DANGER IN THE DIET PILLS?

Doctors at the Mayo Clinic first became suspicious last year, when a 41-year-old woman complaining of shortness of breath came to the Minnesota facility for repair work on a leaky heart valve. When they opened up her heart, surgeons noticed that the valve was white and shiny, suggesting some sort of drug reaction. The drugs she had been taking, it turned out, were fen/phen, the appetite suppressants fenfluramine and phentermine that have become the diet pills of choice among weight-conscious Americans.

Soon other patients with similar conditions turned up at Mayo and the MeritCare Medical Center in Fargo, N.D. By the time doctors had identified two dozen fen/phen users with heart-valve trouble, they realized they had a problem of potentially significant proportions on their hands. More than 18 million fen/phen prescriptions were written last year.

No one should stop taking fen/phen without consulting a physician; there are dangers in stopping cold turkey, and it is too early to say for certain that the culprit is fen/phen. But health officials are taking no chances. The Food and Drug Administration last week mailed letters to doctors asking them to be on the alert. And the New England Journal of Medicine, which is scheduled to publish the Mayo-MeritCare study in late August, lifted its news embargo seven weeks early. "We don't do that very often--perhaps once or twice a year," says Dr. Gregory Curfman, a deputy editor. "We do it only when the public-health significance is fairly immediate."

It was the latest in a series of setbacks for the new generation of diet pills. They were initially seen as an improvement over the old "speed"-based pills because they were nonaddictive and worked more subtly, stimulating production of the brain chemical serotonin, which is associated with feelings of satisfaction and satiety. But earlier this year neuroscientists complained that the FDA was not being forceful enough in pushing for follow-up studies on another serotonin-type diet pill, Redux, which is known to cause brain damage in rats. The FDA approved Redux last summer, despite its known problems, because it determined that for patients who are seriously obese, the benefits justified the risk--at least for short-term use.

Not so fen/phen. The FDA approved fenfluramine and phentermine more than 20 years ago, but the drugs' synergistic effect has never been vetted in a large-scale clinical trial, and the FDA never gave its blessing to their combined use.

There may be a lesson here. The use of fen/phen has been enthusiastically promoted as some sort of miracle drug and heavily prescribed by trendy doctors not just for the obese but for patients who want to fit into a smaller size. They would have been better advised to try a little less food and a little more exercise.

--By Christine Gorman