The male contraceptive pill could be less than ten years away, claim scientists at Manchester University.
Fred Wu, senior lecturer in medicine, said his research confirmed that sperm production could be suppressed using weekly hormone injections. The hormones could form the basis of a male contraceptive as effective as the female pill.
"This is an important landmark in contraceptive development and has given us the impetus to perfect the methodology," Dr Wu said.
Surveys had indicated a potential demand for a new form of male contraceptive. However, pharmaceutical firms needed convincing. "We are receiving some support from industry but at the moment it is not very wholehearted," Dr Wu said. "The future of this research depends on adequate funding because we as scientists cannot create the product, only the knowledge base. A commercial incentive is needed."
The male pill was not as attractive a proposition for investment as, say, cancer drugs partly because of fears of litigation. "No contraception is 100 per cent safe and some companies have become involved in very expensive lawsuits," Dr Wu said.
The nature of the drug meant that it would be taken for long periods by young people for non-life threatening reasons and therefore the chances of suffering damaging side effects or drug failure were greater.
"There is no question that a new male reversible contraceptive is required, it is a question of whose responsibility it is to put the method on the market," Dr Wu said. The male pill is technically difficult to perfect since it must suppress the production of 150 million sperm per day compared to just one egg per month for a female contraceptive.
The next stage of the trials will focus on longer-acting preparations of combined testosterone and progesterone - to maintain sex drive - which could be effective for three to four months. The efficacy of pills, patches and injections will be compared and the results shared with the University of Washington which is conducting similar research.
During the course of his work Dr Wu has uncovered some interesting inter-ethnic differences between Caucasian and Asian men.
In the Caucasian sample 70 per cent of men taking the hormone ceased sperm production altogether compared to 95 per cent of Chinese and Indonesian subjects. The remaining men in both samples had their sperm production suppressed to about 1 to 2 per cent of the norm.
Dr Wu said that so far the hormones had appeared safe with no significant side effects. The effects took a few weeks to wear off. "The idea is to provide more choice for men and complement the existing options open to women," he said.