Current Challenges in Male Contraceptive Research
Despite the diversity of approaches and advances in research, no novel male contraceptive has come to market. Many challenges continue to impede progress toward a viable male method, especially in the hormonal field. One of the biggest issues, first identified in the initial WHO trials, is the large ethnic difference in efficacy of hormonal contraception, with Asian men consistently showing higher rates of therapeutic azoospermia (~95%) than Caucasian men (60–70%). These variations raise doubt as to whether a hormonal male method would ever be as universally effective as current female methods. Furthermore, because most methods deliver testosterone subdermally or parenterally, there are concerns over the potential acceptability of the delivery system. As with any new pharmaceutical product, it is also necessary to address issues of side effects and long-term safety. As contraceptives are administered to a relatively young and healthy population for potentially long periods of time, understanding these long-term effects is particularly important. Finally, female methods of birth control have been improved over time and are now safer and less expensive than when they first emerged, giving novel male products steeper competition.
Perhaps a greater challenge in male contraceptive development is uncertainty over whether the revenue from the market would justify the investments necessary to resolve the remaining obstacles in product development. Although Bayer, Wyeth and Organon were once active in research and development of a male method, all three discontinued their programs between 2005 and 2008, although the industry continues to actively pursue programs for hormonal contraception and hormonal-replacement therapy for women. In withdrawing support, company representatives cited corporate changes in direction and the perception that safety standards demanded by regulatory bodies would require such extensive evidence as to make further research financially infeasible. This paper reviews the challenges that have impeded the progress of male contraceptive development, namely efficacy, safety and acceptability. We then synthesized data from a number of sources to estimate the current potential market for male contraception in view of recent trends in the costs men bear for unwanted pregnancies.
Expert Rev Pharmacoeconomics Outcomes Res. 2012;12(5):605-613. © 2012 Expert Reviews Ltd.