Male hormonal contraceptives.

As the world human population continues to explode, the need for effective, safe and convenient contraceptive methods escalates. Historically, women have borne the brunt of responsibility for contraception and family planning. Except for the condom, there are no easily reversible, male-based contraceptive options. Recent surveys have confirmed that the majority of men and women would consider using a hormonal male contraceptive if a safe, effective and convenient formulation were available. Investigators have sought to develop a male hormonal contraceptive based on the observation that spermatogenesis depends on stimulation by gonadotropins, follicle-stimulating hormone (FSH) and luteinising hormone (LH). Testosterone (T) and other hormones such as progestins suppress circulating gonadotropins and spermatogenesis and have been studied as potential male contraceptives. Results from two large, multi-centre trials demonstrated that high-dosage T conferred an overall contraceptive efficacy comparable to female oral contraceptives. This regimen was also fully reversible after discontinuation. However, this regimen was not universally effective and involved weekly im. injections that could be painful and inconvenient. In addition, the high dosage of T suppressed serum high-density lipoprotein (HDL) cholesterol levels, an effect that might increase atherogenesis. Investigators have attempted to develop a hormonal regimen that did not cause androgenic suppression of HDL cholesterol and that was uniformly effective by suppressing spermatogenesis to zero in all men. Studies of combination regimens of lower-dosage T and a progestin or a gonadotropin-releasing hormone analogue have demonstrated greater suppression of spermatogenesis than the WHO trials of high-dosage T but most of these regimens cause modest weight gain and suppression of serum HDL cholesterol levels. Overall, the data suggest that we are close to developing effective male hormonal contraceptives. The focus is now on developing effective oral regimens that could be safely taken daily or long-acting depot formulations of a male hormonal contraception that could be conveniently injected every 3 - 6 months. In this article, we shall review the exciting new developments in male hormonal contraception.