Currently, women have a multitude of available options for birth control including oral contraceptives, diaphragms, IUDs, and tubal ligation. For men, choices are limited to condoms and vasectomy. A group in Germany is exploring a third option: injectable medication to that reduces sperm production.
The team led by Dr. Hermann Behre of Martin Luther University of Halle-Wittenberg, Germany, reported on injection therapy with both long acting testosterone and progestin in an effort to drive down sperm production in men and allow effective contraception. Men received injections every 8 weeks over the course of a year. Out of 266 men involved in the trial, 4 unplanned pregnancies were initiated. Given when during the course of the year pregnancies were initiated, failure rate was calculated to be about 7.5 % which compares favorably to oral contraceptives for women. Furthermore, when examining sperm production, examination revealed sperm concentration dropped to less than 1 Million per Ml in 86% of men after 24 weeks.
However, there were side effects of the medication such as mood disorder including hostility and aggression as well as acne, injection site pain, muscle pain. A total of 1491 adverse events were reported during the study and 20 men did drop out of the study due to side effects. In fact the study was stopped earlier than planned due to side effects.
There are also theoretical concerns. Use of testosterone to drive down sperm production is sometimes so effective that sperm production may not rebound after it is discontinued. Average time to recovery of sperm production in this study was 24 weeks, but 8 participants failed to have full recovery after 52 weeks.
Also, use of progestin in men is like venturing out in fairly uncharted waters. Progestin is a form of Progesterone which acts as an antagonistic hormone to estrogen in women. In men, increasing this hormone to higher than normal levels may have additional risks.
Looking to the future, other non hormonal medications are being developed which may attack sperm function in order to enable contraception. Until then, for men, it’s condoms, vasectomy or abstinence.
