While Sanofi's diet drug Rimonabant (Acomplia / Zimulti) remains stalled at the FDA, a potential competitor currently in phase III trials, Merck's MK-0364, now has an official generic name: Taranabant.

Taranabant is Merck's cannabinoid-1 (CB-1) receptor inverse agonist, and from reports we periodically receive from participants in the phase III trial of this diet drug, taranabant is as effective for weight loss as rimonabant with fewer side effects.

While Merck has not reported interim results from the phase III trial, which obviously could prove different from the anecdotal reports we receive, the company has said the pill was well tolerated in extensive phase II trials and that it plans to seek FDA approval for Taranabant next year.

Meanwhile Pfizer, which also has a CB-1 receptor antagonist in phase III trials, has as of yet not moved forward with a name for the diet drug known only as CP-945598.

Merck and Pfizer both will be watching intently the coming June FDA advisory panel meeting on rimonabant, which is expected to focus heavily on safety issues associated with this novel class of drugs that affect receptors in the brain.