Male contraceptive gel proven to work in monkeys

A new method of male contraception has been proven to work in monkeys, but it might be a good few years before approval is given for use on humans

A new type of male contraceptive, a gel that blocks sperm flow, has been proven to work in monkey trials. Vasalgel is injected under anaesthetic into sperm tubes and, acting as a physical barrier, stops the sperm swimming down to the penis.

Researchers at The University of California tested the gel on 16 adult male monkeys, 10 of who were already fathers. They were monitored for a week after the injection, and then released back into their enclosure to rejoin some fertile females. Mating occurred, but no female monkeys became pregnant. A few of the male monkeys displayed side effects, and one needed an operation as the injection went wrong and damaged his tubes.

The trial, which has been taking place over two years, has been published in Basic and Clinical Andrology. Parsemus Foundation, the non-profit company researching the gel, is hoping to have enough evidence, and funding, to begin tests on men within a few years. So far, it has used only grants and fundraising to pay for the study.

Allan Pacey, professor of andrology at the University of Sheffield, said; “The study shows that, in adult male monkeys at least, the gel is an effective form of contraception. But in order for it to have a chance of replacing the traditional surgical method of vasectomy, the authors need to show that the procedure is reversible. I would imagine there is a worldwide market for a new male contraceptive, but trials in humans and more long-term safety data are required before we will know if it is a success.”

Currently, men only have two methods of contraception; condom, and vasectomy. Vasalgel has the same effect as a vasectomy – blocking sperm from mixing with semen – but researchers hope it should be easier to reverse if a man later decides he wants to have children. Another injection would need to be administered to dissolve the gel plug, with tests proving successful in rabbits.