A group of scientists announced Wednesday that they had created a male oral contraceptive that was 99% effective in mice and had no detectable adverse effects, with the drug likely to begin human trials by the end of this year.
The results, which will be presented at the American Chemical Society's spring meeting, are an important step toward increasing birth control options - as well as responsibilities - for men.
Since the female birth control pill was originally licensed in the 1960s, researchers have been looking for a male equivalent, according to Md Abdullah Al Noman, a Ph.D. student at the University of Minnesota who will discuss the findings.
"Multiple studies showed that men are interested in sharing the responsibility of birth control with their partners," he said.
However, until now, there were only two viable options: condoms or vasectomies. Vasectomy reversal surgery is costly and does not always work.
The female pill uses hormones to disrupt the menstrual cycle, and previous attempts to create a male equivalent focused on testosterone, the male sex hormone.
The problem with this method was that it resulted in weight gain, depression, and higher levels of a cholesterol called low-density lipoprotein, which raises the risk of heart disease.
Noman, who works in Professor Gunda Georg's lab, focused on a protein called "retinoic acid receptor (RAR) alpha" to produce a non-hormonal drug.
Inside the body, vitamin A is transformed into several forms, including retinoic acid, which is essential for cell development, sperm production, and embryo development.
To achieve these tasks, retinoic acid must interact with RAR-alpha, and laboratory tests have revealed that mice lacking the gene that produces RAR-alpha are infertile.
Noman and Georg created a chemical that inhibits RAR-alpha activity as part of their research. They used a computer model to determine the optimal molecular structure.
In order to reduce potential adverse effects, their chemical, known as YCT529., was also engineered to bind specifically with RAR-alpha rather than two other related receptors, RAR-beta and RAR-gamma.
The female pill has adverse effects as well, including the risk of blood clotting, but because women are more likely to become pregnant without contraception, the risk assessment is different.
In a mating trial, YCT529 was 99% effective in reducing sperm counts and preventing conception when given orally to male mice for four weeks.
The researchers kept track of the mice's weight, hunger, and overall activity and found no negative effects, despite the fact that mice can't report side effects like headaches or mood swings.
"I'm optimistic this will move forward quickly," Georg said, predicting a five-year or less timeline to market.
