Behind the headlines: Would a male contraceptive pill work?

A sperm-blocking contraceptive could be available for men in five years. Sanjay Tanday reports

What is the story?

A contraceptive pill for men is to be tested in human studies and could become available on the market in five years’ time, according to media reports.

The papers claim that the ‘male pill’ will allow couples to share the responsibility for contraception, a role that tends to fall to the woman.

The male oral contraceptive would be taken each day or a few hours before sexual intercourse.

Unlike hormone-based male contraceptives being developed, the pill would not have any long-term impact on a man’s fertility. This should return to normal within hours of stopping the treatment, they said.

The pill acts by preventing the longitudinal muscle in the vas deferens from contracting to propel sperm out of the penis, the reports explained.

What is the research?

The media reports are based on a series of papers by UK researchers, who observed that the antipsychotic drug, thioridazine (Mellaril), and the BP drug, phenoxybenzamine (Dibenzyline), were preventing ejaculation in clinical trials.

Neither drug, however, could itself be used as a contraceptive. Thioridazine can cause drowsiness while phenoxybenzamine can cause dizziness.

The researchers suggest that the drugs were selectively inhibiting the longitudinal muscle of the vas deferens. This inhibition caused it to behave as a functional sphincter.

The researchers then performed tests on human tissue. These tests were to identify chemicals that could have the same effect on ejaculation as thioridazine and noxybenzamine.

Current studies in humans are now under way to investigate the mechanisms regulating contractility in longitudinal and circular muscle layers of human vas deferens.

Functional analysis of the adrenergic pathway is to be conducted. From this analysis the researchers can understand just how the identified chemicals can alter the movement of sperm in the human vas deferens.

What do the researchers say?

Lead researcher Dr Chris Smith, from the department of applied biomedical research at Kings College London, said that there was now a need for the chemicals found in the two drugs to be tested in clinical trials to identify the common targets of the drugs.

Testing the chemicals in animals, such as rats, proved not to be of much use because of the difference in biology between rats and humans, he said.

‘It could be possible to develop a male contraceptive pill within five years, because two of the chemicals that we have identified are found in pre-existing drugs meaning that there would not be any delays with testing for safety.’

Dr Nnaemeka Amobi, a researcher from Kings College London who was also involved with the study, said that the time scale for the development of a male pill was dependent on the amount of pharmaceutical funding it could attract.

‘There are benefits of a non-hormonal pill over a hormonal contraceptive,’ he said. ‘Unlike the hormonal contraceptives, which take time to start working, the non-hormonal pill would have an immediate effect.

‘There are also problems with the delivery of hormonal contraceptives. They have to be administered daily by injection, which many men dislike.’

What do the experts say?

North London GP Dr Richard Ma, of the RCGP’s sex, drugs and HIV working party, welcomed the news saying that men needed to take more responsibility for contraception.

‘This pill is likely to be many years away from mass production, so it is important that we tackle the issue of education while it is being developed,’ he said.

‘It will take years to educate men into thinking about the responsibilities and importance of contraception use in the same way that women do.’

Dr Ma added that even if men were using a contraceptive pill, it would be likely that women would continue to use a form of contraception themselves.

Rebecca Findley, press and campaigns manager of the Family Planning Association, said that it had conducted a contraception awareness survey. The results from the survey showed that men were willing and ready to take more control over the use of contraception.

Informing patients

  • UK researchers are developing a non-hormonal male contraceptive pill that could be ready in five years.
  • The pill works by preventing the longitudinal muscle in the vas deferens from contracting.
  • The pill needs to be tested in clinical trials before it can be successfully manufactured.

what the papers said

“Sperm-blocking contraceptive hope” bbc

“UK scientists invent pill that can be taken hours before sex” daily mail

“Male pill is ready to work in hours” the sun

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