Nutrition Frenzy

Possible psychiatric side effects may have doomed companies’ research

French drugmaker Sanofi-Aventis said Wednesday it is halting all research on a diet drug sold in Europe, Acomplia, and rival Pfizer Inc. hours later said it is ending research on an experimental weight-loss drug in the same class.

Both drugs work by blocking the pleasure centers that give marijuana smokers the “munchies” — the cannabinoid type 1, or CB1, receptors.

Given that obesity and related complications are arguably the world’s biggest public health problem, the demise of both drugs will be a big disappointment for patients and doctors, and possibly for investors. The decisions leave New York-based Pfizer, the world’s top drugmaker by sales, and Paris-based Sanofi-Aventis, ranked No. 4, suddenly without drugs in a category all but guaranteed as a blockbuster.

Two weeks ago, Sanofi-Aventis temporarily stopped sales in Europe, where the pill had been marketed in 18 European Union countries since 2006. That move came after the European Medicines Agency recommended the European Commission temporarily suspend sales of Acomplia, saying its risks — depression, anxiety and stress disorders — outweighed its benefits.

At the time, Sanofi-Aventis said it “remains committed to Acomplia to bring an important therapeutic approach to obese and overweight patients,” about 700,000 of whom it said had used Acomplia and gained health benefits. The company said it planned to provide additional evidence for health officials to re-evaluate its risks and benefits in patients with diabetes and heart disease.

In the U.S., a Food and Drug Administration advisory panel unanimously rejected the drug on June 13, 2007, citing psychiatric problems including increased risk of suicidal thoughts. Two weeks later, Sanofi-Aventis withdrew its application for U.S. approval.

For the first nine months of this year, Accomplia had sales of only 81 euros, about $113 million, not even making the company’s top 15 products.

On Wednesday, Pfizer said it ended final-stage human testing of a drug known only by the designation CP-945,598 — not explicitly for safety concerns but because of “changing regulatory perspectives on the risk/benefit profile of the CB1 class and likely new regulatory requirements for approval.”