Since the first female oral contraceptive Pill was approved for use in the UK around 60 years ago, there have been many promises that science was on the verge of coming up with a male version.
Yet the ‘male Pill’ remains conspicuous by its absence; male contraception remains largely confined to using condoms or having a vasectomy — a surgical procedure that seals the tubes that carry sperm from the testicles.
The search has been hampered by the complexities of finding something as effective as the female Pill (99 per cent when taken properly) but without the side-effects that may deter men from taking it.
Most attempts at a male Pill have involved suppressing levels of the hormone testosterone, which is responsible for stimulating the production of sperm in the testes.
In a report in March in the journal ACS Nano, the scientists described how they made the experimental gel from water and sodium alginate — a substance found in seaweed. Once injected, it hardens and blocks a man’s tubes. But it is easily reversed by firing ultra-sound at it. A file photo is used above
Yet depleted testosterone can cause lower libido, erectile dysfunction, thinning bones, reduced muscle strength and hot flushes.
But are scientists finally closing in on their target? Certainly, some experts say so, thanks partly to a large injection of cash.
‘The search for a male Pill has been one big failure so far, partly because the female contraceptive Pill has been so successful that the general perception has mistakenly been we don’t need a male one,’ says Professor Christopher Barratt, head of reproductive medicine at Dundee University.
Professor Barratt and his team last year received £1.2 million from the Bill & Melinda Gates Foundation to screen hundreds of different drug compounds in a bid to speed up the search for a male Pill.
‘I think the first one will be ready for use within the next three years,’ says Professor Barratt.
Here are some of the front runners…
Rub-on-gel stops sperm production
One of the main new hopes is not actually a pill but a contraceptive gel being trialled by hundreds of couples in Britain, including at St Mary’s Hospital in Manchester.
The gel, which is rubbed into the shoulders or upper arms daily, contains testosterone and segesterone acetate (brand name Nestorone), a synthetic version of a female sex hormone that switches off sperm production.
The two are combined because the segesterone acetate can also cause a drop in the amount of testosterone produced by the testes, potentially reducing libido and causing unwanted side-effects such as erectile problems, muscle weakness and hot flushes. Adding testosterone compensates for this.
The trial, which began in April 2019, runs until September 2023, with the first results due in 2024.
But even if it is effective, there will still be drawbacks, warns Professor Barratt, because suppressing sperm production sufficiently to ensure contraception takes around three months.
Tablet without the side-effects
Researchers from the University of Minnesota, U.S., recently announced a breakthrough in the search for a non-hormonal male Pill that doesn’t rely on the suppression of testosterone (which can trigger unpleasant side-effects) to reduce sperm count.
And initial results from animal studies, presented at the annual American Chemical Society conference in March, suggest the experimental pill is 99 per cent effective, researchers claim.
Code-named YCR529, it blocks the effects of a protein — retinoic acid receptor alpha — that plays a crucial role in sperm formation. The drug stops it from binding to sperm cells properly, preventing their growth.
When mice were given the pill daily for four weeks, it dramatically reduced sperm counts and was 99 per cent effective in preventing pregnancy — with no noticeable side-effects. Four to six weeks after the drug was stopped, the male mice were able to father offspring again.
Researchers said they plan human clinical trials by the end of 2022. But it could still be five years before it is routinely available.
Code-named YCR529, it blocks the effects of a protein — retinoic acid receptor alpha — that plays a crucial role in sperm formation. The drug stops it from binding to sperm cells properly, preventing their growth. A file photo is used above
Tube-blocking-gel that’s reversible
Scientists at Harbin Medical University in China are working on a radical form of male contraception that involves blocking the passage of sperm from the testes by injecting the vas deferens — the tube that carries sperm out of the body — with a gel that sets firm in under three minutes.
When a couple decide they might want children, the gel can be dissolved in minutes by beaming sound waves through the skin with a hand-held ultrasound device — clearing the way for sperm to leave the body.
In a report in March in the journal ACS Nano, the scientists described how they made the experimental gel from water and sodium alginate — a substance found in seaweed.
Once injected, it hardens and blocks a man’s tubes. But it is easily reversed by firing ultra-sound at it, turning it into a harmless liquid that gets absorbed by surrounding tissue. The seaweed-based gel has only been tested on animals, but in their report the researchers said: ‘This could be a reliable, safe and reversible male contraceptive strategy.’
After-dinner pill to curb fertility
A once-a-day pill that’s taken straight after dinner could give men an effective contraceptive that lowers testosterone levels without significant side-effects.
The pill, called dimethandrolone undecanoate (DMAU), is taken after the main meal of the day, as food significantly increases the amount that gets absorbed into the bloodstream.
Rather than target testosterone directly, it suppresses two other hormones — follicle-stimulating hormone and luteinising hormone. Both are important for the production of healthy levels of sperm.
Blocking their production reduces sperm levels enough that conception is extremely unlikely.
Since it doesn’t directly target testosterone, it’s hoped the drug will be largely side-effect free.
Early trials have suggested it is safe — now a study, involving 84 men, is under way at the University of Washington, which is also investigating whether the drug could be given as a single jab that might act as a contraceptive for up to six months.
Could heat be the answer?
It’s known that sperm count is reduced by high temperatures, and scientists at Nantong University in China are using that effect to develop an unusual form of contraception.
It involves injecting tiny iron nanoparticles into a vein in the arm or thigh — and then moving a hand-held magnet over the body to guide the particles into the testicles, while monitoring their progress via X-ray.
Once in position, the particles are exposed to a magnetic field — where an electric current is run through a wire — that heats them to 104f, enough to temporarily shrink the testicles and reduce sperm production.
In tests, a single session stopped mice fathering offspring for a month, according to a July 2021 report in the journal ACS Nano Letters.
The tattoos being used for medical purposes. This week: To monitor blood sugar levels
Researchers at Harvard University and Massachusetts Institute of Technology, both in the U.S., have developed a smart tattoo that can tell someone with diabetes if their blood sugar level is rising.
It works by using traditional tattooing techniques but with ‘biosensitive’ inks that change colour according to changes in the body’s chemistry. The inks developed so far change from green to brown as blood sugar increases — there’s also a green ink that gets darker as sodium concentration increases, indicating dehydration (this could be used to monitor elite athletes, for instance).
It’s thought that the inks overcome some of the limitations of monitoring devices that patients wear, as they’re more seamlessly integrated with our bodies.
The suggestion is that the inks could one day be incorporated into long-lasting tattoos for diabetes and other chronic conditions, or into temporary designs for shorter-term monitoring.