Male contraceptive comes a step closer

The promise of a male contraceptive may finally be about to come true.

The first trials for a reversible male contraceptive began in 1990, but the male pill has still not arrived, largely because of suspicions that there is no market for it.

However, the pharmaceutical company Schering and Organon seems convinced that men could be persuaded to use a chemical contraceptive, and the five-year prediction may at last have a ring of truth.

John Guillebaud, professor emeritus of family planning and reproductive health at University College London, says: "It is rather like the tide coming in, an incremental process, and it comes in a little further each time. But I do believe that the male pill will happen." He believes implants would be the most effective delivery method.

"Men cannot be relied upon to take tablets. The contraceptive injections and implants have a far higher success rate for women. For men, this will be even more important because they do not have the investment in avoiding a baby."

Professor Guillebaud expects that by 2011 there will be implants with supplementary injections, and by 2016, an implant that can be buried under the skin for three years.

"This will be ideal," he says, "because men are wimps when it comes to pain."

The male contraceptive consists of two hormones, progestin and testosterone. Progestin stops the pituitary glad making the hormones that stimulate sperm production, while testosterone, in the form of androgen, stops fatigue, hair loss and replaces the libido. The amount of androgen must be carefully balanced to avoid mood swings or increased violence.

Recently Dr Peter Liu, at the Los Angeles Biomedical Research Institute, published an analysis of 1500 individuals who have taken part in male contraceptive trials over the past 15 years. He found that men regained full fertility (20 million sperm a ml) after three to four months of not taking the hormones. "These findings pave the way for new drugs that allow men to share the burden of family planning more fairly," he says.

The main fear about the male pill is that, like the female Pill, its long-term effects cannot be known until people try it.

David Neal, professor of surgical oncology at Cambridge University, says minor hormonal changes can alter the risk of prostate cancer - although they could have a positive effect.

He expects that male contraceptives will be most popular with couples in long-term relationships because, like the female Pill, it will offer no protection against sexually transmitted diseases.

Richard Anderson, professor of clinical reproductive science at Edinburgh University, who has led a series of trials, believes both the male pill and implant should be made available.

"The implant is likely to be the first method available, but in surveys men in Britain have said they would rather take the pill."

His latest studies have been "very positive", using two implants which dissolve over several months.

Development has been hindered by a lack of investment, but he says it is encouraging that pharmaceutical companies are now backing major studies. "The industry has been reluctant to believe that there really is a market for this."

There has also been a lack of development of new forms of testosterone, so until recently men have needed an injection every few weeks.

And when will we see a drug for the public?

"A few years - it still needs a big study, but people can now see how it is going to pan out," says Professor Anderson.

- Independent