This Male Contraceptive 'Turns Off' Sperm in Monkeys Without Any Side Effects

A compound called EP055 has shown promise in slowing down the sperm of monkeys without disrupting their hormones, according to a new study published in the journal PLOS ONE.

This could, one day, lead to a male contraceptive "pill" which won't have significant side effects—although this is still a long way off.

Researchers from the University of North Carolina at Chapel Hill (UNC) and the Oregon National Primate Research Center found that the sperm of the male rhesus macaques that were tested stopped moving 30 hours after the compound was administered intravenously.

"Our compound stops sperm from swimming," Michael O'Rand, a retired professor of cell biology and physiology at the UNC School of Medicine and lead author of the study, told Newsweek.

"It works by binding to the protein EPPIN on the surface of sperm. This is a non-hormonal approach to male contraception," O'Rand said. "Unlike a hormonal approach, this compound does not stop sperm from being made in the testis or interfere with male hormones."

Currently, the only contraception options open to men are condoms and vasectomies, which are expensive and difficult to reverse. While there are several different approaches for male contraception being trialed, most affect hormones which can have negative side effects (much like female contraceptive pills).

In their study, the researchers did not observe any physical side effects in the monkeys. Eighteen days after being given the contraception, the animals showed signs of complete recovery, indicating that the effects are reversible.

"So far, all indications are that the compound is safe," O'Rand said. "No adverse events were noted in the monkeys given the compound."

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Could men soon be taking contraceptive pills like those available to women? PHILIPPE HUGUEN/AFP/Getty Images

Monkey studies will not necessarily reproduce the same results as superior human clinical trials, however, O'Rand noted that they are probably as good a model as possible. The monkeys are "certainly superior to rodent models" which have very different reproductive systems.

Nevertheless, much more research needs to be conducted into the compound before it is ready for human use. The scientists have begun testing a pill form of the compound and the next step will be to eventually conduct a monkey mating trial to test EP055's effectiveness against pregnancy.