Pam Belluck rounds up the latest for the NYT:
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.
It seems to me that doesn’t work for everyone and questions about side effect remain characterizes existing methods of contraception for women. That’s one of the reasons why a variety of different methods have been developed. But isn’t the real issue with male contraceptives the question of trust? After all, if something goes wrong, it’s the woman who ends up pregnant and has a lot more on the line.