Future developments in contraception
Aitken, J.
Practitioner 232(1441): 46-52
1988
ISSN/ISBN: 0032-6518 PMID: 3217321 Document Number: 362555
Research in the improvement of current contraceptive methods includes the development of longacting, biodegradable steroid delivery systems; antiviral spermicides; and condoms made of better materials than latex rubber. At the forefront of research are the development of male contraceptive pills and contraceptive vaccines. Progestagens cannot be used to suppress spermatogenesis without suppressing libido unless they are accompanied by replacement androgen therapy. Moreover, it is extremely difficult to inhibit spermatogenesis completely, so antispermatogenic substances must also render surviving spermatozoa infertile. The zona-free hamster egg penetration test has been developed to test antispermatozoal agents, and a combination of Depo-Provera and testosterone enanthate is being tested in Scotland. Gossypol has been found to suppress male fertility in China, but it has toxic side effects. Another Chinese antifertility agent is the plant Tripterygium wilfordii, but its active component has not yet been identified. The drug sulfasalazine has also been found to induce reversible infertility in men, but it also has toxic side effects. Efforts to develop an antifertility vaccine have concentrated on immunizing women against the surface antigens of the spermatozoa or against the surface antigens of the zona pellucida, which surrounds the ovum. A 3rd approach would be to immunize women against the human chorionic gonadotropin and thus prevent implantation of the blastocyst.