Topiramate (Topamax)

Topiramate (Topomax) is a drug approved by FDA for the treatment of epilepsy and prophylaxis of migraine headaches. However, there is substantial evidence for its effectiveness for weight loss. It has been successfully used off-label for weight reduction and maintenance in some populations.

The mechanism by which topiramate induces weight loss (or suppresses seizures for that matter) is somewhat unclear. The proposed mechanisms include increased energy expenditure; reduction in the activity of salivary enzymes, which are partially responsible for taste; reduction in leptin and corticosteroid concentrations; and reduction in blood glucose and insulin concentrations.

However it works, the evidence of weight loss produced by topiramate is substantial. Several placebo-controlled studies with patients receiving daily doses of topiramate from 32 to 384 mg per day, reported weight loss in the range from about 5% to as high as 16% from baseline. In most studies, 75% or more patients treated experienced weight loss.

While there is solid evidence that topiramate promotes substantial weight loss in the majority of patients, a number of caveats remain. First, no large and/or long-term studies to evaluate its safety in this setting have been done. The use of topiramate is associated with considerable side effects, such as parasthesias (pins and needles sensation), memory impairment, taste distortion, fatigue, insomnia, difficulty concentrating, and dizziness. High incidence and intensity of side effects is one of the main reasons why topiramix has not been approved by the FDA as a weight loss drug. There is some ongoing research into creating a variant of topiramate, whether by chemical modification or formulation adjustment, with better side-effects profile.

Considering the side-effect profile of topiramate in its current formulation, most experts are reluctant to recommend it solely for weight loss. However, it may be useful in patients who have other indications, such as epilepsy or migraines, in addition to obesity.

See also the index of related studies and drug label information for topiramate (Topamax).