Valeant Pharmaceuticals International ended 2005 on a sour note after it received a non-approvable letter from the US Food and Drug Administration for Cesamet (nabilone), a cannabinoid drug for treating nausea and vomiting in patients undergoing cancer chemotherapy.

Valeant said the FDA requested additional information to address concerns over potential class-related adverse events before it would give the nod to new labelling for the Cesamet. The company is hoping to position the product as a second-line treatment in patients who fail to respond to anti-emetic therapy with drugs such as GlaxoSmithKline’s Zofran (ondansetron), Roche’s Kytril (granisetron) and Sanofi-Aventis’ Anzemet (dolasetron).

Valeant said it plans to meet with the FDA promptly to discuss the details of the letter. The FDA had asked Valeant to update the labelling when it purchased Cesamet from Eli Lilly last year, and the company has been holding back launch until this is approved.

The news is also a setback for Par Pharmaceuticals which, in early November, signed an agreement with Valeant to promote Cesamet in the USA. Valeant said the deal is still in place, though the marketing of the drug will be delayed.

Cesamet was approved in 1985 for the treatment of nausea and vomiting associated with cancer chemotherapy in patients who failed to respond to conventional anti-emetic treatments. It is already sold in Canada and has an 88% share of the cannabinoid market there, according to IMS data.