Endometriosis drug effective in trials.
An experimental drug is showing promise against endometriosis, a common and painful disease of the female reproductive system that is frequently associated with infertility. In what is reported to be the largest, most carefully controlled study of its kind, the drug -- a synthetic molecule taken as a nasal spray -- proved as effective as the only currently approved treatment and was reported to cause significantly fewer side effects.
Affecting as many as 1 in 15 women of reproductive age, endometriosis occurs when tissue from the uterine lining migrates to other parts of the body, usually in the vicinity of the reproductive tract, and begins to grow. These islands of tissue remain responsive to monthly releases of reproductive hormones, which can cause a painful inflammatory response. Treatment has revolved around suppressing secretion of the female hormone estrogen.
Only one drug, danazol, made by New York City-based Sterling Drug Co., is approved for treatment of endometriosis in the United States. But danazol is a derivative of the male hormone testosterone and has a number of undesirable side effects, including voice lowering, increased growth of body hair, liver damage and a shift in blood lipid levels similar to those associated with cardiovascular disease. For women who cannot tolerate danazol, the only effective intervention is surgical removal of the ovaries.
The new drug, nafarelin, made by Syntex Research in Palo Alto, Calif., belongs to a class of synthetic compounds called gonadotropin-releasing hormone (GnRH) agonists. These chemicals resemble naturally occurring GnRH, which normally stimulates pituitary secretion of reproductive hormones. They differ from natural GnRH, however, in that they bind more readily to pituitary receptors and are less easily broken down by regulatory enzymes. Scientists have found that these tenacious analogues confuse hormonal regulatory controls so that estrogen production is suppressed.
The latest research was led by Milan R. Henzl, head of Reproductive Medicine at Syntex and an assistant clinical professor at the University of California at San Francisco, and was performed at 20 research centers in the United States and abroad. It involved double-blind comparisons of nafarelin and danazol in 213 women over a six-month span, using a standardized measure of endometriosis severity that included periodic examination of endometrial masses by laparoscopy. The study, which appears in the Feb. 25 NEW ENGLAND JOURNAL OF MEDICINE, shows that more than 80 percent of the patients in both groups had significant reduction of endometriosis, with nafarelin causing far fewer side effects.
"Nafarelin has a very straightforward action," says Henzl, "but it's a new class of compounds and we still must be quite cautious about it." Previous studies have shown that GnRH agonists cause some loss of bone mass, although the loss appears to be reversible. Other side effects include hot flashes and decreased libido.
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|Date:||Mar 5, 1988|
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