A Pill a Day Keeps the Sperm Away
July 19, 2000 -- They multiply by the millions each day, they travel in packs, and once unleashed they are single-minded in their goal: succeed or die. Sperm, it's fair to say, are a relentless lot.
And they are no easier to stop before they're released. Which is one of the reasons a male contraceptive has been such an elusive goal. It's easier to stop a woman's monthly ovulation than it is to completely stop the production of millions of sperm a day. After all, it only takes one of the little critters to do the trick.
But it seems a team of researchers in Scotland may have hit on the right formula to stop sperm production, and it could hit the market within the decade. Sixty men, half in Scotland and half in China, were given a regimen consisting of a daily pill that contained a steroidal hormone and an implant placed under the skin, such as Norplant is used in women.
The pill contains a synthetic hormone found in some female oral contraceptive pills called desogestrel, and the implant contains testosterone.
Here's the basic logic: the pill's steroidal hormone works to block the production of sperm, but a side effect is it minimizes the production of the body's testosterone. That is what makes men men, so to speak. Without it, they can lose facial and pubic hair, grow breasts, or suffer a whole host of side effects. So the implant replaces the body's testosterone.
"I think keeping the testosterone concentrations normal, neither too high or too low, is perhaps the secret," says Richard Anderson, MD, PhD, clinical scientist at the University of Edinburgh Centre for Reproductive Biology. Anderson and his colleagues developed the regimen.
He says the men's sperm counts dropped to zero -- "not a single sperm to be seen." Plus, "It starts working immediately, but it does take a while for the sperm count to fall to zero. It's like after a vasectomy; it takes several months, often, to go down to zero, because you have to wash out all the sperm that are already produced. But some men have sperm counts, within six to eight weeks, of zero."
Louis DePaolo, PhD, program director for the National Institute of Child Health and Development's reproductive sciences branch, explains it further by saying the steroidal hormone stops the pituitary gland in the brain from releasing hormones that set sperm production into motion. The testosterone is mainly at "maintenance levels, to maintain libido and all the other actions that androgen [male hormone] has in the body."
Anderson says the treatment is 100% reversible, with few side effects. "Most people feel absolutely normal; they don't notice any difference at all. Some of the men put on a couple of pounds, but not enough to drop out of the study, and we didn't have any other significant side effects."