The prospect of a viable male contraceptive option inches closer to becoming a reality.
A novel hormonal gel for men has shown promising results in a recent clinical trial. The gel, which is applied to the shoulders once daily, inhibits the production of sperm through a blend of nestorone and testosterone. The gel was created by the National Institutes of Health and the nonprofit Population Council. It mirrors the approach of birth control pills for females, utilizing two hormones: nestorone, a form of progestin, and testosterone, a male sex hormone. Nestorone restricts testicular testosterone production, resulting in decreased sperm development.
However, testosterone has various functions in the human body, such as sustaining muscular maintenance and libido. The gel provides a sufficient quantity of testosterone to support health while hindering sperm production.
Since 2005, researchers have been refining the gel's dose and concentration. In this latest test, involving more than 300 couples, they believe they found the perfect balance.
Normal sperm counts span between approximately 15 million and 200 million sperm per milliliter of semen. Studies show that counts below 1 million per milliliter can prevent conception. In this trial, 86% of men achieved low sperm counts within 15 weeks of using the gel. For some, the suppression of sperm production occurred more quickly, between 4 and 8 weeks.
Researcher Diana Blithe, head of the National Institute of Child Health and Human Development's branch at the NIH, is delighted with the findings. Presenting the results at the annual meeting of the Endocrine Society in Boston, Blithe said, “We’ve been really excited by the results. The combination seems to provide better, faster suppression than we expected.”
She declined to disclose any unintended pregnancies during the trial and noted that study results would be published in a medical journal.
Compared to contraceptives for women, such as pills, rings, and patches, with failure rates of about 7% and condoms with a 13% failure rate, the gel appears to have several benefits. In the case of women, missing a day or two of pills could trigger ovulation and raise the chances of an unplanned pregnancy. On the other hand, if a man accidentally misses a day or two of using the gel, his hormone levels would return to normal but would take approximately 8 to 10 weeks to reach sperm-producing levels.
Blithe stated that the participants in the study reported fewer mood swings and depression, unlike with female birth control pills.
Previous testing by the World Health Organization using injections with a similar hormonal combination resulted in stopping the study in 2011 due to significant side effects, including serious depression. Blithe attributes this to hormone levels clearing at dissimilar rates when injected. With the gel, a consistent concentration of hormones accumulates in the skin, leading to a slow and steady release.
Matthew Trevino, a 35-year-old from Sacramento, California, took part in the research. Using the gel morning is now part of his daily routine, similar to showering and brushing his teeth. Trevino cited minor weight gain and an increase in sex drive as potential side effects, but overall, he was satisfied with the outcome.
Couples interested in joining the trial had to be in a committed relationship and pledge to remain in the study for two years. Men using the gel underwent a range of possible side effects, including dry or oily skin, varying libido levels, and hair growth or loss, with mood swings being the most prevalent issue. However, Blithe stated that only a small percentage of participants experienced mood swings.
Trevino shared with a podcast his long-term interest in a male contraceptive option. He feels it's not fair that the responsibility of birth control falls solely on women.
Typically, women release an egg once a month, while men produce approximately 1,000 sperm per second.
"Perhaps the burden should lie on the opposite side," Trevino explained. "I believe it's not fair that it always falls on women."
Once men cease using the gel, their sperm count returns to normal levels within around two to three months. Post-trial recovery, many participants became fathers, demonstrating the gel's complete reversibility, according to Blithe.
Currently, the only birth control choices accessible to men are condoms, which have a high failure rate, and vasectomy, a surgical procedure that can be challenging to reverse.
The scientists have initiated discussions with the US Food and Drug Administration regarding how to test the gel in its final, definitive trial. No male contraceptive strategy has ever progressed this far.
Generally, medications that reach this point must be tested against a placebo. Nonetheless, it wouldn't be ethical to conduct such a test for a research project aiming to prevent pregnancy, stated Dr. Christina Wang, an investigator in the trial and a specialist in male reproductive biology at the Lundquist Institute at UCLA's Harbor Medical Center.
If the FDA approves the trial, the researchers anticipate beginning the final phase of testing in 2025. This period will take a couple more years, and Wang plans to expand the study to additional locations and enlist more couples.
Large-scale trials often necessitate considerable investment. Blithe is optimistic they'll receive support from pharmaceutical companies.
Dr. Brian Nguyen, an obstetrician-gynecologist at the University of Southern California, who assisted participants with the social and behavioral aspects during the trial, is excited to witness the gel hit the market and initiate a new age of gender equity in birth control.
"We generally believe of men as being unaware or uninterested," he said. "But when you think about males in close relationships, how does a female partner conceal the fact that they are in pain, or experiencing abnormal bleeding, or mood swings? This medication is partner-driven, which is exceptionally unique."
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The gel, containing nestorone and testosterone, is applied to the shoulders once daily by the man to inhibit sperm production. The gel provides a sufficient quantity of testosterone to support health while hindering sperm production.
