Olanzapine and risperidone are the leading antipsychotic drugs ("Vital Signs: Zyprexa Sales Led Antipsychotic Market in 2004," July 2005, p. 1), but which one is better for the treatment of schizophrenia?
We searched the Cochrane database (www.cochrane.org) and found a pertinent comparison of the two drugs (Cochrane Database Syst. Rev. 2005;(2): CD005237; www.cochrane.org/cochrane/revabstr/AB005237.htm).
For this Cochrane publication, all randomized controlled studies directly comparing the efficacy and toxicity of olanzapine (Zyprexa, Eli Lilly & Co.) and risperidone (Risperdal, Janssen Pharmaceutica) for schizophrenia, schizoaffective disorders, and schizophreniform disorders were included. Patients with primary problems of substance abuse were excluded. In all, 14 studies were included in the review: 7 were short term (up to 12 weeks); 1 was medium term (13-26 weeks); and 6 trials, with a total of 774 patients, were long term (more than 26 weeks). The mean age of study participants was late 30s to early 40s. Risperidone was given in doses of 2-10 mg/day and olanzapine in doses of 5-20 mg/day. Outcomes were measured using the Clinical Global Impressions scale, rehospitalization, Positive and Negative Syndrome Scale (PANSS), Brief Psychiatric Rating Scale (BPRS), Scale for the Assessment of Negative Symptoms (SANS). Hamilton Rating Scale for Depression (HAMD), and neurocognitive functioning.
No important difference in global effect between olanzapine and risperidone was noted. Only one study provided good data on rehospitalization. At 12 months, the number of patients rehospitalized was far lower in the olanzapine group, a conclusion based upon a single study funded by Eli Lilly. Use of additional benzodiazepines was not significantly different between the olanzapine and risperidone groups.
Longer-term data showed some advantage of olanzapine over risperidone in terms of a 50% decrease in PANSS and BPRS end point scores, another conclusion based upon a single study funded by Eli Lilly. The use of PANSS or SANS to generate end point-negative symptom subscores showed no difference between olanzapine and risperidone. The use of the PANSS to generate end point-positive scores also did not favor either medication. No significant differences were found between either antipsychotic on the HAM-D and neurocognitive functioning scores.
Approximately two-thirds of patients given olanzapine or risperidone experienced a side effect. There was no difference between olanzapine and risperidone in terms of reported effects on the cardiovascular, gastrointestinal, hematologic, or respiratory systems. Females given olanzapine were no more likely to experience endocrine disturbances than were those given risperidone. …