Science one step closer to male contraceptive

A Houston-Boston research partnership has found the ingredients for a male birth control pill, a breakthrough approach that promises the first reversible contraceptive for men since the introduction of the condom centuries ago.

In a paper published Thursday, the team described a compound that, worming its way past the barrier that separates blood and sperm, makes mice temporarily infertile - without putting a damper on their sex drive. The mice's sperm rebounded and produced healthy offspring when they stopped getting the compound.

"With all the unplanned pregnancies, this is an important discovery," said Dr. Martin Matzuk, a Baylor College of Medicine developmental biologist and the paper's first author.

Scientists have been trying to develop an oral male contraceptive since the birth control pill for women hit the market 52 years ago. But the goal has proved elusive, largely because men make 1,000 sperm every second, compared to women's one egg a month. Turning that production off is difficult.

The compound itself isn't a candidate for human use as a male contraceptive. But Dr. James Bradner of Harvard University's Dana Farber Cancer Institute, Matzuk's collaborator, said the study findings offer a blueprint for the development of a drug derivative. He said the team is working on that now.

The study, detailed in the journal Cell, provides the first evidence supporting a molecular approach to male contraception. Most previous research has involved hormones, which have worked in testing but cause side effects such as lowered libido, mood swings and depression.

So many men reported such side effects in a recent eight-country, hormone-based contraception study that the World Health Organization last year brought an early halt to the project. Drug companies have stopped investing in the approach.

But the demand for a male pill remains high, particularly given the hundreds of thousands of American births and abortions involving teenagers and global statistics that half a million women a year die from complications of pregnancy and childbirth.

Dr. John Amory, a University of Washington professor of medicine and contraceptive researcher, says surveys show two-thirds of American men say they're interested in and would be willing to use a birth control pill. The same surveys show 98 percent of women say they'd trust their partner to take such a pill. (Only 70 percent said they'd trust "all men.")

Even now, despite the limited options, men account for 30 percent of couples' contraceptive efforts - condoms representing 20 percent and vasectomies 10 percent.

The new compound was created as a possible anti-cancer agent. But when Bradner found it also inhibits a related protein involved in the development of sperm and essential for fertility, he sent it to Matzuk for testing.

Bradner acknowledged that the research is at such an early stage that a derivative won't make it to market anytime soon. But he also expressed confidence the work with mice should be completely adaptable to men.

The team recently received funding from the National Institutes of Health to further the research over the next five years.

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