When will we have a male birth control pill? Researchers say ‘soon’

After several years of trying and multiple failed attempts, researchers believe that they are close to developing an oral contraceptive for men, according to new research presented Sunday at the 251st National Meeting & Exposition of the American Chemical Society (ACS).
By tweaking promising experimental compounds, Jillian Kyzer, a graduate student working with Dr. Gunda I. Georg at the University of Minnesota College of Pharmacy, and her colleagues said they have made progress towards a pill that would pause fertility in males without any significant side effects – some 50 years after a similar product was first released for women.
Such a pill “would have to be soluble so it could be taken by mouth,” Dr. George said, according to the Daily Mail. “It would start working fairly quickly and it wouldn’t diminish libido. It would be safe even if taken for decades,” and since some users may eventually want to have children, it would have to be “reversible, with no lingering ill effects on sperm or embryos.”
“That’s a very high bar for bringing a male contraceptive to market,” she added, noting that these difficulties have caused many scientists to throw in the towel. Her team continues their search for the perfect male birth control pill recipe, however, saying that it “would be wonderful to provide couples with a safe alternative because some women cannot take birth control pills.”
Hybrid compounds could hold the key
As Kyzer explained in a statement, testosterone is being studied as a potential contraceptive for men, because it can cause infertility at certain doses. However, it is ineffective in one-fifth of all males and can lead to side effects such as weight gain and a decrease in HDL cholesterol levels.
Last year, scientists identified an enzyme used by sperm to penetrate the egg, which is a potential target for an oral contraceptive, and some drug companies are working on experimental products of their own. However, they note, some – such as a compound being developed by Bristol-Myers Squibb, is effective at inhibiting fertility, but is not soluble and cannot be taken orally.
Another experimental compound being developed by the pharmaceutical company can be taken orally, but has proven to be less selective about what it targets. Not only does it interact with the intended target, retinoic acid receptor-α, but with other receptors not involved with fertility. As a result, it could result in harmful side effects, Kyzer and her colleagues explained.
The researchers are working to build on Bristol-Myers Squibb’s work by developing substances similar in nature to the company’s products in terms of chemical structure, and their work has led them to find several small changes than can be made to alter how these test compounds affect the body. For instance, they found adding a polar group to the first molecule would increase its solubility, and replacing an amide bond with similar, but slightly different bonds enhanced their stability, allowing them to last longer after being taken.
Unfortunately, these alterations also reduced the specificity of the compounds, but the group is making progress and plans to continue refining the compound’s chemical structures. Their quest for a male contraceptive that can be taken orally, is stable and performs as expected, without harmful side effects, will now lead them to investigate hybrid compounds that use scaffolds and borrow structural features from other compounds known to interact with retinoic acid receptors.
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