sanofi dealt FDA Acomplia blow

French firm sanofi-aventis suffered a setback after the US Food and Drug Administration (FDA) declined to approve its most promising new product, weight loss drug Acomplia (rimonabant).

sanofi had been hoping to market the potential blockbuster as a treatment for both obesity and smoking, with forecasted annual sales of $3bn. The company said it had received a so-called `approvable' letter for the drug as a weight loss treatment, and a `not approvable' letter for use as a smoking cessation drug.

The 'not approvable' letter effectively ends sanofi's chances of entering the lucrative smoking cessation market with Acomplia.

The drug has created much excitement as it uses a new mechanism for inducing weight loss, blocking receptors in the brain and in fat cells that regulate appetite.

The firm said in a statement that it ìwill continue to work in close collaboration with the FDAî.

Analysts at Dresdner Kleinwort Wasserstein maintained their `hold' rating on sanofi-aventis and said they expected the final FDA approval for Acomplia to be delayed until 2007, adding that if the regulator seeks more data, it could be delayed even further.

In a study published last week in the Journal of the American Medical Association, researchers found that after one year, 48.6 per cent of the people taking the higher dose of the drug, 20mg, had lost 5 per cent or more of their weight, compared with 20 per cent of those taking placebo.

Those who took the drug for a second year managed to keep the weight off, while patients who switched to placebo after taking rimonabant regained some weight.

The study also found that participants showed higher rates of psychiatric side effects such as anxiety and depression.