Though pharmaceutical companies are still far from marketing a contraceptive pill for men, scientists are making new discoveries that may make such medication safe and available in the years to come. The New York Times reports:
Male contraceptives are attracting growing interest from scientists, who believe they hold promise for being safe, effective and, also important, reversible.
"We have a number of irons in the fire," said Diana L. Blithe, program director for contraceptive development for the National Institute of Child Health and Human Development. "I think men actually do want to do this."
The most studied approach in the United States uses testosterone and progestin hormones, which send the body signals to stop producing sperm. While effective and safe for most men, they have not worked for everyone, and questions about side effects remain.
So scientists are also testing other ways of interrupting sperm production, maturation or mobility.
One potential male birth control pill, gamendazole, derived from an anticancer drug, interrupts sperm maturation so "you're making nonfunctional sperm," said Gregory S. Kopf, associate vice chancellor for research administration at the University of Kansas Medical Center. The center has begun discussions with the Food and Drug Administration about the drug, already tested in rats and monkeys.
Dr. John K. Amory, a reproductive scientist at the University of Washington, is studying a drug that was developed for worm infections and was later tried on men because it caused infertility. Using rabbits, Dr. Amory said, he discovered the drug blocks production of retinoic acid, important for sperm production.
At Harvard, Dr. David Clapham, a neurobiologist, discovered that sperm tails contain calcium ion channels, with electrically charged atoms "turbo-charging the sperm" to reach eggs, he said. He is developing a drug to disable the channel.
"You just turn off the motor, rather than alter the people in a car," he explained.
Elaine Lissner, director of the Male Contraception Information Project, formed a foundation to develop other approaches. One, "reversible inhibition of sperm under guidance," or Risug, involves injecting gel into the scrotum to inactivate sperm. Another involves briefly heating the testes with ultrasound, which can halt sperm production for months, she said.