For decades, women have largely carried the responsibility for contraception thanks to the pill, but a male equivalent has long eluded scientists. Now a new breakthrough could lead to a safe, effective and reversible male contraceptive pill, as a compound from traditional Chinese medicine has been shown in tests to render mice and monkeys temporarily infertile.

The compound in question is called triptonide, which is extracted from a Chinese herb known as T. wilfordii Hook F. Traditionally the herb has been used to treat ailments like rheumatoid arthritis, but since the 1980s it’s been reported that men taking the supplement over several months have displayed infertility. Obviously that’s an unfortunate side effect for treating arthritis, but it’s exactly what you need in a male contraceptive.

So for the new study, the researchers investigated how effective it might be in that role. The team examined 10 compounds from this herb and singled out triptonide as the most ideal contraceptive candidate.

In animal tests, the team found that a single daily oral dose rendered male mice infertile within three to four weeks, and monkeys in five to six weeks. The compound seems to work by deforming almost 100 percent of the test animals’ sperm so they can no longer swim forwards, throwing an effective spanner in their journey to the egg.

“Thanks to decades of basic research, which inspired us to develop the idea that a compound that targets a protein critical for the last several steps of sperm assembly would lead to the production of nonfunctional sperm without causing severe depletion of testicular cells,” says Dr. Wei Yan, lead author of the study. “We are very excited that the new idea worked and that this compound appears to be an ideal male contraceptive.”

The team says that triptonide ticks all the right boxes. Not only is it effective and easy to take as a pill, but it’s non-hormonal, so it shouldn’t result in any unwanted mood or behavioral changes. No toxic side effects were noted either, and perhaps most importantly, the process is completely reversible – when the treatment is halted, fertility returns within four to six weeks.

Triptonide is far from the only male contraceptive in development. Many other compounds have been investigated that disrupt sperm development or movement, with some already showing promise in human clinical trials. Other methods involve ultrasound pulses that kill off sperm, gel injections that block their release long-term, or self-applied gels that have the bonus of boosting libido.

The team on the new study hope to begin human clinical trials of triptonide soon.

The research was published in the journal Nature Communications.

Source: The Lundquist Institute