CHICAGO -- An experimental diet drug that scientists hope is safer than the ill-fated Redux and fen-phen helped obese people shed pounds and keep them off in a two-year study, researchers say.
Orlistat, trade-named Xenical, has been judged safe and effective enough for the U.S. market by an advisory panel to the Food and Drug Administration. The FDA usually follows advisers' recommendations, and the drug's manufacturer, Hoffman LaRoche Inc., expects a decision soon.
Redux and Pondimin -- which is generically named fenfluramine and was paired with phentermine in "fen-phen" -- were recalled in 1997 over concerns that they caused heart-valve damage. The only prescription weight-loss drugs left on the U.S. market are sibutramine, sold as Meridia, and phentermine. They regulate brain chemicals affecting appetite.
Orlistat works differently. It blocks absorption of about one-third of fat that people consume, said one of the study's authors, Dr. Steven B. Heymsfield of St. Luke's-Roosevelt Hospital in New York.
Four out of every five people report such side effects as intestinal cramping, gas and oily or loose stools, but the problems usually subside, Heymsfield said.
In addition, some patients need vitamin supplements because orlistat also blocks some absorption of fat-soluble vitamins D, E and beta carotene, he said.
A report on his 1992-95 study, part of the data being considered by the FDA, is published in Wednesday's Journal of the American Medical Association.
In the study of 892 obese adults, all were put on weight-loss diets, counseled about exercise and assigned to one of two groups for a year. The group given orlistat lost an average of 19 pounds, compared with about 12 pounds among those given dummy pills.
In the second year, every orlistat taker was put on a weight-maintenance diet. Some were continued on full doses of orlistat. Some were given half doses, and the rest were given dummy pills.
The full-dose takers regained only 35 percent of their lost weight, compared with 51 percent among half-dose takers and 63 percent among placebo takers.
A researcher not involved in the study said orlistat's benefits were modest.
"Will the yet-to-be-proven health benefits of these drugs be generalizable to any but a small minority of obese patients?" asked David F. Williamson of the federal Centers for Disease Control and Prevention.
Williamson wrote in an editorial accompanying the study that any weight-loss approach seems unlikely to work unless Americans change their attitudes about exercising and eating.
"There is no magic bullet," Heymsfield agreed. "Losing weight and keeping it off for a long time is hard work. And we know that the cornerstone of that is still diet and exercise."
Orlistat is available in parts of Europe and Latin America. Studies on about 4,000 people worldwide have found an increased risk of breast cancer, although Heymsfield's study found no connection, he said.
But since people may take the drug much longer than two years, Heymsfield said, "it's very important to continue that surveillance of any kind of side effects to avoid another fen-phen type of problem."