Wed, Oct 08, 2003 - Page 5 News List

Scientists excited about breakthrough male contraceptive


A new hormone-based contraceptive treatment which stops men from producing sperm has prevented pregnancy among 55 couples during a 12-month test, researchers said yesterday.

The study, a US government-funded program sponsored by Virginia-based family planning organization CONRAD, was able to successfully and reversibly turn off sperm production in the men who took part, said Rob McLachlan, director of clinical research at Prince Henry's Institute of Medical Research in Sydney, Australia.

Australian researchers pitched the study and won financial backing from CONRAD, which often funds medical studies outside of the US and works closely with the WHO.

"This is the first time the combination of long-acting testosterone and a progestin have been used in an effectiveness study. This is the first to be reported in the world," McLachlan said. "We're very pleased and excited the results are so positive."

It was an 18-month commitment by the 55 couples involved, McLachlan explained.

The trial was conducted in two phases. The first, over three to six months, involved taking testosterone and progestin to turn off sperm production. Then when the sperm count was zero or close to zero, the 12-month trial period began.

"What was unusual was the fact that this was an effectiveness study," McLachlan said. "Once the sperm was suppressed the couples used this as their [contraceptive] method. Other studies only monitor how far the sperm count falls."

Over the 12 months of the trial, the men continually took implants of testosterone and injections of progestin, a reproductive hormone. The implants require minor surgery to put them under the skin, McLachlan said.

"Normally there are signals from the brain to the testes that promote production of sperm and to make testosterone, which is important for general health in men -- it gives them strength, energy, sex drive. When you give the testosterone and the progestin together, you turn off the brain signals which normally go to the testicle. As a result the testicle stops making sperm and stops making testosterone," McLachlan said.

At the end of the trial, the sperm levels of the all the male participants recovered to the levels they were at before undergoing the program, McLachlan said, although it took six to 12 months for this to happen.

McLachlan said the risk of cancer in men taking the contraceptive would be similar to that of women on female contraception.

"There's no evidence for this problem at this point. Cardiovascular and prostate health are long-term safety issues that we'll need to keep a close eye on, but so far so good," he said.

Tony Morrow, an endocrinologist from Sydney's Mona Vale hospital, who was not linked to the research, concurred. "There's been no evidence reported that higher levels of testosterone could be related to prostate cancer. If men are on such treatments they would be monitored," he said.

He said more research with larger groups was necessary to evaluate other possible side effects such as sleep disorders and breathing difficulties.

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