WO2011112576A1

WO2011112576A1 - Microspheres for sustained release of octreotide acetate

Info

Publication number: WO2011112576A1
Application number: PCT/US2011/027538
Authority: WO
Inventors: Alain Cabana; Bonabes De Rouge; Peter Markland
Original assignee: Ambrilia Biopharma Inc.
Priority date: 2010-03-10
Filing date: 2011-03-08
Publication date: 2011-09-15

Abstract

The present invention provides Octreotide acetate-loaded microspheres comprised of a linear PLGA co-polymer having a ratio of Octreotide acetate to PLGA co polymer of between 0.03 and 0.07 (g/g). Microspheres of the invention, compositions and formulations thereof are free of chlorinated solvent and contain less than 5% residual solvent. The Octreotide-loaded microspheres of the invention can be injected intra-muscularly to provide sustained release of Octreotide acetate over a period of up to 6 weeks. Pharmaceutical formulations of the invention are useful for treatment of disorders including but not limited to acromegaly and diarrhoea and flushing associated with malignant carcinoid tumors and VIPomas.

Description

MICROSPHERES FOR SUSTAINED RELEASE OF OCTREOTIDE ACETATE

Background of the Invention

Microspheres including Octreotide acetate micro-encapsulated in a polymer, such as linear poly (DL-lactide-co-glycolide) (PLGA) and poly (L-lactide), or star shaped poly (DL- lactide-co-glycolide), provide sustained release of Octreotide acetate in vivo. One such sustained release formulation, Sandostatin® LAR Depot (SLAR), is commercially available for long-term maintenance therapy in acromegalic patients and treatment of severe diarrhoea and flushing associated with malignant carcinoid tumors and vasoactive intestinal peptide tumors (VIPoma tumors). SLAR consists of microspheres made of Octreotide acetate encapsulated in a biodegradable poly (DL-lactide-co-glycolide)-glucose star polymer.

Generally, SLAR containing 10, 20, 30 or 40 mg of Octreotide acetate is administered by intramuscular injection at two to four week intervals to provide sustained and therapeutic release of Octreotide acetate.

Octreotide acetate, an acetate salt of a cyclic octapeptide, is known chemically as L- Cysteinamide, D-Phenylalanyl-L-cysteinyl-L-phenylalaynyl-D-tryptophyl-L-lysyl-L-threonyl-N- [2-hydroxy-1-(hydroxymethyl)propyl]-, cyclic (2 -7)-disulfide; [R-R^*, R^*)], acetate. Octreotide acetate exerts pharmacological actions similar to the natural hormone somatostatin.

However, Octreotide acetate is a more potent inhibitor of growth hormone, glucagon and insulin than somatostatin. Octreotide acetate suppresses lutenizing hormone (LH) response to gonadotrophin releasing hormone (GnRH), decreases splanchnic blood flow, and inhibits the release of serotonin, gastrin, vasoactive intestinal peptide (VIP), secretin, motilin, and pancreatic polypeptide. Because Octreotide acetate reduces growth hormone and/or somatomedin C (IGF-1 ) levels, sustained release formulations are used to treat patients suffering from acromegaly. Octreotide acetate is also used to treat symptoms associated with metastatic carcinoid tumors (flushing and diarrhoea), and Vasoactive Intestinal Peptide (VIP) secreting adenomas (watery diarrhoea).

Octreotide acetate reduces blood levels of growth hormone (GF) and IGF-1 in acromegaly patients who have had inadequate response to or cannot be treated with surgical resection, pituitary irradiation, and bromocriptine mesylate at maximally tolerated doses. The goal of treatment with Octreotide acetate is to normalize GH and IGF-1 levels. In patients with acromegaly treated with sustained release Octreotide acetate serum levels of GH are reduced to normal levels in 50 % of patients and IGF-1 levels are reduced to normal levels in 50 to 60 % of patients. Since effects of pituitary irradiation may take several years to reach maximum efficacy, Octreotide acetate can be administered after irradiation and until the effects of radiation are sufficient to control the disease.

In patients with malignant carcinoid syndrome treated by IM injection of SLAR, and once steady-state serum Octreotide levels are reached, 35 to 40% of patients require supplemental subcutaneous Octreotide acetate to control exacerbation of carcinoid symptoms. After 6 months of treatment this percentage increases to 50% to 70% of patients.

The rate and duration of Octreotide acetate release from SLAR are largely governed by gradual biodegradation of the microsphere polymer in the muscle and subsequent release of the encapsulated Octreotide acetate from the degraded polymer. In the first 1 - 12 hours immediately following intramuscular injection Octreotide acetate is released by mechanisms that are independent of polymer degradation. During this release phase, known as the initial release phase or initial burst, the rate of release is higher relative to the rate of release that occurs due to polymer degradation. Once Octreotide acetate is released from the polymer and diffuses into the systemic circulation it is distributed and eliminated according to its known pharmacokinetic properties.

SLAR can also be used in the treatment of hypothalamic obesity, which is a common sequela to tumours of the hypothalamic region and their treatment with surgery and radiotherapy, and in the treatment of thyroid-stimulating hormone (TSH)-producing pituitary and endocrine-active gastroenteropancreatic tumors.

The efficacy and safety of sustained release compositions depends on controlled and reproducible Octreotide acetate release over the duration of the treatment period, generally 4 weeks. Efforts to develop similar products using various types of PLGA, other than poly (DL- lactide-co-glycolide)-glucose, have not yet proven successful and led to regulatory approval of alternative PLGA based alternative products. Improvements or advantages could include reduced cost of production, increased efficacy, reduced toxicity, eliminate the use of chlorinated solvents to reduce toxic residuals, longer duration of release, a reduction in the rate of release during the initial release phase, reduced time to reach steady-state therapeutic levels, reduced variation during the steady state.

One ongoing challenge in the development of new sustained release drug formulations, and in particular those including linear poly (DL-lactide-co-glycolide) polymer, has been reproducibly controlling the rate and duration of drug release to provide maximum efficacy and safety. For example, safety can be improved by preventing or reducing the excessive release during the initial release phase which can be associated with toxicity, negative side effects. In the development of sustained release compositions of Octreotide- loaded PLGA microspheres it has proven difficult to reproducibly achieve a safe initial burst followed by continuous release of a therapeutic dose of Octreotide acetate over a treatment period of at least 4 to 6 weeks. Developing new formulations of microspheres that include Octreotide acetate encapsulated in a linear PLGA polymer that provide therapeutic release over 4 - 6 weeks has proven challenging. To date, no microsphere formulations for sustained release of Octreotide acetate that include a linear PLGA co-polymer have been successfully developed or brought to market. Various methods for controlling the initial release phase have been proposed to date such as: raising the polymer concentration during encapsulation, reducing drug particle size during encapsulation, decreasing the content of low molecular weight water-soluble impurities in the polymer material, heating the microsphere product, coating the microsphere with a high viscosity polymer, washing the microsphere surface to remove excess drug at the surface and incorporating additives during microsphere formation. However none of these methods have been successfully applied in the development of a linear PLGA co-polymer microsphere formulation that provides safe and therapeutic release of Octreotide acetate for treatment of acromegaly, flushing and diarhea associated with VIPomas and carcinoid tumors, or any other indications in which SLAR may be indicated.

Summary of the Invention

The present invention provides Octreotide acetate-loaded microspheres that are free of chlorinated solvent and that include a linear PLGA co-polymer having a ratio of Octreotide acetate to co polymer (g/g) of between 0.03 and 0.07.

Microspheres of the invention include linear PLGA co-polymer encapsulating Octreotide acetate and having a ratio of Octreotide acetate to co-polymer (g/g) between 0.03 and 0.07, desirably between 0.04 and 0.06, or of 0.05. The ratio of Octreotide acetate to copolymer can be 0.03, 0.04, 0.05, 0.06, 0.07 or any number in between.

The linear PLGA-co-polymer includes a plurality of poly (DL-lactide-co-glycolide) polymer units each weighing between 5.0 kDa and 25 kDa, 9 kDa and 20 kDa, or 9 kDa and 15 kDa. Microspheres of the invention include a linear PLGA-co-polymer containing poly (DL- lactide-co-glycolide) polymer units having a molecular weight of 9 kDa, 10 kDa, 1 kDa, 12 kDa, 13 kDa, 14 kDa, 15 kDa, 16 kDa, 17 kDa, 18 kDa, 19 kDa, 20 kDa, or any number in between. Desirably, the polymer units each weigh approximately 12 kDa.

The linear PLGA-copolymer contains a ratio of lactide to glycolide (hereafter referred to as lactide/glycolide) (g/g) between 1.8 and 5.8, between 2.5 and 3.5, or between 2.7 and 3.3 (e.g., 2.75 and 3.25). Desirably, the linear PLGA-copolymer contains a lactide/glycolide ratio (g/g) 3.00. Microspheres of the invention include a linear PLGA-co-polymer with a ratio of lactide/glycolide (g/g) of 1.8, 2.0, 2.5, 3.00, 3.5, 4.0, 4.5, 5.0, 5.5, 5.8 or any number in between.

The linear PLGA-copolymer included in the microspheres of the present invention has a polymer polydispersity (Mw/Mn) of between 1.5 and 2.5, desirably between 1.7 and 2.3. Microspheres of the invention include a linear PLGA-co-polymer having a polydispersity of 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1 , 2.2, 2.3, 2.4, 2.5, or any number in between. In one embodiment, the linear PLGA-co-polymer has a polydispersity of 2.0. Microspheres of the invention are free of residual chlorinated solvents, contain no residual chlorinated solvent, and are manufactured using only non-chlorinated solvents. In some embodiments, microspheres of the invention are manufactured using only non- chlorinated solvent, preferably ethyl acetate, and contain less than 5% g/g residual non- chlorinated solvent. In one embodiment microspheres of the invention contain between 1 % and 5% g/g residual ethyl acetate.

Microspheres of the invention have a diameter between about 25 pm and about 150 pm. A plurality of microspheres of the invention have diameters within the range between 25 pm and 150 pm or within a narrower range such as 40 pm and 50 pm or 75 and 100 pm. The average diameter, of a plurality of microspheres of the invention, is between 40 and 80 pm, preferably between 50 and 70 pm. The average diameter of a plurality of microspheres of the invention can be 40 pm, 45 pm, 50 pm, 55 pm, 60 pm, 65 pm, 70 pm, 75 pm, 80 pm or any number in between.

In preferred embodiments of the invention, microspheres of the invention have a porous surface and a dense non-porous interior.

In one embodiment microspheres of the invention have a ratio of Octreotide acetate to PLGA-co-polymer between 0.03 and 0.07 (g/g) and a ratio of lactide/glycolide between 1.8 and 5.8.

In one embodiment microspheres of the invention have a ratio of Octreotide acetate/co-polymer between 0.03 and 0.07 (g/g) and a ratio of lactide/glycolide between 2.5 and 3.5.

In one embodiment microspheres of the invention have a ratio of Octreotide acetate/co-polymer between 0.03 and 0.07 (g/g) and a ratio of lactide/glycolide between 2.75 and 3.25.

In one embodiment microspheres of the invention have a ratio of Octreotide acetate/co-polymer between 0.03 and 0.07 (g/g) and a ratio of lactide/glycolide of 3.0.

In one embodiment microspheres of the invention have a ratio of Octreotide acetate/co-polymer between 0.03 and 0.07 (g/g) and a ratio of lactide/glycolide between 1.8 and 5.8, wherein each poly (DL-lactide-co-glycolide) polymer unit weighs between 10 to 20 kDa, and the co-polymer has a polydispersity between 1.7 and 2.3.

In another embodiment, microspheres of the invention have a ratio of Octreotide acetate/co-polymer of 0.05 (g/g) and a ratio of lactide/ glycolide between 1.8 and 5.8, wherein each poly (DL-lactide-co-glycolide) polymer unit weighs between 10 to 20 kDa, and the copolymer has a polydispersity between 1.7 and 2.3.

In another embodiment, microspheres of the invention have a ratio of Octreotide acetate/co-polymer of 0.05 (g/g) and a ratio of lactide/ glycolide between 1.8 and 5.8, wherein each poly (DL-lactide-co-glycolide) polymer unit weighs between 10 to 20 kDa, and the copolymer has a polydispersity of 2.0.

In another embodiment, microspheres of the invention have a ratio of Octreotide acetate/co-polymer of 0.05 (g/g) and a ratio of lactide/glycolide of between 2.5 and 3.5, wherein each poly (DL-lactide-co-glycolide) polymer unit weighs between 10 to 20 kDa, and the co-polymer has a polydispersity between 1.7 and 2.3.

In another embodiment, microspheres of the invention have a ratio of Octreotide acetate/co-polymer of 0.05 (g/g) and a ratio of lactide/ glycolide of between 2.75 and 3.25, wherein each poly (DL-lactide-co-glycolide) polymer unit weighs between 10 to 20 kDa, and the co-polymer has a polydispersity between 1.7 and 2.3.

In one embodiment, microspheres of the invention have a ratio of Octreotide acetate/co-polymer of 0.05 (g/g) and a ratio of lactide/ glycolide of 3.0, wherein each poly (DL- lactide-co-glycolide) polymer unit weighs between 10 to 20 kDa, and the co-polymer has a polydispersity between 1.7 and 2.3.

In one embodiment, microspheres of the invention have a ratio of Octreotide acetate/co-polymer between 0.04 and 0.6 (g/g) and a ratio of lactide/ glycolide of 3.0, wherein each poly (DL-lactide-co-glycolide) polymer unit weighs between 10 to 20 kDa, and the copolymer has a polydispersity of 2.0.

In one embodiment, microspheres of the invention have a ratio of Octreotide acetate/co-polymer between 0.04 and 0.06 (g/g) and a ratio of lactide/glycolide of 3.0, wherein each poly (DL-lactide-co-glycolide) polymer unit weighs between 5 to 25 kDa, and the co-polymer has a polydispersity of 2.0.

In one embodiment, microspheres of the invention have a ratio of Octreotide acetate/co-polymer between 0.04 and 0.06 (g/g) and a ratio of lactide/glycolide of 3.0, wherein each poly (DL-lactide-co-glycolide) polymer unit weighs between 10 to 20 kDa, and the co-polymer has a polydispersity of 2.0.

In one embodiment microspheres of the invention have a ratio of Octreotide acetate/co-polymer between 0.04 and 0.06 (g/g) and a ratio of lactide/ glycolide of 3.0, wherein each poly (DL-lactide-co-glycolide) polymer unit weighs between 15 to 25 kDa, and the co-polymer has a polydispersity of 2.0.

In one embodiment, microspheres of the invention have a ratio of Octreotide acetate/co-polymer between 0.04 and 0.06 (g/g) and a ratio of lactide/ glycolide of 3.0, wherein each poly (DL-lactide-co-glycolide) polymer unit weighs between 15 kDa, and the copolymer has a polydispersity of 2.0.

In one embodiment, microspheres of the invention have a ratio of Octreotide acetate/co-polymer between 0.04 and 0.06 (g/g) and a ratio of lactide/glycolide between 1.8 and 5.8, wherein each poly (DL-lactide-co-glycolide) polymer unit weighs between 10 to 20 kDa, and the co-polymer has a polydispersity of 2.0.

In one embodiment, microspheres of the invention have a ratio of Octreotide acetate/co-polymer between 0.04 and 0.06 (g/g) and a ratio of lactide/glycolide between 2.5 and 3.5, wherein each poly (DL-lactide-co-glycolide) polymer unit weighs between 15 to 25 kDa, and the co-polymer has a polydispersity of 2.0.

In one embodiment microspheres of the invention have a ratio of Octreotide acetate/co-polymer between 0.04 and 0.06 (g/g) and a ratio of lactide/ glycolide between 2.25 and 3.75, wherein each poly (DL-lactide-co-glycolide) polymer unit weighs between 5 kDa, and the co-polymer has a polydispersity of 2.0.

Microspheres of the invention, pharmaceutical compositions, and formulations thereof may be administered to patients, for example humans, by intramuscular injection, at a dose between 0.2 mg/kg to 0.4/mg/kg. Desirably, the microspheres of the invention,

pharmaceutical compositions, and formulations thereof are administered to patients, in an amount and for a time sufficient to provide safe and therapeutic release of Octreotide acetate for up to 42 days. Although administration and dosing may vary, generally, a quantity of microspheres containing 10 mg to 40 mg of Octreotide acetate is injected intramuscularly every 4 to 6 weeks, preferably every 6 weeks.

Microspheres of the invention, pharmaceutical compositions, and formulations thereof provide sustained release of Octreotide acetate when administered to a patient by intramuscular injection. In one desired embodiment, microspheres of the invention compositions and formulations thereof administered by intra-muscular injection release less than 2%, of the total amount of Octreotide administered, into the blood during the first 24 hours following injection.

Microspheres of the invention, pharmaceutical compositions, and formulations thereof, when administered to rabbits at a dose of 4 mg/kg by intra-muscular injection, provide a minimum blood concentration of 250 pg of Octreotide acetate/ml of blood, for up to 42 days.

Microspheres of the invention, pharmaceutical compositions, and formulations thereof, when administered to rabbits at a dose of 4 mg/kg by intra-muscular injection can provide a maximum blood concentration of 10,000 pg of Octreotide acetate/ml of blood, during the first 48 hours following administration.

The present invention provides pharmaceutical compositions and formulations that include any of the Octreotide acetate-loaded microspheres of the invention.

The present invention provides a method of treating acromegaly by administering a pharmaceutical composition that include the Octreotide acetate-loaded microspheres of the invention. The present invention provides a method of treating diarrhoea and flushing associated with carcinoid syndrome, vasoactive intestinal peptide tumors (VIPoma), acquired immune deficiency syndrome (AIDS), HIV infection or chemotherapy by administering a pharmaceutical composition that includes the microspheres of the invention.

The present invention provides a method of decreasing circulating levels of GH or

IGF-1 in a patient in need thereof by administering a pharmaceutical composition that includes the Octreotide acetate-loaded microspheres of the invention.

The present invention provides a method of treating hypothalamic obesity by administering a pharmaceutical composition that includes the Octreotide-acetate microspheres of the invention.

The present invention provides a method of reducing, shrinking or inhibiting the growth of GH secreting pituitary adenomas by administering a pharmaceutical composition that includes the Octreotide-acetate microspheres of the invention.

The present invention provides a method of treating thyroid-stimulating hormone (TSH)-producing pituitary and endocrine-active gastroenteropancreatic tumors by administering a pharmaceutical composition that includes the Octreotide-acetate microspheres of the invention.

The present invention provides a method of treating diarrhoea due to disease or treatment-related causes by administering a pharmaceutical composition that includes the Octreotide-acetate microspheres of the invention.

Pharmaceutical formulations of the present invention can be used as a therapeutic alternative to SLAR to treat the same diseases and conditions where SLAR is indicated.

Pharmaceutical formulations of the present invention are useful in providing therapeutic sustained release of Octreotide acetate over a period of 2 to 6 weeks.

Pharmaceutical formulations of the present invention, may also be useful in the treatment in the range of indications described herein and including but not limited to bowel obstruction, nausea and vomiting, upper Gl-bleeding due to gastric ulcers and oesophageal varicies, death rattle, gastrointestinal fistulae, pain, hypercalcaemia, ectopic hormone syndromes, ectopic growth hormone releasing hormone syndrome, medullary thyroid carcinomas, pituitary resistance to thyroid hormones, tall stature children, diabetes mellitus and diabetic complications, polycystic ovary syndrome and Graves' ophthalmopathy,

In another aspect the present invention provides a method of using microspheres of the invention for manufacturing a pharmaceutical composition.

In another aspect the present invention provides a method of using microspheres of the invention for manufacturing a pharmaceutical composition for treatment of acromegaly. In another aspect the present invention provides a method of using microspheres of the invention for treating diarrhoea and flushing associated with carcinoid syndrome, vasoactive intestinal peptide tumors (vipoma), acquired immune deficiency syndrome (AIDS), HIV infection, and chemotherapy.

In another aspect the present invention provides a method of using microspheres of the invention for treatment of thyroid-stimulating hormone (TSH)-producing pituitary and endocrine-active gastroenteropancreatic tumors.

In another aspect the present invention provides a method of using microspheres of the invention for treatment of diarrhoea due to disease or treatment-related causes.

In another aspect the present invention provides a method of using microspheres of the invention for manufacturing a pharmaceutical composition that provides therapeutic sustained release of Octreotide acetate over a period of 2 to 6 weeks.

In another aspect the present invention provides a method of administering

Octreotide to a patient in need of sustained Octreotide therapy, said method including administering a pharmaceutical composition that includes the Octreotide-acetate

microspheres of the invention.

In another aspect the present invention provides a process for the production of Octreotide acetate-loaded microspheres of the present invention where the process includes the steps of:

a. Dispersing Octreotide acetate in a solution of linear PLGA co-polymer in ethyl

acetate, or a similar non-chlorinated organic solvent, to form a dispersion having a ratio of Octreotide acetate/co-polymer (g/g) between 0.05 and 0.20and a ratio of lactide/glycolide (g/g) between 1.8 and 5.8, wherein the co-polymer includes poly (DL-lactide-co-glycolide) polymer units weighing between 5 and 25 kDa and has a polydispersity between 1.7 and 2.3;

b. combining the dispersion with an effective amount of an aqueous continuous process medium (CPM) and mixing to form an emulsion containing the CPM and micro- droplets of the dispersion;

c. after formation of the emulsion, adding a solvent extraction medium to the emulsion to; extract the organic solvent from the emulsion, harden the co-polymer, encapsulate the dispersed Octreotide-acetate and form microspheres; and

d. mixing the Octreotide-loaded microspheres of step (c) in an aqueous solvent for 15 to 180 minutes and collecting the microspheres by sieving.

In another aspect the present invention provides a process for the production of Octreotide acetate-loaded microspheres of the present invention includes the steps of: a. Dispersing Octreotide acetate in a 50% solution of linear PLGA co-polymer in ethyl acetate, or a similar non-chlorinated organic solvent, to form a dispersion having a ratio of Octreotide acetate/co-polymer (g/g) between 0.05 and 0.20 and a ratio of lactide/glycolide (g/g) between 1.8 and 5.8, wherein the co-polymer includes poly (DL-lactide-co-glycolide) polymer units weighing between 5 and 25 kDa and has a polydispersity between 1.7 and 2.3;

b. combining the dispersion with an effective amount of a continuous process medium, in a mixer, to form an emulsion that contains the continuous process medium and micro-droplets of the dispersion;

c. after formation of the emulsion pumping an effective amount of a solvent extraction medium into and through a mixer, containing the emulsion, to extract the solvent from the emulsion forming microspheres, and collecting the effluent in a holding tank; and d. mixing the effluent collected in the holding tank for 15 to 180 minutes and pumping the effluent across a sieve to collect the microspheres.

In another aspect the present invention provides a process for the production of Octreotide acetate-loaded microspheres of the present invention includes the steps of:

a. dispersing Octreotide acetate in a solution of linear PLGA co-polymer in ethyl acetate (with a ratio of PLGA/ethyl acetate of 1), or a similar non-chlorinated organic solvent, to form a dispersion having a ratio of Octreotide acetate/co-polymer (g/g) of 0.10 and a ratio of lactide/glycolide of 3.0, wherein the co-polymer includes poly (DL-lactide-co- glycolide) polymer units weighing between 10 and 20 kDa and has a polydispersity of 2.0;

b. combining the dispersion with an effective amount of a continuous process medium and mixing to form an emulsion containing the CPM and micro-droplets of the dispersion;

d. mixing the Octreotide-loaded microspheres of step (c) in an aqueous solvent for 15 to 80 minutes and collecting the microspheres by sieving.

a. dispersing Octreotide acetate in a solution of linear PLGA co-polymer in ethyl acetate (with a ratio of PLGA/ethyl acetate of 1 ), or a similar non-chlorinated organic solvent, to form a dispersion having a ratio of Octreotide acetate/co-polymer (g/g) of 0.05 and a ratio of lactide/glycolide of 3.0, wherein the co-polymer includes poly (DL-lactide-co- glycolide) polymer units weighing between 10 and 20 kDa and has a polydispersity of 1.7;

c. after formation of the emulsion pumping an effective amount of a solvent extraction medium into and through the mixer, containing the emulsion, to extract the solvent from the emulsion forming microspheres, and collecting the effluent in a holding tank; and

d. mixing the effluent collected in the holding tank for 15 to 180 minutes and pumping the effluent across a sieve to collect the microspheres.

In another aspect the present invention provides octreotide-loaded microspheres produced using a process of the present invention.

Pharmaceutical compositions and formulations of the present invention provide sustained release of Octreotide over a period of 14 to 42 days and can be used to treat acromegaly, and diarrhoea and flushing associated with vasoactive intestinal peptide tumors (vipoma), carcinoid tumors and chemotherapy.

The release profile of the pharmaceutical compositions of the present invention differs from that of SLAR in that the duration of therapeutic Octreotide acetate release is longer (e.g., by at least 1 day, 2 days, 3 days, 4 days, 5 days, 6 days, 7 days, 8 days, 9 days, 10 days, 11 days, 12 days, 13 days, 14 days, 15 days, 16 days, 17 days, 18 days, 19 days, 20 days, or more), allowing for a dose interval (or treatment period/injection) of up to a maximum of 42 days rather than up to a maximum 28 days.

In example of a therapeutic method of the invention, following intra-muscular administration of 0.2 mg/kg to 0.4 mg/kg of a pharmaceutical composition of the present invention less than 2% of the total Octreotide acetate administered (total amount of

Octreotide acetate contained in the microspheres administered) is released during the first 24 hrs following administration (initial burst or initial release phase).

All percentages and ratios used herein are expressed as gram/gram except where otherwise specified.

Definitions

The following explanations of certain terms are meant to be illustrative rather than exhaustive. These terms have their ordinary meanings given by usage in the art and in addition include the following explanations. "And/or" as used herein means any one of the items, any combination of the items, or all of the items with which this term is associated.

"Admixture" as used herein means a mixture of two or more components or polymers together. "Admixing" refers to the mixing of two or more components or polymers. There may or may not be chemical or physical interactions between the components of an admixture.

Singular forms "a," "an," and "the", as used herein, include plural reference unless the context clearly dictates otherwise. Thus, for example, a reference to "a composition" includes a plurality of such compositions, so that a composition of drug X includes compositions of drug X.

"Biodegradable" as used herein means that the material, substance, compound, molecule, polymer or system is cleaved, oxidized, hydrolyzed or otherwise broken down by hydrolytic, enzymatic or another mammalian biological process for metabolism to chemical units that can be assimilated or eliminated by the mammalian body.

"Drug" as used herein means any chemical substance that, when absorbed into the body of a living organism, alters bodily function including but not limited to peptides, hormones, analogues of endogenous hormones, agonists, antagonists, organic small molecules, polypeptides, antibodies, oligonucleotides such as siRNA and the like. Drugs can be used for the treatment, cure, prevention, or diagnosis of disease or used to otherwise enhance physical or mental well-being. Drugs of the invention are micro encapsulated in a linear

PLGA copolymer as part of a microsphere that provides sustained in vivo release. Exemplary drugs include but are not limited to ligands, antigens, adjuvants, hormones, antibiotics, enzymes, and so on. Drugs" or "compounds" are not limited to a single agent, but is intended to include a plurality of active agents, such as combinations of antigens, combinations of antigen(s) and adjuvants, and so on.

"Encapsulation" as used herein denotes a method for formulating a drug into a polymer-based composition useful for sustained release of the drug. Examples of polymers for encapsulation of drugs include polyesters, and especially polymers PLGA, or polylactide.

"Polypeptide" as used herein refers generally to peptides and proteins having at least about two amino acids.

"Peptide" as used herein means a sequence of 2 to about 50 amino acids (e.g. as defined herein above) or peptidyl residues. The sequence may be linear or cyclic. For example, a cyclic peptide can be prepared or may result from the formation of disulfide bridges between two cysteine residues in a sequence. Preferably a peptide includes 3 to 30, or 5 to 20 amino acids. Peptide derivatives can be prepared as disclosed in U.S. Patent Numbers 4,612,302; 4,853,371 ; and 4,684,620. Peptide sequences specifically recited herein are written with the amino terminus on the left and the carboxy terminus on the right. "Combination" as used herein when referring to components of a polymer, means a physical mixture or blend of co-polymers, a non-homogenous mixture of co-polymers, multiple layers of individual co-polymers or homogenous mixture of co-polymers.

"Device" as used herein means any drug composition, implant, or sustained release formulation that can be implanted in vivo and provides drug delivery over more than 7 days, more preferably more than 21 days and most preferably more than 30 days, 40 days, or 42 days.

"Dispersion" as used herein means a mixture of a solid in solution wherein the solid is not soluble in the solution. A quantity of a solid such as a drug powder is mixed thoroughly, but not solubilized, in a volume of a solution or organic solvent.

"Drug delivery" or "Drug release" as used herein means release of a drug from a

pharmaceutical composition which is administered by injection and implanted in vivo.

Desirably, for the present invention, release is generally sustained release of the drug (e.g., Octreotide acetate) from an intramuscular implantation site into the blood.

Dispersion or as used herein means a solvent containing un-solubilized particles of drug mixed such that the particles are not solubilized but are distributed evenly throughout the solution.

"Emulsion" as used herein means a mixture of two immiscible solutions or a solution and a dispersion that are immiscible. A smaller volume of a first solution or a dispersion is mixed in a larger volume of second solution (the continuous phase or continuous process medium). For example, an emulsion of a 50 ml solution of polymer in organic solvent in 500 ml of aqueous solvent containing a water soluble drug (an oil-in-water emulsion) or a 10 ml solution of drug in aqueous solvent in 50 ml of a solution of polymer in organic solvent (an water-in-oil emulsion). In one example a smaller volume of a dispersion, is mixed in a larger volume of an aqueous solvent (continuous process medium) to form an emulsion. Emulsions used in processes of the present invention include a dispersion of octreotide in a solvent and aqueous continuous phase, in such an emulsion the dispersion is present throughout the continuous phase in the form of micro-droplets.

"Continuous process medium" as used herein means the solution that forms the continuous phase of an emulsion.

"Solvent extraction medium" as used herein means an aqueous solvent used to extract organic solvent from an emulsion.

"Initial burst phase" or "initial burst" as used herein means the release of drug, from a sustained release pharmaceutical composition, that occurs within the first 0 to 48 hours, preferably the first 0 to 24 hours following administration. This initial release of drug is often pulsile and is distinct from the later continuous phase where drug is release at a constant rate for the remainder of the treatment period. "Microsphere" as used herein refers to a spherical, or substantially spherical, particle that includes a polymer or co-polymer matrix micro-encapsulating a drug, wherein the polymer acts as an excipient for the release of drug from the microsphere in an aqueous or physiological environment.

"Optional" or "optionally" as used herein means that the subsequently described event, step, method, component or circumstance may or may not occur, consistent with the methods and compositions described herein and in the prior art.

"Linear PLGA" as used herein means an amorphous co-polymer that includes poly (DL- lactide-co-glycolide) polymer units. PLGA is synthesized by means of random ring-opening co-polymerization of two different monomers, the cyclic dimers (1 ,4-dioxane-2,5-diones) of glycolic acid and lactic acid. Common catalysts used in the preparation of this polymer include tin(ll) 2-ethylhexanoate, tin(ll) alkoxides, or aluminum isopropoxide. During polymerization, successive monomeric units (of glycolic or lactic acid) are linked together in PLGA by ester linkages, thus yielding a linear, aliphatic polyester as a product. Depending on the ratio of lactide to glycolide used for the polymerization, different forms of PLGA can be obtained: these are usually identified in regard to the monomers' ratio used (e.g. PLGA 75:25 (or ratio of 3.0) identifies a co-polymer whose composition is 75% lactic acid and 25% glycolic acid). It should be noted that as used herein, the ratio of lactide/glycolide can be expressed either as the percent of each component (e.g., 75% and 25%), a ratio of the percentages of each component (e.g., 75/25), or the numeric value of the ratio (e.g., 3.0). PLGA co-polymer is amorphous rather than crystalline and shows a glass transition temperature in the range of 40-60 °C. Unlike the homo-polymers of lactic acid (polylactide) and glycolic acid

(polyglycolide) which show poor solubilities, PLGA can be dissolved by a wide range of common solvents, including chlorinated solvents, tetrahydrofuran, acetone or ethyl acetate. PLGA degrades by hydrolysis of its ester linkages in the presence of water. It has been shown that the time required for degradation of PLGA is related to the monomers' ratio used in production: the higher the content of glycolide units, the lower the time required for degradation.

"Pores" or 'Pore" as used herein refers to round or irregular openings within a polymer matrix having a diameter greater than 0.5 pm, preferably 1 pm to 10 μιτι, desirably 1 pm to 4 pm. Pores are larger than the spaces within the polymer matrix and can be observed using electron microscopy. Pores may contain precipitated drug, dissolved drug, dissolved polymer, or solvent and any combination thereof.

"Porosity" as used herein means a measure of the void spaces in a material. Porosity can be expressed as the density of pores (# pores/area as viewed in cross-section).

"Porous" as used herein means containing pores having a diameter greater than 0.5 pm, preferably 1 pm to 10 pm and more preferably 1 pm to 4 pm. "Star shaped PLGA" as used herein means a reaction product of a polyol containing at least 3 hydroxyl groups and having a molecular weight of up to 20,000 or a reactive derivative thereof, with a lactic acid or glycolic acid containing co-polymer or a reactive derivative thereof.

"Dosing interval" as used herein refers to the time between intra-muscular injections of a sustained release octreotide formulation as part of a therapeutic regimen. For the sustained release formulations of the present invention the dosing interval is 2 to 6 weeks, preferably 4 to 6 weeks and most preferably 6 weeks.

"Polydispersity" is used herein to refer to the distribution of molecular weights of polymers in a given sample. The polymers of the co-polymer of the present invention include lactide and glycolide, specifically poly (DL-lactide-co-glycolide) polymer units. The Polydispersity Index (PDI) is a specific measure of polydispersity and is the weight average molecular weight (Mw) divided by the number average molecular weight (Mn) and relates to the distribution of individual molecular weights in a given sample of polymers. PDI can be determined using Gel Permeation Chromatography (GPC). As the polymer chains in a given sample approach uniform chain length, PDI approaches 1.

"Polymer" is used herein to refer to a chemical species containing a plurality of repeating units which are bonded to each other. A polymer may contain more than one different repeating unit. The repeating unit typically derives from polymerization of a monomer. A co-polymer specifically refers to a polymer containing two or more structurally different repeating units, the co-polymer of the present invention includes repeating units containing lactide and glycolide polymer, specifically poly (DL-lactide-co-glycolide) polymer units. The different repeating units of a polymer may be randomly ordered in the polymer chain or the same repeating units may be grouped into contiguous blocks in the polymer. When there are contiguous blocks of the two or more repeating units in a polymer, the polymer is a block copolymer. As used herein the term polymer refers to a chemical species containing a total of more than 10 repeating units (there may be one or more repeating units).

"Chlorinated solvent" as used herein means an organic solvent that includes an organic compound containing at least one covalently bonded chlorine atom.

"Non-chlorinated solvent" as used herein means an organic solvent that does not contain compounds containing at least one covalently bonded chlorine atom or halogen atom.

Examples of non-chlorinated solvents preferred for use in the present invention include ethyl acetate. Brief Description of the Drawings

Figure 1 shows the plasma concentration of Octreotide acetate-loaded microspheres of the invention over 42 days in New Zealand albino rabbits administered (C2L formulation produced by method described in Example 1). A dose of 4 mg/kg was administered in a dose volume of 0.75mL by injection into the lateral compartment of the right or left thigh. Plasma Octreotide acetate levels were determined using LC-MS/MS.

Figure 2 shows an electron micrograph of a microsphere prepared as described herein and in Example 1 , illustrating the morphology of the microsphere surface relative to the core.

Detailed Description of the Invention

Improved sustained-release compositions that provide safe and therapeutic release of Octreotide acetate are needed. The safety and therapeutic efficacy of sustained release compositions depends on controlled and reproducible Octreotide acetate release over the duration of the treatment period, generally 4 weeks. Efforts to develop similar products using various types of PLGA, other than poly (DL-lactide-co-glycolide)-glucose, have not yet proven successful and no PLGA based alternative sustained-release compositions have been approved for therapeutic uses. Improved Octreotide acetate sustained-release compositions could have an associated reduced cost of production, increased efficacy, reduced toxicity, eliminate the use of chlorinated solvents to reduce toxic residuals, longer duration of release, a reduction in the rate of release during the initial release phase, reduced time to reach steady-state therapeutic levels, and reduced variation during the steady state.

The present inventors have discovered linear PLGA co-polymer microspheres for the sustained release of Octreotide acetate for treatment of acromegaly, flushing and diarhea associated with VIPomas and carcinoid tumors, or other indications in which SLAR may be indicated. These formulations provide an improvement over the present standard of care in a number of respects. The octreotide-loaded microspheres and pharmaceutical formulations of the invention are free of toxic chlorinated solvent. The octreotide-load microspheres and pharmaceutical formulations of the invention can be administered a longer dosing intervals resulting is cost saving, a reduction in the use of healthcare resources and a more convenient treatment regimen for the patient. Production of PLGA co-polymer Octreotide acetate loaded microspheres

The efficacy and safety of sustained release compositions depends on controlled and reproducible Octreotide acetate release over the duration of the treatment period. The controlled and reproducible release is affected by a number of factors including but not limited to permeability, ratio of the polymer phase to continuous phase, the type of emulsion used, and porosity.

Permeability is a primary factor for controlling initial drug release from microspheres (the initial burst) (Wang J. ef. a/., 2002). The initial permeability is influenced by the porosity of the polymer, the structure of the pore network and the distribution of drug within the microsphere, on the surface of the microsphere, and within any pores or channels present at the surface of the microsphere and accessible to the physiological media prior to polymer degradation.

During the preparation of microspheres by solvent extraction from an emulsion, the ratio of the polymer phase (polymer solution/drug) to continuous phase (aqueous solvent) has impact the release profile. Decreasing the ratio of polymer phase to continuous phase provides microspheres with a reduced initial release of drug. Furthermore, the polymer concentration of the polymer phase also has an effect on the initial release of such that increasing the concentration of polymer reduces the initial release of drug.

The homogenization speed used for mixing an emulsion for polymer encapsulation of drug and preparation of Octreotide-loaded microspheres has an effect on both the size and porosity of the microspheres prepared (Mao S. er. al. 2007). Mao showed that size and porosity increased with higher stirring rates, and that microspheres prepared at higher emulsion stirring rates provided higher initial release rates. Mao also found that the initial rate of Octreotide release decreased with increasing drug loading. The type of emulsion used in encapsulation of a drug has an impact on the surface porosity and the rate of initial rate of release from microspheres; a single emulsion provides microspheres with a smooth surface and very few pores, double emulsion provides microsphere with many pores of around 1 um in diameter at the surface. Comparing similar compositions, microspheres prepared using a double emulsion method provided a 13.5% burst and single emulsion no detectable burst.

Taking in to account the above factors which affect efficacy and safety of sustained release compositions, we have discovered the following general methods and parameters which can be used to produce the Octreotide acetate loaded microspheres of the invention.

The following methods are meant to exemplify methods for production of octreotide- loaded microspheres. They are not meant to limit the invention in any way.

Linear PLGA co-polymer is preferably dissolved in ethyl acetate at a ratio of 0.8 - 1.0 g of PLGA/0.8 - 1.0 g of ethyl acetate (a ratio of 0.80 to 1.25 polymer/solvent) and un- solubilized Octreotide acetate is dispersed throughout the PLGA-ethyl acetate solution forming a dispersion. The amount of Octreotide acetate dispersed is 0.05 to 0.20 (Octreotide acetate/PLGA, g/g) and preferably 0.01 or 10%. The PLGA solution containing dispersed Octreotide acetate, the dispersed phase (DP), can be mixed using a high speed mixer, preferably a Silverson mixer. In a preferred method, the mixer is in line with 3 reservoirs: a reservoir containing a continuous process medium (CPM), a reservoir containing solvent extraction medium (SEM) and a collection reservoir. Pumps and tubing maybe provided for pumping media into the mixer from the CPM and SEM reservoirs and for pumping media from the mixer into the collection reservoir. Alternately the DP and CPM can be simultaneously added to or pumped into a mixer and mixed to form an emulsion. The CPM is an aqueous solution preferably containing a stabilizing agent such as a surfactant, preferably polyvinyl alcohol in an amount of from about 0.1 to about 5%, e.g. 2%. The volume of CPM used to prepare the emulsion is selected to ensure that the emulsion is saturated with the organic solvent, preferably ethyl acetate present in the DP.

The CPM and DP can be simultaneously pumped into the Silverson mixer running between 500 and 2500 rpm. Following addition of the CPM to the DP, the emulsion is mixed and homogenized at a rate of 500 - 2500 rpm. Following homogenization, SEM is pumped into the mixer and the SEM/CPM-DP emulsion is pumped simultaneously from the mixer into the collection reservoir at the same rate.

The ratio of CPM to DP in the emulsion is between 10:1 and 30:1 , preferably 20:1 and the ratio of SEM to CPM, for solvent extraction, is between 15:1 and 5:1 preferably 10: 1.

The effluent in collection reservoir is mixed for 15 to 180 minutes preferably 30 to 90 minutes.

Hardened and formed microspheres are isolated by pumping the suspension from collection reservoir first across 150 pm mesh sieve and then a 25 pm mesh sieve. Oversized microspheres (diameter greater than 150 pm) collected on the 150 pm sieve are disposed of and microspheres collected on the 25 pm sieve (diameter between 25 and 150 pm) are retained and dried.

The solvent extraction processes, parameters and methods disclosed herein provide microspheres with less than 5% ethyl acetate content. Relative to higher ethyl acetate content, an ethyl acetate content of less than 5% w/w enables reduced release of ethyl acetate and solubilization of Octreotide by ethyl acetate during the initial burst phase;

reducing the initial burst of Octreotide in the first 24 hours following administration.

The present invention also provides pharmaceutical compositions that include the microspheres of the invention. The pharmaceutical composition may be in a dry form or contain an aqueous vehicle to facilitate reconstitution and administration by injection. A vehicle for suspension of the microspheres of the invention may include a viscosity increasing agent and/or wetting agent and additionally water.

Microspheres of the present invention, pharmaceutical compositions, and formulations thereof are advantageous over similar compositions known in the art, such as SLAR. For example, microspheres of the present invention provide prolonged therapeutic release of Octreotide (up to 42 days), reconstitute more easily for injection, and do not contain residual chlorinated solvents. In addition, while reconstituted SLAR must be injected immediately, generally within 2 to 3 minutes of reconstitution, due to the tendency of the reconstituted solution to agglomerate and become impossible to inject, reconstituted solutions of microspheres of the present invention do not have a tendency to agglomerate and can be injected for up to 60 minutes, following reconstitution. This makes injections of pharmaceutical compositions of the present invention easier and more convenient compared to SLAR and reduces the loss of drug due to agglomeration prior to injection.

Mannitol may be used as both an anti-agglomerating agent and an isotonizing agent in the present invention. Suitable viscosity-increasing agents may also be included in the pharmaceutical compositions of the invention, such as carboxymethyl cellulose sodium and preferably carboxymethyi cellulose sodium having a low viscosity from 10 to 15 mPA when measured as a 1 % (wt/v) aqueous solution at 25°C. Anti-agglomerating agents such as mannitol can be used in dry pharmaceutical compositions of the Octreotide-loaded microspheres of the present invention.

Non-ionic surfactants or other wetting agents can be included in the pharmaceutical compositions of the invention. In one embodiment polyoxyethylene block co-polymers are used having a molecular weight between 2000 and 8000 daltons and a degree of polymerization of the ethylene moiety of between 20 to 60 units. Polyoxethylene-sorbitan- fatty acid esters such as mono- and trilauryl, palmityl, stearyl and oleyl esters eg of the type known and commercially available under the trade name TWEEN: preferably 40

[polyoxyethylene (20) sorbitanmonopalmitate] (TWEEN 40) and 80 [polyoxethylene (20 sorbitanmonoleate] (TWEEN 80). Such non-ionic surfactants are preferably present at about 0.10 to 0.1% of the pharmaceutical composition. Pharmaceutical compositions of the invention also include Octreotide-loaded microspheres of the inventions admixed or in association with a non-ionic surfactant.

The amount of liquid vehicle for suspension is preferably between 1.0 to 3.0 ml, and providing for example 2.0 to 2.5 ml per dose. The vehicle may be mixed with the Octreotide- loaded microspheres of the invention or pharmaceutical composition thereof prior to administration. The suspension is mixed manually for 30 seconds or more and can be injected up to 60 minutes after reconstitution.

A dry pharmaceutical composition of the invention and an aqueous vehicle for reconstitution may be housed separately in a double chamber syringe or in separate vessels as part of a kit containing a pharmaceutical composition of the invention and an aqueous vehicle for reconstitution.

Example 1 : Preparation of C2L Octreotide-Loaded Microspheres

(1) Preparation of the Dispersed Phase (DP)

100 g of poly-(DL-Lactide-co-glycolide) having a ratio of lactide to glycolide ratio of 3.0 (g/g), molecular weights between 10 and 20 kDa and a polydispersity of approximately 2.0 was dissolved in 100 g of ethyl-acetate and 10 g of Octreotide acetate was dispersed into in the polymer solution; forming a dispersed phase (DP). (2) Preparation of the Emulsion

The dispersed phase (DP) was pumped simultaneously with a 2 L of continuous process medium (CPM) containing, 2% (g/g) polyvinyl alcohol (PVA) in water, into a Silverson L4RT mixer. The CPM was prepared using sterile water for injection and filtered through a 0.22 pm filter. Within the Silverson mixer an emulsion was formed by mixing at 1000 rpm for 5 minutes; forming micro-droplets of DP in CPM.

(3) Solvent Extraction

The emulsion was transferred into a collection reservoir containing 300 L of water and mixed for 2 minutes; allowing for extraction of the solvent from of the emulsion and hardening (formation) of microspheres from the DP micro-droplets. The formed microspheres were incubated with the solvent extraction medium in the collection reservoir for 30 to 60 minutes

(4) Isolation of Microspheres by Sieving

Flow from the collection reservoir was passed though a 25 pm mesh sieve and subsequently a 150 mesh sieve. Microspheres with diameters between 25 and 150 pm were collected and air dried. The octreotide loaded microspheres obtained (C2L formulation) contain an average of 5 g of Octreotide acetate per 100 g.

(5) Preparation of a 30 mg C2L formulation for injection

600 mg of the C2L microspheres, containing 30 mg of Octreotide acetate, was dispersed in a suitable buffer as described herein, mixed and loaded into a syringe for intramuscular injection, preferably intra-gluteal.

For preparation of microspheres of the present invention a DP is prepared containing linear PLGA co-polymer dissolved in ethyl acetate at a ratio of 0.80 to 1.25 (g/g), preferably 0.95 to 1.10 and more preferably 1.0.

The mixture of the DP and CPM are emulsified at room temperature by mixing at high speed, generally about 500 to 2500 rpm, preferably using a Silverson Mixer. This high speed mixing produces an emulsion containing micro-droplets of the dispersed phase within the CPM. These micro-droplets have a diameter of 25 to 150 pm and are hardened to form microspheres of polymer encapsulated Octreotide during solvent extraction. Organic solvent is preferably extracted after sufficient emulsification generally about 0.5 to 10 minutes, preferably about 1 minute. In the emulsion the CPM is saturated with organic solvent from the DP, to prevent solvent extraction and polymer hardening during emulsification. Preferably the organic solvent used to prepare the DP has a solubility of 1 part per 100 parts to about 25 parts per 100 parts in the SEM used for hardening the micro-droplets. In preferred embodiments the solvent used to dissolve the polymer (Step 1 ) is ethyl acetate. The volume of organic solvent used in the DP and the volume of CPM used in the emulsion of is selected so that the emulsion is saturated with organic solvent.

A stabilizing agent, preferably PVA, is added to the emulsion to prevent agglomeration and allow for the formation of a stable emulsion. The concentration of the stabilizing agent can affect the final size of the microspheres prepared from an emulsion. Generally the concentration of the stabilizing agent is between 0.01 to about 20% depending on the type of agent used, the organic solvent used in the polymer solution and the type of CPM used in the emulsion. Generally a surfactant, such as PVA, is used at 0.025 to 1.0% (w/w), preferably 2%. Other suitable stabilizing agents include: polyvinyl pyrolidone including Povidone K12 F, Povidone K15 or Povidone k17, preferably, the polyvinyl pyrolidone is present is present in an amount of from about 0.1 to about 20%, e.g. 5%; low molecular weight carboxymethyl cellulose sodium with a viscosity up to 20 cP for a 2% aqueous solution or a viscosity of from 8 to 25 mPa.s, a degree of substitution from about 1.15 to about 1.45 and a sodium content is about 0.5% to about 12%; Porcine or Fish gelatin with a viscosity of 25 to 35 cps in a 10% solution at 20°C; polyvinyl alcohol (PVA) with a molecular weight from about 10000 to about 90000 daltons, e.g. about 30000 daltons. Preferably PVA is used, preferred brands include Mowiol 4-88 and 8-88 available from Clariant AG Switzerland. Preferably the polyvinyl alcohol is present in an amount of from about 0.1 to about 5%, e.g. 0.5%. Other examples of compounds that can be used as surfactants include but are not limited to Tween 80, Tween 20, and the like.

Solvent extraction, for preparation of microspheres of the invention, is carried our using an aqueous solvent as the solvent extraction medium, preferably water. The organic solvent used to dissolve the polymer and in the emulsion must have a limited solubility in the solvent extraction medium, such as from about 1 part per 100 to about 25 parts per 100. The solubility of ethyl acetate in water is 8 parts per 100.

An excess of SEM, such as water, is used. An excess volume of SEM, between 200 - 1000 fold and preferably 500 to 1000 fold, is added to the emulsion to extract the organic solvent from the emulsion and harden the co-polymer to form microspheres. The SEM maybe added to the emulsion using methods known in the art, preferably it is pumped through the mixer, into the emulsion, and subsequently to the reservoir tank. This method of solvent extraction and polymer micro-encapsulation is described in U.S. Pat. No. 5,407,609.

The linear PLGA co-polymer used in the manufacture of microspheres of the present invention may be produced using conventional techniques known in the art such as polycondensation and ring-opening of dimers. The co-polymer may be a reaction product of lactic acid or a reactive derivative there of, preferably a racimate of D,L-lactide, and glycolic acid or a derivative thereof, preferably glycolide. A catalyst may be used in the production of linear PLGA co-polymer such as zinc oxide, zinc carbonate, basic zinc carbonate, diethyl zinc, organotin compounds, for example stannous octoate (stannous 2-ethylhexanoate), tributylaluminium, titanium, magnesium or barium compounds or litharge Stannousoctoate (stannous 2-ethylhexanoate) is preferred.

The inherent viscosity of the linear PLGA co-polymer used in the production of Octreotide-loaded microspheres of the present invention is preferably between 0.1 to .25 dl/g, more specifically 0.1 to 0.20 dl/g in hexafluorisopropanao or preferably chloroform when measured at 20°C and under standard conditions.

The co-polymer used in the production of Octreotide-loaded microspheres of the present invention contains low levels of residual monomers, preferably less than or equal to 2.5% D, L-lactide and 0.1 % glycolide.

The exterior surface of the Octreotide-loaded microspheres of the present invention is porous and the interior is dense and nonporous. The surface and interior morphology of the Octreotide-loaded microspheres of the present invention can be viewed using electron microscopy. This morphology is determined by the specific physiochemical properties of the emulsion, as well as the solvent extraction media, extraction and isolation methods used in the preparation of the microspheres of the present invention.

Pharmaceutical compositions of the invention may contain a preservative, a buffer or buffers, multiple excipients, such as polyethylene glycol (PEG) in addition to trehalose or mannitol, or a nonionic surfactant such as Tween® surfactant. Non-ionic surfactants include polysorbates, such as polysorbate 20 or 80, and the poloxamers, such as poloxamer 184 or 188, Pluronic® polyols, and other ethylene oxide/propylene oxide block co-polymers, etc. Amounts effective to provide a stable, aqueous composition will be used, usually in the range of from about 0.1 % (w/v) to about 30% (w/v). Suitable preservatives for us in pharmaceutical compositions of this invention include phenol, benzyl alcohol, meta-cresol, methyl paraben, propyl paraben, benzalconium chloride, and benzethonium chloride. Preferred preservatives include about 0.2 to 0.4% (w/v) phenol and about 0.7 to 1 % (w/v) benzyl alcohol, although the type of preservative and the concentration range are not critical.

The pH of the pharmaceutical compositions of this invention is generally about 5 to 8, preferably about 6.5 to 7.5. Suitable buffers to achieve this pH include, for example, phosphate, Tris, citrate, succinate, acetate, or histidine buffers, depending on the pH desired. Preferably, the buffer is in the rangeof about 2 mM to about 100 mM.

In general, pharmaceutical compositions of this invention may contain other components in amounts not detracting from the preparation of stable forms and in amounts suitable for effective, safe pharmaceutical administration. For example, other

pharmaceutically acceptable excipients well known to those skilled in the art can form a part of the subject compositions. These include, for example, salts, various bulking agents, additional buffering agents, chelating agents, antioxidants, co-solvents and the like; specific examples of these include tris-(hydroxymethyl)aminomethane salts ("Tris buffer"), and disodium edetate.

The microspheres are placed into pharmaceutically acceptable, sterile, isotonic compositions together with any required cofactors, and optionally are administered by standard means well known in the field. Microsphere compositions are typically stored as a dry powder. Figure 1 shows an electron micrograph of a microsphere prepared as described in above illustrating the morphology of the microsphere surface relative to the core.

Example 2: In Vivo Pharmacokinetic Analysis in Rabbits

4 mg/kg of the C2L octreotide-loaded microspheres, manufactured as described in

Example 1 was administered intramuscularly to New Zealand Albino rabbits and the plasma concentration of Octreotide acetate was monitored using standard LC-MS/MS methods. Figure 2 shows the average of data obtained from 6 animals and shows that the

microspheres of the invention, injected intra-muscularly, provided sustained release of Octreotide acetate over a period of 42 days in vivo. 4 mg/kg in a dose volume of 0.75 mL was injected into the lateral compartment of the right or left thigh using a 19G 1.5" syringe.

Example 3: In Vivo Pharmacokinetic Analysis in Healthy Subjects

A randomized, single-dose, open-label, 1-way parallel comparative bioavailability study was carried out in healthy subjects to evaluate the rate and extent of absorption of 30 mg C2L (Treatment A) versus 30 mg SLAR (Treatment B). On day 1 , subjects in group A were administered a 30 mg dose of C2L (Treatment A) and subjects in group B were administered a 30 mg dose of SLAR (Treatment B). Blood samples were collected from subjects prior to study drug administration and 0.50, 1.0, 2.0, 3.0, 4.0, 6.0, 9.0, 12.0, and 24.0 hours post-dose, and on the mornings of Days 4, 7, 14+1 , 21+1 , 28±1 , 35±2, 38±2, 42±2, 45±2, 49±2, 56±2, 63±2, 77+2, 91±2, and 105+2, after administration.

30 mg SLAR (SANDOSTATIN LAR® Depot 30 mg) was purchased from Novartis Pharmaceuticals Corporation, USA and prepared for injection and injected as recommended on the product packaging.

30 mg C2L was manufactured and prepared for injection and injection as described in

Example 1 above.

Mean plasma concentrations of Octreotide acetate in the 2 treatment groups were monitored over 80 days. Plasma octreotide concentrations were determined using standard LC MS/MS methods (limit of detection of 99.76 pg/mL). A therapeutic plasma concentration of approximately 1000 pg/ml of Octreotide acetate was maintained in the C2L group for a longer duration (more than 42 days), than in the SLAR group showing that the C2L 30 mg formulation can be administered at a 4 or 6 week dosing interval while maintaining a plasma concentration of at least 1000 pg/ml. Furthermore under the same in vivo conditions and using identical analytical methods for determining plasma levels, the two formulations have a similar release profile. Example 4: Evaluation of C2L 30 mg in Acromegalic Patients

In a randomized comparative study of 65 acromegalic patients was carried out to evaluate the efficacy and safety of 30 mg C2L administered every 6 weeks to that of the current standard of care 30 mg SLAR administered every 4 weeks. The duration to the study was 84 days, 2 doses of 30 mg C2L were administered IM at 6 week intervals and 3 doses of SLAR were administered IM at 4 week doses. The clinical response to C2L and SLAR in this study was identical between the treatment groups. The clinical response for each patient was determined based on symptoms of acromegaly and the acromegaly index score.

In an extension of this study all patients in the C2L group continued to receive injections of 30 mg C2L at 6 week intervals for an additional 84 days. Patients that were treated with SLAR injections every 4 weeks were switched to CTL injections every 6 weeks over 84 days. In the extension study GH and IGF-1 levels were stable during the extension study and unchanged from end of the first part of the study. Improvements, decreases, in GH and IGF-1 levels observed in patients treated with SLAR during the first part of the study, were maintained during the extension when patients were switched to treatment with 30 mg C2L injected every 6 weeks.

These data support that C2L 30 mg is effective and well tolerated and can be administered every 6 weeks with an efficacy equivalent to that of SLAR administered every 4 weeks.

Example 5: Dosing and Administration

For treatment of acromegaly or diarrhoea and flushing associated with carcinoid tumors and VIPomas, 20 mg, 30 mg and 40 mg doses of Octreotide acetate can be administered by intramuscular injection of a formulation that includes the microspheres of the present invention. Injections of microspheres of the present invention that include 20 mg of Octreotide acetate can be administered at a dosing interval between 3 to 4 weeks, preferably 4 weeks. Injections of microspheres of the present invention that include 30 mg or 40 mg of Octreotide acetate can be administered at a dosing interval between 4 to 6 weeks, preferably 6 weeks. The injection is intramuscular (IM), preferably intra-gluteal

Patients with acromegaly not previously treated with Octreotide acetate, are generally treated initially with subcutaneous Octreotide acetate at a dose of 50 meg t.l.d. to evaluate the patient's response to Octreotide acetate, including serum GH and IGF-1 levels.

Subcutaneous administration of Octreotide acetate is recommended for at least 2 weeks to determine the patients' response and tolerance to the treatment. Patients who respond to and tolerate subcutaneous Octreotide acetate can then be switched to a sustained release formulation that includes the microspheres of the present invention. A 20 mg dose administered every 3 to 4 weeks can be first administered for at least 3 months. Following which the dose can be modified or maintained according to the following criteria: (1) if serum GH concentration is≤ 2.5 ng/mL, serum IGF concentration is in the normal range and clinical symptoms are controlled: maintain a dose of 20 mg/3 to 4 weeks,

(2) if serum GH concentration is > 2.5 ng/mL, serum IGF concentration is elevated above the normal range and clinical symptoms are uncontrolled: increase dose to 30 mg/4 -6 weeks,

(3) if serum GH concentration is≤ 1.0 ng/mL, serum IGF concentration is in the normal range and clinical symptoms are controlled: reduce the dose to 10 mg/3 - 4 weeks,

If symptoms are not adequately controlled at a dose of 30mg/4 -6 weeks then the dose may be elevated to 40 mg/4 -6 weeks.

Patients, with acromegaly and being treated with subcutaneous Octreotide acetate, can be immediately administered a sustained release formulation that includes the microspheres of the present invention. These patients can be treated initially with a 20 mg dose IM administered every 3 - 4 weeks and for at least 6 - 8 weeks (two doses) before evaluation of the treatment efficacy. These patients may also continue to receive subcutaneous Octreotide acetate for at least 2 weeks after the first IM injection to maintain a therapeutic dose while a steady-state level is achieved from the sustained release formulation. Following 6 to 8 weeks of treatment (2 doses of 20 mg) the dose can be modified or maintained according to the following criteria:

(1) if serum GH concentration is≤ 2.5 ng/mL, serum IGF concentration is in the normal range and clinical symptoms are controlled: maintain a dose of 20 mg/3 to 4 weeks,

(2) if serum GH concentration is > 2.5 ng/mL, serum IGF concentration is elevated above the normal range and clinical symptoms are uncontrolled: increase dose to 30 mg/4 to 6 weeks,

(3) if serum GH concentration is≤ 1.0 ng/mL, serum IGF concentration is in the normal range and clinical symptoms are controlled: reduce the dose to 10 mg/3 to 4 weeks,

If symptoms are not adequately controlled at a dose of 30mg/4 -6 weeks then the dose may be elevated to 40 mg/4 to 6 weeks. Alternately patients that achieve full control of the symptoms at a 20 mg dose can be lowered to a 10 mg dose for a trial period.

In general when the dose or dose interval is modified in the treatment of a given patient, the efficacy of the treatment to reduce symptoms is evaluated after administration of at least 2 doses and near the end of the second dose interval.

In patients that have suffered renal failure and who require dialysis, the half-life of Octreotide acetate may be increased necessitating a lower maintenance dosage.

Patients suffering diarrhoea and flushing associated with carcinoid tumors and VIPomas and not previously treated with Octreotide acetate (ether subcutaneous or IM sustained release) should first be administered Octreotide acetate subcutaneously to evaluate the patient response and tolerance to Octreotide acetate. A dose between 100 to 600 meg/day in 2 - 4 divided doses should be administered and adjusted on a individual basis. Once a patient has responded well to subcutaneous Octreotide acetate for at least 2 weeks patients can be switched to a sustained release formulation of the present invention at a dose of 20 mg IM injection at a dosing interval of 4 to 6 weeks. During the first 2 weeks of treatment with the 20 mg sustained release formulation patients may continue to take subcutaneous injections of Octreotide acetate until steady-state therapeutic levels are obtained.

Other Embodiments

The description of the specific embodiments of the invention is presented for the purposes of illustration. It is not intended to be exhaustive or to limit the scope of the invention to the specific forms described herein. Although the invention has been described with reference to several embodiments, it will be understood by one of ordinary skill in the art that various modifications can be made without departing from the spirit and the scope of the invention, as set forth in the claims. All patents, patent applications, and publications referenced herein are hereby incorporated by reference. Other embodiments are in the claims.

What is claimed is:

Claims

1. A plurality of Octreotide acetate-loaded microspheres that are free of chlorinated solvent and comprised of a linear PLGA co-polymer having a ratio (g/g) of Octreotide acetate to PLGA co-polymer of 0.030 to 0.070 (g/g) and a ratio (g/g) of lactide/ glycolide of 1.8 to 5.8.

2. The microspheres of claim 1 , wherein the diameter of each microsphere is between 25 pm and 150 pm.

3. The microspheres of claim 2, wherein the average diameter of the plurality of

microspheres is between 40 μιη and 80 pm.

4. The microspheres of claim 2, wherein the average diameter of the plurality of

microspheres is between 50 pm and 70 pm.

5. The microspheres of any of claims 1-4, wherein the linear PLGA copolymer is

comprised of poly (DL-lactide-co-glycolide) polymer units weighing between 5.0 kDa and 25 kDa.

6. The microspheres of claim 5, wherein the linear PLGA copolymer is comprised of poly (DL-lactide-co-glycolide) polymer units weighing between 9 kDa and 20 kDa.

7. The microspheres of claim 6, wherein the linear PLGA copolymer is comprised of poly (DL-lactide-co-glycolide) polymer units weighing between 9 kDa and 15 kDa.

8. The microspheres of any of claims 1-7, wherein the ratio (g/g) of lactide to glycolide is between 2.50 and 3.50.

9. The microspheres of claim 8, wherein the ratio of lactide to glycolide is between 2.75 and 3.25.

10. The microspheres of claim 9, wherein the ratio of lactide to glycolide is about 3.00.

1 . The microspheres of any of claims 1-10, wherein the ratio of Octreotide acetate to PLGA co-polymer is between 0.04 and 0.07

12. The microspheres of claim 1 , wherein the ratio of Octreotide acetate to PLGA copolymer is 0.05.

13. The microspheres of any of claims 1-12 having a polydispersity (Mw/Mn) of 1.5 to 2.5.

14. The microspheres of claim 13, wherein the polydispersity is 1.7 to 2.3.

15. The microspheres of claim 14, wherein the polydispersity is 2.0.

16. The microspheres of any of claims 1-15, containing residual ethyl acetate at a level less than or equal to 5% (g/g).

17. The microspheres of claim 16, wherein the level of residual ethyl acetate is between 1 % and 5% (g/g).

18. The microspheres of any of claims 1-17, having a porous surface and a dense non- porous interior.

19. The microspheres of claim 1 having a ratio (g/g) of Octreotide acetate to linear PLGA co-polymer between 0.03 and 0.07 and a ratio (g/g) of lactide to glycolide between 2.50 and 3.50.

20. The microspheres of claim 19, wherein the linear PLGA copolymer is comprised of poly (DL-lactide-co-glycolide) polymer units weighing 15 kDa and has a polydispersity between 1.7 and 2.3.

21. The microspheres of claim 20, wherein the polydispersity is 2.0.

22. The microspheres of claim 21 , wherein the ratio of Octreotide acetate to linear PLGA co-polymer is 0.05.

23. The microspheres of claim 21 wherein the ratio of lactide to glycolide is 3.0.

24. A pharmaceutical formulation comprising the plurality of microspheres of any of claims 1 to 23.

25. The pharmaceutical formulation of claim 24, wherein said formulation is for

intramuscular injection.

26. The pharmaceutical formulation of claim 24, wherein said formulation comprises between 10mg and 40mg of Octreotide acetate.

27. The pharmaceutical formulation of claim 24, wherein the pharmaceutical formulation provides a therapeutic dose of Octreotide acetate for at least 4 weeks.

28. The pharmaceutical formulation of claim 27, wherein the pharmaceutical formulation provides a therapeutic dose of Octreotide acetate for at least 5 weeks

29. The pharmaceutical formulation of claim 28, wherein the pharmaceutical formulation provides a therapeutic dose of Octreotide acetate for at least 6 weeks.

30. The pharmaceutical formulation of claim 24, wherein a dose of 4 mg/kg of Octreotide acetate is administered to an animal by intramuscular injection and the concentration of Octreotide acetate in the blood of the animal, during the first 48 hours after injection, is not more than 10,000 pg/m.

31. The pharmaceutical formulation of claim 24 further comprising a pharmaceutically acceptable carrier.

32. An injectable sustained release drug composition comprising the microspheres of claims 1 to 23.

33. A method of reducing circulating GH or IGF-1 levels in a patient in need thereof, said method comprising administering said patient a pharmaceutical formulation of any of claims 24-31 or the injectable sustained drug release drug composition of claim 32.

34. A method of treating acromegaly comprising administering a pharmaceutical

formulation of any of claims 24-31 or the injectable sustained drug release drug composition of claim 32.

35. A method of treating diarrhoea or flushing associated with carcinoid syndrome,

vasoactive intestinal peptide tumors (VIPoma), or chemotherapy in a patient in need thereof, said method comprising administering the pharmaceutical formulation of any of claims 24-31 or the injectable sustained drug release drug composition of claim 32.

36. A method of treating hypothalamic obesity in a patient in need thereof, said method comprising administering the pharmaceutical formulation of any of claims 24-31 or the injectable sustained drug release drug composition of claim 32.

37. A method of treating thyroid-stimulating hormone (TSH)-producing pituitary and

endocrine-active gastroenteropancreatic tumors in a patient in need thereof, said method comprising administering pharmaceutical formulation of any of claims 24-31 or the injectable sustained drug release drug composition of claim 32.

38. A method of treating disease- or therapy-induced diarrhoea in a patient in need

thereof, said method comprising administering the pharmaceutical formulation of any of claims 24-31 or the injectable sustained drug release drug composition of claim 32.

39. A method of providing therapeutic sustained release of Octreotide acetate over a period of 2 to 6 weeks in a patient in need thereof, said method comprising administering the pharmaceutical formulation of any of claims 24-31 or the injectable sustained drug release drug composition of claim 32.

40. A method of reducing, shrinking or inhibiting the growth of GH secreting pituitary adenomas comprising administering the pharmaceutical formulation of any of claims 24-31 or the injectable sustained drug release drug composition of claim 32.

41. The method of any one of claims 33 to 40, wherein said pharmaceutical formulation is administered at a dosing interval between 4 and 6 weeks.

42. The method of any one of claims 33 to 40, wherein said pharmaceutical formulation is administered at a dosing interval of 6 weeks.

43. Use of the microspheres of any one of claims 1 to 23 for treating acromegaly.

44. Use of the microspheres of any one of claims 1 to 23 for treating diarrhoea or flushing associated with carcinoid syndrome, vasoactive intestinal peptide tumors (VIPoma), or chemotherapy.

45. A process for producing Octreotide acetate-loaded PLGA microspheres comprising the steps of:

a. dispersing Octreotide acetate in a solution of linear PLGA co-polymer in ethyl acetate, or a similar non-chlorinated organic solvent, to form a dispersion having a ratio of Octreotide acetate/co-polymer (g/g) between 0.05 to 0.20 and a ratio of lactide/glycolide (g/g) between 1.8 and 5.8, wherein the copolymer is comprised of poly (DL-lactide-co-glycolide) polymer units weighing between 5 and 25 kDa and has a polydispersity between 1.7 and 2.3;

b. combining the dispersion with an effective amount of an aqueous continuous process medium (CPM) and mixing to form an emulsion containing the CPM and micro-droplets of the dispersion;

c. after formation of the emulsion, adding a solvent extraction medium to the emulsion to; extract the organic solvent from the emulsion, harden the copolymer, encapsulate the dispersed Octreotide-acetate and form microspheres; and

46. The process of claim 45, wherein in step (d) an effective amount of a solvent

extraction medium is pumped into and through a mixer, containing the emulsion, to extract the solvent from said emulsion forming microspheres, and collecting the effluent in a holding tank.

47. The process of claim 45, wherein the effluent collected in the holding tank is mixed for 15 to 180 minutes and then pumped across a sieve to collect the microspheres.

48. The process of claim 45, wherein ratio of linear PLGA co-polymer to ethyl acetate in the polymer solution of step (a) is 1.0 (g/g).

49. The process of claim 45, wherein the ratio of Octreotide acetate to co-polymer in the dispersion of step (a) is 0.10.

50. The process of claim 45, wherein the ratio of lactide to glycolide in the solution of step (a) is 3.0.

51. The process of claim 45, wherein the lactide and glycolide contained in the solution of step (a) weigh between 10 and 20 kDa and have a polydispersity between 1.5 and 2.5.

52. The process of claim 51 , wherein the polydispersity is 2.0.

53. The process of claim 45, wherein the co-polymer contains lactide and glycolide weighing between 5 and 25 kDa and having a ratio between 1.8 and 5.8 and a polydispersity between 1.5 and 2.5.