According to a Sydney scientist a hormone-based contraceptive for men has the ability to reverse its effect just four months after stopping its use.

Dr. Peter Liu of the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, led the research team, and says the hormonal male contraceptive methods could be on the market in five to 10 years.

Dr. Liu found evidence in the results of a trial conducted in Sydney three years ago that a hormone based treatment can switch on and off sperm production.

Liu who has collated the results of trials from the United Kingdom, the United States, China, Indonesia and Melbourne, says he has found a 100 per cent success rate with the injections and pills of male hormones, which prevent sperm production.

He says all the studies showed male sperm production returned to normal three to four months after the treatment, so long term reversibility is no longer an issue.

The hormone-based contraceptive for men appears to produce few side effects, but long term side effects are unclear at present.

According to Liu and his team most of the trials of the male contraceptives are being held in China and Europe.

As many as 1,549 healthy men, took part in 30 trials conducted during 1990-2005.

Their sperm production was monitored every month and after a period of stopping the use of the pill, their sperm count was found to reach 20 million per milliliter, which is considered fertile.

The researchers found however that several factors, including age, original sperm count, duration of treatment and ethnicity influenced the reversal aspect.

Scientists already knew the production of sperm can be controlled with the hormone androgen or a combination of androgen and progestagen but the long-term impact of the hormones was not clearly known until now.

Currently, a study involving androgen treatment is in phase III stage, while another study, involving androgen-progestin combination is in phase II stage.

The existing methods of contraception for men, such as condoms or undergoing a vasectomy, may be unacceptable to some couples, therefore the new hormonal treatment offers another option.

Pharmaceutical companies are now undertaking trials on two methods of treatments, one injection and one implant.

Dr. Liu says the data gathered by his team provides convincing evidence that the previously described efficacy of hormonal male contraceptives is coupled with highly predictable recovery to sperm characteristics that are compatible with fertility.

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Source: Reuters