In 1961 a small round pill was introduced to the UK on the condition that it could only be prescribed to married women. This was the country’s first taste of the female contraceptive pill: a drug with the potential to create a revolution.
Despite initial attempts to limit its impact, the pill would go on to reshape the nation and the wider world by empowering women to take control of their own fertility. Almost sixty years on from the introduction of the pill, more than 100 million women worldwide currently use it to manage when, if and with whom they decide to have children.
But something important is still missing from the contraceptive mix. Although there are a number of very promising studies in the works, no male contraceptive pill or injection is currently available. In fact, since the invention of the condom in the mid-1800s, we haven’t seen much more in the way of progress.
So why have male contraceptives proved so elusive? Well, one reason is that there are considerable biological barriers to creating drugs that work with the male reproductive system.
Female contraceptive pills, implants and injections target the production of eggs to prevent fertilisation and subsequent pregnancy. They generally only have to stop one egg from being produced – that’s not too tricky.
But men produce many millions of sperm. For a male contraceptive pill to be effective, it would have to prevent all of these from generating. And to get to the sperm, drugs may also need to cross from the bloodstream into the testes – that’s no mean feat. On top of the logistical challenges involved, scientists working on contraceptives need to be mindful of side-effects and long-term repercussions.
There are certainly challenges inherent in creating new forms of male contraception, but there may also be some clever ways of getting around the problems. In recent years, research has revealed new insights into the molecular processes involved in sperm generation and how those processes can be safely and effectively manipulated.
In recent human trials, a male contraceptive injection demonstrated significant successes, and we may well see it available in the near future. Although in its current form, the jab was accompanied by side-effects including acne and mood disorders, and in some participants sperm count hadn’t returned to normal a full year after the study ended.
In another landmark study from 2012, scientists discovered a potential way of disabling ‘bromodomain’: an aptly-named protein involved in sperm generation. They found that, by latching on to the complex framework of this protein, a small molecule can be used to inhibit its action and thus suppress sperm production.
In trials on mice, the bromodomain inhibitor was found to produce a contraceptive result without causing any visible side-effects. If exposure to the molecule was removed, sperm count returned to normal. Libido was not affected and no reactions were seen in offspring.
However, the inhibitor has a short half life, meaning that it would need to be taken twice daily to confer an effect. The compound would also need refining to ensure that it is specifically targeted to bromodomain in order to counteract side effects.
These are exciting results, but there’s still a way to go. We need more research before we can expect to see a viable male contraceptive pill on the shelves.
Nonetheless, studies like this add weight to the growing body of research into new male contraceptives that work with the complex microbiology of the reproductive system.
Over half a century ago, the introduction of the female pill heralded monumental political and social change. We’ve come a long way since then, but there is still a profound need to enhance access to and effectiveness of contraceptives.
Time and time again, we’ve seen that science and medicine are capable of incredible feats. If the journey towards new forms of contraception tells us anything, it’s that science has the potential to transform society and change lives, one molecule at a time.
A version of this article was originally published in the Oxford Mail.