"There should be a birth control pill for men. Then it would be your responsibility to take it every day.”
My girlfriend says stuff like this to me. A lot. And I'm sure most guys have heard the same thing. But let's face it, the birth control burden is lopsided, and those among us packing a Y chromosome have it easy. Well, the female gender's collective cry for pregnancy-preventing equality may be happening in the not-too-distant future, as two drugs designed to help transplant patients have shown some viability as a birth control alternative... for dudes.
Essentially (and this is a very elementary summary, so bear with me), the aforementioned drugs, cyclosporine A (CsA) and FK506 (tacrolimus) prevent the immune systems of organ donor recipients from rejecting their new organs by inhibiting an enzyme called calcineurin. Here's where your balls come into play: Japanese scientists have discovered a type of calcineurin found only in sperm.
By using some very, very lucky mice as test subjects, the scientists determined that the mice sperm filled with the drugs lacked "hyperactivation," (the act of the little sperm tails whipping back and forth) and had a head that was too rigid to penetrate the female's egg. Even better news? When the mice stopped taking the drug, their fertility returned in one week. There's no timetable on human testing, or anything close to it yet, but the scientists who led the effort stated that "...calcineurin may be a target for reversible and rapidly acting human male contraceptives."