April 17, 2000 -- Although it may be 10-15 years before a male "birth control pill" is ready for the market, researchers are testing several promising types of hormonal contraceptives for men. Not only could these methods be effective for birth control, researchers say, some might offer protection from some types of cancer and even help to reduce baldness.
"Available options for contraception in the male are limited to vasectomy and condoms; for a lot of men those options are not very attractive," says John Amory, MD, who reviewed the recent research for an article in the journal Trends in Endocrinology and Metabolism. "Vasectomy is difficult to reverse, and condoms are not 100% effective. A hormonal contraceptive would be reversible, and it would be much more effective than condoms." Amory is acting instructor of medicine at the University of Washington School of Medicine in Seattle.
"At long last, it does look like we may be getting somewhere on hormonal contraceptive methods for men," says David Baird, MD, who reviewed the article for WebMD. Baird is a professor at the Center for Reproductive Biology at the University of Edinburgh in Scotland. If a male pill or shot is developed, he says, "not everyone will want to use it. [But] it will give people a wider choice."
Apparently, many men would be interested in using hormonal contraceptives if they were available. The Edinburgh center recently conducted a large survey of men's attitudes on this issue; the same questions were asked in Edinburgh and in South Africa, Hong Kong, and Shanghai. "About 90% of men thought a male hormonal contraceptive was a good idea," Baird says. "About 60-70% said if it was available now, they would use it sometime within the next decade."
Female birth-control pills have other uses aside from contraception, Amory notes. He believes that a pill for men could have similar benefits.
"Potentially, the male pill could reduce the risk of prostate cancer and testicular cancer," he says. "Depending on the specific makeup of the medication, it might reduce acne, benign [enlarged prostate], and male pattern baldness."
One approach that has been tested uses the hormone testosterone by itself, injected once a week or once a month. This suppresses sperm counts, but the effect varies, so a small percentage of men remain fertile. For unexplained reasons, testosterone alone appears to be more effective in Asian men than in men studied in the U.S., Europe, and Australia.
"The Chinese are interested in this approach and likely to be the first to introduce it on a non-experimental basis, using longer-acting testosterone that can be injected once a month," Amory says.
The most promising hormonal approaches for non-Asian men combine testosterone with another substance to enhance its effect. One possibility is combining testosterone with a chemical called gonadotropin-releasing hormone antagonists, which block another type of hormone involved in sperm production. But these chemicals are expensive and must be injected under the skin.
Another possibility is combining testosterone and progestin hormones. Many researchers believe this combination is the most likely to work in non-Asian populations, the study's authors write.
In the latest tests of male hormonal contraceptives, men have remained on the methods for up to a year. "In all of them, once they stopped taking it, their sperm count come up to normal within six months of stopping, and several have had children," Baird says. "However, if you ask me, 'What will happen if I take it for 30 years?,' we can't know that until enough men have taken it for 30 years."
How soon could male hormonal contraceptives reach drugstore shelves? "Twenty years ago, people were saying 'in five years' and they turned out to be wrong, so I'm hesitant to make predictions," Amory says. "There are technical hurdles that need to be overcome. Conservatively, let's estimate 10 to 15 years. Or if there were a major breakthrough, it could be five years."
- Researchers are continuing work on developing more birth-control options for men.
- Early studies have been conducted with injections of testosterone, alone or in combination with other substances.
- The hope is to find male birth control that has positive side effects, such as reducing the risk of prostate and testicular cancer, acne, benign enlarged prostate, and male pattern baldness