In France, as of early 2012, phentermine (an amphetamine-based drug) was classified as a narcotic, in all its forms and routes of administration. Since the beginning of the 2000s, phentermine has become the most widely used appetite suppressant in the world.
In France, at the beginning of this year, no phentermine-based drug was commercially available. The USA, Canada and Australia have maintained it on the market for obese patients, even though it has no proven efficacy in preventing complications related to obesity.
The harms associated with phentermine are similar to those of other amphetamine-based appetite suppressants: neuro-psychological disorders (headaches, insomnia, nervousness, depression, etc.), cardiovascular (arterial hypertension, palpitations, cardiac arrhythmia), and, more rarely, pulmonary arterial hypertension and valve disease when combined with other appetite suppressants, as was the case with Mediator° (benfluorex).
More worryingly, at the beginning of 2012, the European Medicines Agency (EMA) and the US Food and Drug Administration (FDA) were considering marketing authorisation applications for an anti-obesity drug under the name of Qnexa° that combines phentermine with topiramate, an anti-epileptic drug. Topiramate’s adverse digestive effects – anorexia and weight loss – are used to aid slimming. But topiramate exposes patients to an array of other adverse effects including neuro-psychological and ocular disorders and metabolic problems.
Hopefully the EMA has learned the lesson of Mediator° and will refuse to authorise this undesirable drug.
©Prescrire 1 September 2012
"Phentermine: an appetite-suppressant amphetamine classified as a narcotic in France. Is a combination with topiramate on the horizon?" Prescrire Int 2012; 21 (130): 209. (Pdf, subscribers only).