Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Implant or insert
Reexamination Certificate
2003-02-24
2004-08-10
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Implant or insert
C424S422000, C424S423000, C424S424000, C514S772300
Reexamination Certificate
active
06773714
ABSTRACT:
BACKGROUND OF THE INVENTION
Leuprolide acetate is an LHRH agonist analog that is useful in the palliative treatment of hormonal related prostate cancer, mammary cancer, endometriosis, and precocious puberty. With continued use, leoprolide acetate causes pituitary desnsitizing and down-regulation to affect the pituitary-gonodal axis, leading to suppressed circulating levels of luteinizing and sex hormones. In patients with advanced prostate cancer, achieving circulating testosterone levels of less than or equal to 0.5 ng/ml (chemical castration level) is a desired pharmacological indicator of therapeutic action.
Originally, leuprolide acetate was launched in the United States as a daily subcutaneous (s.c.) injection of the analog solution. The inconvenience of chronic repetitive injections was later eliminated by the development of a one month sustained release depot product based on poly(DL-lactide-co-glycolide) microspheres (Lupron® Depot). Currently, one, three, and four month formulations are widely available as intramuscular (i.m.) injections of microspheres.
Although the current Lupron® Depot microspheres appear to be effective, the microsphere products are difficult to manufacture, and they all require a deep intramuscular (i.m.) injection using large volumes of fluid to ensure that all of the microspheres are properly administered to the patient. These injections are often painful and lead to tissue damage.
Biodegradable polymers other than Lupron® Depot have been employed in many medical applications, including drug delivery devices. The drug is generally incorporated into the polymeric composition and formed into the desired shape outside the body. This solid implant is then typically inserted into the body of a human, animal, bird, and the like through an incision. Alternatively, small discrete particles composed of these polymers can be injected into the body by a syringe. Preferably, however, certain of these polymers can be injected via syringe as a liquid polymeric composition.
Liquid polymeric compositions useful for biodegradable controlled release drug delivery systems are described, e.g., in U.S. Pat. Nos. 4,938,763; 5,702,716; 5,744,153; 5,990,194; and 5,324,519. These compositions are administered to the body in a liquid state or, alternatively, as a solution, typically via syringe. Once in the body, the composition coagulates into a solid. One type of polymeric composition includes a nonreactive thermoplastic polymer or copolymer dissolved in a body fluid-dispersible solvent. This polymeric solution is placed into the body where the polymer congeals or precipitatively solidifies upon the dissipation or diffusion of the solvent into the surrounding body tissues. It is expected that these compositions would be as effective as Lupron® Depot, since leuprolide of these compositions is the same as are in the Lupron® Depot and the polymers are similar.
Surprisingly, however, it has been discovered that the liquid polymeric compositions according to the present invention are more effective in delivering leuprolide acetate than Lupron® Depot. Specifically, the testosterone levels obtained with the liquid polymeric compositions of the present invention containing the leuprolide acetate are lower at extended times in dogs compared to Lupron® Depot, and also at the six month point in humans, compared to the value reported in the literature for Lupron® Depot (Sharifi, R.,
J. Urology
, Vol. 143, Jan., 68 (1990)).
SUMMARY OF THE INVENTION
The present invention provides a flowable composition that is suitable for use as a controlled release implant of leuprolide acetate. The flowable composition includes a biodegradable thermoplastic polyester that is at least substantially insoluble in an aqueous medium or body fluid. The flowable composition also includes a biocompatible polar aprotic solvent. The biocompatible polar aprotic solvent can be an amide, an ester, a carbonate, a ketone, an ether, or a sulfonyl. The biocompatible polar aprotic solvent is miscible to dispersible in aqueous medium or body fluid. The flowable composition also includes leuprolide acetate. The leuprolide acetate is preferably present in about 2 wt. % to about 4 wt. % of the composition or in about 4 wt. % to about 8 wt. % of the composition. Preferably, the flowable composition is formulated as an injectable subcutaneous delivery system. The injectable composition preferably has a volume of about 0.20 mL to about 0.40 mL or about 0.30 mL to about 0.50 mL. The injectable composition is preferably formulated for administration about once per month, about once per three months, or about once per four months to about once per six months. Preferably, the flowable composition is a liquid or a gel composition, suitable for injection into a patient.
Preferably, the biodegradable thermoplastic polyester is a polylactide, a polyglycolide, a polycaprolactone, a copolymer thereof, a terpolymer thereof, or any combination thereof. More preferably, the biodegradable thermoplastic polyester is a polylactide, a polyglycolide, a copolymer thereof, a terpolymer thereof, or a combination thereof. More preferably, the suitable biodegradable thermoplastic polyester is 50/50 poly (DL-lactide-co-glycolide) having a carboxy terminal group or is 75/25 poly (DL-lactide-co-glycolide) with a carboxy terminal group that is protected. The suitable biodegradable thermoplastic polyester can be present in any suitable amount, provided the biodegradable thermoplastic polyester is at least substantially insoluble in aqueous medium or body fluid. The suitable biodegradable thermoplastic polyester is preferably present in about 30 wt. % to about 40 wt. % of the flowable composition or is present in about 40 wt. % to about 50 wt. % of the flowable composition. Preferably, the biodegradable thermoplastic polyester has an average molecular weight of about 23,000 to about 45,000 or about 15,000 to about 24,000.
Preferably, the biocompatible polar aprotic solvent is N-methyl-2-pyrrolidone, 2-pyrrolidone, N,N-dimethylformamide, dimethyl sulfoxide, propylene carbonate, caprolactam, triacetin, or any combination thereof. More preferably, the biocompatible polar aprotic solvent is N-methyl-2-pyrrolidone. Preferably, the polar aprotic solvent is present in about 60 wt. % to about 70 wt. % of the composition or is present in about 45 wt. % to about 55 wt. % of the composition.
The present invention also provides for a method for forming a flowable composition. The flowable composition is useful as a controlled release implant. The method includes mixing, in any order, a biodegradable thermoplastic polyester, a biocompatible polar aprotic solvent, and leuprolide acetate. These ingredients, their properties, and preferred amounts are as disclosed above. The mixing is performed for a sufficient period of time effective to form the flowable composition for use as a controlled release implant. Preferably, the biocompatible thermoplastic polyester and the biocompatible polar aprotic solvent are mixed together to form a mixture and the mixture is then combined with the leuprolide acetate to form the flowable composition.
The present invention also provides for a biodegradable implant formed in situ, in a patient. The biodegradable implant product is prepared by the process of injecting a flowable composition within the body of the patient and allowing the biocompatible polar aprotic solvent to dissipate to produce a solid biodegradable implant. These ingredients, their properties, and preferred amounts are as disclosed above. Preferably, the patient is a human. The solid implant preferably releases the effective amount of leuprolide as the solid implant biodegrades in the patient.
The present invention also provides for a method of forming a biodegradable implant in situ, in a living patient. The method includes injecting the flowable composition of the present invention within the body of a patient and allowing the biocompatible polar aprotic solvent to dissipate to produce a solid biodegradable implant. The flowable composition includes an effecti
Chandrashekar Bhagya L.
Dunn Richard L.
Garrett John Steven
Ravivarapu Harish
Atrix Laboratories, Inc.
Bennett Rachel M.
Page Thurman K.
Schwegman Lundberg Woessner & Kluth P.A.
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