Despite female contraceptive pills existing since the 1950s, a reliable male contraceptive (that isn’t a condom) has never made it to market. Creating one is especially hard – as of now, we have few safe and effective methods of delivering modified oral testosterone, with any available options requiring males to dose up several times a day.
Unfortunately, this has led to much of the contraceptive buck stopping at women, many of which involve hormonal imbalances or invasive surgeries.
In an effort to combat this, a collaboration between Chinese and US scientists has developed a contraceptive agent that they claim is reversible, non-hormonal, and non-toxic in mouse and primate models. The new compound looks extremely promising and, with extensive human trials, may finally create a single-dose male contraceptive.
“There are no non-hormonal male contraceptives currently on the market despite decades of efforts toward the development of ‘male pills’,” write the authors in a paper to Nature Communications.
“Here, we report that triptonide, a natural compound purified from the Chinese herb Tripterygium Wilfordii Hook F displays reversible male contraceptive effects in both mice and monkeys.”
Triptonide has been under investigation for its contraceptive prowess since 2000, when a paper suggested the compound directly lowers the production of sperm. Produced by the "thunder duke vine" (Tripterygium Wilfordii), triptonide is part of an array of clinically-relevant compounds that have been isolated from the plant. Examples include triptolide, which has potential uses in polycystic kidney disease and pancreatic cancer, and triptolidenol, which is being studied for use against renal cell carcinoma.
The thunder duke vine was first identified as a contraceptive after a report in 1993 found that males taking the herb for other reasons had reduced sperm counts, reduced sperm motility, and deformed sperm shape. Since then, the many isolated compounds from the vine have been extensively studied as a male contraceptive. However, despite reducing sperm count in various clinical trials, some of the isolates are too toxic to use.
In the latest study, the researchers trialed triptonide to test for safety and efficacy in animal models. The study involved mice and 12 healthy male adult cynomolgus monkeys. After a single daily dose of triptonide, the mice and monkeys demonstrated almost 100 percent sperm deformation between 3-4 and 5-6 weeks respectively, making them infertile. Fertility was restored once the dosing stopped after 4-6 weeks, suggesting the compound is reversible. Following analysis of the vital organs, no side-effects were noted in the animals, making triptonide differ from the other isolates from the herb in overall toxicity.
Of course, the trials are preliminary animal studies and proof-of-concept of the compound – it will now require either refinement or continue to human trials before they are approved. However, the results offer hope to many that are eagerly awaiting a male contraceptive, either to ease the burden from women or to provide the security of almost complete protection without the use of condoms.