Scientists working on a male contraceptive pill have found the medication to be 99 percent effective in preventing pregnancy in mice.
The breakthrough findings, which were presented at the spring meeting of the American Chemical Society today (23 March), resulted from animal testing of the non-hormonal pill.
In addition to being effective on the mice, there were no reported side effects, an issue that has been raised in previous attempts to develop contraception for males.
Up until now, the only options for birth control available to men have been male condoms and vasectomy.
This has meant it's often left to women to carry the burden of contraception, whether that be from hormone injections, a daily pill at the same time each day, or having a copper coil inserted into them.
In 2019, the male contraceptive pill passed its first round of human safety tests, but a majority of these target the male sex hormone testosterone, which leads to side effects typically associated with the female pill such as weight gain and depression.
Presenting the findings of this new compound, which is non-hormonal, Dr Abdullah Al Noman said at the meeting: "Scientists have been trying for decades to develop an effective male oral contraceptive, but there are still no approved pills on the market.
"We wanted to develop a non-hormonal male contraceptive to avoid these side effects."
Well there's been a viable male contraceptive pill available for decades but the side effects of depression and blood clots that are acceptable in women are apparently not acceptable in men. I've heard this about 2 separate trials.
- Fanon Dynes (@LustyGobbles) April 26, 2021
The graduate student at the University of Minnesota in Minneapolis went on to explain: "Safety is very important for birth control pills because people are not taking it for a disease, so they are less tolerant of side effects."
To develop the male contraceptive, the researchers targeted a protein called the retinoic acid receptor alpha (RAR-α), which is responsible for binding retinoic acid, a form of vitamin A that plays a significant role in sperm formation.
Tests on mice showed that by inhibiting the RAR-α, they were sterile but without obvious side effects.
Over a period of four weeks, the compound, which was named YCT529, dramatically reduced sperm counts in the mice and was 99 percent effective in preventing pregnancy.
According to Gunda Georg, Ph.D., one of the leads of the researchers at the University of Minnesota, YCT529 will begin testing in human clinical trials in the third or fourth quarter of 2022.
She added: "Because it can be difficult to predict if a compound that looks good in animal studies will also pan out in human trials, we're currently exploring other compounds, as well."
Words by: Daisy Phillipson