, 0.025 wt% Tween-20, 0.02 wt% NaNs, 290 mOsm / kg, pH 6.5) at 37 °C. At predetermined time points, following centrifugation of the vials, aliquots of 100 pl release buffer are collected. Ropivacaine concentrations in the release buffer are determined via reversed phase ultra-performance liquid chromatography (LIPLC) with UV-detection using a Waters Acquity H-Class LIPLC system, equipped with a PDA or UV detector, an Acquity BEH C18 column (50 x 2.1 mm, 1.7 .m), maintained at 40 °C. Mobile phase A consists of a 20 mM phosphate buffer pH 6.5 and acetonitrile at a ratio of 90 / 10 v / v and 100 % of acetonitrile is used as mobile phase B. The mobile phase composition starts at 30 vol% B and increased to 70 vol% B in 2 min, at a constant flow rate of 0.600 ml / min. Detection is performed at 235 nm. The ropivacaine-loaded microparticles showed relatively fast release of ropivacaine with release duration varying from a few days to several weeks.

[0304] Example 18

[0305] Water-solubility of biodegradable polymers

[0306] POZ-PE copolymers with varying LA / POZ ratios (Table 14) were evaluated for their aqueous solubility following the procedure outlined in the analytical techniques section. LA / POZ is defined as DPLA\ DPPOZ, with DP the degree of polymerization as determined from Mnas determined by1H-NMR. The solubility of the biodegradable polymers in water was determined by preparing a 2 wt% solution of biodegradable polymer in deionized water in a 15 mL glass vial. The solution was stirred using a magnetic stirring bead by means of a magnetic stirrer with a stirring speed of 200 rpm at 22 °C 24 hours, whereafter the solutions were visually inspected. For all selected POZ-PE copolymers, undissolved biodegradable polymer was visible in the solution, indicating that the biodegradable polymers are waterinsoluble polymers.

[0307] Table 14. Solubility of biodegradable polymers according to the present invention

Claims

CLAIMS1 . A pharmaceutical composition comprising: a. 20-75 wt% of a biodegradable polymer according to Formula (1)POZx y-(B-R)z(1), wherein POZx yis a polyoxazoline, B = a hydrophobic moiety, R = H, or a C1-C18 alkylgroup, x = the number of chain ends of the POZX’y, and is 2, 3, 4, 5 or 6, y = the number of attachment points for B-R at each chain end of the POZx y, and is 1 or 2, and z is the number of (B-R) groups per biodegradable polymer, and is 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12; b. 20-79 wt% of a biocompatible organic solvent; and c. 1-40 wt% of an active pharmaceutical ingredient; wherein the weight percentages of (a), (b) and (c) are defined relative to the sum of (a)+(b)+(c); wherein the weight fraction of the POZx yranges between 4-40 wt% relative to the total weight of the biodegradable polymer, wherein the weight fraction of the POZx yis determined by1H-NMR.

2. The pharmaceutical composition according to claim 1 , wherein the biodegradable polymer is water-insoluble.

3. The pharmaceutical composition according to claim 1 , wherein the total amount of ingredients (a), (b) and (c) is at least 75 wt% relative to the total weight of the pharmaceutical composition, preferably at least 90 wt% or 95 wt% relative to the total weight of the pharmaceutical composition.

4. The pharmaceutical composition according to any one of the preceding claims, wherein the weight fraction of the POZx yranges between 4-25 wt% relative to the total weight of the biodegradable polymer.

5. The pharmaceutical composition according to any one of the preceding claims, wherein the biodegradable polymer has a number average molecular weight (Mn)between 4000-30000 g / mol, preferably between 4500-20000 g / mol, more preferably between 5000-15000 g / mol, wherein the Mnof the POZx yranges between 400-5000 g / mol, preferably between 450-3000 g / mol, or between 500-2500 g / mol; and wherein the Mnof each B moiety ranges between 500-10 000 g / mol, preferably between 600- 5000 g / mol, more preferably between 750-4000 g / mol, wherein the Mnof the biodegradable polymer, the POZx y, and each B moiety are determined by1H-NMR.

6. The pharmaceutical composition according to any one of the preceding claims, wherein the pharmaceutical composition is injectable.

7. The pharmaceutical composition according to any one of the preceding claims, wherein a dynamic viscosity of the composition ranges between 0.01-5 Pa s, preferably ranges between 0.01-1 Pa s, more preferably ranges between 0.01-0.5 Pa s, most preferably ranges between 0.01-0.1 Pa s.

8. The pharmaceutical composition according to any one of the preceding claims, wherein POZx yis a poly(2-oxazoline) moiety, preferably a poly(2-alkyl-2-oxazoline) moiety, and wherein preferably the poly(2-oxazoline) moieties are poly(2-ethyl-2- oxazoline) moieties, poly(2-methyl-2-oxazoline) moieties and / or water soluble copolymers of 2-ethyl-2-oxazoline or 2-methyl-2-oxazoline with more hydrophobic monomers such as 2-n-propyl-2-oxazoline, 2-n-propyl-2-oxazoline, 2-iso-propyl-2- oxazoline, 2-sec-butyl-2-oxazoline, 2-cyclopropyl-2-oxazoline, preferably the poly(2- oxazoline) moieties are poly(2-ethyl-2-oxazoline) moieties.

9. The pharmaceutical composition according to any one of the preceding claims, wherein x is 2, 3 or 4, most preferably 2 or 4, and wherein z is 2, 4, 6 or 8.

10. The pharmaceutical composition according to any one of the preceding claims, wherein the POZx yis built from an initiator, wherein the initiator is chosen from ethylene glycol bis-p-toluenesulfonate, diethylene glycol di(p-toluenesulfonate), triethylene glycol di(p-toluenesulfonate), ethyleneglycol bistriflate, 1 ,4-dibenzyl bromide, trans-1 , 4-dibromo-2-butene and pentaerythritol tetratriflate.11 . The pharmaceutical composition according to any one of the preceding claims, wherein the B moiety is a polymer comprising at least one of the monomers from the group consisting of glycolide, lactide, e-caprolactone, p-dioxanone (1 ,4-dioxan-2-one), trimethylene carbonate (1 ,3-dioxan-2-one), 1 ,4-dioxepan-2-one (including its dimer 1 ,5, 8, 12-tetraoxacyclotetradecane-7, 14-dione), 1 ,5-dioxepan-2-one, 6,6-dimethyl-1 ,4-dioxan-2-one, 2,5-diketomorpholine, pivalolactone, diethylpropiolactone, ethylene carbonate, ethylene oxalate, 3-methyl-1 ,4-dioxane-2, 5-dione, 3,3-diethyl-1 ,4-dioxan-2.5-dione, 6,8-dioxabicycloctane-7-one, p-propiolactone, y-butyrolactone, 6- valerolactone, c-decalactone, 3-methyl-1 ,4-dioxane-2, 5-dione, 1 ,4-dioxane-2, 5-dione,2.5-diketomorpholine, a,a-diethylpropiolactone, y-butyrolactone, 1 ,4-dioxepan-2 -one,1.5-dioxepan-2-one, 6,6-dimethyl-dioxepan-2-one, 6,8-dioxabicycloctane-7-one, 5,5- dimethyl-1 ,3-dioxan-2-one, including mixtures of these monomers.

12. The pharmaceutical composition according to any one of the preceding claims, wherein the monomers of the B moiety are chosen from the group consisting of glycolide, lactide, e-caprolactone, p-dioxanone (1 ,4-dioxan-2-one), trimethylene carbonate (1 ,3-dioxan-2-one), 1 ,4-dioxepan-2-one (including its dimer 1 ,5,8,12- tetraoxacyclotetradecane-7, 14-dione) and 1 ,5-dioxepan-2-one, including mixtures of these monomers, preferably the monomers of the B moiety are chosen from the group consisting of glycolide, lactide, and e-caprolactone, or the B moiety is a polylactide.

13. The pharmaceutical composition according to any one of the preceding claims, wherein the weight fraction of the biodegradable polymer ranges between 20-75 wt% relative to the total weight of (a)+(b)+(c) and the weight fraction of the biocompatible organic solvent ranges between 20-79 wt% relative to the total weight of (a)+(b)+(c); preferably the weight fraction of the biodegradable polymer ranges between 30-60 wt% relative to (a)+(b)+(c) and the weight fraction of the biocompatible organic solvent ranges between 20-69 wt% relative to the total weight of (a)+(b)+(c).

14. The pharmaceutical composition according to any one of the preceding claims, wherein the pharmaceutical composition comprises a biodegradable polymer according to Formula (1), a biocompatible organic solvent, and an API, wherein the weight fraction of the biodegradable polymer ranges between 30-60 wt% relative to the total weight of (a)+(b)+(c), the Mnof the POZx yranges between 400-2200 g / mol, the Mnof each B moiety ranges between 750-2500 g / mol, and x = 2, y=2, and z=4.

15. The pharmaceutical composition according to any one of the preceding claims, wherein the biocompatible organic solvent is chosen from the group consisting of N- methyl-2-pyrolidone (NMP), N-ethyl-2-pyrolidone , dimethyl sulfoxide (DMSO), dimethyl isosorbide (DMI), benzyl alcohol, benzyl benzoate, ethyl lactate, ethyl benzoate, ethyl acetate, 2-pyrrolidone, tetraglycol, triacetin, tripropionin, tributyrin,glycofurol, polyethyleneglycol dimethyl ether and mixtures thereof; preferably wherein the biocompatible organic solvents are selected from NMP, DMSO, triacetin, tripropionin and benzyl benzoate or mixtures thereof.

16. The pharmaceutical composition according to any one of the preceding claims, wherein the weight fraction of the biodegradable polymer ranges between 29-49 wt% relative to the total weight of (a)+(b)+(c), the weight fraction of the biocompatible organic solvent ranges between 50-69 wt% relative to the total weight of (a)+(b)+(c), and the weight fraction of the API ranges between 1-21 wt% relative to the total weight of (a)+(b)+(c).

17. The pharmaceutical composition according to any one of the preceding claims, wherein the active pharmaceutical ingredient is chosen from a small molecule, a polypeptide, an oligonucleotide, or any combinations thereof.

18. The pharmaceutical composition according to claim 1 , wherein the pharmaceutical composition comprises: a. 30-60 wt% of a biodegradable polymer according to Formula (1)POZx y-(B-R)z(1), wherein POZx yis a polyoxazoline, B = a hydrophobic moiety, R = H, x = the number of chain ends of the POZX’y, and is 2, y = the number of attachment points for B-R at each chain end of the POZx y, and is 2, z = the number of (B-R) groups per biodegradable polymer, and is 4; b. 20-68 wt% of a biocompatible organic solvent; and c. 2-20 wt% of an API ; wherein the weight percentages of (a), (b) and (c) are defined relative to the sum of (a)+(b)+(c); wherein the Mnof the POZx yranges between 1000 and 2500 g / mol, the weight fraction of the POZx yranges between 20 and 40 wt% relative to the weight of the biodegradable polymer, and the Mnof each B moiety ranges between 500 and 5000 g / mol.

19. The pharmaceutical composition according to claim 1 , wherein the pharmaceutical composition comprises: a. 30-60 wt% of a biodegradable polymer according to Formula (1)POZx y-(B-R)z(1), wherein POZx yis a polyoxazoline,B = a hydrophobic moiety,R = H, x = the number of chain ends of the POZX’y, and is 2, y = the number of attachment points for B-R at each chain end of the POZx y, and is 2, z is the number of (B-R) groups per biodegradable polymer, and is 4; b. 20-68 wt% of a biocompatible organic solvent; c. 2-20 wt% of an API; and wherein the weight percentages of (a), (b) and (c) are defined relative to the sum of (a)+(b)+(c); wherein Mnof the POZX’yranges between 500 and 1250 g / mol, the weight fraction of the POZx yranges between 4 and 12 wt% relative to the weight of the biodegradable polymer, and the Mnof each B moiety ranges between 500 and 5000 g / mol.

20. A biodegradable polymer according to Formula (1),POZx y-(B-R)z(1), wherein POZx yis a polyoxazoline,B = a hydrophobic moiety,R = H, or a C1-C18 alkylgroup, x = the number of chain ends of the POZX’y, and is 2, 3, 4, 5 or 6, y = the number of attachment points for B-R at each chain end of the POZx y, and is 1 or 2 when x=3 or 4, and y=2 when x=2, and z is the number of (B-R) groups per biodegradable polymer, and is 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12; wherein the weight fraction of the POZx yranges between 4-40 wt% relative to the total weight of the biodegradable polymer, wherein the weight fraction of the POZx yis determined by1H-NMR.

21. A pharmaceutical composition in the form of microparticles, microgranules, microspheres or an implant comprising a biodegradable polymer according to claim 1 and at least one active pharmaceutical ingredient, wherein the microparticles, microgranules, microspheres or implant contain between 80-100 wt% of the block copolymer and the at least one active pharmaceutical ingredient, relative to the total weight of the microparticles, microgranules, microspheres or implant.

22. Microparticles, microgranules, microspheres or and implant, according to claim 21 , wherein the amount of the at least one active pharmaceutical ingredient is between 1-70 wt%, preferably 10-60 wt%, more preferably 20-50 wt% relative to the total weight of the microparticles, microgranules, microspheres or implant.

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