Schizophrenic patients treated with atypical antipsychotics commonly suffer weight gain. Additive flow of using these drugs lead to more researches to solve this problem. Weight gain is associated not only with several medical conditions (such as hypertension, diabetes, cardiovascular disease, etc) but also may be related to treatment noncompliance. Topiramate is an anticonvulsant drug that has been used in psychiatric disorders and also leads to weight reduce. Many researches have been studied this effect of topiramate and positive outcomes of weight reduce without creation or development of psychotic signs have already been reported. as there is no approved therapeutic dose of topiramate for appropriate weight loss and also no study referred to its prophylactic effect of weight gain in these patients, in this study we proceed to check forenamed subjects.

Forty - eight schizophrenic patients treated with olanzapine in beginning of hospitalization in Ibn-e-Sina Hospital were selected and randomly placed in four groups: placebo, 50, 100, 200 mg topiramate daily was added to their treatment regimen. Patients were followed for 12 weeks for body weight changes, BMI, waist and wrist diameters. Data were analyzed by SPSS software.

Only BMI and waist diameter had significant difference in patients treated with 200 mg topiramate daily in compare with placebo group in 12th week. other data had no significant difference in handling.

Prophylactic treatment of obesity in schizophrenic patients with topiramate is effective in 200 mg daily dosage and no significant adverse effects were found.