Male contraceptive pill: effectiveness of drug in preventing pregnancy - and when human trials will start

A new contraceptive pill for males has been found to be 99% effective in preventing pregnancy in lab tests on mice.

The breakthrough medication offers hope of new birth control options, helping to balance the contraceptive burden as far fewer options are currently available to men.

Women can take several pills to prevent pregnancy, or use patches and intrauterine devices, while men only have the option of single-use condoms, which are prone to failure, or vasectomies.

It is possible for vasectomies to potentially be reversed, but the procedure is generally considered a permanent form of male sterilisation.

Researchers say the reversal surgery is “expensive and not always successful”, showing the need for “an effective, long-lasting but reversible contraceptive, similar to the birth control for women”.

What have researchers said?

Scientists presented their findings at the spring meeting of the American Chemical Society in San Diego on Wednesday (23 March), following successful results from lab tests on mice.

Dr Abdullah Al Noman, from the University of Minnesota in Minneapolis who presented the work, said he and his team gave male mice a daily dose of a molecule called YCT529 over a four week period.

Over this time, they found that the sperm count of the mice plummeted.

Between four and six weeks after the mice stopped receiving the non-hormonal treatment, they could reproduce as normal with no obvious side effects.

The team tested more than 100 molecules to identify a drug candidate that targets a protein called retinoic acid receptor alpha (RAR-a), which blocks the effects of retinoic acid - a derivative of vitamin A that plays an important role in sperm development.

Dr Noman said there are several compounds undergoing clinical trials but they target the male sex hormone testosterone, which could result in side effects including weight gain and depression.

He said: “We wanted to develop a non-hormonal male contraceptive to avoid these side effects.”

When will human trials start?

Dr Noman and his team have now licensed the drug to private company YourChoice Therapeutics.

The team is aiming to begin carrying out human clinical trials in the US in the second half of this year.

The team hopes to begin human clinical trials in the second half of this year.

Dr Georg, head of the medicinal chemistry department at the University of Minnesota, added: "Because it can be difficult to predict if a compound that looks good in animal studies will also pan out in human trials, we’re currently exploring other compounds as well."

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