The National Institute for Health and Care Excellence has published draft guidelines turning down Orexigen’s weight loss pill Mysimba for routine NHS use.

In an Appraisal Consultation Document, the Institute said it does not recommend the drug’s use for managing overweight and obesity in adults with a Body Mass Index (BMI) of 30 or more, or 27 to 30 with if the patient has one or more weight-related co-morbidities.

Explaining the decision, NICE’s Committee said while Mysimba (naltrexone/bupropion) provides “an innovative option after lifestyle measures have failed, and where orlistat is the only pharmaceutical alternative,” there were concerns “about the validity of the economic analysis and the robustness of the results”.

It concluded that the economic model had important limitations in its structure, implementation, key assumptions, and clinical data used, and therefore it was not possible to generate an accurate estimate of cost effectiveness.

A consultation on NICE’s guidelines will run until May 30.