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Hormonal gel trial shows promise

On Sunday, at the Endocrine Society’s conference in Boston, researchers with the National Institutes of Health’s Contraceptive Development Program presented encouraging phase 2 trial results on the hormonal gel.

The trial involved 222 men, ages 18 to 50, who applied 5 milliliters of the gel (about a teaspoon) to each of their shoulder blades once per day.

The second part of the two-part trial is still underway. Initial findings showed that the contraceptive worked faster than expected, according to Diana Blithe, chief of NIH’s Contraceptive Development Program.

After 12 weeks of applying the gel every day, 86% of trial participants achieved sperm suppression, meaning they had only up to 1 million sperm per milliliter of semen, the amount the researchers deemed effective for contraception. On average, the timing for effective contraception was eight weeks.

In comparison, normal sperm counts without contraception can range from 15 million to 200 million per milliliter.

The faster-than-expected timing to suppress sperm is an encouraging sign, especially since past attempts have taken longer to reach these sperm levels, Blithe said in a news release about the new data.

Prior efforts using testosterone alone have required higher doses of the hormone, which can cause side effects. Because the gel includes both testosterone and Nestorone, it acts more quickly and requires less testosterone, she said.

Nestorone is a type of synthetic hormone called a progestin that’s already used in the vaginal ring contraceptive. Combining Nestorone and testosterone in the new gel is meant to keep men from producing sperm without affecting their sex drive or causing other side effects.

So far, the men in the gel clinical trial have shown low enough blood levels of testosterone to maintain their normal sexual function.

Researchers are now tracking how well the gel works to prevent pregnancy. Because of pregnancy risk, male participants are required to be in committed, monogamous relationships, and need consent from their female partners too. The couple must agree to use the gel as their only birth control and to have sex at least once a month for a year. Throughout the study, men have their sperm counts tested periodically, which is a good predictor of fertility. If the sperm counts remain low, the chances of pregnancy are slim.

After decades of early-stage attempts and failures, there are no federally approved male birth control drugs. Only a handful have even advanced into human trials.

It’s not because the approaches haven’t shown potential, researchers say, but because there hasn’t been enough funding or financial investment to complete expensive advanced human trials.

https://www.nbcnews.com/health/mens-heal...rcna153349