Nizatidine treatment and its relationship with leptin levels in patients with olanzapine-induced weight gain.

It has been reported that nizatidine may reduce the weight gain in schizophrenic patients receiving olanzapine treatment. Previous studies have demonstrated a relation between olanzapine-induced weight gain and serum leptin levels. Therefore, in the present study, it was planned to investigate the efficacy of nizatidine on the treatment of olanzapine-induced weight gain, and if available, whether leptin levels were associated with reductions in weight gain. Of the patients with schizophrenia on olanzapine treatment, 59 who gave informed consent entered a 3 month open-label screening period. Of them, 35 patients (59%) showed weight gain in excess of 2.5 kg. These patients were randomly divided into two groups; olanzapine plus nizatidine (group I) and olanzapine plus placebo (group II) for an 8-week double-blind phase. The patients were evaluated at the baseline and at week 8 with respect to the positive and negative syndrome scale, body mass index, weight and serum leptin levels. In the open-label period, olanzapine led to a considerable marked increase in weight and in serum leptin levels. There was no statistically significant difference between the groups with respect to weight at the beginning of the 8-week double-blind treatment period. Throughout the 8 week double-blind period, in group I, the weight decreased by 4.5 +/- 2.2 kg ( p<0.05). In contrast, weight increased in group II by a mean of 2.3 +/- 0.9 kg ( p>0.05). The leptin levels decreased by 4.4 +/- 2.3 ng/ml in group I ( p<0.01), and increased by 1.8 +/- 0.6 ng/ml in group II ( p>0.05). These changes were accompanied by changes in the leptin levels in both groups I and II. It is concluded that leptin seems to be strongly associated with olanzapine-induced weight gain and that nizatidine treatment may reduce the weight gain and the correlated leptin levels in patients with schizophrenia on olanzapine treatment.