United States Patent:  6,117,441

Assignee:  The Population Council, Inc. (New York, NY)

Filed:  July 2, 1998

This invention features an implantable system for use as a male contraception and as a treatment of benign prostate hypertrophy and other conditions. The implant system includes an implant intended for subcutaneous or local administration having a core comprising a silicone elastomer and drug matrix which is encased in an ethyl vinyl acetate coating or membrane.

SUMMARY OF THE INVENTION

While it was previously concluded that SILASTIC.RTM. and other silicone-based polymers should be avoided when constructing subcutaneous implants for the delivery of androgen, it has now been discovered that silicone elastomers such as SILASTIC.RTM. can play a role in the production of male contraceptive implants after all. Indeed, there are advantages to constructing an androgen containing implant from a core of a silicone elastomer so long as ethyl vinyl acetate or other suitable material is used as the rate limiting membrane surrounding the reservoir or core. These advantages include providing a sustained and constant release of a daily dose of a drug and having a near zero-order release rate profile. This result was particularly surprising in view of the original observation that exclusively silicone-based implants exhibited an unsatisfactory release rate profile. In addition, the availability of silicone elastomers as a core-forming materials provides significant benefits as silicone elastomers may have enhanced compatibility with specific androgens and their analogues. Because silicone elastomers can be modified to provide properties which are different than ethyl vinyl acetate monomers, it may be possible to affect the properties of the core by the use of one or another specific material. Adding SILASTIC.RTM. or silicone elastomers to the arsenal of potential core source materials is therefore of great benefit.

In accordance with one aspect of the present invention, there is provided a subcutaneous implant for the delivery of androgen. The implant includes a core comprising a silicone elastomer and drug matrix encased in a rate limiting EVA coating or membrane. This device may be used alone for hormone replacement therapy and to treat various conditions for which androgen therapy is a recognized treatment.

In a particularly preferred embodiment in accordance with the present invention, this silicone elastomeric cored implant can be used in combination with a suitable implant for the delivery of a sterilant such as LHRH, its analogues or functionally related compounds. In this instance, by the use of two implants, for example, both contraception and a retention in male function can be realized. Kits including one or more of these implants are also contemplated.

Claim 1 of 21 Claims

1. An implantable system, comprising: a first implant intended for subcutaneous or local administration of an androgen, said first implant including an androgen selected from a group consisting of 7.alpha.-methyl-19-nortestosterone, 7.alpha.-methyl-19-nortestosterone acetate, testosterone, esters of testosterone, methandroil, oxymetholone, methandienone, oxymesterone, nondrolone phenylpropionate and norethandrolone, in an amount which is sufficient to provide the daily dose of a pharmaceutically effective amount of said androgen over a predetermined time dispersed in a core formed of a silicone elastomer, and a membrane encasing said core, said membrane formed of an ethylene vinyl acetate copolymer; and

a second implant intended for subcutaneous or local administration of a sterilant, said second implant including said sterilant in an amount sufficient to provide for the daily dose of a pharmaceutically effective amount of said sterilant over said predetermined time.

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