May 13, 2010
A Male Birth Control Pill?
According to this CNN story, it is still "5 to 10 years away . . .":
"The joke in the field is: The male pill's been five to 10 years away for the last 30 years," said Dr. John Amory, researcher at the University of Washington.
Researchers have been promising a male hormonal contraceptive option for a long time, but there are good reasons why it's so hard to get that technology right. While women make one egg a month, men produce about 1,000 sperm every second, Amory said.
"It proves more difficult to shut down that level of production," he said.
The female pill uses hormones to make the woman's brain think she is pregnant and turns off egg production. But men don't have periods where they turn off sperm production, so it's harder to get them into that state, he said.
The male hormonal methods in progress uses a combination of testosterone and progestin, which turn off signals from the brain to the testes. Approximately 3,000 men have been enrolled across more than 30 studies on the topic over the last 30 years.
About two-thirds of men who have had hormone injections suppress sperm production totally, and in 90 percent overall, it's very low. For the remaining 10 percent, however, it does not adequately protect against possible pregnancy.
But a large study on more than 1,000 men in China, published in 2009 in the Journal of Clinical Endocrinology and Metabolism, showed more than 95 percent efficacy for hormonal injections in men. Men received the injections and relied on them as the sole method of contraception; researchers looked at whether the couples got pregnant.
It's unclear why hormonal contraceptives appear to work better in men in China than in the United States, he said.
"It's something to do presumably with the genetics of the Chinese," Amory said. The regulatory agencies have not approved this method in China, he said.
Male contraceptive gels and injections are farther along than the pill in clinical trials because they're easier to dose, Amory said.
The gel, in phase 2 trials looking at efficacy, absorbs across the skin of the arm, chest or upper back, akin to putting on sunscreen, he said. Phase 3 would be large-scale trials.
"It could be very effective in preventing pregnancy, but if there isn't a clear market for it, companies understandably are a little reluctant to invest heavily in it," said Andrea Tone, professor of history at McGill University in Montreal, Canada. Tone has written extensively about the history of contraceptives.
Researchers are also working on an at-home sperm count test, similar to a pregnancy test, so that men (and their female partners) would be able to see that the hormonal contraception is working, Amory said.
There has also been talk of a spray-on condom, which began testing in 2007. It works by spraying liquid latex over the penis, ensuring a perfect fit. The challenge, however, is getting the latex to dry fast enough.
Read more here.
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