CA2216371C - Novel "burst-free" sustained release poly-(lactide/glycolide) microspheres - Google Patents
Novel "burst-free" sustained release poly-(lactide/glycolide) microspheres Download PDFInfo
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- CA2216371C CA2216371C CA002216371A CA2216371A CA2216371C CA 2216371 C CA2216371 C CA 2216371C CA 002216371 A CA002216371 A CA 002216371A CA 2216371 A CA2216371 A CA 2216371A CA 2216371 C CA2216371 C CA 2216371C
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
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Abstract
Novel burst-free, sustained release biocompatible and biodegradable microcapsules which can be programmed to release their active core for variable durations ranging from 1-100 days in an aqueous physiological environment. The microcapsules are comprised of a core of polypeptide or other biologically active agent encapsulated in a matrix of poly(lactide/glycolide) copolymer as a blend of uncapped (free carboxyl end group) and end-capped forms ranging in ratios from 100/0 to 1/99.
Description
"BURST-FREE" SUSTAINED RELEASE POLY-(LACTIDE/GLYCOLIDE) MICROSPHERES
S This invention relates to providing novel biocompatible and biodegradable microspheres for burst-free programmable sustained released of biologically active agents, inclusive of polypeptides, over a period of up to 100 days in an aqueous physiological environment.
,.
i~
i WO 97/26869 PCTlUS96/19440 I0. HAC1CGROUND OF THE INVENTION
Several publications and patents are available for sustained release of $ctive agents from biodegradable polymers, particularly, poly(lacti.de/glycolides) (PLGA). Prior usages of PLGA for controlled release of polypeptides have involved the use of molar ratios of lactide/glycalide (L/G) of 75/25 to 100/0 for molecular weights >20,000. Further prior art preparations of PLGA
utilized fillers or additives in the inner aqueous layer to improve the stability and encapsulation efficency and/or to increase the viscosity of the aqueous layer, thereby modulating polymer hydrolysis and the biologically active agent or polypeptide release.
In addition, the prior art use of PLGA copolymers were end-capped, i.n that the terminal carboxyl end groups were blocked. In these end-capped co-polymers, the microcapsule preparations exhibited a low to moderate burst release of - 10-40% of the 2o entrapped polypeptide in the first 24 hours after placement in an aqueous physiological environment. In part, these characteristics are due to the use of fillers in the inner aqueous phase.
Further, a 1-month release of polypeptide is known with the use of a 75/25 co-polymer of PLGA of Mw <20,000.
Investigations in controlled release research has been proceeding especially to obtain a 1 to 2 month delivery system , ' 3 for biologically active agents or polypeptides using poly(lactide/glycolide) polymers. However, most of these systems have one or more of the following problems: Poor encapsulation r efficency and large 'burst release' followed by an intermediate 'no release' or 'lag phases until the polymer degrades. In general, release from these polymers occur over a period from about 4 weeks to about several months. In addition, in order to achieve this release a 50/50 copolymer of Mw > 30,000 or a 75/25 copolymer of Mw > 10,000 are employed which often results in residual polymer remaining at the site of administration long after the release of active core.
V. SUMMARY OF THE INVENTION
This invention provides biocompati.ble and biodegradable microspheres that have ben designed for novel., burst free, programmable sustained release of biologically active agents, including polypeptides over a period of up to 100 days in an aqueous physiological environment.
Unlike currently availab:l.e :re=Lease systems, which rely on the use of fillers/additive~~ such as gelatin, albumin, dextran, pectin, polyvinyl pyrrolidone, polyethylene <~lycol, sugars, etc., and are :till prone to low encapsulation efficiencies and "burst effects", t=his invention achieves hicah e=ncap;~ul.<~ition and "bu.r~st-free" release without the use of any additive. Ln this invention, burst-free, programmable sustained relF~a~>e is a<<hieved through the use of a unique blend of the ' unc:apped' and end--cad>ped forms of holy(lac:tide/glycolide) polymer that. is preferably in the molecular weight range of 2,000 to E>0,000 daltons.
In general, m:icrosphc=ores de;~cribed in this invention are produced by a unique emu7_;-if icatior_ technique wherein an inner water-in-oil (w/o) emul;~:icm is ;~t:abi Li.zed by dispersing in a ;solvent-saturated aqueous pha:>e cont:aining an emulsion stabilizer.
A ternary w/o/w emulsion i~ then foxmec~ by emulsifying the above w/o emulsions in an external p.r~~-coo:led aqueous pha~~e containing an o/w emulsified. For example, the inner w/o emulsion may include an aqueous layer containing from -2 to about 20% (w/w) of the active agEvnt to be entrapped and an oil layer containing poly(=Lactide/glycolide) copolymer in concentrations ranging from --- 5 to about. -- 50% (w/w oil phase).
5 The copolymer preferably inc_Ludes molecular weight ranging from 2,000 to about 60,000 dalto:ns, with molar composition of lactide/glycolide from 90/1_0 to 40/60 and a blend of its uncapped and end-capped forms in a ratio of100/0 to 1/99. Very high encapsu:Lation efficiencies o.f about 80 to 100° are achieved depending on polymer molecular weight and structural form.
Programmable release of active core over variable durations between 1-100 days is acriieved by a judicious selection of process parameters such as polymer concentration, pept:ide concentration and the aqueous/oil phase rat.:ic->.
IS Th=is invention is part i cul.arly suitable for hicth encapsulation efficiencies and burst-iree, continuous programm~ible release of polypept=ides of mo.lecula:r we:ig:Eat~:=~ ranging from 1, 000 to about 250,000 daltons, and als~~ other :~iologically active agents over a period of 1-100 days. A uniqueness of the invention is that when using a 100/0 blend of the uncapped anti capped polymer, the final phase of active core re:~ease is concurrent with the complete solubilization of t;he polymer t.o innocuous components, such as lactic <~nd glycolic acids. ~L'Izi~; is a significant advantage over the currently available 30 day-release systems wherein a major regulatory concern is about t~ox::icit~,T of residi_ral polymer at the site of administration, Long 6 _ after xelease of the active core.
The microcapsules described in this invention are suitable for administration via several routes such as parenteral (intramuscular, subcutaneous), oral, topical, nasal, rectal and vaginal routes.
VI. BRIEF DESCRIPTION OF DRAiPINGB ' FIG. 1 shows a comparison of drug release from a conventional system versus a controlled release system. Peak and 1o valley levels from conventional administrations are shown, in contrast to the steady therapeutic levels from the controlled release administration.
FIG. 2 shows a scanning electron micrograph of PLGA
microspheres prepared by the process described in the invention using 50/50 uncapped polymer of Mw 8-12k dalton and shows superior sphere morphology, sphere integrity, and narrow size distribution.
FIG. 2a shows a scanning electron micrograph of PLGA
microspheres prepared by conventional solvent evaporation method using a 50/50 12k uncapped polymer of Mw 8-12k dalton.
FIG. 3 shows cumulative Histatin release from PLGA
microspheres, wherein release profiles from several batches are prepared using 50/50, uncapped polymer (of Mw 8-i2k dalton) and wherein the process parameters are varied to modulate release between 1 and 35 days.
FIG. 4 shows a scanning electron micrograph of solid, smooth .
WO 97126869 PCTlLT596/19440 spherical surfaces of PLGA microspheres prepared by the method of in the invention using 50/50, end-capped polymer (of Mw 30-40k dalton).
FIG. 5 shows cumulative Histatin release from PLGA
microspheres, wherein the release profiles are from several batches prepared using 50/50, uncapped and end-capped polymer of Mw 30-40k daltons, and wherein the process parameters are varied to modulate release between 28 to 60 days.
FIG. 6 shows cumulative Histatin release from PLGA
microspheres, wherein combined release profiles from several batches have been prepare' using 50/50, uncapped and end-capped polymer of Mw 8-40k daltons, while varying the process parameters to modulate release between 1 and 60 days.
FIG. 7 shows a cumulative percent release of LHRH from PLGA
micraspheres prepared using uncapped polymer of Mw 8-12 daltons.
DETAILED DESCRIPTION OF THE INVENTION
This invention relates to the design of biocompatible and biodegradable microspheres for novel, programmable sustained release of biologically active agents, including polypeptides over a period of up to 100 days in an aqueous physiological environment with little or no burst release.
Unlike currently available release systems which rely on the use of fillers/additives such as gelatin, albumin, dextran, pectin, polyvinyl pyrrolidone, polyethylene glycol, sugars, etc., and are still prone to low encapsulation efficiencies and ~~burst effects", this invention achieves high encapsulation efficiency g and 'burst-free' release without tree use of any additive. In this :invention, burst-free, programmable sustained release is achieved through the use of a unique blend c;f the 'uncapped' and end-capped forms of: poly(lactide/gl~~c=olide) Polymer.
The 'capped' form refers t:o ""poly (lactide/glycolide) with free carboxyl end groups" whl.c:h renders the polymer more hydrophilic compared to the routinely used end-capped form. Currently used 'end-capped' polymer hydrates between 4--12 weeks depending on the molecular weight, resulting in <~n irutermediate 'no release' or a 'lag phase'. The uncapped po~yme.r. hydrates typically between 5 to 50 days depending on the mo:lecul<~r_ weight, thus releasing its core continuously without. a lag pha:>e. A careful blend of the two forms and appropriate molecular weights and L/G ratios, results in a continuous release between 1 to 100 days. In addition, release within this time i.s pro<~rarnmable by a judicious selection of process parameters such as po:l.ymer concentration, peptide concentration and the aque:ous/oi:1 phase ratio.
The coploymer i_n thi s :invention preferably includes molecular weight ranging from 2,000 to 60,000 daltons, a lactide/glycolide ratio of 90/10 to 40/60 and a blend of the uncapped/capped forms in t;he rat=io of 100/0 to 1./99. 'clue molecular weight of the polypept.ide may be in the rancfe of 1000 to 250, 000 daltons while t: hat of other biologically active a.gent:~ may be in the range of 100 t:o 100,000 daltons.
Mic:rocapsules descrLbed :in r_hi.s invention are prepare by a unique aqueous emulsification techinique which has been developed for use with the uncapped polymer to provide superior sphere morphology, sphere integrity and narrow size distribution. This is accomplished by first preparing an inner water-in-oil (w/o) by mixing the solutions of polymer in an organic solvent such as methylene chloride and the biologically active agent in water.
This is followed by stabilization of the w/o emulsion in a solvent-saturated aqueous solution containing an o/w emulsifier such as polyvinyl alcohol. A ternary emulsion is then formed by emulsifying the w/o emulsion in an external aqueous phase containing the same emulsifier as above at concentrations ranging from.-0.25 - 1% w/v. Microcapsules are hardened upon solvent removal by evaporation, rinsed to remove residual emulsifier and lyophilized. Low temperature is used both at the time of primary Z5 emulsification (w/o emulsion formation) and during the formation of the final w/o/w emulsion to achieve stable emulsion and superior sphere characteristics.
In the context of the invention, a biologically active agent is any water-soluble hormone drugs, antibiotics, antitumor agents, antiinflammatory agents, antipyretics, analgesics, antitussives, expectorants, sedatives, muscle relaxants, antiepileptics, antiulcer agents, antidepressants, antiallergic drugs, cardiotonics, antiarrhythmic drugs, vasodilators, antihypertensives, diuretics, anticoagulants, antinarcotics, etc.
WO 97126869 - PCT/dTS96/19440 More precisely, applicants have discovered a pharmaceutical composition and process with the following itemized features:
1. A controlled release microcapsule pharmaceutical 5 formulation far burst-free, sustained, programmable release of a -biologically active agent over a duration from 1-100 days, comprising an active agent and a blend of uncapped and end-capped biodegradable poly(lactide/glycolide).
2. The pharmaceutical formulation of item 1, wherein the 1o biodegradable poly(lactide/glycolide) is a blend of uncapped and capped forms, in ratios ranging fram 100/0 to 1/99.
S This invention relates to providing novel biocompatible and biodegradable microspheres for burst-free programmable sustained released of biologically active agents, inclusive of polypeptides, over a period of up to 100 days in an aqueous physiological environment.
,.
i~
i WO 97/26869 PCTlUS96/19440 I0. HAC1CGROUND OF THE INVENTION
Several publications and patents are available for sustained release of $ctive agents from biodegradable polymers, particularly, poly(lacti.de/glycolides) (PLGA). Prior usages of PLGA for controlled release of polypeptides have involved the use of molar ratios of lactide/glycalide (L/G) of 75/25 to 100/0 for molecular weights >20,000. Further prior art preparations of PLGA
utilized fillers or additives in the inner aqueous layer to improve the stability and encapsulation efficency and/or to increase the viscosity of the aqueous layer, thereby modulating polymer hydrolysis and the biologically active agent or polypeptide release.
In addition, the prior art use of PLGA copolymers were end-capped, i.n that the terminal carboxyl end groups were blocked. In these end-capped co-polymers, the microcapsule preparations exhibited a low to moderate burst release of - 10-40% of the 2o entrapped polypeptide in the first 24 hours after placement in an aqueous physiological environment. In part, these characteristics are due to the use of fillers in the inner aqueous phase.
Further, a 1-month release of polypeptide is known with the use of a 75/25 co-polymer of PLGA of Mw <20,000.
Investigations in controlled release research has been proceeding especially to obtain a 1 to 2 month delivery system , ' 3 for biologically active agents or polypeptides using poly(lactide/glycolide) polymers. However, most of these systems have one or more of the following problems: Poor encapsulation r efficency and large 'burst release' followed by an intermediate 'no release' or 'lag phases until the polymer degrades. In general, release from these polymers occur over a period from about 4 weeks to about several months. In addition, in order to achieve this release a 50/50 copolymer of Mw > 30,000 or a 75/25 copolymer of Mw > 10,000 are employed which often results in residual polymer remaining at the site of administration long after the release of active core.
V. SUMMARY OF THE INVENTION
This invention provides biocompati.ble and biodegradable microspheres that have ben designed for novel., burst free, programmable sustained release of biologically active agents, including polypeptides over a period of up to 100 days in an aqueous physiological environment.
Unlike currently availab:l.e :re=Lease systems, which rely on the use of fillers/additive~~ such as gelatin, albumin, dextran, pectin, polyvinyl pyrrolidone, polyethylene <~lycol, sugars, etc., and are :till prone to low encapsulation efficiencies and "burst effects", t=his invention achieves hicah e=ncap;~ul.<~ition and "bu.r~st-free" release without the use of any additive. Ln this invention, burst-free, programmable sustained relF~a~>e is a<<hieved through the use of a unique blend of the ' unc:apped' and end--cad>ped forms of holy(lac:tide/glycolide) polymer that. is preferably in the molecular weight range of 2,000 to E>0,000 daltons.
In general, m:icrosphc=ores de;~cribed in this invention are produced by a unique emu7_;-if icatior_ technique wherein an inner water-in-oil (w/o) emul;~:icm is ;~t:abi Li.zed by dispersing in a ;solvent-saturated aqueous pha:>e cont:aining an emulsion stabilizer.
A ternary w/o/w emulsion i~ then foxmec~ by emulsifying the above w/o emulsions in an external p.r~~-coo:led aqueous pha~~e containing an o/w emulsified. For example, the inner w/o emulsion may include an aqueous layer containing from -2 to about 20% (w/w) of the active agEvnt to be entrapped and an oil layer containing poly(=Lactide/glycolide) copolymer in concentrations ranging from --- 5 to about. -- 50% (w/w oil phase).
5 The copolymer preferably inc_Ludes molecular weight ranging from 2,000 to about 60,000 dalto:ns, with molar composition of lactide/glycolide from 90/1_0 to 40/60 and a blend of its uncapped and end-capped forms in a ratio of100/0 to 1/99. Very high encapsu:Lation efficiencies o.f about 80 to 100° are achieved depending on polymer molecular weight and structural form.
Programmable release of active core over variable durations between 1-100 days is acriieved by a judicious selection of process parameters such as polymer concentration, pept:ide concentration and the aqueous/oil phase rat.:ic->.
IS Th=is invention is part i cul.arly suitable for hicth encapsulation efficiencies and burst-iree, continuous programm~ible release of polypept=ides of mo.lecula:r we:ig:Eat~:=~ ranging from 1, 000 to about 250,000 daltons, and als~~ other :~iologically active agents over a period of 1-100 days. A uniqueness of the invention is that when using a 100/0 blend of the uncapped anti capped polymer, the final phase of active core re:~ease is concurrent with the complete solubilization of t;he polymer t.o innocuous components, such as lactic <~nd glycolic acids. ~L'Izi~; is a significant advantage over the currently available 30 day-release systems wherein a major regulatory concern is about t~ox::icit~,T of residi_ral polymer at the site of administration, Long 6 _ after xelease of the active core.
The microcapsules described in this invention are suitable for administration via several routes such as parenteral (intramuscular, subcutaneous), oral, topical, nasal, rectal and vaginal routes.
VI. BRIEF DESCRIPTION OF DRAiPINGB ' FIG. 1 shows a comparison of drug release from a conventional system versus a controlled release system. Peak and 1o valley levels from conventional administrations are shown, in contrast to the steady therapeutic levels from the controlled release administration.
FIG. 2 shows a scanning electron micrograph of PLGA
microspheres prepared by the process described in the invention using 50/50 uncapped polymer of Mw 8-12k dalton and shows superior sphere morphology, sphere integrity, and narrow size distribution.
FIG. 2a shows a scanning electron micrograph of PLGA
microspheres prepared by conventional solvent evaporation method using a 50/50 12k uncapped polymer of Mw 8-12k dalton.
FIG. 3 shows cumulative Histatin release from PLGA
microspheres, wherein release profiles from several batches are prepared using 50/50, uncapped polymer (of Mw 8-i2k dalton) and wherein the process parameters are varied to modulate release between 1 and 35 days.
FIG. 4 shows a scanning electron micrograph of solid, smooth .
WO 97126869 PCTlLT596/19440 spherical surfaces of PLGA microspheres prepared by the method of in the invention using 50/50, end-capped polymer (of Mw 30-40k dalton).
FIG. 5 shows cumulative Histatin release from PLGA
microspheres, wherein the release profiles are from several batches prepared using 50/50, uncapped and end-capped polymer of Mw 30-40k daltons, and wherein the process parameters are varied to modulate release between 28 to 60 days.
FIG. 6 shows cumulative Histatin release from PLGA
microspheres, wherein combined release profiles from several batches have been prepare' using 50/50, uncapped and end-capped polymer of Mw 8-40k daltons, while varying the process parameters to modulate release between 1 and 60 days.
FIG. 7 shows a cumulative percent release of LHRH from PLGA
micraspheres prepared using uncapped polymer of Mw 8-12 daltons.
DETAILED DESCRIPTION OF THE INVENTION
This invention relates to the design of biocompatible and biodegradable microspheres for novel, programmable sustained release of biologically active agents, including polypeptides over a period of up to 100 days in an aqueous physiological environment with little or no burst release.
Unlike currently available release systems which rely on the use of fillers/additives such as gelatin, albumin, dextran, pectin, polyvinyl pyrrolidone, polyethylene glycol, sugars, etc., and are still prone to low encapsulation efficiencies and ~~burst effects", this invention achieves high encapsulation efficiency g and 'burst-free' release without tree use of any additive. In this :invention, burst-free, programmable sustained release is achieved through the use of a unique blend c;f the 'uncapped' and end-capped forms of: poly(lactide/gl~~c=olide) Polymer.
The 'capped' form refers t:o ""poly (lactide/glycolide) with free carboxyl end groups" whl.c:h renders the polymer more hydrophilic compared to the routinely used end-capped form. Currently used 'end-capped' polymer hydrates between 4--12 weeks depending on the molecular weight, resulting in <~n irutermediate 'no release' or a 'lag phase'. The uncapped po~yme.r. hydrates typically between 5 to 50 days depending on the mo:lecul<~r_ weight, thus releasing its core continuously without. a lag pha:>e. A careful blend of the two forms and appropriate molecular weights and L/G ratios, results in a continuous release between 1 to 100 days. In addition, release within this time i.s pro<~rarnmable by a judicious selection of process parameters such as po:l.ymer concentration, peptide concentration and the aque:ous/oi:1 phase ratio.
The coploymer i_n thi s :invention preferably includes molecular weight ranging from 2,000 to 60,000 daltons, a lactide/glycolide ratio of 90/10 to 40/60 and a blend of the uncapped/capped forms in t;he rat=io of 100/0 to 1./99. 'clue molecular weight of the polypept.ide may be in the rancfe of 1000 to 250, 000 daltons while t: hat of other biologically active a.gent:~ may be in the range of 100 t:o 100,000 daltons.
Mic:rocapsules descrLbed :in r_hi.s invention are prepare by a unique aqueous emulsification techinique which has been developed for use with the uncapped polymer to provide superior sphere morphology, sphere integrity and narrow size distribution. This is accomplished by first preparing an inner water-in-oil (w/o) by mixing the solutions of polymer in an organic solvent such as methylene chloride and the biologically active agent in water.
This is followed by stabilization of the w/o emulsion in a solvent-saturated aqueous solution containing an o/w emulsifier such as polyvinyl alcohol. A ternary emulsion is then formed by emulsifying the w/o emulsion in an external aqueous phase containing the same emulsifier as above at concentrations ranging from.-0.25 - 1% w/v. Microcapsules are hardened upon solvent removal by evaporation, rinsed to remove residual emulsifier and lyophilized. Low temperature is used both at the time of primary Z5 emulsification (w/o emulsion formation) and during the formation of the final w/o/w emulsion to achieve stable emulsion and superior sphere characteristics.
In the context of the invention, a biologically active agent is any water-soluble hormone drugs, antibiotics, antitumor agents, antiinflammatory agents, antipyretics, analgesics, antitussives, expectorants, sedatives, muscle relaxants, antiepileptics, antiulcer agents, antidepressants, antiallergic drugs, cardiotonics, antiarrhythmic drugs, vasodilators, antihypertensives, diuretics, anticoagulants, antinarcotics, etc.
WO 97126869 - PCT/dTS96/19440 More precisely, applicants have discovered a pharmaceutical composition and process with the following itemized features:
1. A controlled release microcapsule pharmaceutical 5 formulation far burst-free, sustained, programmable release of a -biologically active agent over a duration from 1-100 days, comprising an active agent and a blend of uncapped and end-capped biodegradable poly(lactide/glycolide).
2. The pharmaceutical formulation of item 1, wherein the 1o biodegradable poly(lactide/glycolide) is a blend of uncapped and capped forms, in ratios ranging fram 100/0 to 1/99.
3. The microcapsules of items 1 or 2 wherein the copolymer (lactide to glycolide L/G) ratio for uncapped and endcapped polymer is 52/48 to 48/52.
4. The microcapsules of items 1 or 2 wherein the copolymer L/G ratio for uncapped and end-capped polymer is 90/10 to 40/60.
5. The microcapsules of items 1 or 2 or 3 or 4 wherein the molecular weight of the copolymer is between 2,000-60,000 daltons.
6. The microcapsules of items i or 2 or 3 or 4 or 5 wherein the biologically active agent is a peptide or polypeptide.
7. The microcapsules of item 6, wherein said polypeptide is histatin consisting of 12 amino acids and having a molecular weight of 1563.
8. The microcapsules of items 1 or 2 or 3 or 4 or 5 or 6 characterized by the capacity to completely release histatin in lI _ an aqueous physiological environment from 1-35 days with a 100/0 blend of uncapped and end-capped poly(lactide/glycolide) having a L/G ratio of 48/52 to 52/48, and a molecular weight <15,000.
9. The microcapsules of items 1 or 2 or 3 or 4 or 5 or 6 characterized by the capacity to completely release histatin in an aqueous physiological environment from 18-40 days with a 100/0 blend of uncapped and end-capped poly(lactide/glycolide) having a L/G ratio of 48/52 to 52/48 and a molecular weight range of 28,000-40,000.
9. The microcapsules of items 1 or 2 or 3 or 4 or 5 or 6 characterized by the capacity to completely release histatin in an aqueous physiological environment from 18-40 days with a 100/0 blend of uncapped and end-capped poly(lactide/glycolide) having a L/G ratio of 48/52 to 52/48 and a molecular weight range of 28,000-40,000.
10. The microcapsules of items 1 or 2 or 3 or 4 or 5 or 6 characterized by the capacity to release up to 90% of the histatin in an aqueous physiological environment from 28-70 days with a 0/100 blend of uncapped and end-capped poly(lactide/giycolide) having a L/G ratio of 48/52 to 52/48 and a molecular weight range of 10,000-40,000 daltons.
11. The microcapsules of items i or 2 or 3 or 4 or 5 or 6 characterized by the capacity to release up to 80% of histatin in an aqueous physiological environment from 56-100 days with a 0/100 blend of uncapped and end-capped poly(lactide/glycolide) having a L/G ratio of 75/25 and a molecular weight of < 15,000 daltons.
12. The microcapsules of items 7 or 8 or 9 or 10 or li having analogs of histatin with chain lengths of from 11-24 amino acids of molecular weights from 1,500-3,000 daltons and characterized by the following structures:
1. D S H A K R H H G Y K R K F H ~ K H H S H R G Y
WO 97!26869 PCT/US96/19440 12 _ 2. ,K R H H G Y K R K F H ~ K H H S H R G Y R
3. K R H H G Y K R K F H E K H H S H R
R K F H E K H H S H R G Y R
5. A K R H H G Y K R K F H
6. *A K R H H G Y K R K F H
Z~ K R H H G Y K R K F -* D-amino acid 13. The microcapsules of items 1 or 2 or 3 or 4 or 5 wherein the biologically active agent is a polypeptide Leutinizing hormone releasing hormone (LHRH) that is a decapeptide of molecular weight 1182 in its acetate form, and having the structure:
p- E H W S Y G L R P G
1. D S H A K R H H G Y K R K F H ~ K H H S H R G Y
WO 97!26869 PCT/US96/19440 12 _ 2. ,K R H H G Y K R K F H ~ K H H S H R G Y R
3. K R H H G Y K R K F H E K H H S H R
R K F H E K H H S H R G Y R
5. A K R H H G Y K R K F H
6. *A K R H H G Y K R K F H
Z~ K R H H G Y K R K F -* D-amino acid 13. The microcapsules of items 1 or 2 or 3 or 4 or 5 wherein the biologically active agent is a polypeptide Leutinizing hormone releasing hormone (LHRH) that is a decapeptide of molecular weight 1182 in its acetate form, and having the structure:
p- E H W S Y G L R P G
14. The microcapsule of items 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 having a molecular weight of from 1,000 to 250,000 daltons.
15. The microcapsules of items 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14 Wherein release profiles of variable rates and durations are achieved by blending uncapped and capped microspheres as a cocktail in variable amounts.
16. The microcapsules of items 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14 wherein release of profiles of variable rates and duration are achieved by blending uncapped and capped polymer in different ratios within the same microshreres.
17. The microcapsules of items 6 or 7 or 8 or 9 or 10 or 13 WO 97!26869 PCTIUS96/19440 ar 12 or 13 or 14 or 15 or 16 wherein the entrapped polypeptide i.s any of the vaccine agents against enterotoxigenic E. coli (ETEC) such as CFA/I,CFA/II,CS1,CS3,CS6 and CS17 and other ETEC-related enterotoxins.
18. The microcapsules of items 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14 or 15 or 16 or 17 wherein the entrapped polypeptide consists of peptide antigens of molecular weight range of about 800-5000 daltons for immunization against enterotoxigenic E. coli (ETEC).
19. The microcapsules of items 1 or 2 or 3 or 4 or 5 wherein said biologically active agents are selected from the group consisting of water-soluyie hormone drugs, antibiotics, antitumor agents, anti inflammatory agents, antipyretics, analgesics, antitussives, expectorants, sedatives, muscle relaxants, antiepileptics, antiulcer agents, antidepressants, antiallergic drugs, cardiotonics, antiarrhythmic drugs, vasodilators, antihypertensives, diuretics, anticoagulants, and antinarcotics, in the molecular weight range of 100-100,000 daltons.
20. The microcapsules of items 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 wherein said biodegradable poly(lactide/glycolide) is in an oil phase, and is present in about 1-50% (w/w).
21. The microcapsules of items 1 or 2 or 3 or 4 or 5 or 6 or 8 or 9 or 10 or 11 or 12 or 13 or 14 or 15 or 16 or 17 wherein concentration of the active agent is in the range of O.1 to about so% (w/w).
22. The microcapsules of items 1 or 2 or 3 or 4 or 5 or 6 or 8 or 9 or 10 or 11 or 12 or 13 or 14 or 15 or 16 or 17 wherein a -ratio of the inner aqueous to oil phases is about 1/4 to 1/40(v/v).
23. A process for preparing controlled release microcapsule formulations characterized by burst-free, sustained, programmable release of biologically active agents comprising: Dissolving biodegradable poly (lactide/glycolide), in uncapped form in methylene chloride, and dissolving a biologically active agent or active core in Water; adding the aqueous layer~to the polymer 30 solution and emulsifying to provide an inner water-in-oil (w/o) emulsion; stabilizing the w/o emulsion in a solvent-saturated aqueous phase containing a oil-in-water (o/w) emulsifier; adding said w/o emulsion to an external aqueous layer containing oil-in-water emulsifier to form a ternary emulsion; and stirring the resulting water-in-oil-in-water (w/o/w) emulsion for sufficient time to remove said solvent, and rinsing hardened microcapsules with water and lyophilizing said hardened microcapsules.
24. A process for preparing controlled release microcapsule formulations characterized by burst-free, sustained, programmable release of biologically active agents comprising:
dissolving biodegradable poly(lactide/glycolide) in end-capped form in methylene chloride, and dissolving a biologically active agent or active core in water; adding the aqueous layer to the polymer solution and emulsifying to provide an inner water-in-oil emulsion; stabilizing the w/o emulsion in a solvent-saturated aqueous phase containing a oil-in-water (o/w) WO 97/26869 PCT/iTS96l19440 emulsifier; adding said w/o emulsion to an external aqueous layer containing oil-in-water emulsifier to form a ternary emulsion;
and stirring a resulting water-in-oil-water (w/o/w) emulsion for sufficient time to remove said solvent; and rinsing hardened 5 microcapsules with water; and lyophilizing said hardened microcapsules.
dissolving biodegradable poly(lactide/glycolide) in end-capped form in methylene chloride, and dissolving a biologically active agent or active core in water; adding the aqueous layer to the polymer solution and emulsifying to provide an inner water-in-oil emulsion; stabilizing the w/o emulsion in a solvent-saturated aqueous phase containing a oil-in-water (o/w) WO 97/26869 PCT/iTS96l19440 emulsifier; adding said w/o emulsion to an external aqueous layer containing oil-in-water emulsifier to form a ternary emulsion;
and stirring a resulting water-in-oil-water (w/o/w) emulsion for sufficient time to remove said solvent; and rinsing hardened 5 microcapsules with water; and lyophilizing said hardened microcapsules.
25. The process of items 23 or 24 wherein a solvent-saturated external aqueous phase is added to emulsify the inner w/o emulsion prior to addition of the external aqueous layer, to 10 provide microcapsules of narrow size distribution range between 0.05-500~Cm.
'2s. The process of items 23 or 24, wherein a low temperature of about 0-4°C is provided during preparation of the inner w/o emulsion, and a low temperature of about 4-20°C is provided 15 during preparation of the w/o/w emulsion to provide a stable emulsion and high encapsulation efficiency.
27. The process of items wherein a 100/0 blend of uncapped and end-capped polymer is used to provide release of the active core in a continous and sustained manner without a lag phase.
28. The microcapsules of items 6, wherein, when the entrapped polypeptide is active at a low pH, such as LHRH, adrenocorticotropic hormone, epidermal growth factor, calcitonin released polypeptide is bioactive.
29. The microcapsules of items 6 or 7 or 8 or 9 or 10 or 11, wherein, when entrapped peptide such as histatin is inactive at a low pH, a pH-stabilizing agent of inorganic salts are added to WO 97/26869 ~ PCT/US96/19440 the inner aqueous phase to maintain biological activity of the released peptide.
30. The microcapsules of items 6 or 7 or 8 or 9 or 10 or 11 wherein, when entrapped polypeptide such as histatin is inactive at a low pH, a non-ionic surfactant such as polyoxyethylene sorbitan fatty acid esters (Tween 80, Tween 60 and Tween 20) and polyoxyethylene - polyoxypropylene block copolymers (Pluronics) is added to the inner aqueous phase to maintain biological activity of the released polypeptide.
31. The microcapsules of items 29, wherein placebo spheres loaded with the pH-stabilizing agents are coadministered with polypeptide-loaded spheres to maintain the solution pH around the microcapsules and preserve the biological activity of the released peptide in instances where the addition of pH-stabilizing agents in the inner aqueous phase is undesirable for the successful encapsulation of the acid pH sensitive polypeptide.
32. The microcapsules of item 30 wherein placebo spheres loaded with non-ionic surfactant are coadministered with polypeptide-loaded spheres to maintain biological activity of the released peptide where the addition of non-ionic surfactants in the inner aqueous phase is undesirable for successful encapsulation of the acid pH sensitive polypeptide.
33. The microcapsules of items 1 or 2 ar 3 or 4 or 5 or 6 or 8 or 9 or 10 or 11 or i2 or 13 or 14 or 15 or 16 or 17 comprising .a blend of uncapped and capped polymer, wherein complete solubilization of the copolymer leaves no residual polymer at the site of administration and occurs concurrently with the complete release of the entrapped agent.
34. A process of using microcapsules of items 1 or 2 or 3 or 4 or 5 or 6 ar 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14 or 15 or 16 or 17 or 18 or 19 or 20 for human administration via parenteral routes, such as intramuscular and subcutaneous.
35. A process of using microcapsules of items 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14 or 15 or 16 or 17 or 18 or 19 or 20 for human administration via topical route.
'36. A process of using microcapsules of items 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14 or 15 or 16 or 17 or 18 or 19 or 20 for human administration via oral routes.
37. A process of using microcapsules of items 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14 or 15 or 16 or 17 or 18 or 19 or 20 for human admininstration via nasal, transdermal, rectal, and vaginal routes.
ZS
~ons~ervatio of bioactivity of polvpeptida$
As the polymer degrades rapidly, there is a preciptitous drop in pH accompanied by the release of soluble oligomers in the microenvironment which may affect the biological activity of acid pIi-sensitive peptides/proteins. In such instances, biological activity can be maintained by the use of inorganic salts yor buffering agents in the inner aqueous phase codissolved With the peptide.
l0 The following unique advantages are characteristics of this invention:
' 1. Burst-free, prolonged, sustained release of polypeptides and other biocompatible and biodegradable microcapsules. up to 100 days in an aqueous physiological environment without the use of 1~ additives in the core.
2. Release of active core programmable for variable durations over 1-100 days, by using a blend of uncapped and capped polymer of different molecular weights and copolymer ratio, and by manipulating the process parameters.
20 3. Complete release of the active core is concurrent with complete solubilization of the carrier polymer to innocuous components, such as lactic and glycolic acids, especially When using a 100/0 blend of uncapped/capped polymer. This is of tremendous significance, as most biodegradable polymers currently 25 used for 1-30 day delivery, do not degrade completely at the end of the intended release duration, thereby causing serious concern WO 97/26869 i g PCT/US96119440 of regulatory authorities on the effects of residual polymer at the site of administration.
4. Ease of administration of the microcapsuies in various dosage forms via several routes, such as parenterai ' S (intramuscular and sucutaneous), oral, topical, nasal, vaginal, etc.
The hydrophilic homo-and co-polymers based on D,L-lactide and glycolide contains hydrophilic adjusted homo-and co-polymers with free carboxylic end groups, and is characterized by the formula:
Paly(D,L-lsctide-co~-glycolide) 50:50 -a O-ct~-c C.~3H~02)n(C2H202)~ n:m ~ I:i Wherein Z= Molecular Weight/130; for example Z=92 for Mw 12,000 and 262 for Mw 34,000.
While the molar ratio of the lactide to glycolide may vary, it is most preferred that the lactide to glycolide copolymer ratio be 50:50.
Reference is now made to FIG. 1 which depicts a blood-drug concentration versus time graph that shows conventional drug administration using a series of dosages compared to an ideal controlled release system. Unfortunately, many drugs have a therapeutic range, above which they are toxic and below which they are ineffective. Oscillating drug levels that are commonly observed following systemic administration causes alternating periods of ineffectiveness and toxicity. A sustained-release 5 encapsulated biologically active agent or polypeptide preparation, ideally, will maintain the drug in the desired therapeutic range by means of a single dose, as depicted in the THERAPEUTIC RANGE in FIG.1 , where the ideal case for controlled release is shown.
10 In FIG. 2, there is shown a scanning electron micrograph of PLGA microspheres prepared using 50/50 uncapped polymer of Mw 8-I2k tlalton. The uncapped polymer has solid, smooth spherical surfaces, and is suited to provide a "burst free" release system..
Table I is a summarization of the microsphere process 15 description for preparing a peptide system (Histatin peptide) having a controlled release over the course of from 1 to 100 days.
Release profiles can be modified by a judicious blend of uncapped and capped polymers either in separate microspheres or 20 in the same microspheres. Release from microcapsule formulations 1 through 21 listed in Table 1, occur independently of each other and hence the cumulative release from blends of these formulations are additive. 8y blending several formulations of uncapped and end-capped microspheres, release curves of any desired duration can be tailored. In addition, based on the release characteristics of uncapped and end-capped polymers, -WO 97/26869 . PCTIUS96/19440 blending of the two forms in a single formulation comprising different ratios of uncapped to capped polymer, would significantly influence the polymer hydration and hence release of the active core thereby providing release curves of any desirable pattern. Manipulation of polymer hydration and degradation resulting in modulation of release of active core is achieved by the addition of uncapped polymer to end-capped polymer in amounts as low as 1~ up to 100.
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'2s. The process of items 23 or 24, wherein a low temperature of about 0-4°C is provided during preparation of the inner w/o emulsion, and a low temperature of about 4-20°C is provided 15 during preparation of the w/o/w emulsion to provide a stable emulsion and high encapsulation efficiency.
27. The process of items wherein a 100/0 blend of uncapped and end-capped polymer is used to provide release of the active core in a continous and sustained manner without a lag phase.
28. The microcapsules of items 6, wherein, when the entrapped polypeptide is active at a low pH, such as LHRH, adrenocorticotropic hormone, epidermal growth factor, calcitonin released polypeptide is bioactive.
29. The microcapsules of items 6 or 7 or 8 or 9 or 10 or 11, wherein, when entrapped peptide such as histatin is inactive at a low pH, a pH-stabilizing agent of inorganic salts are added to WO 97/26869 ~ PCT/US96/19440 the inner aqueous phase to maintain biological activity of the released peptide.
30. The microcapsules of items 6 or 7 or 8 or 9 or 10 or 11 wherein, when entrapped polypeptide such as histatin is inactive at a low pH, a non-ionic surfactant such as polyoxyethylene sorbitan fatty acid esters (Tween 80, Tween 60 and Tween 20) and polyoxyethylene - polyoxypropylene block copolymers (Pluronics) is added to the inner aqueous phase to maintain biological activity of the released polypeptide.
31. The microcapsules of items 29, wherein placebo spheres loaded with the pH-stabilizing agents are coadministered with polypeptide-loaded spheres to maintain the solution pH around the microcapsules and preserve the biological activity of the released peptide in instances where the addition of pH-stabilizing agents in the inner aqueous phase is undesirable for the successful encapsulation of the acid pH sensitive polypeptide.
32. The microcapsules of item 30 wherein placebo spheres loaded with non-ionic surfactant are coadministered with polypeptide-loaded spheres to maintain biological activity of the released peptide where the addition of non-ionic surfactants in the inner aqueous phase is undesirable for successful encapsulation of the acid pH sensitive polypeptide.
33. The microcapsules of items 1 or 2 ar 3 or 4 or 5 or 6 or 8 or 9 or 10 or 11 or i2 or 13 or 14 or 15 or 16 or 17 comprising .a blend of uncapped and capped polymer, wherein complete solubilization of the copolymer leaves no residual polymer at the site of administration and occurs concurrently with the complete release of the entrapped agent.
34. A process of using microcapsules of items 1 or 2 or 3 or 4 or 5 or 6 ar 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14 or 15 or 16 or 17 or 18 or 19 or 20 for human administration via parenteral routes, such as intramuscular and subcutaneous.
35. A process of using microcapsules of items 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14 or 15 or 16 or 17 or 18 or 19 or 20 for human administration via topical route.
'36. A process of using microcapsules of items 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14 or 15 or 16 or 17 or 18 or 19 or 20 for human administration via oral routes.
37. A process of using microcapsules of items 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14 or 15 or 16 or 17 or 18 or 19 or 20 for human admininstration via nasal, transdermal, rectal, and vaginal routes.
ZS
~ons~ervatio of bioactivity of polvpeptida$
As the polymer degrades rapidly, there is a preciptitous drop in pH accompanied by the release of soluble oligomers in the microenvironment which may affect the biological activity of acid pIi-sensitive peptides/proteins. In such instances, biological activity can be maintained by the use of inorganic salts yor buffering agents in the inner aqueous phase codissolved With the peptide.
l0 The following unique advantages are characteristics of this invention:
' 1. Burst-free, prolonged, sustained release of polypeptides and other biocompatible and biodegradable microcapsules. up to 100 days in an aqueous physiological environment without the use of 1~ additives in the core.
2. Release of active core programmable for variable durations over 1-100 days, by using a blend of uncapped and capped polymer of different molecular weights and copolymer ratio, and by manipulating the process parameters.
20 3. Complete release of the active core is concurrent with complete solubilization of the carrier polymer to innocuous components, such as lactic and glycolic acids, especially When using a 100/0 blend of uncapped/capped polymer. This is of tremendous significance, as most biodegradable polymers currently 25 used for 1-30 day delivery, do not degrade completely at the end of the intended release duration, thereby causing serious concern WO 97/26869 i g PCT/US96119440 of regulatory authorities on the effects of residual polymer at the site of administration.
4. Ease of administration of the microcapsuies in various dosage forms via several routes, such as parenterai ' S (intramuscular and sucutaneous), oral, topical, nasal, vaginal, etc.
The hydrophilic homo-and co-polymers based on D,L-lactide and glycolide contains hydrophilic adjusted homo-and co-polymers with free carboxylic end groups, and is characterized by the formula:
Paly(D,L-lsctide-co~-glycolide) 50:50 -a O-ct~-c C.~3H~02)n(C2H202)~ n:m ~ I:i Wherein Z= Molecular Weight/130; for example Z=92 for Mw 12,000 and 262 for Mw 34,000.
While the molar ratio of the lactide to glycolide may vary, it is most preferred that the lactide to glycolide copolymer ratio be 50:50.
Reference is now made to FIG. 1 which depicts a blood-drug concentration versus time graph that shows conventional drug administration using a series of dosages compared to an ideal controlled release system. Unfortunately, many drugs have a therapeutic range, above which they are toxic and below which they are ineffective. Oscillating drug levels that are commonly observed following systemic administration causes alternating periods of ineffectiveness and toxicity. A sustained-release 5 encapsulated biologically active agent or polypeptide preparation, ideally, will maintain the drug in the desired therapeutic range by means of a single dose, as depicted in the THERAPEUTIC RANGE in FIG.1 , where the ideal case for controlled release is shown.
10 In FIG. 2, there is shown a scanning electron micrograph of PLGA microspheres prepared using 50/50 uncapped polymer of Mw 8-I2k tlalton. The uncapped polymer has solid, smooth spherical surfaces, and is suited to provide a "burst free" release system..
Table I is a summarization of the microsphere process 15 description for preparing a peptide system (Histatin peptide) having a controlled release over the course of from 1 to 100 days.
Release profiles can be modified by a judicious blend of uncapped and capped polymers either in separate microspheres or 20 in the same microspheres. Release from microcapsule formulations 1 through 21 listed in Table 1, occur independently of each other and hence the cumulative release from blends of these formulations are additive. 8y blending several formulations of uncapped and end-capped microspheres, release curves of any desired duration can be tailored. In addition, based on the release characteristics of uncapped and end-capped polymers, -WO 97/26869 . PCTIUS96/19440 blending of the two forms in a single formulation comprising different ratios of uncapped to capped polymer, would significantly influence the polymer hydration and hence release of the active core thereby providing release curves of any desirable pattern. Manipulation of polymer hydration and degradation resulting in modulation of release of active core is achieved by the addition of uncapped polymer to end-capped polymer in amounts as low as 1~ up to 100.
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While referring to Table Z in conjunction With FIG. 3, it can be seen that the cumulative Histatin release from PLGA
microspheres from several batches prepared using 50/50 and 75/25 uncapped and end-capped, polymer modulates release between 1 to 100 days by varying the process parameters. 1-35 days by uncapped 50/50, i8-56 days by capped 50/50 and 56-100 days by capped 75/25.
In referring to FIG. 4, n view is provided through a scanning electron micrograph of PLGA microspheres designed for a~~
one to two month release system prepared using. end-capped polymer of Mw 30-40k daltons.
FIG. 5 depicts the cumulative Histatin release from PLGA
microspheres, in which the release profiles are from several batches prepared using 50/50, uncapped and capped polymer., and varying the process parameters to modulate release between 28 to 60 days.
Figure 6 represents cumulative Histatin release from PLGA
microspheres --- these combined release profiles are from several batches prepared using 50/50 uncapped and capped polymer, and varying the process parameters to modulate release between 1-60 days.
In the context of the invention, a biologically active agent is any water-soluble antibiotics, antitumor agents, antipyretics analgesics, anti-inflammatory agents, antitussives, expectorants, sedatives, muscle relaxants, anti epileptics, antiulcer agents, 27 _ anti-depressants, anti-allergic drugs, cardiotonics, antiarrhythmics drugs, vasodilators, antihypertensives, diuretics, anticoagulants, hormone drugs, anti-narcotics, etc.
In general, "burst free" sustained release delivery of biologically active agents from PLGA microshperes is accomplished ' in the context of this invention using of 90/10 to 40/60 molar ratios, and ratios of uncapped polymer to end-capped polymer of 100/0 to 1/99.
In general, the approaches for designing the biologically active agents encapsulated in the uncapped and combination uncapped/end-capped PLGA microspheres and characteristics of these encapsulants are briefly set forth below as follows:
1. Providing PLGA microspheres of surface morphologies using 50/50 uncapped and capped polymers of Mw - 8-40K daltons as shown in Figs. 2 and 4.
2. Providing in vitro release of a polypeptide, Histatin from PLGA microspheres, as shown in Figs. 3 and 5, using uncapped and capped polymer of Mw - 8-40K daltons and molar ratios such as 50/50 and 75/25.
For example, design of a 1-12 weeek bioactive compound release system is achieved using PLGA with the following s~iecif ications 1. Polymer molecular weight:
-about~2-60K daltons 2. Copolymer molar ratio (L/G):
- 90/10 to 40/60 3. Polymer end groups:
- uncapped and /or end-capped and combining judiciously within the following parameters:
4. Polymer concentration - from 5 to 50%
5. Inner aqueous to oil phase ratio:
- 1:5 to 1:20 (v/v) 6. Peptide loads:
- from 2 to about 40% (w/w polymer) WO 97/26869 . PCT/CTS96/19440 and by using the unique aqueous emulsification method described in the invention.
The uniqueness and novelty of invention may generally be summarized in a brief way as follows:
1. Use of uncapped poly(lactide/glycolide) to achieve burst-free, continuous, sustained, programmable release of biologically active agents over 1-100 days.
l0 2. Use of a unique aqueous emulsification system to achieve superior microsphere characteristics such as uniform sphere morphology and narrow size distribution.
3. Burst-free, prolonged, sustained release of polypeptides and other biologically actice agents from biocompatible and biodegradable microcapsules up to 100 days in an aqueous physiological environment without the use of additives in the inner core.
4. Release of active core programmable for variable durations over 1-100 days by using a blend of uncapped and capped polymer for different molecular weights and copolymer rations and manipulating the process parameters.
5. Complete release of the active core concurrent with complete solubilization of carrier polymer to innocuous components such as lactic and glycolic acids, especially when using a 100/0 blend of uncapped/capped polymer. This is of tremendous significance as most biodegradable polymers currently in use for 1-30 day delivery, do not degrade completely at the end of the intended release duration causing serious concern for regulatory authorities on the effects of residual polymer at the site of administration.
6. Ease of administration of the microcapsules in various dosages forms via several routes such as parenteral (intramusclar and subcutaneous), oral, topical, nasal, vaginal, etc.
The following examples are illustrative of, but nat limitations upon the microcapsule compositions pertaining to this invention.
Example 1 Polylactide/glycolide (PLGA) microcapsuies are prepared by a unique aqueous emulsification technique which has been developed for use with the uncapped polymer to provide superior sphere morphology, sphere integrity and narrow size distribution (See Figures la and ib). This is accomplished by dissolving the polymer in a chlorinated hydrocarbon solvent such as methylene chloride and dissolving the biologically active agent in water. A
WO 97/2b8b9 PCTlUS96/I9440 w/o emulsion is then formed by mixing the solutions of polymer and the active agent by sonication, followed by emulsion -stabilization in a solvent - saturated aqueous solution containing polyvinyl alcohol. A ternary emulsion is then formed by emulsifying the w/o emulsion in an external, pre-cooled aqueous phase containing polyvinyl alcohol (0.25 - 1% w/v).
Microcapsules are hardened upon removal of solvent by evaporation, rinsed to remove any residual emulsifier, and then lyophilized.
Table 1 lists the micracapsule compositions, Nos. 1-21 thus prepared, consisting of a biologically active polypeptide, Histatin (composed of 12 amino acids and a molecular weight of 1563) and blends of uncapped and capped polymer of ratios 100/0 to 1/99, and having a lactide/glycolide ratio of 90/10 to 40/60, and a molecular weight range between 2000 to 60,000 daltons.
Example 2 Microcapsule compositions are prepared as described in Example 1 wherein the copolymer L/G ratio is 48/52 to 52/48, and the ratio of uncapped/capped polymer is 100/0. The active core is Histatin (Mw 1563), the polymer molecular weight is < 15,000 and the polymer concentrations vary from 7% to - 40% w/w.
Compositions 1,2,4 12-14 and 16-18 are listed in Table 1.
Release profiles of the active core from the compositions in an aqueous physiological environment, such as phosphate-buffered saline, pH 7.0 maintained at 37 ~ 1~C are plotted as cumulative percentage release versus time, and presented in Figure 2.
Burst-free, variable release from 1-35 days is achieved by varying the polymer concentration from 7 to - 40% w/w in the oil phase.
Example 3 Microcapsule compositions are prepared as described in Example 2, wherein the aqueous /oil ratio is varied from 1/4 to 1/20 (v/v). Compositions 1,2,4 and 12 are listed in Table 1.
Release profiles of the active core from the compositions in an aqueous physiological environment described in Example 2 are plotted as cumulative percentage release versus time, and presented in Figure 2.
Burst-free, continuous release from 1-35 days, with different onset and completion times are achieved by selecting 30 _ different w/o ratios in the inner core.
Example 4 Microcapsule compositions are prepared as described in Example 2, wherein the polymer molecular weight is 28,000-40,000 and polymer concentrations vary from 5% to - 15% w/w.
Compositions 19-21 ase listed in Table 1.
Release profiles of the active core from the compositions in an aqueous physiological environment are described in Example 2 are plotted as cumulative percentage release versus time and presented in Figure 3.
Burst-free, variable release from 18-40 days is achieved by varying the polymer concentration.
Example 5 Microcapsule compositions are prepared as described in Example 2, wherein the ratio of uncapped/capped polymer is 1/99 and polymer concentrations vary between 5% to - 12% w/w.
Compositions 10 and 11 are listed in Table 1.
Release profiles of the active core from the compositions in an aqueous physiological environment are described in Example 2, and plotted as cumulative percentage release versus time and presented in Figure 2.
Burst-free, variable release from 28-?O days is achieved by varying the polymer concentration in the oil phase.
Examine 6 Microcapsule compositions are prepared as described in Example 5, wherein polymer molecular weight is 28,000-40,000 and polymer concentrations vary between 5% to - 12% w/w. Compositions 5 and 6 are listed in Table 1.
~o Release profiles of the active core from the compositions in an aqueous physiological environment are described in Example 2 and are plotted as cumulative percentage release versus time, and presented in Figure 3.
Burst-free, variable release from 28-70 days is achieved by varying the polymer concentration.
Examvle ?
Microcapsule compositions are prepared as described in Example 6, wherein the aqueous/oil ratio varies between 1/5 to WO 97/26869 PCT/LTS96l19440 JZ
1/25 (v/v). Compositions 3 and 7 are listed in Table 1.
Release profiles of the active core from the compositions in an aqueous physiological environment are described in Example 2, and plotted as cumulative percentage release versus time, and presented in Figure 3.
Burst-free, variable release from 28-70 days is achieved by varying the aqueous/oil ratios.
~xamt3le 8 Microcapsule compositions are prepared as described in Example 5, wherein the copolymer ratio is 75/25 and polymer concentrations vary between 5% to - 25% w/w. Compositions 8 and 9 are listed in Table 1.
Release profiles of the active core from the compositions in an aqueous physiological environment are described in Example 2, and are plotted as cumulative percentage release versus time, and presented in Figure 2.
Burst-free, variable release from 56->90 days is achieved by varying the polymer concentration in the oil phase.
Example 9 Microcapsule compositions are described in Example 2, wherein the active core is leutinizing hormone releasing hormone (LHRH, a decapeptide of molecular weight 1182) and the polymer concentration is -40% w/w. Release profiles of the active core from the composition in an aqueous physiological environment is described in Example 2, and is plotted as cumulative percentage release versus time, and presented in Figure 4.
Burst-free, continuous and complete release is achieved Within 35 days, similar to Histatin acetate.
~xamole 10 Microcapsule compositions are prepared as described in Example 2, wherein an additive such as sodium salt (carbonate or bicarbonate) is added to the inner aqueous phase at concentrations of 1-10% w/w to maintain the biological activity of the released polypeptide.
Burst-free, variable release from 1-28 days is achieved similar to Examples 2 & 3, and the released polypeptide is biologically active until 30 days, due to the presence of the - sodium salt.
~xamole I1 ~licrocapsule compositions are prepared as described in Example 2, wherein an additive such as a nonionic surfactant, polyoxyethylene/polyoxypropylene block copolymer (Pluronics F68 and F127) is added to either the inner oil or the aqueous phase at concentrations from 10-100% w/w, to maintain the biological activity of the released polypeptide.
Burst-free, continuous release from 1-35 days is achieved similar to Examples 2 & 3, and the released polypeptide is bioactive due to the presence of the surfactant.
Example 12 Cumulative histatin release from the microcapsule compositions described in Examples 1 through 11 and release profiles plotted in Figures 2 and 3 show the burst-free, programmable peptide release for variable duration from 1-100 days. Virtually any pattern of cumulative release is achievable over'a i0o day duration by a judicious blending of several compositions, as shown in these figures.
microspheres from several batches prepared using 50/50 and 75/25 uncapped and end-capped, polymer modulates release between 1 to 100 days by varying the process parameters. 1-35 days by uncapped 50/50, i8-56 days by capped 50/50 and 56-100 days by capped 75/25.
In referring to FIG. 4, n view is provided through a scanning electron micrograph of PLGA microspheres designed for a~~
one to two month release system prepared using. end-capped polymer of Mw 30-40k daltons.
FIG. 5 depicts the cumulative Histatin release from PLGA
microspheres, in which the release profiles are from several batches prepared using 50/50, uncapped and capped polymer., and varying the process parameters to modulate release between 28 to 60 days.
Figure 6 represents cumulative Histatin release from PLGA
microspheres --- these combined release profiles are from several batches prepared using 50/50 uncapped and capped polymer, and varying the process parameters to modulate release between 1-60 days.
In the context of the invention, a biologically active agent is any water-soluble antibiotics, antitumor agents, antipyretics analgesics, anti-inflammatory agents, antitussives, expectorants, sedatives, muscle relaxants, anti epileptics, antiulcer agents, 27 _ anti-depressants, anti-allergic drugs, cardiotonics, antiarrhythmics drugs, vasodilators, antihypertensives, diuretics, anticoagulants, hormone drugs, anti-narcotics, etc.
In general, "burst free" sustained release delivery of biologically active agents from PLGA microshperes is accomplished ' in the context of this invention using of 90/10 to 40/60 molar ratios, and ratios of uncapped polymer to end-capped polymer of 100/0 to 1/99.
In general, the approaches for designing the biologically active agents encapsulated in the uncapped and combination uncapped/end-capped PLGA microspheres and characteristics of these encapsulants are briefly set forth below as follows:
1. Providing PLGA microspheres of surface morphologies using 50/50 uncapped and capped polymers of Mw - 8-40K daltons as shown in Figs. 2 and 4.
2. Providing in vitro release of a polypeptide, Histatin from PLGA microspheres, as shown in Figs. 3 and 5, using uncapped and capped polymer of Mw - 8-40K daltons and molar ratios such as 50/50 and 75/25.
For example, design of a 1-12 weeek bioactive compound release system is achieved using PLGA with the following s~iecif ications 1. Polymer molecular weight:
-about~2-60K daltons 2. Copolymer molar ratio (L/G):
- 90/10 to 40/60 3. Polymer end groups:
- uncapped and /or end-capped and combining judiciously within the following parameters:
4. Polymer concentration - from 5 to 50%
5. Inner aqueous to oil phase ratio:
- 1:5 to 1:20 (v/v) 6. Peptide loads:
- from 2 to about 40% (w/w polymer) WO 97/26869 . PCT/CTS96/19440 and by using the unique aqueous emulsification method described in the invention.
The uniqueness and novelty of invention may generally be summarized in a brief way as follows:
1. Use of uncapped poly(lactide/glycolide) to achieve burst-free, continuous, sustained, programmable release of biologically active agents over 1-100 days.
l0 2. Use of a unique aqueous emulsification system to achieve superior microsphere characteristics such as uniform sphere morphology and narrow size distribution.
3. Burst-free, prolonged, sustained release of polypeptides and other biologically actice agents from biocompatible and biodegradable microcapsules up to 100 days in an aqueous physiological environment without the use of additives in the inner core.
4. Release of active core programmable for variable durations over 1-100 days by using a blend of uncapped and capped polymer for different molecular weights and copolymer rations and manipulating the process parameters.
5. Complete release of the active core concurrent with complete solubilization of carrier polymer to innocuous components such as lactic and glycolic acids, especially when using a 100/0 blend of uncapped/capped polymer. This is of tremendous significance as most biodegradable polymers currently in use for 1-30 day delivery, do not degrade completely at the end of the intended release duration causing serious concern for regulatory authorities on the effects of residual polymer at the site of administration.
6. Ease of administration of the microcapsules in various dosages forms via several routes such as parenteral (intramusclar and subcutaneous), oral, topical, nasal, vaginal, etc.
The following examples are illustrative of, but nat limitations upon the microcapsule compositions pertaining to this invention.
Example 1 Polylactide/glycolide (PLGA) microcapsuies are prepared by a unique aqueous emulsification technique which has been developed for use with the uncapped polymer to provide superior sphere morphology, sphere integrity and narrow size distribution (See Figures la and ib). This is accomplished by dissolving the polymer in a chlorinated hydrocarbon solvent such as methylene chloride and dissolving the biologically active agent in water. A
WO 97/2b8b9 PCTlUS96/I9440 w/o emulsion is then formed by mixing the solutions of polymer and the active agent by sonication, followed by emulsion -stabilization in a solvent - saturated aqueous solution containing polyvinyl alcohol. A ternary emulsion is then formed by emulsifying the w/o emulsion in an external, pre-cooled aqueous phase containing polyvinyl alcohol (0.25 - 1% w/v).
Microcapsules are hardened upon removal of solvent by evaporation, rinsed to remove any residual emulsifier, and then lyophilized.
Table 1 lists the micracapsule compositions, Nos. 1-21 thus prepared, consisting of a biologically active polypeptide, Histatin (composed of 12 amino acids and a molecular weight of 1563) and blends of uncapped and capped polymer of ratios 100/0 to 1/99, and having a lactide/glycolide ratio of 90/10 to 40/60, and a molecular weight range between 2000 to 60,000 daltons.
Example 2 Microcapsule compositions are prepared as described in Example 1 wherein the copolymer L/G ratio is 48/52 to 52/48, and the ratio of uncapped/capped polymer is 100/0. The active core is Histatin (Mw 1563), the polymer molecular weight is < 15,000 and the polymer concentrations vary from 7% to - 40% w/w.
Compositions 1,2,4 12-14 and 16-18 are listed in Table 1.
Release profiles of the active core from the compositions in an aqueous physiological environment, such as phosphate-buffered saline, pH 7.0 maintained at 37 ~ 1~C are plotted as cumulative percentage release versus time, and presented in Figure 2.
Burst-free, variable release from 1-35 days is achieved by varying the polymer concentration from 7 to - 40% w/w in the oil phase.
Example 3 Microcapsule compositions are prepared as described in Example 2, wherein the aqueous /oil ratio is varied from 1/4 to 1/20 (v/v). Compositions 1,2,4 and 12 are listed in Table 1.
Release profiles of the active core from the compositions in an aqueous physiological environment described in Example 2 are plotted as cumulative percentage release versus time, and presented in Figure 2.
Burst-free, continuous release from 1-35 days, with different onset and completion times are achieved by selecting 30 _ different w/o ratios in the inner core.
Example 4 Microcapsule compositions are prepared as described in Example 2, wherein the polymer molecular weight is 28,000-40,000 and polymer concentrations vary from 5% to - 15% w/w.
Compositions 19-21 ase listed in Table 1.
Release profiles of the active core from the compositions in an aqueous physiological environment are described in Example 2 are plotted as cumulative percentage release versus time and presented in Figure 3.
Burst-free, variable release from 18-40 days is achieved by varying the polymer concentration.
Example 5 Microcapsule compositions are prepared as described in Example 2, wherein the ratio of uncapped/capped polymer is 1/99 and polymer concentrations vary between 5% to - 12% w/w.
Compositions 10 and 11 are listed in Table 1.
Release profiles of the active core from the compositions in an aqueous physiological environment are described in Example 2, and plotted as cumulative percentage release versus time and presented in Figure 2.
Burst-free, variable release from 28-?O days is achieved by varying the polymer concentration in the oil phase.
Examine 6 Microcapsule compositions are prepared as described in Example 5, wherein polymer molecular weight is 28,000-40,000 and polymer concentrations vary between 5% to - 12% w/w. Compositions 5 and 6 are listed in Table 1.
~o Release profiles of the active core from the compositions in an aqueous physiological environment are described in Example 2 and are plotted as cumulative percentage release versus time, and presented in Figure 3.
Burst-free, variable release from 28-70 days is achieved by varying the polymer concentration.
Examvle ?
Microcapsule compositions are prepared as described in Example 6, wherein the aqueous/oil ratio varies between 1/5 to WO 97/26869 PCT/LTS96l19440 JZ
1/25 (v/v). Compositions 3 and 7 are listed in Table 1.
Release profiles of the active core from the compositions in an aqueous physiological environment are described in Example 2, and plotted as cumulative percentage release versus time, and presented in Figure 3.
Burst-free, variable release from 28-70 days is achieved by varying the aqueous/oil ratios.
~xamt3le 8 Microcapsule compositions are prepared as described in Example 5, wherein the copolymer ratio is 75/25 and polymer concentrations vary between 5% to - 25% w/w. Compositions 8 and 9 are listed in Table 1.
Release profiles of the active core from the compositions in an aqueous physiological environment are described in Example 2, and are plotted as cumulative percentage release versus time, and presented in Figure 2.
Burst-free, variable release from 56->90 days is achieved by varying the polymer concentration in the oil phase.
Example 9 Microcapsule compositions are described in Example 2, wherein the active core is leutinizing hormone releasing hormone (LHRH, a decapeptide of molecular weight 1182) and the polymer concentration is -40% w/w. Release profiles of the active core from the composition in an aqueous physiological environment is described in Example 2, and is plotted as cumulative percentage release versus time, and presented in Figure 4.
Burst-free, continuous and complete release is achieved Within 35 days, similar to Histatin acetate.
~xamole 10 Microcapsule compositions are prepared as described in Example 2, wherein an additive such as sodium salt (carbonate or bicarbonate) is added to the inner aqueous phase at concentrations of 1-10% w/w to maintain the biological activity of the released polypeptide.
Burst-free, variable release from 1-28 days is achieved similar to Examples 2 & 3, and the released polypeptide is biologically active until 30 days, due to the presence of the - sodium salt.
~xamole I1 ~licrocapsule compositions are prepared as described in Example 2, wherein an additive such as a nonionic surfactant, polyoxyethylene/polyoxypropylene block copolymer (Pluronics F68 and F127) is added to either the inner oil or the aqueous phase at concentrations from 10-100% w/w, to maintain the biological activity of the released polypeptide.
Burst-free, continuous release from 1-35 days is achieved similar to Examples 2 & 3, and the released polypeptide is bioactive due to the presence of the surfactant.
Example 12 Cumulative histatin release from the microcapsule compositions described in Examples 1 through 11 and release profiles plotted in Figures 2 and 3 show the burst-free, programmable peptide release for variable duration from 1-100 days. Virtually any pattern of cumulative release is achievable over'a i0o day duration by a judicious blending of several compositions, as shown in these figures.
Claims (34)
1. A microcapsule pharmaceutical formulation, comprising:
a biologically active agent; and a carrier encapsulating said active agent, said carrier comprising an amount of uncapped biodegradable poly(lactide/glycolide)polymer and an amount of end-capped biodegradable poly(lactide/glycolide) polymer, such that the duration of a sustained, burst-free release of ingredient may be programmed from 1 to 100 days by selective variation of the quantitative ratio uncapped polymer to end-capped polymer.
a biologically active agent; and a carrier encapsulating said active agent, said carrier comprising an amount of uncapped biodegradable poly(lactide/glycolide)polymer and an amount of end-capped biodegradable poly(lactide/glycolide) polymer, such that the duration of a sustained, burst-free release of ingredient may be programmed from 1 to 100 days by selective variation of the quantitative ratio uncapped polymer to end-capped polymer.
2. The microcapsules of claim 1, wherein the biodegradable poly(lactide/glycolide) is a blend of uncapped and end-capped forms, in ratios ranging from 99/1 to 1/99.
3. The microcapsules of claims 1 or 2, wherein the copolymer (lactide to glycolide L/G) ratio for uncapped and endcapped polymer is 52/48 to 48/52.
4. The microcapsules of claims 1 or 2, wherein the copolymer L/G ratio for uncapped and end-capped polymer is 90/10 to 40/60.
5. The microcapsules of claim 3, wherein the molecular weight of the copolymer is between 2,000-60,000 daltons.
6. The microcapsules of claim 1, wherein the biologically active agent is a peptide or polypeptide.
7. The microcapsules of claim 6, wherein said polypeptide is histatin consisting of 12 amino acids and having a molecular weight of 1563.
8. The microcapsules of claim 7, characterized by the capacity to completely release histatin in an aqueous physiological environment from 1-35 days with a 99/1 blend of uncapped and end-capped poly(lactide/glycolide) having a L/G ratio of 48/52 to 52/48, and a molecular weight <15,000.
9. The microcapsules of claim 7, characterized by the capacity to completely release histatin in an aqueous physiological environment from 18-40 days with a 99/1 blend of uncapped and end-capped poly(lactide/glycolide) having a L/G ratio of 48/52 to 52/48 and a molecular weight range of 28,000-40,000.
10. The microcapsules of claim 7, characterized by the capacity to release up to 90% of the histatin in an aqueous physiological environment from 28-70 days with a 1/99 blend of uncapped and end-capped poly(lactide/glycolide) having a L/G ratio of 48/52 to 52/48 and a molecular weight range of 10,000-40,000 daltons.
11. The microcapsules of claim 7, characterized by the capacity to release up to 800 of histatin in an aqueous physiological environment from 56-100 days with a 1/99 blend of uncapped and end-capped poly(lactide/glycolide) having a L/G ratio of 75/25 and a molecular weight of <
15,000 daltons.
15,000 daltons.
12. The microcapsules of claim 6, wherein said polypeptide is histatin.
13. The microcapsules of claim 6 wherein said polypeptide is an analog of histatin with chain lengths of from 10-24 amino acids of molecular weights from 1,500-3,000 daltons and characterized by the following structures:
1. D S H A K R H H G Y K R K F H E K H H S H R G Y
2. K R H H G Y K R K F H E K H H S H R G Y R
3. K R H H G Y K R K F H E K H H S H R
4. R K F H E K H H S H R G Y R
5. A K R H H G Y K R K F H
6. *A K R H H G Y K R K F H
7. K R H H G Y K R K F
* D-amino acid
1. D S H A K R H H G Y K R K F H E K H H S H R G Y
2. K R H H G Y K R K F H E K H H S H R G Y R
3. K R H H G Y K R K F H E K H H S H R
4. R K F H E K H H S H R G Y R
5. A K R H H G Y K R K F H
6. *A K R H H G Y K R K F H
7. K R H H G Y K R K F
* D-amino acid
14. The microcapsules of claim 6, wherein the biologically active agent is a polypeptide Leutinizing hormone releasing hormone (LHRH) that is a decapeptide of molecular weight 1182 in its acetate form, and having the structure:
p- E H W S Y G L R P G
p- E H W S Y G L R P G
15. The microcapsule of claim 6 having a molecular weight of from 1,000 to 250,000 daltons.
16. The microcapsules of claims 6 or 7 or 8 or 9 or 10 or 11 or 13 or 14, wherein release profiles of variable rates and durations are achieved by blending uncapped and capped microspheres as a cocktail in variable amounts.
17. The microcapsules of claims 6 or 7 or 8 or 9 or 10 or 11 or 13 or 14 or 15, wherein release of profiles of variable rates and duration are achieved by blending uncapped and capped polymer in different ratios within the same microspheres.
18. The microcapsules of claims 6 or 7 or 8 or 9 or 10 or 11 or 13 or 14 or 15, wherein the entrapped polypeptide is a vaccine agent against enterotoxigenic E. coli (ETEC).
19. The microcapsules of claims 6 or 7 or 8 or 9 or 10 or 11 or 13 or 14 or 15, wherein the entrapped polypeptide consists of peptide antigens of molecular weight range of 800-5000 daltons for immunization against enterotoxigenic E. coli (ETEC).
20. The microcapsules of claims 1 or 2 or 3 or 4 or 5, wherein said biologically active agents are selected from the group consisting of water-soluble hormone drugs, antibiotics, antitumor agents, anti inflammatory agents, antipyretics, analgesics, antitussives, expectorants, sedatives, muscle relaxants, antiepileptics, antiulcer agents, antidepressants, antiallergic drugs, cardiotonics, antiarrhythmic drugs, vasodilators, antihypertensives, diuretics, anticoagulants, and antinarcotics, in the molecular weight range of 100-100,000 daltons.
21. The microcapsules of claims 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8, wherein said biodegradable poly(lactide/glycolide) is in an oil phase, and is present in an amount of 1-50% (w/w).
22. The microcapsules of claims 1 or 2 or 3 or 4 or 5 or 6 or 8 or 9 or 10 or 11 or 13 or 14 or 15, wherein concentration of the active agent is in the range of 0.1 to 60% (w/w).
23. A process for preparing microcapsule formulations, comprising the steps of:
dissolving biodegradable poly(lactide/glycolide) polymer in uncapped form and in capped form in methylene chloride to form a polymer solution;
dissolving a biologically active agent or active core in water to form an aqueous solution;
adding aqueous solution to said polymer solution and emulsifying to provide an inner water-in-oil emulsion;
stabilizing the w/o emulsion in a solvent-saturated aqueous phase containing an oil-in-water (o/w) emulsifier;
adding said w/o emulsion to an external aqueous layer containing oil-in-water emulsifier to form a ternary water-in-oil (w/o/w) emulsion, then stirring said ternary emulsion for a sufficient time to remove the solvent; and rinsing with water the hardened microcapsules which had been produced and then lyophilizing said hard microcapsules;
wherein a controlled, sustained and burst-free release of the active agent or active core in ordinary use is programmed from 1 to 100 days by selectively varying the quantitative ratio of said uncapped polymer to said end-capped polymer.
dissolving biodegradable poly(lactide/glycolide) polymer in uncapped form and in capped form in methylene chloride to form a polymer solution;
dissolving a biologically active agent or active core in water to form an aqueous solution;
adding aqueous solution to said polymer solution and emulsifying to provide an inner water-in-oil emulsion;
stabilizing the w/o emulsion in a solvent-saturated aqueous phase containing an oil-in-water (o/w) emulsifier;
adding said w/o emulsion to an external aqueous layer containing oil-in-water emulsifier to form a ternary water-in-oil (w/o/w) emulsion, then stirring said ternary emulsion for a sufficient time to remove the solvent; and rinsing with water the hardened microcapsules which had been produced and then lyophilizing said hard microcapsules;
wherein a controlled, sustained and burst-free release of the active agent or active core in ordinary use is programmed from 1 to 100 days by selectively varying the quantitative ratio of said uncapped polymer to said end-capped polymer.
24. A process for preparing controlled release microcapsule formulations characterized by burst-free, sustained, programmable release of biologically active agents, comprising the steps of:
dissolving selected amounts of biodegradable poly(lactide/glycolide) in uncapped form and in endcapped form in methylene chloride;
dissolving a biologically active agent or active core in water;
adding the aqueous layer to the polymer solution and emulsifying to provide an inner water-in-oil (w/o) emulsion;
stabilizing the w/o emulsion in a solvent-saturated aqueous phase containing an oil-in-water (o/w) emulsifier;
adding said w/o emulsion to an external aqueous layer containing oil-in-water emulsifier to form a ternary emulsion, then stirring the resulting water-in-oil (w/o/w) emulsion for sufficient time to remove the solvent; and rinsing the resultant hardened microcapsules with water and then lyophilizing said hardened microcapsules, wherein through variation of the ratio of said uncapped polymer to said end-capped polymer, said microcapsules exhibit a controlled, sustained and burst-free release of the active agent or active core having a programmed duration from 1 to 100 days.
dissolving selected amounts of biodegradable poly(lactide/glycolide) in uncapped form and in endcapped form in methylene chloride;
dissolving a biologically active agent or active core in water;
adding the aqueous layer to the polymer solution and emulsifying to provide an inner water-in-oil (w/o) emulsion;
stabilizing the w/o emulsion in a solvent-saturated aqueous phase containing an oil-in-water (o/w) emulsifier;
adding said w/o emulsion to an external aqueous layer containing oil-in-water emulsifier to form a ternary emulsion, then stirring the resulting water-in-oil (w/o/w) emulsion for sufficient time to remove the solvent; and rinsing the resultant hardened microcapsules with water and then lyophilizing said hardened microcapsules, wherein through variation of the ratio of said uncapped polymer to said end-capped polymer, said microcapsules exhibit a controlled, sustained and burst-free release of the active agent or active core having a programmed duration from 1 to 100 days.
25. The process of claims 23 or 24, wherein a low temperature of 0-4°C is provided during preparation of the inner w/o emulsion, and a low temperature of about 4-20°C is provided during preparation of the w/o/w emulsion to provide a stable emulsion and high encapsulation efficiency.
26. The process of claim 23, wherein a 99/1 blend of uncapped and end-capped polymer is used to provide release of the active core in a continuous and sustained manner without a lag phase.
27. The microcapsules of claim 6, wherein, when the entrapped polypeptide is active at a low pH, selected from the group consisting of LHRH, adrenocorticotropic hormone, epidermal growth factor and calcitonin the released polypeptide is bioactive.
28. The microcapsules of claims 6 or 7 or 8 or 9 or 10 or 11, wherein, when entrapped peptide is inactive at a low pH, a pH-stabilizing agent or inorganic salts are added to an inner aqueous phase to maintain biological activity of the released peptide.
29. The microcapsules of claims 6 or 7 or 8 or 9 or 10 or 11, wherein, when entrapped polypeptide is inactive at a low pH, a non-ionic surfactant selected from the group consisting of polyoxyethylene sorbitan fatty acid esters and polyoxyethylene - polyoxypropylene block copolymers is added to an inner aqueous phase to maintain biological activity of the released polypeptide.
30. A microcapsule mixture comprising:
the microcapsules of any one of claims 6-11; and placebo spheres located with pH stabilizing agents for maintaining the solution pH around the microapsules and preserving the biological activity of the released peptide in instances where the addition of pH-stabilizing agents in the inner aqueous phase of the microcapsules is undesirable for the successful encapsulation of the acid pH sensitive polypeptide.
the microcapsules of any one of claims 6-11; and placebo spheres located with pH stabilizing agents for maintaining the solution pH around the microapsules and preserving the biological activity of the released peptide in instances where the addition of pH-stabilizing agents in the inner aqueous phase of the microcapsules is undesirable for the successful encapsulation of the acid pH sensitive polypeptide.
31. A microcapsule mixture comprising:
the microcapsules of any one of claims 6-11; and placebo spheres loaded with non-ionic surfactant for maintaining the biological activity of the released peptide where the addition of non-ionic surfactants in the inner aqueous phase of the microcapsules is undesirable for the successful encapsulation of the acid pH sensitive polypeptide.
the microcapsules of any one of claims 6-11; and placebo spheres loaded with non-ionic surfactant for maintaining the biological activity of the released peptide where the addition of non-ionic surfactants in the inner aqueous phase of the microcapsules is undesirable for the successful encapsulation of the acid pH sensitive polypeptide.
32. A microcapsule mixture comprising:
the microcapsules of any one of claims 6-11; and placebo spheres loaded with non-ionic surfactant for maintaining the biological activity of the released peptide where the addition of non-ionic surfactants in the inner aqueous phase of the microcapsules is undesirable for the successful encapsulation of the acid pH sensitive polypeptide.
the microcapsules of any one of claims 6-11; and placebo spheres loaded with non-ionic surfactant for maintaining the biological activity of the released peptide where the addition of non-ionic surfactants in the inner aqueous phase of the microcapsules is undesirable for the successful encapsulation of the acid pH sensitive polypeptide.
33. The microcapsules of claim 29, wherein said polyoxyethylene sorbitan fatty acid esters are selected from the group consisting of Tween.TM. 80, Tween.TM. 60 and Tween.TM. 20.
34. The microcapsules of claim 29, wherein said polyoxyethylene - polyoxypropylene block copolymer is Pluronics.TM.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US59097396A | 1996-01-24 | 1996-01-24 | |
| US08/590,973 | 1996-01-24 | ||
| PCT/US1996/019440 WO1997026869A1 (en) | 1996-01-24 | 1996-11-18 | Novel 'burst-free' sustained release poly-(lactide/glycolide) microspheres |
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|---|---|
| CA2216371A1 CA2216371A1 (en) | 1997-07-31 |
| CA2216371C true CA2216371C (en) | 2005-11-01 |
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|---|---|---|---|
| CA002216371A Expired - Fee Related CA2216371C (en) | 1996-01-24 | 1996-11-18 | Novel "burst-free" sustained release poly-(lactide/glycolide) microspheres |
Country Status (1)
| Country | Link |
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| CA (1) | CA2216371C (en) |
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Effective date: 20131119 |