Rationale: The results from case-control and retrospective studies revealed that olanzapine might be associated with more increased risks of metabolic dysfunction than risperidone. The crossover design can minimize the influence of individual variation in metabolic profiles and demographic variables, such as age, sex, concomitant medication use and personal life styles.
Objectives: We design a crossover study to evaluate the metabolic effect of olanzapine and risperidone.
Methods: Fifteen schizophrenic patients were shifted from olanzapine and risperidone or from risperidone and olanzapine due to poor treatment response. The body weights, lipid profiles and fasting glucose levels were assessed before medication switch and 3 months after crossover.
Results: In the seven patients taking risperidone at the time of inclusion (risperidone-first group), after shifting to olanzapine, there was a significant increase in triglyceride level (p=0.048) and body weight (p=0.008). In the other eight patients (olanzapine-first group), after shift to risperidone, there was a decrease in triglyceride level (p=0.009), body weight (p=0.049) and body mass index (BMI; p=0.04). When comparing the metabolic profiles in all patients after olanzapine and after risperidone (irrespective of the order of treatment), the mean triglyceride level (p=0.001), body weight (p=0.001) and BMI (p=0.015) were significantly higher in patients receiving olanzapine than in those receiving risperidone. Furthermore, there was a small increase in total cholesterol level (p=0.091) and a small decrease in high-density lipoprotein (HDL) level (p=0.061) in olanzapine group, but the differences did not reach a significant level. There was no significant difference between olanzapine and risperidone in fasting glucose and low-density lipoprotein (LDL).
Conclusions: This study confirms that elevated levels of triglyceride and body weight could be associated with the use of olanzapine as compared with risperidone. The changes in body weights and lipid profiles should be closely monitored in patients during treatment with atypical antipsychotic drugs.