Since the late 1950’s to 1960’s women have had access to the female birth control pill. This innovation in contraception changed the course of family planning worldwide. However, for a variety of reasons, not every woman wants to take hormonal birth control. Despite numerous attempts and partial success under clinical conditions, no comparable product has yet been made available for men. Nonetheless, the drawbacks of female contraception and the limited options available to men (e.g. condoms or vasectomy) leave an unsatisfied demand for a male birth control pill. In this article, we will look at the history of male contraceptive drug development and try to see if there is any hope for a product in the future.
History of the male birth control pill
Pharma companies have long been eager to sell a male pill to the public. Although condoms have existed in one form or another for centuries, the appeal for couples would be a barrier-free method in cases where the woman did not wish to use hormonal birth control. If a hormonal pill could be developed for women, why not one for men as well?
The first serious attempt to develop a male contraceptive drug was in 1957 in a study led by Gregory Pincus, a man who was also involved with developing the first female pill. This and similar drugs were based on regularly administering a chemical similar to testosterone. The presence of excess testosterone in the blood causes a negative feedback loop that shuts down sperm production. Basically, the body detects that the blood contains too much testosterone, and turns off the primary functions of the testicle: sperm and testosterone production. See our article on steroids and fertility for more detail.
Although the direct hormonal approach can be effective in men, it is tricky to make it into a usable pill or injection for several reasons. First, the high required doses of testosterone or similar chemicals tend to cause side-effects such as acne, baldness, and thick blood (high red cells). Second, administering external testosterone can shut down the body’s natural production of testosterone causing the man to suffer withdrawal symptoms. Third, continuous long term use of a chemicals similar to testosterone has been known to cause permanent infertility. In any case, it may take over a year to fully recover a man’s original sperm count after prolonged hormonal suppression. Finally, shutting down sperm production and clearing out the existing sperm from the testicles takes 3 months (incidentally, this wait period also applies for vasectomies). Therefore, unlike the female pill which is effective within weeks, there would be a significant waiting period for the proposed male drugs.
Pharma companies have attempted to balance these risks by careful chemical modifications and dosing. Nonetheless, for one reason or another all clinical trials of male hormonal birth control to date have been suspended before they were complete. In a recent high-profile case, a late stage trial for a candidate injectable hormonal cocktail was discontinued due to unexpected side effects on the mood of certain subjects. Although the effectiveness was comparable to female birth control and it was popular with the subjects (75% were in favor of using the contraceptive), it was decided that the side-effects presented an unacceptable risk for proceeding.
Because side effects on mood are quite common with female hormonal birth control, the reason for discontinuing the study was widely panned in print and social media. Nonetheless, because male contraceptives are new the study sponsors decided that the unexpected nature of the risk required re-evaluating and re-designing the study. It should also be noted that this trial was funded by a consortium of international non-governmental organizations (NGOs) and non-profits rather than a pharmaceutical company.
In short, hormonal treatments *almost* work but they aren’t quite there yet. Research into hormonal birth control for men continues with support from pharmaceutical companies, startups, and non-profits.
Other approaches to male contraception
It has long been known that applied heat can be used as a contraceptive for men by shutting down sperm production. Although this is a potential low cost approach, the lack of an obvious business model has meant that the large studies required to prove the safety and effectiveness of the method have never been conducted. Known methods also take considerable dedication or strange styles of underwear and therefore have not seen significant uptake
One of the primary drawbacks of all methods that shut down sperm production is the long wait time for sperm count to increase or decrease. There are some potential drugs that could disable the sperm cells rather than stopping their production and therefore could become effective more quickly. For instance, the calcium channel blocker nifedipine prevents essential reactions within the sperm cell that are required for fertilization. Other compounds have shown promise in preventing sperm maturation (sperm are no longer motile) or preventing external ejaculation without effecting semen quality. These methods has been shown to be effective and reversible in animals, and it is possible that we will see a quick action male fertility drug sometime in the future.
Finally, there have been advanced trials with various methods that effectively produce a reversible vasectomy by affecting sperm that normally pass through the vas deferens before ejaculation. Perhaps most prominently, RISUG employs an injectable polymer that would disable sperm as they passed through the vas deferens and can be washed out with a second injection. Reversible plugs or gate devices have also been proposed for insertion into the vas deferens and are under development. Although promising, it should be noted that these approaches would have the same waiting period that currently applies to the vasectomy.
Male birth control is coming…
Although significant research has gone into a male contraceptive drug since the 1950s, we don’t have anything ready for the masses yet. That said, there have been a number of methods that *almost* work but have been placed on hold for a variety of reasons. We can’t promise anything, but it wouldn’t be surprising if we see something for men hit the market in the next decade.
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