Researchers hope to develop a male pill that does not affect hormones. They are looking for chemicals that can disable a handful of enzymes that scientists have identified as critical to male fertility.

The researchers plan to test about a half-million chemical compounds to find a pill that does not involve hormones that men could take weekly or monthly. They also hope to find something that is close to 100 percent effective and has no risky side effects.

The research is being conducted with a $7.9 million grant from the National Institutes of Health. Scientists will test compounds at a high-tech laboratory on the university's Lawrence campus.

It will be at least five years before clinical trials could be conducted on men.

Shift in Attitude

While women have been using the pill since the 1960s, men generally have had two contraception choices: condoms or sterilization.

"Half of the population has been ignored," said Joseph Tash, a reproductive biologist at the University of Kansas School of Medicine.

Only 27 percent of women who practice contraception rely on their partners to use condoms or have vasectomies, according to data from the Alan Guttmacher Institute.

"I think some couples would like to have that option," said Gunda Georg, lead researcher on the project. "There's been a shift in attitude. Some men would like to share more in that responsibility."

Testosterone Injections

The new, five-year contract will build on work begun four years ago. Under another NIH grant, Kansas researchers identified a chemical compound that caused temporary infertility in male rats. The university has filed a patent application for that compound. The team now hopes to discover a half-dozen more compounds.

Male contraceptives being tested in China and Europe are hormone-based, involving either large injections of a male hormone similar to testosterone or a combination of testosterone and a female hormone.

Preliminary studies have shown hormonal contraception to be effective and that men regain their fertility after several months, said Douglas Colvard, associate director of Conrad, a nonprofit organization at Eastern Virginia Medical School that promotes research on reproductive health. But testosterone injections raise concerns about side effects, such as elevated cholesterol levels and promoting cancer growth, Colvard said.

The Kansas researchers are looking for a male pill that does not affect hormones. Instead, they are looking for chemicals that can disable a handful of enzymes that scientists have identified as critical to male fertility.

'Goal Is 100 Percent Effectiveness'

The researchers have selected more than 100,000 compounds that might work, Georg said, and will test about 400,000 compounds from the NIH.

After the number of compounds are reduced, the researchers will study them at the molecular level to see how they bind to the enzymes.

The best compounds then will go to the Kansas School of Medicine, where Tash will test them on mice or rats to see if they are effective and safe, and whether the rodents regain fertility after they stop receiving them.

"Obviously, the goal is 100 percent effectiveness," Tash said. "The female pill is 95 to 99 percent effective. We hope to at least meet that level."