DIET PILLS ARE COMING BACK

By Anastasia Toufexis

This is the season when Americans gingerly try on bathing suits before bedroom and dressing-room mirrors and wish there were a diet pill that would erase those fleshy bulges. They may never get their wish, but they may be getting closer. Last week the U.S. Food and Drug Administration approved a new antiobesity drug called dexfenfluramine that will be sold in America perhaps as early as June by Wyeth-Ayerst under the brand name Redux. It is the first diet drug approved for use in the U.S. in the past 23 years and represents a new generation of smarter, more subtle antiobesity medications.

Diet pills got a bad name in the '70s, when doctors prescribed amphetamines (a.k.a. "speed") and their patients became addicted. Unlike amphetamines, which burn up extra calories by jacking up the body's metabolism, dexfenfluramine gets people to eat less food by shutting off appetite. It does this by triggering the release of serotonin, a brain chemical that induces feelings of fullness and satisfaction.

It's an approach to weight control that reflects medicine's new understanding of obesity as a chronic disease rather than a failure of willpower. "Some people will need to take [weight-control] medications all their life, just as some need to take medication for hypertension," says Dr. Michael Hamilton, director of the Duke Diet and Fitness Center at Duke University. That could be an expensive proposition: a month's worth of Redux is expected to cost $75. Some who can improve their eating and exercise habits, Hamilton suggests, may eventually be able to wean themselves from the pills.

The FDA is expected to approve more diet drugs in the next few years. Knoll Pharmaceutical's sibutramine is a serotonin drug, like dexfenfluramine and its predecessor, fenfluramine. Roche Laboratories' orlistat uses a different approach: it binds to food in the intestines, blocking the absorption of about one-third of dietary fat.

Are these pills safe? Not everyone agrees. Twenty-two neurologists petitioned the FDA last winter to delay approval of dexfenfluramine, citing studies that show it causes brain damage in laboratory animals ranging from mice to baboons. Critics are also concerned about an increased risk of pulmonary hypertension, a condition that can lead to heart failure. The FDA, however, judged the threats minimal. Proponents point out that dexfenfluramine has been used abroad by millions of people over the past decade with no major problems.

Still, even dexfenfluramine supporters do not believe that it--or any other pill--will ever be a dieter's dream come true. Studies show that people who take dexfenfluramine shed an average of only 10% of their weight. Doctors also caution that the drug is intended for those who are 20% or more above their recommended weight range. "It's not a magic pill," stresses Dr. Richard Wurtman, a neurologist at the Massachusetts Institute of Technology who helped develop dexfenfluramine. "It must be used as part of a package that includes good nutritional advice and a good exercise program."

--By Anastasia Toufexis. Reported by Alice Park/New York

With reporting by Alice Park/New York