New Male Contraceptive

Written by Mike McRae | Science Alert on . Posted in News & Updates

A new type of male contraceptive not only prevents babies; It's reversible!

We've been waiting a long time for this. Until now, men have had only two serious options for preventing baby-making: condoms or 'the snip'. A promising new product could be set to change all that, with animal trials indicating that it's not only close to 100 percent effective, but that it can also be fully reversed, making it less drastic than the vasectomy while still offering similar benefits.

 Trademarked under the name Vasalgel, the contraceptive is a polymer gel being developed by the non-profit Parsemus Foundation in California, which aims to "find low cost solutions that have been neglected by the pharmaceutical industry".

We reported on Vasagel back in February after it showed itself to be effective in preventing rhesus monkeys from getting pregnant for up to two years.

The gel acts as a barricade to sperm when injected into the thin tube that channels sperm from each teste to the ejaculatory ducts – a tube also known as the vas deferens.

Sperm produced in the testes usually travel up the vas deferens to meet with other glands that add various substances to make up semen; when blocked by the gel, they are either embedded in the material or are simply reabsorbed by the body.

If you're curious to know why it's taken until the 21st century to figure out how to do something as simple as plug up the sperm highway rather than cut it in half, it might have something to do with the fact that the material needs to be inert, easily injected into a small space, remain fairly flexible, stay in one place, and filter out spermatozoa with maximum efficiency without blocking the flow of fluids.

Vasagel manages all of that, with earlier trials conducted on a dozen rabbits last year reporting no signs of any sperm cells a month after the procedure, nor in the following 12 months.

Importantly, while there were some slight changes to the cells lining the vasa deferentia in the rabbits, they weren't considered to be all that serious and didn't seem to be worsening with time.

In the following trial, 16 adult male rhesus monkeys housed with up to nine fertile females failed to produce any offspring after a breeding season, with another seven continuing for another year without any pregnancies.

While rhesus monkeys and rabbits aren't exactly human, their biology is similar enough for all of this to make for promising news.

The contraceptive has its origins in a similar gel plug called reversible inhibition of sperm under guidance, or RISUG for short, which although has had a head start by a few years in India is struggling to make it through human trials for want of volunteers.

Parsemus Foundation is hoping to have their first human volunteers test the contraception next year; given it's now been demonstrated to be fully reversible, perhaps they'll have better luck with men signing up.

This time they injected two variants of Vaslagel into seven male rabbits and waited 14 months before hitting the gel plugs with a solution of sodium bicarbonate, also known as baking soda.

The solution neutralised and dissolved the gel's structure, allowing sperm to once again swim freely down the vas deferens in search of ova to fertilise.

"The results of the Vasalgel reversibility study in rabbits indicate the implant could be removed resulting in a quick return of sperm flow," said lead researcher Donald Waller.

While more work needs to be done to completely flush out any remaining bits of Vasalgel – since the material can affect some of the sperm's characteristics – the results are good news for men who want a semi-permanent way to avoid the risk pregnancy.

Read more at: sciencealert.com

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