With a number of studies fairly clearly documenting that Acomplia can facilitate signficant weight loss in the first year of use, as well as improve other cardiometabolic risk factors such as cholesterol, discussion at the June 13th meeting seems certain to center on safety issues.

The diet pill is the first in a class of drugs that operates by blocking CB-1 receptors in the brain, and has been linked to depression and other psychotic side effects.

"Sanofi-Aventis is pleased to have the opportunity to present its data on rimonabant and to exchange with experts," Sanofi said in a statement confirming the FDA advisory panel hearing.

If concerns over safety further delay approval of Acomplia, the result could be a boost for the launch of nonprescription alli (pronounced al-EYE), the first over-the-counter diet pill ever approved by the FDA.

While rimonabant is already on sale in a number of Europe countries as well as Mexico and Argentina as rimonabant, the likelihood is that if approved in the U.S. it will be marketed as Zimulti.

Sanofi announced earlier this year that the FDA had added another three months to its review of the drug to consider additional data, delaying any decision to the end of July.