New Male Contraception Methods

There has been a lot of media coverage in recent years on scientists’ efforts to develop a hormone-based contraceptive pill for men. Just like the contraceptive pill for women, the male version of ‘the pill’ could potentially have longer term consequences for the hormone balance of a man’s body. Some medical experts say there is a possibility that a man’s sperm count, which would be reduced if he were to take the pill, may struggle to get back to a normal, healthy level when he stopped taking the medication – thereby leaving the man with long-term fertility problems. For this and other reasons the male pill is still in trials and some men have expressed reservations about whether or not they would be prepared to try the medication. For some men it seems that assuming a certain degree of physical risk in the name of contraception is quite definitely ‘women’s work’. But what if there were another solution?

Calcium Channel Blockers

Calcium channel blockers are a less-publicised potential birth control method for men. Unlike the male pill, these drugs (should they be successfully developed as contraceptives) would not interfere with a man’s hormones. Scientists have discovered a protein in sperm which they have named the CatSper (short for cation channel of sperm). This protein forms a channel in the membrane of a sperm cell’s tail and allows calcium ions to flow into the sperm cell. These calcium ions give the sperm cell the ability to flick its tail energetically and swim around. Scientists thought that if they could create sperm which did not have the CatSper protein and would therefore receive no calcium ions, perhaps these sperm would not be capable of swimming to fertilize a woman’s egg. Experiments on mice resulted in male mice whose sperm did not have the CatSper protein. Without any calcium ions, their sperm cells were slow and sluggish and didn’t seem to have the same sense of direction as normal mice sperm. Furthermore, it seemed that the violent flicking of a sperm cell’s tail, enabled by calcium ions, was what allowed the sperm to penetrate a female’s egg. The sperm cells of these mice failed to penetrate an egg even when placed directly beside the female cell. So it was clear, blocking the CatSper protein made male mice infertile. The question now was would the same action have the same affect in humans? And if so – what drug could create this effect temporarily?

Existing Drugs

Nifedipine – Nifedipine is an approved drug for high blood pressure which is also a known calcium channel blocker. This medication brings about changes in human sperm cells. Studies have found that many men are sterile while they are taking the drug but regain their fertility after they stop taking the medication. Trials have been done to determine whether or not it is safe to offer nifedipine or a similar medication for contraceptive purposes, and whether or not nifedipine would be a truly reliable contraceptive. There have been reports of some couples conceiving before the male partner stopped taking nifedipine for his high blood pressure. It is also possible that the high blood pressure itself is contributing to the infertility of these men. There is some evidence that the reliability of nifedipine as form of contraception varies between races. There is currently a lack of funding for further research.

Migulstat – Migulstat is another calcium channel-blocking medication which has been approved in the United States and in the European Union for the treatment of a rare genetic disorder called Gaucher’s disease. Scientists are considering this drug’s potential as a contraceptive.

Drugs Of The Future

Whereas drugs such as nifedipine are calcium channel-blocking drugs which also happen to block calcium channels in sperm (as well as other parts of the body), scientists are working to develop a drug which actually blocks the function of the CatSper protein found in sperm only. Experiments on humans and experiments on mice obviously create two very different sets of circumstances. Although mice lacking the CatSper protein can be genetically engineered, their infertility is irreversible. For humans we need a drug that simply blocks the action of the CatSper protein temporarily. Scientists also need to be sure that this drug won’t block the action of other important cell components in the human body. Their work continues…