New obesity pill effective; safety issues under review

The first potential new prescription weight-loss pill to reach the US market in more than a decade is effective and well tolerated, according to the manufacturer's new drug application (NDA), but potential safety issues have stalled its approval by FDA.

The investigational drug Qnexa (tesofensine) is a controlled-release, once-daily pill that combines low-dose, immediate-release phentermine with a controlled-release formulation of the antiseizure drug topiramate.

If it is approved, the drug would be recommended for obese patients (body mass index [BMI] ≥30kg/m²) or overweight patients (BMI ≥27 kg/m²) with weight-related comorbidities such as hypertension, type 2 diabetes, dyslipidemia, or central adiposity (abdominal obesity). It is intended to be used as a component of a diet and exercise program for weight loss and maintenance.

Additional reported risks include kidney stones, hyperammonemia (with or without encephalopathy, oligohydrosis, and hyperthermia), and visual disturbances.

Vivus, the drug's manufacturer, has announced plans to work with the FDA's Endocrinologic and Metabolic Drug Advisory Committee to resolve safety and labeling concerns in anticipation of the agency's scheduled October 28 decision on whether to approve the product.

Vivus Inc. VI-0521 (Qnexa) Advisory Committee Briefing Document. NDA 022580. Endocrinologic and Metabolic Drugs Advisory Committee Meeting. July 15, 2010. http://www.fda.gov/downloads/advisorycommittees/committeesmeetingmaterials/drugs/endocrinologicandmetabolicdrugsadvisorycommittee/UCM218821.pdf. Accessed August 19, 2010.