What is the story?
Scientists in the US working on a reversible and non-surgical alternative to vasectomy have been inundated by requests from men wanting to try this new form of birth control, according to media reports.
The papers claimed a small clinical trial of a contraceptive device had had to be expanded to include men from four US cities because of huge interest.
The intra vas device (IVD), which is designed to be an alternative to vasectomy, uses a tiny plug of silicone gel to block sperm from travelling along the vas deferens. The plugs can be inserted through a small hole in the scrotum, and can also be easily removed, the papers said.
Previous studies had shown the device to be 100 per cent effective in preventing pregnancy.
Because having the IVD inserted does not involve severing or permanently damaging the tubes, men who use the device could have their fertility restored even after years of use, simply by having the plugs removed, the papers added.
What is the research?
The media reports are based on an announcement by Shepherd Medical Company that the phase one clinical trial of its IVD male contraceptive would begin recruiting in St Paul, Minnesota, this month.
The trial would then start accepting patients at centres in St Cloud, Minnesota, Shreveport, Louisiana and Tampa, Florida.
The trial is a preliminary safety and efficacy study designed to determine how successful the IVD is for male reproductive sterilisation. Studies in 1995 and in 1999, which included a total of 35 men, found that properly implanted IVDs provided 100 per cent effective contraception.
A study done in primates suggested that the technique could be reversed. It found that the sperm count and motility of monkeys who had an IVD removed seven months after implantation returned to normal levels within a month.
However, no studies have yet been carried out in human men to see whether fertility can be restored by removing the IVD.
The present study is only recruiting men who are interested in permanent sterilisation, who would otherwise undergo vasectomy. In all, 90 men aged 18 and over will take part in the trial.
Each man will have two tubular silicone plugs inserted into each vas deferens. These plugs are individually sized to fit the vas, so that they fill the lumen but do not stretch the tube.
The two plugs in each tube are inserted with a small space between them so if any sperm pass the first plug they are blocked by the second. The plugs are anchored to the wall of the vas deferens with small sutures.
The trial will measure how successfully the IVD blocks the vas deferens six and 24 months after insertion.
What do the researchers say?
Dr Neil Pollock, one of the founders of Shepherd Medical Company, which is developing the IVD, said: ‘This study is to confirm that the device is an effective contraceptive with a side-effect profile equal to or better than vasectomy.’
He said that following this safety and efficacy trial, another larger study would have to be done before the device was licensed. Only then could the question of how reversible the technique is be addressed.
‘It’s pretty clear that what we plan to do is going to be a lot easier to reverse than a vasectomy, but we have to run a trial to validate that,’ he said.
He added that once the device was licensed in the US, the company would be interested in running trials in the UK. It expects approvals for its use as an alternative to vasectomy by 2010.
What do other experts say?
Dr Allan Pacey, senior lecturer in andrology at the University of Sheffield and secretary of the British Fertility Society, said that this was an ‘interesting and novel approach’.
‘I could see this being attractive to younger men, as a non-condom option, but there is a danger in thinking that the device could be taken in and out at will.’
He said that research needed to show it was truly reversible and did not damage sperm production machinery in the long term.
‘The danger is that if the device is in place for a long time it could in theory lead to the man producing antibodies against his own sperm because there is nowhere for the sperm to go.
‘That in turn could mean that when he is ready to try for a family, he could be more likely to need IVF,’ Dr Pacey said.
Professor Richard Anderson, professor of clinical reproductive science at the University of Edinburgh and member of the Medical Research Council’s contraceptive development unit, agreed: ‘Men start producing antibodies to sperm after having a vasectomy. I don’t see how this would be different.’
He added that other forms of male contraception were in development. A WHO study on the effectiveness of three-monthly injections of testosterone and progesterone would be recruiting men soon in Manchester.
Informing patients
A device that plugs the tubes that sperm travel along could be an alternative to vasectomy.
The device is being tested in 90 men in the US.
Because it does not damage the tubes, removing the device could restore the men’s fertility.
The reversibility of the device has not been tested yet. Only men who do not want to have children in the future should have the device inserted.
What the papers said
“Plug is new contraceptive for men”
times
“Rush for new male birth control”
telegraph
“Male contraceptive study expanded”
BBC
