April 20 (UPI) -- An experimental compound slows the overall mobility of sperm without affecting hormones, and has the potential to lead to a male contraceptive pill without side effects, according to a new study.
In a study with monkeys, researchers found EP055 binds to sperm proteins and slows their mobility. The findings were published Friday in the journal PLOS ONE.
"Simply put, the compound turns off the sperm's ability to swim, significantly limiting fertilization capabilities," Dr. Michael O'Rand, a retired professor of cell biology and physiology at the University of North Carolina at Chapel Hill School of Medicine, said in a press release. "This makes EP055 an ideal candidate for non-hormonal male contraception."
For men, the only safe and effective forms of birth control are condoms and surgical vasectomy.
Hormonal drugs that attack sperm have been tested in clinical trials, but they have effects on natural hormones in many men -- similar to the effects female contraceptives have on hormones.
For the study, rhesus macaques were given a high dose of EP055 at the Oregon National Primate Research Center at the Oregon Health & Science University in Portland. After six hours, sperm motility fell to approximately 20 percent of pre-treatment levels and, after 30 hours, they had no normal sperm activity and no physical side effects. Recovery of sperm activity was shown by 78 hours after the injection.
"At 18 days post-infusion, all macaques showed signs of complete recovery, suggesting that the EP055 compound is indeed reversible," said study co-investigator Dr. Mary Zelinski, a research associate professor at the ONPRC and an associate professor of obstetrics and gynecology in the OHSU School of Medicine.
Zelinski and O'Rand, who is president and CEO of Eppin Pharma, Inc., said more work is needed before EP055 can be used in humans, including tests of a pill form of the compound and a mating trial of its efficacy against pregnancy.