WO2007073596A1

WO2007073596A1 - Degradable polymeric microsphere composition

Info

Publication number: WO2007073596A1
Application number: PCT/CA2006/002078
Authority: WO
Inventors: Lalbin Luo; François RAVENELLE; David Lessard; Damon Smith
Original assignee: Labopharm Inc.; Labopharm Europe Limited; Labopharm (Barbados) Limited
Priority date: 2005-12-27
Filing date: 2006-12-21
Publication date: 2007-07-05
Also published as: AR061655A1; CL2007001878A1; CA2634830A1

Abstract

The present invention is directed towards a biodegradable microsphere composition for prolonged controlled release delivery of at least one biologically active agent in vivo. The instant invention provides microspheres prepared from amphiphilic block, star shape or graft copolymers made of poly(N-vinyl-2-pyrrolidone) segment(s) and biodegradable segment(s), the microspheres incorporating at least one biologically active agent and being adapted for controlled delivery of the active agent to a mammal. Poorly water-soluble biologically active agents are incorporated into the microspheres by a single emulsion method. Hydrophilic biologically active agents are incorporated into the microspheres by a double emulsion method. Amphiphilic biologically active agents are incorporated into the microspheres by either a single or double emulsion method.

Description

DEEGRADABLE POLYMERIC MICROSPHERE COMPOSITION

TECHNICAL FIELD

The present invention is directed towards a polymeric, biodegradable microsphere composition for delivery of biologically active agents; particularly towards preparing microspheres which include a block, star shape or graft copolymer of poly (N-vinyl-2- pyrrolidoixe), PVP, segments) and biodegradable segment(s), such as poly(D,L-lactide), PDLLA₁ segments); most particularly to processes of preparing the above microspheres by encapsulating biologically active agents into the microspheres, for example by either single or double-emulsion methods or both.

BACKGROUND ART

It has been a long sought after goal of the pharmaceutical industry to produce biodegradable microspheres containing pharmaceutical compounds therein, with the ability to precisely control the release rate of encapsulated compounds in vivo.

The instant inventors are interested in the use of microspheres to deliver hydrophobic, hydrophilic and amphipbilic biologically active agents in a controlled release application, particularly to the use of microspheres formed from block, star shape or graft copolymers of poly(N-virryl-2-pyrrolidone) segments and biodegradable hydrophobic segments. The size of the microspheres is about 0.03 to 1 ,000 micrometers. As used in the present specification and in the appended claims, the term microsphere is meant to include also nanospheres, microparticles, and micro-, or nano-assemblies. Microspheres are designed to deliver an active agent via a particular route of administration and with a particular rate of release.

Due to their unique properties, microspheres can be readily manufactured to provide consistent drug release rates and high loading levels. The rate at which the biologically active agent is released is controlled by microsphere size (which controls surface area), porosity, rate of degradation (controlled by the type of polymer used), and its molecular weight (Lerner et al, WO 03/090722, herein incorporated by reference). Microspheres can be loaded with both water-insoluble or water-soluble drugs, releasing them over long periods of time (days, weeks or months).

Many studies, literature articles and patents have been directed toward the use of amphiphilic block copolymers.

The use of microsphere encapsulation in the pharmaceutical art is well known. A great deal of interest has been attributed to improve biodegradable microsphere drug delivery systems. The controlled release mechanism of biodegradable microspheres is thought to occur in two phases, characterized by pore diffusion in the initial phase and erosion, or degradation, at later stages. Both water uptake and degradation properties of the biodegradable polymer determine the release rate. Such mechanisms allow long term (days, weeks or months) delivery profiles to be achieved in vivo , A constant (i.e. zero-order) drug release rate in vivo is often preferred to variable drug release rate avoiding the peaks and troughs in plasma concentration (and therefore efficacy) often associated with other delivery methods.

Hydrophobic polyesters such as PLGA and PLA also have been extensively used in the formation of microsphere systems. However their hydrophobicity hinders the diffusion of water in and out of the microspheres. Thus, when degradation occurs the oligomers and monomers that are formed accumulate within the microspheres leading to an increasingly acidic microenvironment which can destabilize encapsulated acid-sensitive molecules, especially biomolecules such as, but not exclusively, proteins, DNA plasmids and polypeptides. Furthermore the acidic microenvironment contributes to an increase in polymer degradation rate and thus the drug release rate thereby reducing the duration of action of the microsphere. It has also been suggested that the strong hydrophobicity of PLA and PLGA could possibly denature the encapsulated biomolecules. Finally the difference in physicochemical properties between hydrophilic molecules and hydrophobic polymer leads to a reduction in the loading efficiency, and their incompatibility may lead to an increase in the so called burst release phase.

To address the problem of an acidic microenvironment, Jiang et al (Pharm. Res. 18(6), (2001) 575-885) disclose co-encapsulation of poorly water-soluble basic additives such as Mg(OH)₂ into the microspheres. By doing this, the acidic microenvironment is neutralized and the stability of encapsulated proteins was improved.

Pluronics, poly(ethylene oxide)-poly(propylene oxide) (PEO-6-PPO) amphipbilic block copolymers, are widely used in the pharmaceutical industry. Poly(ethylene glycol) (PEG) is the most widely used biocompatible water-soluble polymer, PLGA and PLA have been blended with various PEO-PPOs and PEGs to improve protein delivery and obtain controlled release profiles. A less acidic and more hydrophilic microenvironment was achieved in such blends. More recently, PEG has been combined to PLA to form PEG-PLA block copolymers, The acidity, hydrophobicity, and permeability of microspheres prepared from PEG-PLA block copolymers is adjusted by the amount of PEG in the microspheres. Hence, PEG could facilitate the release of hydrophilic proteins and hydrophobic small molecules. Another potential advantage provided by the PEG segment is that PEG on the surface of microspheres also improves the biocompabiϋty of the microsphere with tissues.

However, the blending of PEO-PPOs and PEGs into the microspheres and the introduction of PEG with PLA forming PEG-PLA block copolymer results in property changes of polymers and of the microparticles prepared from such polymers. Some studies have demonstrated that PEG on the surface of colloids may promote the aggregation of colloids during the ficczc-drying process. Since PEG-PLA block copolymers become more hydrophilic, the compatibility between hydrophobic molecules and polymers may decrease, causing a decrease in encapsulation efficiency. PEG also has been shown to prevent the absorption of proteins to surfaces, due to its physical properties such as unlimited water solubility, large excluded volume and high degree of conformational entropy. Because of the steric effect of PEG to proteins, PEG may decrease the encapsulation efficiency and increase the burst release of proteins.

Poly(N-vinyl-2-ρyπolidone) has been extensively used, especially in the pharmaceutical industry. With its highly polar lactam group surrounded by apolar methylene groups in the backbone, PVP is a water-soluble, relatively amphiphilic polymer. Due to its chemical structure, PVP forms complexes with numerous low molecular weight compounds as well as with many large molecules by hydrogen bonding.

The interaction between PVP and water is so strong that high PVP concentrations can prevent water from freezing, Indeed, PVP lias been used as a cryoprotectant for a wide variety of cells and as a lyoprotectant for proteins. More recently, PVP has been suggested as a stabilizer for colloids to avoid the aggregation of colloids after freeze-drying. The association of plasmid DNA with PVP has been regarded as a useful strategy for increasing the stability and transfection efficiency of plasmids. Complexation of proteins with water-soluble PVP is also of great importance for various fields of pure and applied science.

US Patent 6,338,859 to Leroux ct al (herein incorporated by reference) describes polymeric micelle compositions where the hydrophilic component includes poly(N-vinyl-2- pyixoUdone) and the hydrophobic component is selected from a group consisting of polyesters, polyorthoesters, polyanhydride and derivatives thereof. The polyester group can be selected from poly(D,L-lactic acid), poly(glycolic acid), lactide/glycolide copolymers, poly(ε- caprolactone) and derivatives thereof. A hydrophobic therapeutic agent can be loaded into the hydrophobic core of micelle self-assemblies from such polymers.

Although the maj ority of these prior art delivery systems are effective for the delivery of many bioactive agents, what is presently lacking in the art are amphiphUic polymers capable of forming microsphere assemblies for effective and reliable encapsulation and long term, sustained controlled delivery of at least one biologically active agent, and in particular microspheres with a less acidic microenvironmeiαt, and a more compatible environment to proteins or peptides, while allowing for cryoprotection of the biologically active agents loaded therein.

DISCLOSURE OF PfVENTION

The present invention involves encapsulating hydrophobic and/or hydrophilic and/or amphiphilic drugs inside microspheres for sustained drug release. Hydrophobic active agents can be encapsulated in microspheres by a single emulsion method. Hydrophilic active agents can be encapsulated in microspheres for example by a double-emulsion method. Amphiphilic active agents can be encapsulated in microspheres by a single or double emulsion method.

Accordingly, it is a primary objective of the instant invention to provide a block, star shape or graft copolymer that is formed into aplurality of microspheres, an effective amount of at least one biologically active agent being the biologically active agent is incorporated within the copolymer incorporated within the copolymer and into the formed microspheres, the microspheres being adapted for controlled delivery of the at least one biologically active agent in vivo for prolonged periods, and wherein the block, star shape or graft copolymer comprises poly (N-vinyI-2-pyrrolidone) segments and biodegradable, preferably hydrophobic, segments.

Preferably, the composition comprises about 2-40 weight percent of poly (N-vinyl-2- pyrrolidone segments), most preferably 10 - 20 weight percent.

Another objective of the instant invention is to prepare pharmaceutical compositions from the instantly disclosed polymers by incorporating at least one substance, preferably a biologically active agent, which is illustrated by, but is not limited to, hydrophobic and/or hydrophilic molecules, and/or amphiphilic molecules, examples of which include small molecule drugs and macromolecules such as peptides, proteins, DNA and plasmids.

Iχi the composition according to the invention, the copolymer may be physically mixed with a biodegradable polymer, such as polyesters, polysaccharides, polyamides, polyanhydrides, or combinations thereof, for example poly (caprolactone), polyglycolide, poly (D,L-lactide), poly (D-lactide), poly (L-lactide) or polyhydroxyalkanoates.

A further objective of the present invention is to prepare microsphere assemblies from a graft, block or star shape copolymer wherein the copolymer composition comprises poly (N- vinyl-2-pyrrolidone) segments) and biodegradable, preferably hydrophobic, polymer segments) preferably, but not exclusively, selected from the group consisting of polyesters, polysaccharides, polyamides, polyanhydrides, or combinations thereof, for example poly (caprolactone), polyglycolide, poly (D,L-lactide), poly (D-lactide), poly (L-lactide), polyhydrooxyalkanoates. The size of these microspheres catx be between about 0.03 and 1,000 micrometers thereby forming a colloidal dispersion in water. It is to be noted that in the further text, the terms "microsphere" and "microparticle" assemblies are used interchangeably and essentially mean structures having a size range of between about 0.03 and 1,000 micrometers.

Yet another objective of the instant invention is to provide methods of incorporating biologically active hydrophobic agents and/or hydrophilic agents and/or amphiphilic agents in microsphere assemblies according to the invention, yielding high incorporation efficiencies and high loading levels. Yet another objective of the invention is to provide for the preparation of biodegradable microspheres compositions that are suitable for prolonged (days, weeks or months) controlled delivery of at least one biologically active agent in vivo. This can be achieved by providing at least one block, star shape or graft copolymer comprising poly (N- vinyl-2-pyrrolidone) segments and biodegradable segments, mixing the copolymer with a solvent and at least one biologically active agent, and extracting the solvent, such as by single emulsion or double emulsion solvent extraction, under conditions to provide microspheres wherein the biologically active agen is incorporated within the copolymer microspheres.

Yet another objective of the invention is to provide biodegradable microspheres having incorporated therein at least one biologically active agent preferably selected from anticancer drugs, antibiotics, anti-fungal agents, immunomodulators, anti-viral drugs, anti-bacterial drugs, anti-migraine drugs, neurological agents, anti-Parkinsonism drugs, anti-coagulants, pro- coagulants, cardiac drugs, cardiovascular drugs, lipid lowering drugs, gastrointestinal drugs, muscle relaxants, psychotherapeutic drugs, respiratory tract drugs, gene therapy agents, contraceptives, hormones, analgesics, anaesthetics, antihistamines, antki-allergic drugs, antidotes, anticonvulsants, antidiabetic agents, vaccines, anti-epileptic drugs, steroid drugs, antiinflammatory drugs, and mixtures or combinations thereof and the like.

A still further objective of the present invention is to use these microsphere assemblies for delivery of biologically active agents into the body of a mammal via, albert not limited to, administration intramuscularly; intravenously, subcutaneously, intraarticularly intraperitoneally, intrathecaUy, intracerebrally or orally, or the like. Moreover, the microspheres can be adapted for administration into the dermal or epidermal layer of the skin by injection or needleless injection systems, known in the art. Upon administration, the biologically active molecule incorporated in the microspheres will be protected from the environment and released at a desired rate for aprolonged period be it days, weeks or months, It is yet another objective of the invention to provide microspheres made of PVP derived copolymers wherein the addition of PVP improves water diffusion inside the microspheres to allow for the diffusion of the biologically active agent and of monomers and oligomers out of the microspheres, and also cause the aqueous enviσnmentto stabilize pH, and provide ionic strength of the microenvironment inside the microspheres,

Other objectives and advantages of this invention will become apparent from the following description, inclusive of the experimental working examples, taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention. The drawings constitute a part of this specification and include exemplary embodiments of the instant invention and illustrate various objects and features thereof.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a ¹H-NMR spectrum of PVPOH in CDCl₃;

FIG.2 illustrates a ¹H-NMR spectrum of PVP-έ-PLA in CDCl₃;

FIG. 3 illustrates size-exclusion chromatograph profiles (SEC) of (a) PVPOH

(PVPOH-2500) and (b) PVP-&-PLA shown by refractometry index;

FIG. 4 illustrates size-exclusion chromatograph profiles (SEC) of (a) PVPOH (PVPOH-2500) and (b) PVP-ό-PLA shown by Light scattering data collected at 90° C;

FIG. 5 illustrates a scanning electron micrograph of simvastatin loaded microspheres.

FIG. 6 illustrates loading efficiency of simvastatin in PVP-δ-PLA microspheres.

FIG.7 illustrates in vitro release kinetics of simvastatin from P VP-6-PLA microspheres with different simvastatin loading levels.

DISCLOSURE OF INVENTION In accordance with preferred embodiments) the instant invention provides PVP and PDLLA copolymers to create a novel microsphere system for prolonged controlled release of biologically active agents. PVP-6-PDLLA block copolymers were used to prepare microparticles. Such a microparticle system has remarkable properties. First, PVP will allow the microsphere formulation to be lyophilized without causing microsphere aggregation, as PVP with its high glass transition temperature, acts as a lyoptotectant Second, the amphiphilicity of PVP decreases the interaction of hydrophobic PLA with tissues, and thus improves the biocompatibilty of the microspheres with tissues. Third, the amphiphilic nature of PVP facilitates the uptake of water and therefore the degradation of the microspheres in vivo. This feature in turn enhances both the release of the loaded biologically active agent and the release of the oligomers and monomers formed during degradation. Release of these degradation products prevents the formation of an acidic microenvironment within the microsphere that could adversely affect both the nature and release of the biologically active agent Fourth, since PVP forms complexes with small molecules and biomolecules, the loading efficiency and loading level can be increased and the detrimental burst release phenomenon often associated with microspheres can be reduced. Fifth, because of its highly hygroscopic nature, PVP creates higher intermediate moisture levels in the microspheres, again resulting in a less acidic and more hydrophilic microenvironment. Sixth, the association of PVP with biomolecules can potentially improve the transfection efficiency of plasmids,

EXAMPLES

Non-limiting examples are presented herein and are given solely as representatives of the inventive concepts discussed herein.

Example 1:

Synthesis of poly(N-vinyl-2-pyrrolidone) with a hydroxyl-beating chain end (PVPOH). PVPOH was synthesized by free radical polymerization of N-vmyl-2-pyrrolidone (NVP). A typical procedure is described as following. NVP (30 g, 270 mmol), AMPAHE (0.7783 g, 2.7 mmol) and NTCE (0.844 g₃ 10,8 mmol) were dissolved in 540 mL of IPA. The solution was degassed with argon for 15 min. The polymerization was carried out at 85⁰C for 24 h. Then, most of IPA was removed under reduced pressure. Afterwards, the polymer was precipitated in about 300 raL, of diethyl ether. The polymer was dissolved in 60 mL, of methylene chloride, and precipitated again in 300 mL of diethyl ether. Finally, the product (white powder) was transferred into a Whatman cellulose extraction thimble, and purified by diethyl ether Soxhlet extraction for 24 h. The polymer was dried at 8O⁰C under vacuum overnight.

Example 2: Synthesis of block copolymer poly(N-vinyl-2-pyrrolidone)-6/ocA-poly(D,L- lactide) (PVP-&-PDLLA).

PVP-ZVPDLLA was synthesized by ring-opening polymerization of LA using PVPOH as macroinitiator and stannous 2-ethyl-hexanoate as catalyst. 1.1 g PVPOH (Mn=2450) (0.45mmol) was dissolved in 25 mL toluene. PVPOH was dried by azeotropic distillation using toluene and a Dean-Stark trap. Toluene was then removed by distillation under reduced pressure. The polymer was dried under vacuum at 150⁰C for 4 h. After cooling down to room temperature, 10 mL freshly distilled THF was used to dissolve the polymer. 9 g DL-lactide (62.44 mmol) was placed in a flask and dried under vacuum at 75⁰C for 4 hours, 50 mg stannous 2-ethylhexanoate was added into the flask under nitrogen atmosphere, The chemicals were dried at 75⁰C for one hour. The PVPOH/THF solution was transferred into the flask containing DL- lactide and stannous 2-ethyl-hexanoate under argon atmosphere. After mixing well, THF was removed under vacuum at 75^DC. The polymerization was carried out at 15O⁰C for 16 hrs. The polymer was dissolved in 100 mL chloroform and

precipitated in 1000 mL hcxancs. The polymer was dried at 60^DC.

Example 3:

Illustrates size-exclusion chromatography (hereinafter, SEC) analysis carried out on a Waters system using refractometer Waters 2410 (Milford, Massachusetts), see Figure 3, and light scattering (LS) detector Precision Detectors PD2000 (Bellingham, Massachusetts) shown in Figure 4. LS data were collected at 15 and 90° C. SEC was performed in DMF containing

10 mM LiBr. 100 pi, of solution (about 3%w/v) was injected through a series of 3 columns

Styragel^® Waters HT2, HT3 and HT4 at a flow rate of 1.0 mL/min, in order to separate the molecular weights (MW) ranging from 10² to 10⁶ Da. The temperature of columns (separation) was maintained at 4O⁰C, while the temperature of refractometer /LS detectors was set at 40⁰C.

The instrument was calibrated with monodisperse polystyrene standards.

Example 4: Nuclear magnetic resonance (¹H-NMR)

¹H -NMR spectra were recorded on Varian 400 spectrometer in CDCL₃ at 25⁰C. The PDLLA content (%mol) was determined using equation (1).

where represents signal intensity at 5.2 pprn, and corresponds to the tertiary proton (position of carbonyl group). This signal was normalized to L

The PDLLA weight content (%weight) was calculated using equation (2).

Example 5- Preparation of simvastatin loaded microspheres. The oil-in-water single emulsion solvent evaporation technique was used at 25⁰C to prepare simvastatin-loaded microspheres. Certain amounts of simvastatin (10, 15, or 20 mg) and 100 mg PVP-ZJ-PLA polymer (SEC result: Mn=21 kDa,polydispersityindex=1.343;NMR result: PDLLA(% weight) = 87%) were dissolved in 5 mL dichloϊomethane. The solution was then poured rapidly into 100 mL of PVA (Molecular weight of 78 kDa) solution (2% w/v) under medium stirring for 2 hours. The resulted oil-in-water emulsion was further stirred overnight under slow stirring to completely extract the organic solvent, leaving behind solid microspheres. The final product was collected by centrifugation at a speed of 12,000 rpnj and 4⁰C. The microspheres were washed five times to remove PVA, and then dried by freeze- drying,

Example 6: Scanning electron microscope.

The microspheres were fixed on a conductive tape and subsequently sputter-coated with gold (Polaron Model E5100) for 3 min in an argon atmosphere. The thickness of the coating is 300 - 400 A. The shape of the microspheres were examined on a multipurpose ZEISS DSM 960 microscope at 2.5 kV.

Example 7: Simvastatin loading efficiency.

The loading efficiency is defined as the ratio of the amount of the loaded simvastatin to that of the drug used for microsphere preparation, 10 mg of simvastatin loaded microspheres were dissolved in 1 mL dicholoromethane. After dicholoromethane was evaporated, 20 mL acetonitrile was added into the vial to dissolve the drug using sonication for one hour. The stock solutions were diluted with acetonitrile by 4, 8 and 16 times. The resulted solutions were used to determine the simvastatin concentration by determining the UV absorption at 238 om, Example 8: In vitro release of simvastatin ftom microspheres. About 10 mg of simvastatLπhloaded micros, pheres were placed in tubes, and incubated in 20 mL of 0.01 M pH 7,4 sodium phosphate buffer solution containing 0.1 % SDS at 37⁰C. At desirable intervals, the microsphere suspension was centrifuged at 12,000 rpm for 10 min. 5 mL of supernatant was withdrawn and replaced with 5 mL of fresh release medium. The amount of simvastatin released was determined by using UV absorption at 238 nm.

Il will be apparent to those skilled in the art that he above in vitro results demonstrating slow release of simvastatin over a period of several days are indicative of the true potential of the present invention to carry out similar controlled release in vivo. It will also be obvious to the skilled chemist that other drugs, such as the biologically active agents mentioned above as a non exhaustive list may also be incorporated within the microspheres according to he present invention.

It is to be understood that while a certain form of the invention is illustrated, it is not to be limited to the specific form or arrangement herein described and shown. It will be apparent to those skilled in the art that various changes may be made without departing from the scope of the invention and the invention is not to be considered limited to what is shown and described in the specification and drawings/figures. One skilled in the art will readily appreciate that the present invention is well adapted to cany out the objectives and obtain the ends and advantages mentioned, as well as those inherent therein. The embodiments, methods, procedures and techniques described herein are presently representative of the preferred embodiments, are intended to be exemplary and are not intended as limitations on the scope. Changes therein and other uses will occur to those skilled in the art which are encompassed within the spirit of the invention and are defined by the scope of the appended claims. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention which are obvious to those skilled in the art are intended to be within the scope of the following claims.

Claims

1. A biodegradable microsphere composition comprising a block, star shape or graft copolymer which comprises poly (N-vinyl-2- pyrrolidone) segment(s), and biodegradable segments), said copolymer being formed into a plurality of microspheres, an effective amount of at least one biologically active agent incorporated within said copolymer, into said microspheres, said microspheres being adapted for prolonged controlled delivery of said at least one biologically active agent in vivo.

2. The biodegradable microsphere composision in accordance with claim 1, wherein said biodegradable segments) is (are) hydrophobic.

3. The biodegradable microsphere composition in accordance with claim 1 wherein said biodegradable hydrophobic segment(s) comprise a polyester, a polysacchar de, a polyarm'de, apolyanhydride, or mixtures thereof.

4. The biodegradable microsphere composition in accordance with claim 1 wherein said copolymer is physically mixed with a biodegradable polymer.

5. The biodegradable microsphere composition in accordance with claim 4 wherein said biodegradable polymer comprises a polyester, a polysaccharide, a polyamide, a polyanhydride, or mixtures thereof,

6. The biodegradable microsphere composition in accordance with claim 5 wherein said biodegradable polymer is selected from the group consisting of poly (caprolactone), polygϊycolide, ρoly(D,I^lactide), polyφ-lactide), poly(L-lactideX and polyhydroxyalkanoates.

7. The biodegradable microsphere composition in accordance with claim 1 which comprises about 2-40 weight percent poly(N-vinyl-2-pyrrolidone) segment.

8. The biodegradable microsphere composition in accordance with claim 7 which comprises about 10 - 20 weight percent poly (N-vinyl-2-pyrrolidone) segment.

9. The biodegradable microsphere composition in accordance with claims 1 , 2 or 3 , wherein said biodegradable hydrophobic segments) are selected from the group consisting of poly (caprolactone), polyglycolide, poly (D,L-lactide), poly (D- lactide), poly (L-lactide), and polyhydroxyalkanoates,

10. The biodegradable microsphere composition in accordance with claims 1 to 9, wherein said at least one biologically active agent is selected from the group consisting of hydrophobic biologically active agents, hydrophilic biologically active agents, and amphiphilic biologically active agents.

11. The biodegradable microsphere composition in accordance with claims 1 to 9, wherein said at least one biologically active agent is selected from the group consisting of anticancer drugs, antibiotics, anti-fungal agents, immunomodulators, anti-viral drugs, anti-bacterial drugs, anti-migraine drugs, neurological agents, anti- Parkinsonism drugs, anti-coagulants, pro-coagulants, cardiac drugs, cardiovascular drugs, lipid lowering drugs, gastrointestinal drugs, muscle relaxants, psychotherapeutic drugs, respiratory tract drugs, gene therapy agents, contraceptives, hormones, analgesics, anaesthetics, antihistamines, anti-allergic drugs, antidotes, anti-convulsants, antidiabetic agents, vaccines, anti-epileptic drugs, steroid drugs, anti-inflammatory drugs and mixtures or combinations thereof.

IS

12. The biodegradable microsphere composition in accordance with any one of claims 1 to 9, wherein said poly (N-vinyl-2-pyrrolidone) segment(s) have a molecular weight between about 200 Da and 5000 Da.

13. The biodegradable microsphere composition in accordance with any one of claims

1 to 9 and 12, wherein said block, star shape or graft copolymer has a molecular weight between about 500 Da and about 700,000 Da.

14. The biodegradable microsphere composition in accordance with claims 1 to 9, wherein said copolymer is a block copolymer of PVP and PDI-LA.

15, Use of a composition as defined in any one of claims 1 to 13, for treating a mammal in need of said at least one biologically active agent,

16, Use of a composition as defined in claims 1 to 13, for the preparation of a medicament for treating a mammal in need of said biologically active agent.

17. Method for the preparation of a biodegradable microsphere composition which comprises

a) dissolving a mixture of a block, star shape or graft copolymer which comprises poly (N-vinyl-2-pyrrolidone) segments), and biodegradable segments), and at least one biologically active agent in a solvent to give a solution, b) treating said solution by emulsion under conditions to give said microsphere composition,