Comparison of effects of the use of olanzapine and quetiapine on resting metabolic rate in schizophrenic patients

Schizophrenia is a severe, early onset mental disorder which presents heterogeneity and leads to serious disruptions in thoughts, motions and behavior. One of the side effects of antipsychotic drugs is causing an increase in body weight. The aim of this study is to compare resting metabolic rates among patients with schizophrenia who used olanzapine or quetiapine versus healthy controls.Patients diagnosed as schizophrenia who got treatment with olanzapine (n=20) or quetiapine (n=20), and healthy controls (n=20) who did not use any drug were enrolled in this study. Resting metabolic rates were measured by computerized oxygen and carbon dioxide analyzer. Body mass index was calculated using tight and body weight. The mean dose used for olanzapine and quetiapine groups was 15.3±6.9 mg/day and 467.5±6.9 mg/day, and treatment duration was 9.4±13.9 month and 9.9±14.5 month, respectively. Mean age, body mass index and resting metabolic rate values were not significantly different among olanzapine and quetiapine versus control groups.We suggest that if patients with schizophrenia gained weight with olanzapine or quetiapine treatment, the other factors (interactivities between drug and receptor or drug and hormone, increase of appetite, less daily physical activity, etc.) except for resting metabolic rate might be considered in weight management. Our results also suggest that diet control programmes and exercise therapy which prevent gaining weight can be easily adapted to treatment since they did not significantly decrease resting metabolic rate in schizophrenic patients treated with olanzapine or quetiapine.