Merck plans to deliver the first official report on results of trials of its new diet drug Taranabant -- which like Sanofi's rimonabant works by blocking CB-1 receptors -- on Wednesday, October 24th, at The Obesity Society's annual scientific meeting in New Orleans.

Dr. Ngozi Erondu, senior director of clinical research for Merck, is expected to present the report entitled "effects of taranabant, a novel cannabinoid-1 receptor (CB-1R) inverse agonist, on obese patients over 12 weeks."

This report will be based on results of Merck's phase IIa trials of the diet drug, which was then known as MK-0364 or L-000899055.

While this doesn't sound like a very full picture of Merck's trial experience with taranabant, given that a phase III trial of the diet drug with 2,400 participants has been underway for nearly two years, it nevertheless will be the first public report of any kind by Merck on the studies of its diet pill.

In dramatic contrast to Sanofi-Aventis, which fueled excitement over its CB-1 receptor antagonist rimonabant (Acomplia / Zimulti) with updates on exciting weight-loss results from its clinical trials, Merck has until now provided no data on weight loss or other cardio-metabolic results for study participants.

A Merck spokesperson said the company has no plans to present any data from the phase III trial until sometime in 2008.

But the news about taranabant from the phase IIa trial is expected to be highly positive. Anecdotal reports leaked to DietDrugReport.com by trial participants have been highly encouraging, and Merck itself has said it expects to file for approval to market the diet drug in the United States in spring 2008.

One question that seems likely to be asked in New Orleans, however, will be about taranabant's side-effects. It was the side-effect profile of rimonabant --particularly the incidence of depression and suicidality -- that is keeping the diet drug off the U.S. market, even though Acomplia is on sale in Europe.

Whether taranabant has a better side-effect profile may be key to Merck's hopes of beating rimonabant to market in the United States.