Potential male birth control pill shows promise in early lab tests
Men have long had only two birth control options: condoms or sterilization. Now the first laboratory tests on mice suggest that another option may be on the horizon.These preliminary laboratory tests suggest that it may one day be possible to give men birth control pills to take before sex if needed. This pill is so new it doesn’t have a name — it’s simply called TDI-11861 — and it prevents sperm from traveling through the female reproductive system to fertilize an egg.Male birth control pills on demandIn early laboratory experiments, a single dose of TDI-11861 immobilized mouse sperm for two and a half hours, according to results published in Nature Communications. Some sperm started moving again after three hours, and almost all sperm regained motility after 24 hours.
But there is one big caveat: Men must use it properly.“We anticipate that the final drug we develop will be active within 30 minutes of ingestion and — in a sterile male — remain active for 12 to 18 hours,” said Buck and Levin. “The man has to watch his watch to make sure he doesn’t go beyond the active window.
The experimental drug belongs to a new family of medicines that are designed to block a protein known as soluble adenylyl cyclase (sAC), which plays a key role in helping sperm mature and move. So far, TDI-11861 appears to be a fast-acting sAC inhibitor that works with a single dose and wears off afterwards. This means that men wouldn’t be infertile for very long — only long enough to prevent pregnancy in the hours immediately after use.
Normally, sperms start swimming vigorously through the vagina after ejaculation so they can move up through the cervix and into the uterus, Buck and Levin noted. Once in the uterus, sperm can survive for several days, making it possible for a pregnancy to occur several days after intercourse.
However, sperm from a man who has taken an sAC inhibitor is immobile, which means it gets trapped in the vagina and never gets to the cervix,” Buck and Levin said.When will there be contraceptives for men?They are planning further studies in mice before beginning human trials. Buck and Levin said they hope to begin human trials within two to three years.
While this concept of immobilizing sperm to prevent pregnancy is intriguing, the question remains whether this investigational drug will remain active as long as sperm remain in the female reproductive system to ensure reliable contraception, says Stephanie Page, MD, PhD, a contraception researcher and professor at the University of Washington School of Medicine in Seattle who was not involved in the new study.“In humans, sperm can survive for several days in the female reproductive system, so an effective contraceptive method that targets this aspect of male fertility can last at least 48 hours and possibly longer,” says Dr. book page. Since this new pill would be given to healthy men, the pill would need to be extremely safe for men too, says Dr. Gunda Georg, contraceptive researcher, professor and director of the Institute for Therapeutic Discovery and Development, Dr. University of Minnesota in Minneapolis.“On-demand contraception is an exciting idea,” says Dr. Georg, who was not involved in the new study.”Men would not need to take the pill every day and only before sex, and taking an sAC inhibitor occasionally makes men less likely to experience the drug’s potential side effects.”
“However, sperm which come from a man who took an sAC inhibitor will be immotile, which means they will remain trapped in the vagina and never penetrate the cervix,” Buck and Levin said.
How Soon Could Male Birth Control Be Available?They plan more studies in mice before they start human trials. Buck and Levin said they hope to start human studies within two to three years.
While this concept of immobilizing sperm to prevent pregnancy is intriguing, one open question is whether this experimental drug would remain active the entire time sperm remain in the female reproductive tract in order to reliably provide contraception, says Stephanie Page, MD PhD, a contraceptive researcher and professor at the University of Washington School of Medicine in Seattle, who wasn’t involved in the new study.
“In humans, sperm can live in the female reproductive tract for a few days, so an effective method of contraception targeting this aspect of male fertility may need to last at least 48 hours and perhaps longer,” Dr. Page says.
Because this new pill would be given to healthy men, the pill will also have to be extremely safe for men to take it, says Gunda Georg, PhD, a contraceptives researcher, professor, and director of the Institute for Therapeutics Discovery and Development at the University of Minnesota in Minneapolis.
“Having an agent for on-demand contraception is an exciting idea,” says Dr. Georg, who wasn’t involved in the new study. “Men would not need to take the pill every day and only before intercourse, and occasional use of the sAC inhibitor lowers the possibility that men would experience potential side effects from the drug.”