Male contraceptive '100% effective'
Monday October 6, 2003
Australian scientists announced today that they have developed a 100% effective, injectable male contraceptive that could provide a side effect-free alternative to the female pill.
In the first complete trial of a male contraceptive, 55 men received a treatment comprising testosterone and progestin, the latter being a hormone used in female contraceptive injections.
The five-year study showed that when given to participants every three to four months by injection and implants under the skin of their abdomens, the treatment effectively and reversibly "switched off" sperm production for a full year.
None of the men showed any side effects and none of their partners became pregnant, scientists from the Anzac Research Institute in Sydney said.
Professor David Handelsman said in a statement on the institute's website: "This is the first time a ... male contraceptive that will suppress sperm production reliably and reversibly has been fully tested by couples."
Previous attempts to develop an effective and convenient male contraceptive have encountered problems with reliability, and side effects such as mood swings and a lowered sex drive.
The trial used the progestin, DMPA, and testosterone to flick a reversible "switch" in the brain that initiates puberty, causing the body to stop sperm production. The testosterone also ensured male health and libido, countering the progestin, which causes natural levels of the male hormone to fall.
Some participants in the trial even reported an increase in their libido, and once they came off the trial participants found that their fertility returned within six to seven months.
"We used a hormonal implant to replace testosterone given every four months and the progestin DMPA was injected every three months," Prof Handelsman said. "This shows the way for a final product ... it is now over to the companies to develop a convenient and acceptable one."
The scientists added that their treatment could be made available as a single injection. A tablet version of the contraceptive - a male pill - may be on the market within two to three years, the Daily Mail reported today.
Female contraceptive injections, which involve the periodic application of progestins such as DMPA into a muscle under the skin, have been widely available for several years. So far they have shown no serious side effects, although it can take up to a year for female fertility to return.
A male contraceptive could provide an alternative for couples where the woman runs a higher than normal risk of the rare but serious side effects of the female pill, such as blood clots, heart disease and stroke. It could also prove useful for men whose partners are breastfeeding and so cannot take the female pill.
The scientists described the new male contraceptive as "like a reversible vasectomy"; useful for men who are unsure about whether to undergo surgical sterilisation.
Prof Handelsman said it was about providing people with choice.
"The results of this study foreshadow how men may be able to take greater responsibility for contraception in a convenient and effective way," he said.