French drug titan Sanofi-Aventis is getting ready to market a pill called Acomplia that will help people lose weight, quit smoking and avoid heart attacks.

Approval from the Food & Drug Administration is expected within a year. “In three years,” says Christopher Cannon, a cardiologist at Boston’s Brigham & Women’s Hospital, “it will be the number one drug in the world.”

Heady stuff for a drug that is, in a sense, the antimarijuana. Acomplia blocks the cannabinoid cell receptor famous for giving pot smokers the munchies. The same receptor helps regulate satiety and plays a part in a multitude of cravings in the brain and endocrine system.

Though Acomplia was initially designed as a weight-loss drug, Sanofi researchers had found by 2001 that the affected receptors play a role in how the body processes fat. Blocking those receptors reduces all sorts of risk factors for the heart. In recently completed late-stage trials Acomplia helped people quit their cancer sticks and lose an average of 19 pounds, four times as much as those who got a placebo. Better yet, it lowered blood sugar, raised “good” cholesterol by 25% and reduced blood fat and inflammation of the arteries. It cut down on six of nine risk factors for heart disease.

That has led to hope that the pill could reduce the annual toll of 900,000 Americans felled by heart attacks and strokes.

But there is reason to doubt that Sanofi’s success with Acomplia will come from obesity alone. Half the time patients in Sanofi’s trials stopped taking the pills–typical for a weight-loss trial, which often entails a restrictive diet. And 3% of patients, twice as many as those on placebos, dropped out because of depression. “It’s what you’d expect based on the mechanism,” says Ernst Schaefer, an endocrinologist at Tufts University.

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