Well, Here We Go Again

BALANCING A DRUG'S BENEFITS against its side effects is tricky business. That was the lesson in September when American Home Products, the maker of two drugs for treating obesity--Redux (dexfenfluramine) and Pondimin (fenfluramine, which with the diet drug phentermine constituted ""fen-phen'')--pulled them from the market after suggestions that they might cause a deadly heart-valve disease.

Last week the FDA approved a new anti-obesity drug called Meridia (sibutramine), the first since Redux. While doctors are happy to have a new weapon against obesity, they also remember the hordes of people who scored fen-phen prescriptions in the search for an easy diet. In safety tests, Meridia didn't cause valve disease or primary pulmonary hypertension, the other dangerous side effect of the banned drugs. But it does cause elevated blood pressure, constipation, insomnia and headaches--nothing serious, but no pharmacological free ride.

Like Redux and Pondimin, Meridia acts in the brain to reduce appetite. All work on the multipurpose neurotransmitter serotonin, low levels of which can spark the need to feed. The old obesity drugs increased serotonin production; Meridia keeps it and another neurotransmitter called norepinephrine from being reabsorbed. The result is that people feel more full, don't crave food and have a slightly faster metabolism. In a study of more than 1,000 obese people who took Meridia, exercised and watched their diets, more than a third lost 10 percent of their body weight in six months. ""That's not going to get a person who is 30 percent above normal weight to be cosmetically perfect,'' says Louis Aronne, director of the Comprehensive Weight Control Program at New York Hospital-Cornell Medical Center. ""But it can help their health risks.''

Those risks include diabetes, heart disease, cancer and a host of other problems. For the morbidly obese, that might warrant the risk of increased blood pressure associated with Meridia. People just trying to lose a few pounds can't make the same argument. This time, though, doctors and patients are perhaps a bit more cautious. ""I'm hopeful at least we're not going to see Meridia clinics popping up on every street corner where fen-phen clinics used to stand,'' says Susan Yanovski, director of the Obesity and Eating Disorders Program at the National Institutes of Health. Even Knoll Pharmaceutical Co., Meridia's manufacturer, insists that the drug is only for the dangerously obese. But those kinds of warnings didn't stop anyone last time.