United States Patent:  6,077,523

Appl. No.:  311744

A pharmaceutical implant for the delivery of an effective amount of a bioactive peptide or peptide analog over a period of 1 to 12 months. This implant has a diameter of about 1 to 2 mm, a length of between about 10 and 25 mm and is obtainable from a process which includes the steps of grinding a copolymer of lactic acid and glycolic acid having a ratio of glycolide to lactide units of from about 0 to 5:1 to a particle size of between about 50 and 150 .mu.m; sterilizing the ground copolymer with a dose of between about 1 and 2.5 Mrads of ionizing .gamma.-radiation; wetting the ground and sterilized copolymer with a sterile aqueous slurry of a bioactive peptide or peptide analog; aseptically blending the copolymer and the slurry to obtain a homogeneous mixture of the copolymer and between about 10 and 50% of the bioactive peptide or peptide analog; drying the mixture at reduced pressure and at temperature not exceeding 25^oC.; aseptically extruding the dried mixture at a temperature between about 70 and 110^oC.; and aseptically cutting a cylindrical rod from the extruded mixture to form the pharmaceutical implant.

SUMMARY OF THE INVENTION

The present invention relates to a process for manufacturing pharmaceutical implants for the delivery of an effective amount of a bioactive peptide or peptide analog over a period of 1 to 12 months which comprises: grinding a copolymer of lactic acid and glycolic acid having a ratio of glycolide to lactide units of from about 0 to 5:1 to a particle size of between about 50 and 150 .mu.m; wetting the ground and copolymer with an aqueous slurry of a bioactive peptide or peptide analog; blending the copolymer and the slurry to obtain a homogeneous mixture of the copolymer and between about 10 and 50% of the bioactive peptide; drying the mixture at reduced pressure and at a temperature not exceeding 25^oC.; extruding the dried mixture at a temperature between about 70 and 110^oC.; and cutting cylindrical rods of about 1 to 2 mm diameter and between about 10 and 25 mm in length from the extruded mixture to form the implants.

Advantageously, the ground copolymer is sterilized with a dose of between about 1 and 2.5 Mrads of ionizing .gamma.-radiation before being combined with the bioactive peptide, and the blending, extruding and cutting steps are conducted under aseptic conditions. Also, the implants are generally sterilized in a conventional manner prior to being administered to the subject or patient.

The polymers or copolymers form a biodegradable matrix within which is contained a uniform distribution of the peptide or peptide analog. In these copolymers, an advantageous ratio of glycolide to lactide units ranges from about 0.5:1 to 3:1. One particularly preferred copolymer to be used is soluble in benzene and has an inherent viscosity of from 0.51 to 1 (1% in benzene). The amount of slurry is preferably controlled so that the amount of water in the mixture is between about 35 and 65 ml. per 100 grams copolymer, so that the amount of bioactive peptide in these rods is between about 10 to 50 percent by weight.

The bioactive peptide or peptide analog may be an agonist or antagonist of LHRH, GnRH, growth hormone releasing hormone, growth hormone releasing peptide, angiotensin, bombesin, bradykin, cholecystokinin, enkephalin, neurokinin, tachykinin or substance P. The bioactive peptide may also be an inhibitor such as a renin inhibitor, a protease inhibitor, a metallopeptidase inhibitor, enkephalinase and atrial or brain natriuretic factor degrading enzyme inhibitor. The LHRH analog is preferably a pharmaceutically acceptable salt of an LHRH agonist or antagonist, such as a pharmaceutically acceptable salt of leuprolide, goserelin, triptorelin, buserelin, avorelin, deslorelin, histrelin, cetrorelix, teverelix, ramorelix, antide, nictide, azaline B, azaline C or ganirelix.

Another aspect of the invention relates to the pharmaceutical implants obtained according to the process defined herein. These implants are preferably contained in an implanter device with a retractable needle so that they are suitable for subcutaneous injection under the skin of a mammal.

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