Research into male birth control has come a long way in the last several years, thanks to growing interest from men and increased funding. Surveys by the World Health Organization and others indicate that men are interested in alternative means of contraception that would allow them to be more involved in the prevention of unwanted pregnancies. The new male contraceptives are being tested in many different forms: injections, implants and oral pills. The idea of a “male pill,” in particular, has generated considerable interest, but there are still many questions to be answered about male contraceptive safety for long-term use, cultural acceptance and cost.
1. The methods
Researchers have for years tinkered with methods of male birth control that alter hormones like testosterone, but those methods were never fully reliable. However, more recent studies have shown that contraceptives made from a type of progesterone, in combination with a dose of testosterone for balance, can significantly reduce male fertility. A variety of methods for delivering these hormones are being tested including injections, patches and creams, as well as what is expected to be the most popular combination therapy: injectable progesterone with a separate dose of testosterone gel.
One of the most likely options for a true “male pill” to come to market is with non-hormonal drugs that target specific functions. Both University of Washington and Columbia University Medical Center are testing methods of limiting vitamin A, which is critical for the production of sperm. Their studies indicate that blocking vitamin A can reduce male fertility without much effect on sexual drive. The concern is that the body needs vitamin A for many other functions, so restricting it could cause other long-term problems.
Other pills that try to inhibit sperm production, swimming or effectiveness are also in trials, such as calcium channel blockers. More controversial studies of implants to block sperm, like temporary vasectomies, have not been approved in the U.S.
Some natural substances, like gandarusa from Indonesia, as recently reported by PBS News Hour, are known herbal contraceptives. Gandarusa doesn’t disrupt the regular balance of male hormones. Instead, it makes sperm unable to pierce walls of an egg. But since using herbs or naturally occurring substances are considered alternative health measures, it’s unlikely that insurance companies would cover them as birth control.
So, the hormone-based male contraceptives currently comprised of progesterone injections and testosterone gel seems like the most likely candidate to be mass-marketed in the near future.
2. Regulating the male reproductive system
“For men, thousands of sperm are created every second,” said Dr. John Amory of the University of Washington’s Center for Research in Reproduction and Contraception, which has received funding for several research studies on male contraception. According to Amory, regulating male hormones has many challenges.
“In terms of numbers, it’s much harder,” Amory said, “Men don’t have an analogous cycle. They make sperm until they die.
Unlike the female pill that has on and off days, because women only release eggs once a month, the hormone-based male contraceptives currently in development are on full-time duty. Because of those challenges, the progesterone-testosterone mix is only 80 to 90 percent effective, which is well below the 98 percent effectiveness of female hormonal contraceptives. It does have the benefit of building up in the system so that missing a dose won’t likely increase a man’s fertility — that takes a few months to return.
There are still some unknowns in the studies of the hormonal mix, which are just about to enter the highest phase of medical trials at both University of Washington and UCLA Medical Center. So far, Asian men have better results than other ethnicities and there are some men whose fertility is not diminished enough to prevent pregnancy. Researchers aren’t sure why.
3. Potential side effects
One of the long-standing concerns about developing a male hormonal contraceptive is the risk of permanent infertility or sexual dysfunction. Developing a pill that is definitely reversible, meaning that fertility will return once the pill is stopped, has been critical for success.
The several studies in progress based on using hormone therapy, including the University of Washington’s program, show that, like the female pill, fertility does return within a relatively short time period after a male patient stops taking the contraceptive. Very few side effects have been reported in male hormonal contraceptive trials so far, in part because some are tested on animals that are unable to articulate shifts in mood and because the test groups are still relatively small. It’s possible that the side effects of male hormonal contraceptives could be similar to those found in traditional contraceptives for women: fluctuations in mood and sexual drive, as well as an increased risk of heart disease and stroke.
“The bar for safety is very high,” said Amory. The female pill, he added, “can cause blood clots, but it’s a tenth of the risk of the same blood clots during pregnancy. You can’t say the same for men.”
For potential contraceptives in pill form, there is no safe testosterone. For a true male pill that could restrict vitamin A, the goal will be to target only sperm production because limited vitamin A throughout the body could lead to known side-effects like night blindness or long-term infertility, according to Amory.
4. Funding the research
Dollars for male contraceptive research have been scarce in the past, which is part of the reason that the male pill is still commercially unavailable. Research in the last few years has been sponsored mostly by government agencies, particularly the NIH, which view male contraceptives as another aid in lowering the rate of unplanned pregnancy in the U.S., which is currently more than 40 percent. There are at least 10 research studies currently being funded by the Contraceptive and Reproductive Health Center, under the National Institute of Child Health and Human Development, a branch of the NIH. Notable studies on hormone-based male contraceptives are under way at Columbia University, the University of Washington and UCLA, among others.
While government-sponsored research continues, pharmaceutical companies have taken a wait-and-see approach. Even following larger studies like those done by the World Health Organization, the companies are inclined to wait for FDA approval amid concerns over long-term safety and effectiveness. They are also unsure about whether enough men will buy the contraceptive drugs to make investing in them worthwhile.
5. Time to market
Even if the male pill does well in trials, it will be at least five to 10 years until there’s a viable drug on the market. Like any new pharmaceutical, the various male contraceptives being tested now have to make their way through the long system of trials, approvals and development, which usually takes about 10 or 15 years, before they reach pharmacies.
Hormonal methods are the most advanced in the process, so it’s possible that, on the earliest end, the treatments could be on the market in five years. Researchers are hesitant to commit to a timeline, particularly with the lack of support from pharmaceutical companies.
“The joke is that people have been saying there will be a male pill in five to 10 years for the last 30 years,” said Amory.
Using drugs that are already on the market for other treatments, such as some anticancer agents, antipsychotic drugs and antihypertensives, could speed that timeline. Several have been shown to stunt male fertility either by interrupting the production of sperm or semen or by making the sperm unable to fertilize an egg. But, since they were developed to treat other systems in the body as well, they come with a variety of side effects that could make them undesirable for long-term use.
Planned Parenthood, which is one of the largest distributors of the female pill, said they can’t take a position on male contraceptives while they are still in the research phase. But, they said, once a male pill is on the market, they would consider providing it.