NEW YORK—Globally, 85 million pregnancies (40 percent of all pregnancies) per year are unplanned, potentially contributing to adverse health outcomes for women and infants. Other than condom use, withdrawal during sex and vasectomy, there are no other contraceptive options for men.
The Population Council, the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), the Los Angeles Biomedical Research Institute and the University of Washington School of Medicine recently announced the launch of the first clinical trial to test the safety and efficacy of a gel for men to prevent unintended pregnancy. The NES/T gel is a transparent gel designed to decrease a man's sperm production without reducing his sexual drive or enjoyment.
Three trial sites in the U.S. are now enrolling couples. Health Decisions, a full-service clinical research organization with expertise in contraceptive research, is managing the NES/T trial.
Clint Dart, Health Decisions’ senior director of biostatistics and programming—as well as principal investigator for the Statistical and Clinical Coordinating Center for the Contraceptive Clinical Trials Network of the NICHD—explained that the Nestorone/testosterone gel (NES/T combination gel or NES/T) is composed of testosterone and Nestorone (segesterone acetate), a progestin hormone used for female contraception and initially proposed by Horacio Croxatto, a Chilean researcher and member of the Population Council’s International Committee for Contraception Research.
“Particularly in recent years, men have had a growing willingness to take a more active role in family planning; however, contraceptive options for men remain limited to two choices: vasectomy or condoms,” Dart said. “The Pop Council, NICHD and their research partners recognize the need for additional, reversible methods of male contraception; however, successful male contraception has continued to be a challenge. It requires near-complete suppression of sperm production while maintaining healthy testosterone levels, so as to not impact a man’s sexual drive. Development of an oral method is limited by the lack of an oral form of testosterone; however, early studies illustrated the potential benefits of using topical testosterone in combination with Nestorone.”
The NES/T gel, which is intended to reduce sperm production, does not reduce sexual drive or enjoyment. The progestin (Nestorone) blocks natural testosterone production, reducing sperm production to low or nonexistent levels. The replacement testosterone maintains normal sex drive and other functions that depend on an adequate level of testosterone in the blood.
Dart added that NES/T is absorbed through the skin. Male study participants will apply 5 ml of NES/T gel to their upper arms and shoulders once every day (2.5 ml per shoulder and arm). Per the study design, once the man's sperm count reaches an appropriate level to prevent pregnancy—a process anticipated to take eight to 16 weeks—a couple will be informed that they can begin using the gel as their only form of contraception for one year. The man's sperm count will be checked regularly to help minimize the possibility of pregnancy. After use of NES/T is discontinued, the man will be observed for an additional 24 weeks to ensure recovery of sperm production and hormone levels.
Studies testing the safety and efficacy of NES/T gel are ongoing, but early research has shown that it is well tolerated with no serious adverse events. Previous clinical studies conducted with the Clinical Trial Network of the NICHD have indicated that use of NES/T effectively reduced sperm production to a level considered to indicate successful sperm suppression while maintaining healthy testosterone levels, thereby minimizing side effects such as lower libido, acne, weight gain and altered cholesterol levels.
Previous data have shown that NES/T is reversible if discontinued. However, every patient is different and the exact timeframe for reversal may vary. Dart expects most male study participants to have their sperm count recover within 24 weeks.