PROJECT
Subdermal Implants for Men

Studies have shown that:

• Men are interested in contraceptive options other than the condom, vasectomy, and withdrawal; and

• Women would welcome additional male contraceptive methods.

The Population Council has clinically evaluated the male contraceptive and hormone replacement effects of prolonged delivery of the synthetic androgen MENT^® from subdermal implants.

MENT was identified as a suitable candidate for these indications because it suppresses gonadotropin secretion, which leads to suppression of testosterone and sperm production in the testes. At the same time, MENT replaces testosterone to maintain primary and secondary sex characteristics. MENT has an added advantage in that it does not overstimulate the prostate.

Because MENT is ten times as potent as testosterone, the doses required are lower than those of commercially available testosterone preparations, making it feasible to administer the compound via long-acting subdermal implants. A study in hypogonadal men showed that two MENT implants may provide adequate replacement therapy for most androgen-dependent functions. There was evidence to support selective sparing of the prostate gland.

Several reports indicate that a combination of a synthetic progestin, such as levonorgestrel, and an androgen may be an effective approach for male contraception. Therefore, following completion of a dose-finding study comparing three doses of implants releasing MENT alone, the decision was taken to design a study comparing MENT alone with three MENT-plus-levonorgestrel dose combinations.

A clinical trial to evaluate this approach (using MENT implants in combination with levonorgestrel-releasing Jadelle^® implants) was conducted at International Committee for Contraception Research sites in Los Angeles; Münster, Germany; and Santiago, Chile, and is close to completion. A second study was initiated to compare the effects of MENT combined with a progestin implant (Implanon^®) with testosterone pellets combined with Implanon.

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Population Council researchers

Narender Kumar, Frederick Schmidt, Régine Sitruk-Ware

Non-Council collaborators

Richard Anderson, David T. Baird (MRC Reproductive Biology Unit, Edinburgh)

Horacio Croxatto (ICMER, Chile)

Eberhard Nieschlag (University of Münster, Germany)

Christina Wang (University of California, Los Angeles)

Donors

The Lita Annenberg Hazen Foundation

The George J. Hecht Fund

The William and Flora Hewlett Foundation

US Agency for International Development

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