WO2007081321A1

WO2007081321A1 - Ac2993 lar dosing regimen

Info

Publication number: WO2007081321A1
Application number: PCT/US2006/000551
Authority: WO
Inventors: Wen-I Li
Original assignee: Alkermes, Inc.
Priority date: 2006-01-09
Filing date: 2006-01-09
Publication date: 2007-07-19

Abstract

This invention relates to compositions for the sustained release of biologically active polypeptides, and methods of forming and using said compositions, for the sustained release of biologically active polypeptides. The sustained release compositions of this invention comprise a biocompatible polymer having dispersed therein, a biologically active polypeptide and a sugar.

Description

AC2993 LAR DOSING REGIMEN

BACKGROUND OF THE INVENTION

In the development of a long acting release (LAR) dosage form of AC2993, or other peptide, in biodegradable microspheres, it is often a challenge to achieve a steady plasma concentration of the drug within the therapeutic window. This is due to the nature of the biodegradable polymeric microspheres, which undergo multi-phase release of the incorporated drug. This characteristic gives rise to a variable concentration- time profile, rather than a flatter, sustained concentration-time profile. Solutions that have been proposed to improve the release profile include employing polymer blends and excipients that modulate release. While these strategies have often met with some success, their application to AC2993 LAR formulations remained elusive in view, at least in part, of the constraints in the therapeutic window.

SUMMARY OF THE INVENTION

The invention relates to the discovery that superior release profiles can be achieved by administering via superpositioning an LAR formulation comprising an antidiabetic or glucoregulatory polypeptide, such as GLP-I, GLP-2, exendin-3, exendin-4 or an analog, derivative or agonist thereof, preferably exendin-4 or AC2993. "Superpositioning" is defined herein as a dosing regimen wherein the second or subsequent dose is administered to the subject or patient during the release phase of a first or previous dose. "LAR" refers to long acting release and sustained release, interchangeably.

Preferred formulations of this invention comprise a biocompatible polymer, an agent, such as a biologically active polypeptide, and a sugar and are characterized by a low pore volume. Such formulations are described in PCT/US04/11547, by Wright et al, the contents of which are incorporated herein by reference. The polypeptide and sugar are preferably dispersed in the polymer. The polypeptide and sugar can be dispersed separately or, preferably, together. In a preferred embodiment, the biologically active polypeptide is an antidiabetic or glucoregulatory polypeptide, such as GLP-I, GLP-2, exendin-3, exendin-4 or an analog, derivative or agonist thereof, preferably exendin-4. The sugar is preferably sucrose, mannitol or a combination thereof. A preferred combination includes exendin-4 and sucrose and/or mannitol.

Additionally or alternatively, the formulation consists essentially of or, alternatively consists of, a biocompatible polymer, exendin-4 or AC2993 at a concentration of about 3% w/w and sucrose at a concentration of about 2% w/w. The biocompatible polymer is preferably a poly lactide coglycolide polymer.

The formulation preferably comprises a biocompatible polymer, an agent, such as a biologically active polypeptide and a sugar wherein the formulation has a total pore volume of about 0.1 mL/g or less. In a specific embodiment, the total pore volume is determined using mercury intrusion porosimetry.

The formulations of the invention can be made according to a method which comprises forming a mixture by combining an aqueous phase comprising water, an agent, such as a water soluble polypeptide, and a sugar with an oil phase comprising a biocompatible polymer and a solvent for the polymer; forming a water-in-oil emulsion by, for example, sonicating or homogenizing, the mixture; adding silicone oil to the mixture to form embryonic microparticles; transferring the embryonic microparticles to a quench solvent to harden the microparticles; collecting the hardened microparticles; and drying the hardened microparticles. The preferred formulation contains few components by optimizing the silicone oil to polymer ratio in the manufacturing process, thereby achieving a low pore volume. In a particular embodiment, the silicone oil is added in an amount sufficient to achieve a silicone oil to polymer solvent ratio of about 1.5:1. Additionally or alternatively, the polymer is present in the oil phase at about 10% w/v or less.

The agent or polypeptide, e.g. exendin-4 or AC2993, can be present in the formulation described herein at a concentration of about 0.01 % to about 10% w/w based on the total weight of the final composition. In addition, the sugar, e.g. sucrose, can be present in a concentration of about 0.01% to about 5% w/w of the final weight of the composition.

The composition of this invention can be administered to a human, or other animal, by injection, implantation (e.g., subcutaneously, intramuscularly, intraperitoneally, intracranially, and intradermally), administration to mucosal membranes (e.g., intranasally, intravaginally, intrapulmonary or by means of a suppository), or in situ delivery (e.g., by enema or aerosol spray).

When the formulation has incorporated therein a hormone, particularly an anti-diabetic or glucoregulatory peptide, for example, GLP-I, GLP-2, exendin-3, exendin-4 or agonists, analogs or derivatives thereof, the composition is administered in a therapeutically effective amount to treat a patient suffering from diabetes mellitus, impaired glucose tolerance (IGT), obesity, cardiovascular (CV) disorder or any other disorder that can be treated by one of the above polypeptides or derivatives, analogs or agonists thereof. The use of a sugar improves the bioavailability of the incorporated biologically active polypeptide, e.g, anti-diabetic or glucoregulatory peptides, and minimizes loss of activity due to instability and/or chemical interactions between the polypeptide and other components contained or used in formulating the sustained release composition, while maintaining an excellent release profile.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. IA and IB are graphs showing the predicted release profile of two LAR formulation administered via superpositioning weekly in human subjects.

DETAILED DESCRIPTION OF THE INVENTION

The invention relates to the discovery that superior release profiles can be achieved by administering via superpositioning an LAR formulation comprising an antidiabetic or glucoregulatory polypeptide, such as GLP-I, GLP-2, exendin-3, exendin-4 or an analog, derivative or agonist thereof, preferably exendin-4 or AC2993. "Superpositioning" is defined herein as a dosing regimen wherein the second or subsequent dose is administered to the subject or patient during the release phase of a first or previous dose. "LAR" refers to long acting release and sustained release, interchangeably. Preferred formulations of this invention comprise a biocompatible polymer, an agent, such as a biologically active polypeptide, and a sugar and are characterized by a low pore volume. Such formulations are described in PCT/US04/11547, by Wright et al, the contents of which are incorporated herein by reference. The polypeptide and sugar are preferably dispersed in the polymer. The polypeptide and sugar can be dispersed separately or, preferably, together. In a preferred embodiment, the biologically active polypeptide is an antidiabetic or glucoregulatory polypeptide, such as GLP-I, GLP-2, exendin-3, exendin-4 or an analog, derivative or agonist thereof, preferably exendin-4. The sugar is preferably sucrose, mannitol or a combination thereof. A preferred combination includes exendin-4 and sucrose and/or mannitol.

In another embodiment, the invention relates to dosage regimens of LAR formulations wherein the dosage regimen relies upon superpositioning. Thus, the invention includes the use of the LAR formulations described herein for use in the manufacture of a medicament for use in the methods of the invention.

In a preferred embodiment, the agent is a biologically active polypeptide such as an antidiabetic or glucoregulatory polypeptide, including GLP-I, GLP-2, exendin-3, exendin-4 or an analog, derivative or agonist thereof. Most specifically, the polypeptide is exendin-4. However, other agents can take advantage of the discoveries made herein.

Biologically active polypeptides as used herein collectively refers to biologically active proteins and peptides and the pharmaceutically acceptable salts thereof, which are in their molecular, biologically active form when released in vivo, thereby possessing the desired therapeutic, prophylactic and/or diagnostic properties in vivo. Typically, the polypeptide has a molecular weight between 500 and 200,000 Daltons.

Suitable biologically active polypeptides include, but are not limited to, glucagon, glucagon-like peptides such as, GLP-I, GLP-2 or other GLP analogs, derivatives or agonists of Glucagon Like Peptides, exendins such as, exendin-3 and exendin-4, derivatives, agonists and analogs thereof, vasoactive intestinal peptide (VIP), immunoglobulins, antibodies, cytokines (e.g., lymphokines, monokines, chemokines), interleukins, macrophage activating factors, interferons, erythropoietin, nucleases, tumor necrosis factor, colony stimulating factors (e.g., G- CSF), insulin, enzymes (e.g., superoxide dismutase, plasminogen activator, etc.), tumor suppressors, blood proteins, hormones and hormone analogs and agonists (e.g., follicle stimulating hormone, growth hormone, adrenocorticotropic hormone, and luteinizing hormone releasing hormone (LHRH)), vaccines (e.g., tumoral, bacterial and viral antigens), antigens, blood coagulation factors, growth factors (NGF and EGF), gastrin, GRH, antibacterial peptides such as defensin, enkephalins, bradykinins, calcitonin and muteins, analogs, truncation, deletion and substitution variants and pharmaceutically acceptable salts of all the foregoing.

Exendin-4 is a 39 amino acid polypeptide. The amino acid sequence of exendin-4 can be found in U.S. Patent No. 5,424,286 issued to Eng on June 13, 1995, the entire content of which is hereby incorporated by reference. AC2993 and exenatide are synonymous with the term exendin-4. Exendin-4 has been shown in humans and animals to stimulate secretion of insulin in the presence of elevated blood glucose concentrations, but not during periods of low blood glucose concentrations (hypoglycemia). It has also been shown to suppress glucagon secretion, slow gastric emptying and affect food intake and body weight, as well as other actions. As such, exendin-4 and analogs and agonists thereof can be useful in the treatment of diabetes mellitus, IGT, obesity, etc.

The amount of biologically active polypeptide, which is contained within the polymeric matrix of a LAR formulation or sustained release composition, is a therapeutically, diagnostically or prophylactically effective amount which can be determined by a person of ordinary skill in the art, taking into consideration factors such as body weight, condition to be treated, type of polymer used, and release rate from the polymer.

LAR formulations and sustained release compositions generally contain from about 0.01% (w/w) to about 50% (w/w) of the agent, e.g., biologically active polypeptide (such as exendin-4) (total weight of composition). For example, the amount of biologically active polypeptide (such as exendin-4) can be from about 0.1% (w/w) to about 30% (w/w) of the total weight of the composition. The amount of polypeptide will vary depending upon the desired effect, potency of the agent, the planned release levels, and the time span over which the polypeptide will be released. Preferably, the range of loading is between about 0.1% (w/w) to about 10% (w/w), for example, 0.5% (w/w) to about 5% (w/w). In one embodiment, the agent, e.g. exendin-4, was loaded at about 3% w/w.

A sugar, as defined herein, is a monosaccharide, disaccharide or oligosaccharide (from about 3 to about 10 monosaccharides) or a derivative thereof. For example, sugar alcohols of monosaccharides are suitable derivatives included in the present definition of sugar. As such, the sugar alcohol mannitol, for example, which is derived from the monosaccharide mannose is included in the definition of sugar as used herein.

Suitable monosaccharides include, but are not limited to, glucose, fructose and mannose. A disaccharide, as further defined herein, is a compound which upon hydrolysis yields two molecules of a monosaccharide. Suitable disaccharides include, but are not limited to, sucrose, lactose and trehalose. Suitable oligosaccharides include, but are not limited to, raffinose and acarbose.

The amount of sugar present in the sustained release composition can range from about 0.01% (w/w) to about 50% (w/w), such as from about 0.01% (w/w) to about 10% (w/w), such as from about 0.1% (w/w) to about 5% (w/w) of the total weight of the sustained release composition. In one embodiment, about 2% (w/w) sucrose was incorporated.

Alternatively, the amount of sugar present in the sustained release composition can be referred to on a weight ratio with the agent or biologically active polypeptide. For example, the polypeptide and sugar can be present in a ratio from about 10:1 to about 1:10 weightweight. In a particularly preferred embodiment, the ratio of polypeptide (e.g., exendin-4) to sugar (e.g., sucrose) is about 3:2 (w/w).

Combinations of two or more sugars can also be used. The amount of sugar, when a combination is employed, is the same as the ranges recited above.

When the polypeptide is exendin-4, the sugar is preferably sucrose, mannitol or a combination thereof.

Polymers suitable to form the sustained release composition of this invention are biocompatible polymers which can be either biodegradable or non-biodegradable polymers or blends or copolymers thereof. A polymer is biocompatible if the polymer and any degradation products of the polymer are non-toxic to the recipient and also possess no significant deleterious or untoward effects on the recipient's body, such as a substantial immunological reaction at the injection site. Biodegradable, as defined herein, means the composition will degrade or erode in vivo to form smaller units or chemical species. Degradation can result, for example, by enzymatic, chemical and physical processes. Suitable biocompatible, biodegradable polymers include, for example, poly(lactides), poly(glycolides), poly(lactide-co-glycolides), poly(lactic acid)s, poly(glycolic acid)s, polycarbonates, polyesteramides, polyanydrides, poly(amino acids), polyorthoesters, poly(dioxanone)s, poly(alkylene alkylate)s, copolymers or polyethylene glycol and polyorthoester, biodegradable polyurethane, blends thereof, and copolymers thereof.

Suitable biocompatible, non-biodegradable polymers include nonbiodegradable polymers selected from the group consisting of polyacrylates, polymers of ethylene-vinyl acetates and other acyl substituted cellulose acetates, non-degradable polyurethanes, polystyrenes, polyvinylchloride, polyvinyl flouride, poly(vinyl imidazole), chlorosulphonate polyolefins, polyethylene oxide, blends thereof, and copolymers thereof.

Acceptable molecular weights for polymers used in this invention can be determined by a person of ordinary skill in the art taking into consideration factors such as the desired polymer degradation rate, physical properties such as mechanical strength, end group chemistry and rate of dissolution of polymer in solvent. Typically, an acceptable range of molecular weight is of about 2,000 Daltons to about 2,000,000 Daltons. In a preferred embodiment, the polymer is biodegradable polymer or copolymer. In a more preferred embodiment, the polymer is a poly(lactide-co-glycolide) (hereinafter "PLG") with a lactide:glycolide ratio of about 1 : 1 and a molecular weight of about 10,000 Daltons to about 90,000 Daltons. In an even more preferred embodiment, the molecular weight of the PLG used in the present invention has a molecular weight of about 30,000 Daltons to about 70,000 Daltons such as about 50,000 to about 60,000 Daltons. The PLGs can possess acid end groups or blocked end groups, such as can be obtained by esterifying the acid. Excellent results were obtained with a PLG with an acid end group.

Polymers can also be selected based upon the polymer's inherent viscosity. Suitable inherent viscosities include about 0.06 to 1.0 dL/g, such as about 0.2 to 0.6 dL/g, more preferably between about 0.3 to 0.5 dL/g. Preferred polymers are chosen that will degrade in 3 to 4 weeks. Suitable polymers include polymers sold under the tradename Medisorb®, such as those sold as 5050 DL 3A or 5050 DL 4A. Boehringer Ingelheim Resomer® PLGs may also be used, such as Resomer® RG503 and 503H.

The sustained release composition of this invention can be formed into many shapes such as a film, a pellet, a cylinder, a disc or a microparticle. A microparticle, as defined herein, comprises a polymer component having a diameter of less than about one millimeter and having biologically active polypeptide dispersed or dissolved therein. A microparticle can have a spherical, non-spherical or irregular shape. Typically, the microparticle will be of a size suitable for injection. A typical size range for microparticles is 1000 microns or less. In a particular embodiment, the microparticle ranges from about one to about 180 microns in diameter.

While it is possible that additional excipients can be added to the formulations of the claimed invention as is well known in the art, a surprising discovery of the present invention is that an excellent release profile can be achieved with the simple formulation described herein. Such additional excipients can increase or decrease the rate of release of the agent. Ingredients which can substantially increase the rate of release include pore forming agents and excipients which facilitate polymer degradation. For example, the rate of polymer hydrolysis is increased in non-neutral pH. Therefore, an acidic or a basic excipient such as an inorganic acid or inorganic base can be added to the polymer solution, used to form the microparticles, to alter the polymer erosion rate. Ingredients which can substantially decrease the rate of release include excipients that decrease the water solubility of the agent.

A preferred embodiment of the described sustained release formulations consists essentially of the biocompatible polymer, the agent and the sugar. By "consists essentially of is meant the absence of ingredients which substantially increase the rate of release of the active agent from the formulation.

In yet another embodiment, the formulation consists of the biocompatible polymer, the agent and the sugar. By "consists of is meant the absence of components or ingredients other than those listed and residual levels of starting materials, solvents, etc. from the process.

Alternatively or additionally, the LAR formulations or sustained release composition of the invention has low porosity. In such embodiments, the sustained release composition comprises a biocompatible polymer, a biologically active polypeptide and a sugar wherein the composition has a total pore volume of about 0.1 mL/g or less. In a specific embodiment, the total pore volume is determined using mercury intrusion porosimetry, e.g., as described in more detail below.

The LAR formulations and compositions of the invention can be administered according to methods generally known in the art. The composition of this invention can be administered to a patient (e.g., a human in need of the agent) or other animal, by injection, implantation (e.g., subcutaneously, intramuscularly, intraperitoneally, intracranially, and intradermally), administration to mucosal membranes (e.g., intranasally, intravaginally, intrapulmonary or by means of a suppository), or in situ delivery (e.g., by enema or aerosol spray). The sustained release compositions are administered via superpositioning using a dosing schedule which achieves the desired therapeutic levels for the desired period of time. The subsequent administration of the sustained release composition occurs prior to achieving baseline levels in the patient.

For example, when the sustained release composition has incorporated therein a hormone, particularly an anti-diabetic or glucoregulatory peptide, for example, GLP-I, GLP-2, exendin-3, exendin-4 or agonists, analogs or derivatives thereof, the composition is administered in a therapeutically effective amount to treat a patient suffering from diabetes mellitus, IGT, obesity, cardiovascular (CV) disorder or any other disorder that can be treated by one of the above polypeptides or derivatives, analogs or agonists thereof. Other conditions which can be treated by administering the sustained release composition of the invention include Type I and Type II diabetes which can be treated with a sustained release composition having insulin incorporated therein.

The formulation is preferably selected to permit release of the polypeptide over a period of at least two weeks, more preferably at least four weeks, such as six weeks or more. The formulation is preferably administered weekly, such as biweekly or, in some instances monthly. In a preferred embodiment, the formulation is administered to achieve a release profile approximating the release profile depicted in Figure IA and IB. As used herein, patient can be an animal, such as a human, in need of the agent or therapy, prophylaxis or diagnostic method.

As defined herein, a sustained release of biologically active polypeptide is a release of the polypeptide from the sustained release composition of the invention which occurs over a period which is longer than that period during which a biologically significant amount of the polypeptide would be available following direct administration of a solution of the polypeptide. It is preferred that a sustained release be a release which occurs over a period of at least about one week, such as at least about two weeks, at least about three weeks or at least about four weeks. The sustained release can be a continuous or a discontinuous release, with relatively constant or varying rates of release. The continuity of release and level of release can be affected by the type of polymer composition used (e.g., monomer ratios, molecular weight, block composition, and varying combinations of polymers), polypeptide loading, and/or selection of excipients to produce the desired effect.

As used herein, a therapeutically effective amount, prophylactically effective amount or diagnostically effective amount is the amount of the sustained release composition needed to elicit the desired biological response following administration.

C_maxas used herein is the maximum serum concentration of drug which occurs during the period of release which is monitored. C_ave as used herein, is the average serum concentration of drug derived by dividing the area under the curve (AUC) of the release profile by the duration of the release. It is preferred that the ratio of C_max to C_ave be about 3 or less. This profile is particularly desirable of anti- diabetic or glucoregulatory polypeptides, such as those described above. A ratio of about 3 or less can provide a C_ave in a therapeutic window while avoiding adverse drug side effects which can result from higher ratios.

Bioavailability, as that term is used herein, refers to the amount of therapeutic agent that reaches the circulatory system. Bioavailability can be defined as the calculated Area Under the Curve (AUC) for the release profile of a particular polypeptide during the time period starting at post administration and ending at a predetermined time point. As is understood in the art, the release profile is generated by graphing the serum levels of a biologically active agent in a subject (Y-axis) at predetermined time points (X-axis). Bioavailability is often referred to in terms of % bioavailability, which is the bioavailability achieved for a particular polypeptide following administration of a sustained release composition divided by the bioavailability achieved for a particular polypeptide following intravenous administration of the same dose of drug, multiplied by 100. A modification of the release profile can be confirmed by appropriate pharmacokinetic monitoring of the patient's serum for the presence of the biologically active polypeptide agent. For example, specific antibody-based testing (e.g., ELISA and IRMA), as is well known in the art, can be used to determine the concentration of certain biologically active polypeptide agents in the patient's serum. An example of such testing is described herein for exendin-4.

Pharmacodynamic monitoring of the patient to monitor the therapeutic effects of the agent upon the patient can be used to confirm retention of the biological activity of the released agent. Methods of monitoring pharmacodynamic effects can be selected based upon the biologically active polypeptide agent being administered using widely available techniques.

A number of methods are known by which sustained release compositions (polymer/biologically active polypeptide matrices) of the invention can be formed, particularly compositions having low porosity as described herein. Detailed procedures for some methods of microparticle formation are set forth in the Working Examples. In a preferred embodiment, the method of the invention for forming a composition for the sustained release of biologically active polypeptide includes forming a mixture by combining an aqueous phase comprising water, agent, such as a water soluble polypeptide, and a sugar with an oil phase comprising a biocompatible polymer and a solvent for the polymer; forming a water-in-oil emulsion; adding a coacervation agent, for example silicone oil, vegetable oil or mineral oil to the mixture to form embryonic microparticles; transferring the embryonic microparticles to a quench solvent to harden the microparticles; collecting the hardened microparticles; and drying the hardened microparticles. This process is generally referred to herein as a water-oil-oil process (W/O/0).

Preferably, the polymer can be present in the oil phase in a concentration ranging from about 3% w/w to about 25% w/w, preferably, from about 4% w/w to about 15% w/w, such as from about 5% w/w to about 10% w/w. In one embodiment, a 6% w/w concentration of PLG in the oil phase was used.

The polymer is generally combined with a polymer solvent. Where the polymer is a PLG, such as those preferred herein, the polymer is added to a solvent for PLG. Such solvents are well known in the art. A preferred solvent is methylene chloride.

The agent and sugar are added in the aqueous phase, preferably in the same aqueous phase. The concentration of agent is preferably 10 to 100 mg/g, preferably between 50 to 100 mg/g. The concentration of sugar is preferably 10 to 50 mg/g and 30 to 50 mg/g. The two phases are then mixed to form an emulsion. It is preferred that the emulsion be foπned such that the inner emulsion droplet size is less than about 1 micron, preferably less than about 0.7 microns, more preferably less than about 0.5 microns, such as about 0.4 microns. Sonicators and homogenizers can be used to form such an emulsion. A coacervation agent as used herein refers to any oil in which the polymer solution (polymer and solvent) is not readily solubilized into and thereby forms a distinct phase with the polymer solution. Suitable coacervation agents for use in the present invention include, but are not limited to, silicone oil, vegetable oil and mineral oil. In a particular embodiment, the coacervation agent is silicone oil and is added in an amount sufficient to achieve a silicone oil to polymer solvent ratio from about 0.75:1 to about 2:1. In a particular embodiment, the ratio of silicone oil to polymer is from about 1 : 1 to about 1.5: 1. In a preferred embodiment, the ratio of silicone oil to polymer is about 1.5:1.

The resulting mixture is added to a quench, which comprises a polymer non- solvent. Polymer non-solvents are generally well known in the art. A particularly preferred quench comprises a heptane/ethanol solvent system.

Solid drug can also be encapsulated using a modified version of the process described above. This modified process can be referred to as a solid/oil/oil (S/O/0).

For example, solid exendin-4 was suspended in methylene chloride containing 6% PLG and sonicated for about four minutes on ice. Subsequent processing was conducted in a manner analogous to the W/O/0 method.

Methods for manufacturing the present formulations are described in PCT/US0411547 by Wright et al., the contents of which are incorporated herein by reference in its entirety.

The invention will now be further and specifically described by the following examples.

EXEMPLIFICATIONS MICROPARTICLE PREPARATION I

The sustained release compositions described herein were prepared by a phase separation process. The general process is described below for microparticles containing exendin-4 and sucrose for a 1 kg batch size.

A. Inner Water-in-Oil Emulsion Formation

A water-in-oil emulsion was created with the aid of a homogenizer. Suitable homogenizers include an in-line Megatron homogenizer MT-V 3-65 F/FF/FF, Kinematica AG, Switzerland. The water phase of the emulsion was prepared by dissolving exendin-4 and excipients such as sucrose in water. The concentration of drug in the resulting solution can be from about 50 mg/g to about 100 mg/g. For example, when the drug is exendin-4, the concentration of drug in solution can be from about 30 g to about 60 g per 600 g of water. In a particular embodiment, 50 g exendin-4 and 20 g sucrose were dissolved in 600 g water for irrigation (WFI). The specified amounts listed above represent a nominal load without adjustment to compensate for peptide content strength specific to the lot of exendin-4 used. The oil phase of the emulsion was prepared by dissolving PLGA polymer (e.g., 930 g of purified 50:50 DL4A PLGA (Alkermes, Inc.) in methylene chloride (14.6 kg or 6% w/w). The water phase was then added to the oil phase to form a coarse emulsion with an overhead mixer for about three minutes. Then, the coarse emulsion was homogenized at approximately 10,000 rpm at ambient temperature. This resulted in an inner emulsion droplet size of less than 1 micron. It is understood that inner emulsion formation can be achieved using any suitable means. Suitable means of emulsion formation include, but are not limited to, homogenization as described above and sonication.

B. Coacervate Formation

A coacervation step was then performed by adding silicone oil (21.8 kg of Dimethicone, NF, 350 cs) over about a five minute time period to the inner emulsion. This is equivalent to a ratio of 1.5:1, silicone oil to methylene chloride. The methylene chloride from the polymer solution partitions into the silicone oil and begins to precipitate the polymer around the water phase containing exendin-4, leading to microencapsulation. The embryonic microspheres thus formed are soft and require hardening. Frequently, the embryonic microspheres are permitted to stand for a short period of time, for example, from about 1 minute to about 5 minutes prior to proceeding to the microsphere hardening step.

C. Microsphere Hardening and Rinse The embryonic microspheres were then immediately transferred into a heptane/ethanol solvent mixture. The volume of heptane/ethanol mixture needed can be determined based on the microsphere batch size, typically a 16:1 ratio of methylene chloride to heptane/ethanol solvent. In the present example, about 210 kg heptane and 23 kg ethanol in a 3⁰C cooled, stirred tank were used. This solvent mixture hardened the microspheres by extracting additional methylene chloride from the microspheres. This hardening step can also be referred to as quenching. After being quenched for 1 hour at 3⁰C, the solvent mixture is either decanted and fresh heptane (13 Kg) is added at 3⁰C and held for 1 hour to rinse off residual silicone oil, ethanol and methylene chloride on the microsphere surface or pumped directly to the collection step.

D. Microsphere Drying and Collection

At the end of the quench or decant/wash step, the microspheres were transferred and collected on a 12" Sweco Pharmasep Filter/Dryer Model PH12Y6. The filter/dryer uses a 20 micron multilayered collection screen and is connected to a motor that vibrates the screen during collection and drying. A final rinse with heptane (6 Kg at 3°C) was performed to ensure maximum line transfer and to remove any excess silicone oil. The microspheres were then dried under vacuum with a constant purge of nitrogen gas at a controlled rate according to the following schedule: 6 hours at 3°C; 6 hours ramping to 41⁰C; and 84 hours at 41°C.

After the completion of drying, the microspheres were discharged into a collection vessel, sieved through a 150 μm sieve, and stored at about -20 ⁰C until filling.

For all microparticle formulations which were prepared herein the amount of polypeptide, for example, exendin-4 and excipients present in the prepared formulations is expressed as a % (w/w) based on the final weight of the sustained release composition. The % (w/w) is a nominal percentage, except where indicated.

MICROPARTICLE PREPARATION II

A. Inner Water-in-Oil Emulsion Formation

A water-in-oil emulsion was created with the aid of a sonicator. Suitable sonicators include Vibracell VCX 750 with model CV33 probe head, Sonics and Materials Inc., Newtown, CT. The water phase of the emulsion was prepared by dissolving exendin-4 and excipients such as sucrose in water. The concentration of drug in the resulting solution can be from about 50 mg/ml to about 100 mg/ml. For example, when the drug is exendin-4, the concentration of drug in solution can be from about 3.28 g to about 6.55 g per 65.5 g of water. In a particular embodiment, 5.46 g exendin-4 and 2.18 g sucrose were dissolved in 65.5 g water for irrigation or WFI. The specified amounts listed above represent a 4% overage to target load in order to compensate for losses upon filter sterilization of the components. The oil phase of the emulsion was prepared by dissolving PLGA polymer (e.g., 97.7 g of purified 50:50 DL4A PLGA (Alkermes, Inc.)) in methylene chloride (1539 g or 6% w/v). The water phase was then added to the oil phase over about a three minute period while sonicating at 100% amplitude at ambient temperature. The water phase was pumped through a ¹A" stainless steel tube with a 1" HPLC tube end (ID = 20/1000") at 5 psig, added below the sonication probe inside the sonication zone. Reactor was then stirred at 1400 to 1600 rpm, with additional sonication at 100% amplitude for 2 minutes, followed by a 30 second hold, and then 1 minute more of sonication. This resulted in an inner emulsion droplet size of less than 0.5 microns. It is understood that inner emulsion formation can be achieved using any suitable means. Suitable means of emulsion formation include, but are not limited to, sonication as described above and homogenization.

B. Coacervate Formation

A coacervation step was then performed by adding silicone oil (2294 gr of Dimethicone, NF, 350 cs) over about a three to five minute time period to the inner emulsion. This is equivalent to a ratio of 1.5:1, silicone oil to methylene chloride. The methylene chloride from the polymer solution partitions into the silicone oil and begins to precipitate the polymer around the water phase containing exendin-4, leading to microencapsulation. The embryonic microspheres thus formed are soft and require hardening. Frequently, the embryonic microspheres are permitted to stand for a short period of time, for example, from about 1 minute to about 5 minutes prior to proceeding to the microsphere hardening step.

C. Microsphere Hardening and Rinse

The embryonic microspheres were then immediately transferred into a heptane/ethanol solvent mixture. The volume of heptane/ethanol mixture needed can be determined based on the microsphere batch size. In the present example, about 22 kg heptane and 2448 g ethanol in a 3°C cooled, stirred tank (350 to 450 rpm) were used. This solvent mixture hardened the microspheres by extracting additional methylene chloride from the microspheres. This hardening step can also be referred to as quenching. After being quenched for 1 hour at 3°C, the solvent mixture was decanted and fresh heptane (13 Kg) was added at 3⁰C and held for 1 hour to rinse off residual silicone oil, ethanol and methylene chloride on the microsphere surface.

D. Microsphere Drying and Collection

At the end of the rinse step, the microspheres were transferred and collected on a 6" diameter, 20 micron multilayered screen inside the cone shaped drying chamber which acted as a dead-end filter. A final rinse with heptane (6 Kg at 4°C) was performed to ensure maximum line transfer. The microspheres were then dried with a constant purge of nitrogen gas at a controlled rate according to the following schedule: 18 hours at 3°C; 24 hours at 25°C; 6 hours at 35⁰C; and 42 hours at 38°C. After the completion of drying, the microspheres are discharged into a teflon/stainless steel sterilized collection vessel attached to the drying cone. The collection vessel is sealed, removed from the drying cone and stored at -20 ± 5°C until filling. Material remaining in the cone upon disassembly for cleaning is taken for drug content analysis. The yield was approximately 100 grams of microspheres. For all microparticle formulations which were prepared herein the amount of polypeptide, for example, exendin-4 and excipients present in the prepared formulations is expressed as a % (w/w) based on the final weight of the sustained release composition. The % (w/w) is a nominal percentage, except were indicated.

POLYMER: Examples of specific PLG polymers suitable for use are listed below. All of the polymers employed in the following examples are set forth in the list and all listed polymers were obtained from Alkermes, Inc. of Cincinnati, OH and can be described as follows:

Polymer 2A: Poly(lactide-co-glycolide); 50:50 lactide:glycolide ratio; 12.3 kD MoI. Wt.; IV=O.15 (dL/g). Polymer 4A: Poly(lactide-co-glycolide); 50:50 lactide:glycolide ratio; MoI. Wt. 45-64 kD; IV=0.45-0.47 (dL/g).

PURIFICATION OF PLG: It is known in the art (See, for example, Peptide Acylation by Poly(α-Hydroxy Esters) by Lucke et al., Pharmaceutical Research, Vol. 19, No. 2, p. 175-181, February 2002) that proteins and peptides which are incorporated in PLG matrices can be undesirably altered (e.g., degraded or chemically modified) as a result of interaction with degradation products of the PLG or impurities remaining after preparation of the polymer. As such, the PLG polymers used in the preparation of the majority of microparticle formulations described herein were purified prior to preparation of the sustained release compositions using art recognized purification methods.

CHARACTERIZATION METHODS: It has been determined that the following characterization methods are suitable for identifying microparticles which will provide a desirable release profile of active agent.

POROSITY MEASUREMENT-MERCURY INTRUSION Pore volume distribution in microparticles was determined using a model

SutoPor IV 9500 Moden Mercury Intrusion Porosimeter (Micromeritics, Norcross, GA). Briefly, mercury was forced into a known amount of microparticles in a penetrometer by applying pressure in a step-wise manner up to a maximum pressure of 60,000 Psia. The volume of mercury intruded into the pores at various pressures was measured. This method quantifies the pore distribution in the microparticles. That is, the size of the pores that are intruded is inversely related to the applied pressure. The equilibrium of the internal and external forces on the liquid-solid- vapor system can be described by the Washburn equation. The relationship between applied pressure and the pore size into which mercury is forced to enter is described by:

D=-4γ cosθ P Where: D = pore diameter γ = surface tension (constant) θ = contact angle (constant) P= Pressure

Therefore, the size of the pore into which mercury will intrude is inversely proportional to the applied pressure. Assuming that all pores are tight cylinders, the average pore diameter (D=4V/A) can be calculated by dividing pore volume (V=πD2h/4) by the pore area (A=πDh).

RESEDUAL SOLVENTS

A single method was used for quantitation of heptane, ethanol and methylene chloride. The equipment consisted of an HP 5890 Series 2 gas chromatograph with an Rtx 1301, 30 cm x 0.53 mm column. About 130 mg microparticles were dissolved in 10 ml N,N-dimethylformamide. Propyl acetate was used as the internal standard. The sample preparation was adjusted so that concentrations of methylene chloride as low as 0.03% can be quantitated.

MICROPARTICLE PREPARATION The microparticle batches set forth in Table 1 were prepared as described above at the 100 gram scale using the 4A polymer and a ratio of silicone oil to methylene chloride of either 1.5:1 or 1:1 and the silicone oil had a viscosity of 350 cs. The amount of exendin-4 and the excipients used in the formulation are also set forth in Table 1.

TABLE l

*ALL FORMULATIONS HAD 3% DRUG LOAD WITH THE EXCEPTION OF #5 POROSITY

The total intrusion volume obtained from the mercury intrusion porosimetry and the calculated average pore diameters are given in TABLE 2.

TABLE 2

PREPARATION OF MICROPARTICLES HAVING 3% EXENDIN-4 AND 2% SUCROSE In view of the variation in porosity introduced by the presence of ammoniun sulfate in the microparticle formulations and the identification of porosity as a characteristic which significantly impacts initial release, ammonium sulfate was not pursued in further discovery. IMPACT OF INNER EMULSION DROPLET SIZE

The following study was done to determine the impact of process parameters on forming the inner emulsion as well as stability of the resulting emulsion and resulting 24 hour in vitro release of microspheres produced using the different process parameters. Inner emulsions of the water phase and solvent phase were formed by either sonication as described above for the 100 gr scale or homogenization using an MT5000 homogenizer with a 36/4 generator (Kinematica AG, Switzerland) at either a low speed (10,800 rpm) or high speed (21,300 rpm). Following inner emulsion formation by the different techniques, the emulsions were held in the reactor with gentle agitation with an overhead stirrer for 5, 15 or 60 minutes prior to an aliquot being removed. Following the designated hold times, the inner emulsion was further processed as described above into microparticles and then the 24 hour in vitro release determined for each batch as described below.

Inner emulsion droplet size characterization can be determined using the Horiba particle size analyzer

An aliquot of the inner emulsion was withdrawn from the reactor using a glass pipet. Using a transfer pipet, ~30 drops of the inner emulsion was added to ~10 ml of 6% Medisorb® 50:50 4A PLG polymer solution in a 20 cc screw-cap scintillation vial followed by mixing. The 6% Medisorb® 50:50 4A PLG polymer solution also served as the reference blank solution. About 9 ml of this diluted emulsion sample was then transferred into a clean 10 ml Horiba sample holder. A cover was placed on the sample holder to prevent rapid evaporation of the polymer solvent. The prepared sample was within the acceptable % transmission reading range of 0.65% - 0.90% per the blue bar (Lamp). A relative refractive index setting of 0.94-0.0Oi was selected in the program setup. The sample was then measured by a Horiba particle size analyzer such as model LA 910 for droplet size.

MICROSPHERE CHARACTERIZATION

Exendin-4 microspheres were routinely characterized with respect to drug content, particle size, residual solvents, initial in vitro release, and PK characteristics in rats. Drug was extracted to obtain a preliminary assessment of exendin-4 purity post-encapsulation in selected batches. IN VITRO INITIAL RELEASE

The initial release of exendin-4 was determined by measuring the concentration of exendin-4 after 1 hour in release buffer (10 mM HEPES, 100 mM NaCl, pH 7.4). 150± 5 mg of microspheres were placed in 5.0 mL of 1OmM HEPES, 10OmM NaCl, pH 7.4 buffer at room temperature, vortexed for about 30 seconds to suspend the solution and then placed in a 37 ⁰C air chamber for 1 hour. After 1 hour, the samples were removed from the chamber and inverted several times to mix, followed by centrifuging at 3500 rpm for 10 minutes. The supernatant was removed and analyzed immediately by HPLC using the following conditions: Column: TSK-GEL^®, 7.8 mm x 30 cm, 5 m (TSOH BIOSEP PART #08540);

Column Oven Temperature: Ambient; Autosampler Temperature: 6 ⁰C; Flow Rate: 0.8 mL/minute; Detection: 280 nm; Injection Volume: 10 L; Mobile Phase: 35% Acetonitrile/65% Water with 0.1% TFA/liter (v/v); Run Time: Approximately 20 minutes. Exendin-4 bulk drug substance, 0.2 mg/mL prepared in 30 mM Acetate Buffer, pH 4.5, was used as a standard.

EXAMPLE

A long acting formulation consisting of 5% AC2993, 2% sucrose and Medisorb® 50:50 poly D,L-lactic-co-glycolic acid, manufactured according to the above methods, is used. The subjects will fast (no food or beverage allowed except water) overnight at least 8 hours prior to each visit. The subjects will be dosed during a three day lead in period with exenatide (5μg) twice daily and will return weekly over fourteen weeks to receive a single SC injection. Subjects will be dosed with 0.8 or 2.0 mg microspheres suspended in a vehicle containing 3% carboxymethylcellulose, 0.1% polysorbate 20, 0.9% sodium chloride and water.

While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.

Claims

CLAIMSWhat is claimed is:

1. A method of administering via superpositioning a long acting release formulation comprising a biocompatible polymer, an antidiabetic or glucoregulatory polypeptide and a sugar.

2. The method of Claim 1, wherein the polypeptide is GLP-I, GLP-2, exendin- 3, exendin-4 or an analog, derivative or agonist thereof.

3. The method of Claim 1, wherein the polypeptide is exendin-4.

4. The method of Claim 1, wherein the formulation is administered weekly.

5. The method of Claim 1, wherein the formulation is administered biweekly.

6. The method of Claim 1, wherein the formulation releases the polypeptide for a period of at least two weeks.

7. The method of Claim 1, wherein the formulation releases the polypeptide for a period of at least four weeks.

8. A method of treating a patient suffering from Type 2 diabetes comprising administering via superpositioning a therapeutically effective amount of a long acting release formulation consisting essentially of a biocompatible polymer, a biologically active agent selected from the group consisting of an exendin, exendin analog, derivative, or agonist, and a sugar wherein the ratio of C_max to C_ave is 3 or less.

9. The method of Claim 8, wherein the agent is exendin-4.

10. The method of Claim 9, wherein the biocompatible polymer of the long acting release formulation is selected from poly(lactides), poly(glycolides), poly(lactide-co-glycolides), poly(lactic acid)s, poly(glycolic acid)s, poly(lactic acid-co-glycolic acid)s and blends and copolymers thereof.

11. The method of Claim 9, wherein the sugar is present at a concentration from about 0.01% w/w to about 10% w/w of the total weight of the sustained release composition.

12. The method of Claim 9, wherein the total pore volume of the formulation is about 0.1 mL/g or less as determined by mercury intrusion porosimetry.

13. The method of Claim 9, wherein the polypeptide is present at a concentration of about 0.1% to about 10% of the total weight of the composition.

14. The method of Claim 9, wherein the formulation is administered weekly.

15. The method of Claim 9, wherein the formulation is administered biweekly.

16. The method of Claim 9, wherein the formulation releases the polypeptide for a period of at least two weeks.

17. The method of Claim 9, wherein the formulation releases the polypeptide for a period of at least four weeks.

18. A method of treating a patient suffering from Type 2 diabetes comprising administering via superpositioning a therapeutically effective amount of a long acting release formulation consisting of a poly(lactide-co-glycolide) polymer, exendin-4 and sucrose or mannitol, wherein: the sucrose or mannitol is present at a concentration from about 0.01% w/w to about 10% w/w of the total weight of the long acting formulation; the exendin-4 is present at a concentration of about 0.1% to about 10% of the total weight of the formulation. the total pore volume of the formulation is about 0.1 mL/g or less as determined by mercury intrusion porosimetry; the formulation releases the polypeptide for a period of at least four weeks; and the formulation is administered weekly.

19. A method of administering via superpositioning a long acting release formulation comprising a biocompatible polymer, an antidiabetic or glucoregulatory polypeptide and a sugar characterized in a release profile that approximates the release profile of Figure IA or IB.