Now, a male contraceptive pill successfully limits sperm activity without side effects

A new study has detailed how a compound called EP055 binds to sperm proteins to significantly slow the overall mobility of the sperm without affecting hormones, making EP055 a potential "male pill" without side effects.

"Simply put, the compound turns-off the sperm's ability to swim, significantly limiting fertilization capabilities," said lead investigator Michael O'Rand from the University of North Carolina. "This makes EP055 an ideal candidate for non-hormonal male contraception."

Currently, condoms and surgical vasectomy are the only safe forms of birth control currently available for men. There are hormonal drugs in clinical trials that target the production of sperm, but these affect the natural hormones in men much like female contraceptives affect hormones in women.

During the study, thirty hours following a high-dose intravenous infusion of EP055 in male rhesus macaques, O'Rand and researchers in the Oregon National Primate Research Center at OHSU in Portland, Oregon, found no indication of normal sperm motility. Further, no physical side effects were observed.

"At 18 days post-infusion, all macaques showed signs of complete recovery, suggesting that the EP055 compound is indeed reversible," said study co-investigator Mary Zelinski.

O'Rand and Zelinski indicate that more work is needed before EP055 becomes available for human use. They and their teams have begun to test a pill form of the compound and will eventually conduct a mating trial of EP055's effectiveness against pregnancy.