No cigar! In the last decade, there have been several potential male contraceptive leads which have been abandoned for various reasons. The lessons learned from these research efforts – whether they are biochemical or sociological lessons – will be valuable to future efforts.
Zavesca
Turns out that Zavesca – a medication already approved for treating a rare genetic disorder – is a great male contraceptive for a particular strain of laboratory mouse, but not for men or even other mammals! Exactly how Zavesca acts as a contraceptive for the mice is not known. It's possible that discovering that mechanism might lead to new avenues of male contraceptive research. But for the moment, research on Zavesca as a male pill has stopped.
Gossypol
Gossypol is a compound produced by cotton plants; it's particularly abundant in the seeds. Researchers in China noticed that men who ate foods cooked with unrefined cottonseed oil had unusually high infertility rates. Gossypol is a very effective male contraceptive – in fact, it's too effective. Partly because gossypol's contraceptive effect is not reversible in up to 22% of men, the World Health Organization recommended that plans for further research be abandoned. Some have proposed that gossypol could be developed as a non-surgical alternative to vasectomy.
