Q: Dear 100 Hour Board,
Would someone better versed in things medical explain to me why there isn't really a birth control pill for men? Something that would slow or halt the production of sperm, or just neutralize them while the guy is on it?
-kat
A:
Dear does that make you krazy,
Really short answer: Science is trying but medicine is hard.
Somewhat short answer: A variety of male birth control options (other than the two currently available--condoms and vasectomy) have been proposed or researched. However, so far, either they aren't reliably effective, they are too likely to cause permanent infertility, they have too many side effects, or they can't get sufficient funding to be developed.
Much longer answer: This is a very interesting subject that I've been vaguely interested in for quite a while, so thanks for the excuse to finally research it!
There are quite a few varieties of male-oriented contraceptives in development. Wikipedia directed me to two web sites with fairly comprehensive overviews of the topic, Male Contraceptives (last updated in 2011) and the Male Contraception Information Project. It is from these sites that I draw all of the information in this answer.
One of the most promising male contraceptives in the works is Vasalgel, based on a polymer called RISUG studied in India. The gel is injected into the vas deferens and remains there for ten years, blocking most sperm and destroying the cell walls of those that do pass. It has essentially no side effects, and primate studies indicate that it should be reversible (an additional injection is required). It is in advanced clinical trials in India, and a US group is seeking funding for FDA trials here.
Another option that looks like it could move forward soon is known as the "dry orgasm pill." This is actually based on a high blood pressure medication that had unintended contraceptive side effects, and current research is focused on isolating the contraceptive aspects while avoiding side effects on blood pressure. The pill acts by blocking the contraction of certain smooth muscles in the vas deferens while leaving others uninhibited, which causes it to clamp shut. The result is that while orgasm still occurs, ejaculation is prevented. The pill could be taken two to three hours before intercourse, or for long-term effects a rod could be implanted in the man's body. The drug still needs funding for research and testing, and this is made more difficult because pharmaceutical companies believe that many men would object to a contraceptive that leads to semen-free sex.
Research has been done on several heat- or ultrasound-based varieties of male contraception. Either an ultrasound is applied to the testes, or the man wears a special sort of underwear that pushes them back up into the body. Although these have proven effective at contraception, they are unfortunately not as reversible as once thought, meaning that they are more likely to become a non-surgical alternative to vasectomy rather than a male equivalent of the Pill.
Scientists in Indonesia are working to finish testing on a pill derived from the plant Justicia gendarussa, which could lead to a male contraceptive being available for widespread use within several years. However, in order to get approved for use in the United States, it would likely have to go through the FDA's full study process from start to finish, meaning that it could take ten years or longer for anything to come on the market here.
The drug nifedipine, while not intended as a contraceptive, does have contraceptive side effects. It is intended for use as a high blood pressure medication, and studies have not been done on its use by healthy individuals. Because the drug's patent has expired, pharmaceutical companies have no incentive to go through the lengthy process of experiments and trials to repurpose a drug that can then be replicated by anyone else--without the protection of a patent, they cannot possibly make a profit.
Several male hormonal contraceptives have been researched. They have a variety of delivery methods, and are as safe as female hormonal contraceptives (although side effects do exist). Reversal takes four to six months, since the process of spermatogenesis has to restart from scratch. The biggest problem with male hormonal contraceptives comes in the form of a mystery: for reasons unknown, they have no effect on 5% to 20% of the population (depending on the exact variety being tested). While several correlations have been found (including, interestingly enough, being effective on most Asian men but fewer Caucasian men), nothing conclusive has been discovered so far.
Some time ago, researchers discovered the contraceptive effects of a compound produced by cotton plants--men in China who ate foods cooked in unrefined cottonseed oil had unusually high rates of infertility. The compound is a very effective contraceptive... so effective that over 20% of the time its effects are irreversible. Since it is too likely to cause permanent contraception, it can't be used as a temporary contraceptive; since it is not likely enough to cause permanent contraception, it can't be used as a permanent contraceptive. Thus, despite its initial promise, all research has been abandoned.
Columbia University is conducting research into a drug that inhibits vitamin A receptors in the testes (once again, discovered as an unintended side effect of another medication). Although initial leads are promising, further testing is required to determine whether the drug has any serious negative side effects, particularly on vitamin A receptors elsewhere in the body.
Scientists are in the very earliest stages of researching a contraceptive that would trigger an immune response to sperm, causing the body to kill off its own reproductive cells. Work is still being done on finding the right part of the sperm cell to target. One trial in monkeys led to effective contraception in seven out of nine in the study, and five of the seven were able to recover their fertility. Because of the difficulty in working with immune responses and the extreme variability between individuals even of the same species, this is still very much a long shot.
While this is not a comprehensive overview of every possibility, I think it's safe to say that if a male contraceptive comes on the market in the US in the next decade or so, it will probably be one of these. The various drugs and treatments I've mentioned also provide a good overview of the difficulties in developing a contraceptive, ranging from unknown side effects to insufficient effectiveness to irreversibility to a simple lack of funding. I hope that one or more of these does advance and receive approval for widespread use in the near future, but as with many areas of medicine, the future for now remains unknown.
-yayfulness
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