Serum ghrelin concentrations in patients receiving olanzapine or risperidone

Rationale. Although enhanced appetite and weight gain are potential side effects of treatment with antipsychotic agents, particularly olanzapine and clozapine, the mechanism is poorly understood. Objectives. To test the hypothesis that ghrelin, a gastrointestinal hormone that enhances appetite, is involved in increased food intake and weight gain during treatment with antipsychotics. Methods. Serum ghrelin concentrations were investigated in schizophrenic patients receiving olanzapine or risperidone, and in healthy volunteers. Results. Serum ghrelin concentrations did not increase, but rather decreased, in patients treated with olanzapine or risperidone in comparison with healthy volunteers. No significant difference was found in serum ghrelin concentration between patients treated with olanzapine and risperidone. Conclusions. Our results indicate that ghrelin is not a direct cause of increased food intake and weight gain during treatment with olanzapine or risperidone, whereas ghrelin is associated with metabolic change in patients receiving these agents.