Development of rimonabant and CP-945,598 for obesity is discontinued

One month after Merck announced that the company was discontinuing development of taranabant, an investigational selective blocker of the cannabinoid-1 (CB-1) receptor that was being studied for the treatment of obesity, Sanofi-Aventis and Pfizer announced that they were also halting the development of their investigational CB-1 receptor antagonists (rimonabant and CP-945,598, respectively).

One month after Merck announced that the company was discontinuing development of taranabant, an investigational selective blocker of the cannabinoid-1 (CB-1) receptor that was being studied for the treatment of obesity, Sanofi-Aventis and Pfizer announced that they were also halting the development of their investigational CB-1 receptor antagonists (rimonabant and CP-945,598, respectively).

Sanofi-Aventis’ decision to stop the development of rimonabant came just weeks after the European Medicines Agency (EMEA) recommended that the European marketing authorization of rimonabant (European brand name Acomplia) be suspended because of an increased risk of psychiatric adverse events. After reviewing the available data, including postmarketing information, members of the EMEA’s Committee for Medicinal Products for Human Use (CHMP) stated that the risk of psychiatric disorders is approximately doubled in patients taking rimonabant versus those taking placebo.

Rimonabant is not approved by FDA. In June 2007, Sanofi-Aventis withdrew the rimonabant NDA from FDA consideration after FDA’s Endocrinologic and Metabolic Drugs Advisory Committee recommended against approval of the drug.

Pfizer stated that its decision to discontinue development of CP-945,598 is based not on safety concerns but on “changing regulatory perspectives” on this class of drugs.