Efficacy of add-on topiramate therapy in psychiatric patients with weight gain.

Background: Weight gain is a common adverse effect of many psychotropic medications including antipsychotics, antidepressants, and mood stabilizers. There is a growing body of evidence that topiramate may be useful as an add-on therapy to induce weight loss in patients who have experienced psychotropic-induced weight gain.

Objective: To determine the efficacy and tolerability of topiramate for treatment of weight gain in a naturalistic mental health clinic setting.

Methods: A retrospective chart review was conducted at a community mental health clinic. Subjects were non-elderly adults who received topiramate therapy beginning in 2002-2005 for documented weight gain during treatment with psychotropic drugs. Primary outcome measures included response rate (based on weight loss of any magnitude) and mean changes in weight and body mass index (BMI).

Results: Forty-one patients were included in the study. There was a 58.5% (n = 24) response rate. Mean reductions in weight and BMI were approximately 2.2 kg and 0.5 points, respectively. Responders lost an average of 7.2 kg, whereas nonresponders gained an average of 5.0 kg. Patients with a baseline weight of at least 91 kg and those receiving a greater number of psychotropic medications were more likely to experience success with topiramate therapy. Of the 24 patients who responded to therapy, 22 experienced onset of weight reduction by the next clinic visit (1-4 mo) following either initiation of therapy or titration to the eventual therapeutic dose, and the usual rate of weight loss was 0.45-1.4 kg per month. Therapy was typically initiated at 50 mg/day. The mean maximum dose was 93.9 mg/day and the median maximum dose was 100 mg/day. Seven (17.1%) patients had documented adverse effects to topiramate therapy.

Conclusions: Topiramate therapy resulted in overall modest (ie, <2%) decreases in weight and BMI, but many patients experienced more impressive weight loss. Therapy was generally well tolerated.