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New male contraceptive gel works faster than similar contraceptive methods
Last reviewed: 02.07.2025
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A new male contraceptive gel that combines two hormones, segesterone acetate (called Nestorone) and testosterone, suppresses sperm production faster than similar experimental hormonal contraceptive methods for men, according to a new study.
Results from the ongoing, multicenter Phase 2b clinical trial will be presented Sunday at ENDO 2024, the Endocrine Society's annual meeting in Boston.
“The development of a safe, highly effective, and reliably reversible contraceptive method for men remains an unmet need,” said senior investigator Diana Blythe, PhD, director of the Contraceptive Development Program at the National Institutes of Health (NIH) in Bethesda, Maryland. “While studies have shown that some hormonal agents can be effective for male contraception, the slow onset of suppression of spermatogenesis is a limitation.”
The study included 222 men who completed at least three weeks of daily use of a contraceptive gel. The gel contained 8 milligrams (mg) of segesterone acetate and 74 mg of testosterone. Segesterone acetate is an ingredient in the Annovera vaginal birth control ring. The men applied the gel to each shoulder blade daily.
In the early stages of the study, the researchers measured suppression of sperm production by testing semen samples at four-week intervals. The threshold considered effective for contraception was 1 million or fewer sperm per milliliter of semen, Blythe said.
Most of the study participants (86%) achieved this sperm level by week 15, the researchers reported. In these men, sperm production was suppressed in an average of less than eight weeks of treatment with segesterone-testosterone. Blythe said previous studies of male hormonal contraceptives given by injection have shown average suppression times of nine to 15 weeks.
"A faster suppression time may increase the attractiveness and acceptability of this drug to potential users," Blythe said.
Testosterone treatment alone reduces sperm production, with an average time of 15 weeks, but the addition of segesterone acetate speeds up this process and reduces the dose of testosterone needed to suppress sperm production compared with testosterone alone, she noted. In a daily regimen of segesterone-testosterone gel, blood testosterone levels are maintained within the physiological range to support normal sexual function and other androgen-dependent activities.
The sperm suppression phase of the international Phase 2b trial of segesterone-testosterone gel has been completed. The study continues to test the contraceptive efficacy, safety, acceptability and reversibility of the contraceptive effect after treatment discontinuation.