The race is on to develop a male contraceptive drug similar to that of the female birth control pill. From investigations into an ancient African compound traditionally used to poison arrow tips, to a topical gel that is currently undergoing human clinical trials, there are an intriguing variety of methods being investigated for male contraception. Now promising results from a Phase 1 study into the safety and efficacy of a new male birth control pill are in, revealing the prospective drug to be safe and effective.

This new male contraceptive pill is a drug called dimethandrolone undecanoate, or DMAU. Unlike other forms of oral testosterone, which classically are cleared from the body quickly, this compound contains a specific long-chain fatty acid that slows this clearance making it a perfect "once-a-day" pill.

"DMAU is a major step forward in the development of a once-daily 'male pill'," says senior investigator on the study Stephanie Page. "Many men say they would prefer a daily pill as a reversible contraceptive, rather than long-acting injections or topical gels, which are also in development."

This Phase 1 study into the drug recruited 100 healthy male subjects separated into groups testing three different dosages and including a placebo control. The highest dose group displayed the most effective results showing "marked suppression" of testosterone levels and specific hormones related to sperm production. Two primary side effects were noted as "mild", including a decrease in HDL cholesterol, known as the "good cholesterol", and minor weight gain.

"Despite having low levels of circulating testosterone, very few subjects reported symptoms consistent with testosterone deficiency or excess," says Page. "These promising results are unprecedented in the development of a prototype male pill. Longer term studies are currently under way to confirm that DMAU taken every day blocks sperm production."

It is yet to be seen whether the drug proves to be a safe, effective contraceptive over long-term usage. One of the major hurdles in developing an effective male contraceptive has been the broader, and potentially irreversible, effects resulting from interfering with vital male hormones. A team of Australian researchers has been working to develop a novel non-hormonal form of male contraceptive that blocks sperm transport instead of disrupting sperm maturation.

The team from Monash University discovered in 2013 that two specific proteins are needed to activate the transport of sperm into ejaculate. Further research revealed that a drug, already approved for other long-term uses, can inhibit one of those key proteins. The team is now currently working on developing a second compound to block the other sperm-transporting protein with a goal of bringing a hormone-free, reversible male pill to the general public within ten years.

"Previous strategies have focused on hormonal targets or mechanisms that produce dysfunctional sperm incapable of fertilization, but they also often interfere with male sexual activity and cause long-term irreversible effects on fertility," says Sab Ventura, lead researcher on the Monash University research. "With this non-hormonal approach, sperm are unaffected so the contraception is likely to be readily reversible once the medication has been stopped."

While this research is not as far progressed as the new DMAU study, it highlights the variety of different tactics scientists are investigating to develop an elusive male contraceptive pill.

The results from the new DMAU study will be presented Sunday March 18 at ENDO 2018, the Endocrine Society's 100th annual meeting in Chicago, Ill.