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Only 'Wonder Man' Can Resist Male Contraceptive Shots

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WebMD Health News
Reviewed by Gary D. Vogin, MD

Jan. 29, 2001 -- They call him the Wonder Man. All the other guys who volunteered to try a once-every-six-weeks male contraceptive shot saw their sperm counts drop to zero -- results good enough for a major pharmaceutical company to begin advanced clinical tests of the approach.

Results from the recently completed German trial show that the injections are safe, that they make most men temporarily sterile, and -- perhaps most reassuring of all -- that their effects completely wear off a few months after the treatment ends. The treatment uses a combination of a long-lasting form of testosterone plus another long-lasting drug (norethisterone enanthate) that suppresses reproductive hormones.

The combination apparently worked on 13 of 14 healthy men with robust sperm counts. All of the men received the shots once ever six weeks for 24 weeks. They remained sexually normal with no change in semen volume -- except for the fact that all but one of the men temporarily became sterile.

"We called him the wonder man," study leader Eberhard Nieschlag, MD, PhD, tells WebMD. "He is one of the very rare exceptions who we see in contraception trials who hardly responds at all. He would not be protected by this or any other [hormonal] contraceptive. ... We cannot predict who will and who will not respond. That is a certain disadvantage to this approach."

The study measured sperm counts and sperm motility, which gives fertility experts a very good idea of whether a man can make a woman pregnant.

"We did not expose females to these males, so it is not a real efficacy study, in this regard it is only proof of concept," Nieschlag says. "But we are in contact with the pharmaceutical industry -- in this case Schering AG -- who are doing larger scale clinical trials with this combination."

The study, conducted at the University of Münster, Germany, found that the contraceptive treatment did have some unwanted effects. Most of the men had local pain at the injection site. Some had reversible weight gain (average maximum gain of about eight pounds), night sweats, and/or acne. And some had moderate changes for the worse in their cholesterol levels, although all of the men remained within the normal range.

"Adverse effects are inherent to these compounds, but they were not really serious," Nieschlag asserts. "There was some increase in body weight, and some complained of nightly sweating, but this was a dose question. We think in later studies we can adjust the dose on an individual basis to minimize these effects."

Ronald S. Swerdloff, MD, is the chief of the division of endocrinology at Harbor-UCLA Medical Center, director of a World Health Organization collaborative center in reproduction, and director of a Mellon Foundation center for contraceptive development. He agrees with Nieschlag's assessment of the "wonder man."

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