Switching From Depot Antipsychotic Drugs to Olanzapine in Patients With Chronic Schizophrenia

Background: Patients with chronic schizophrenia (DSM-IV criteria) often receive depot antipsychotic medications to assure longer administration and better compliance with their treatment regimen. This study evaluated whether patients stabilized on depot antipsychotic medication could be successfully transitioned to oral olanzapine.

Method: In a 3-month open-label study, 26 clinically stable patients with schizophrenia taking depot antipsychotics for over 3 years were randomly assigned to continue on their current depot dose or to switch to oral olanzapine. Clinical ratings (Positive and Negative Syndrome Scale [PANSS], Global Assessment of Functioning [GAF] scale, and Clinical Global Impressions [CGI] scale) and side effect parameters (Abnormal Involuntary Movement Scale [AIMS], Barnes Akathisia Scale, AMDP-5 scale, vital signs, and weight) were obtained monthly.

Results: Oral olanzapine patients (N = 13) demonstrated significant clinical improvement over the depot control group (N = 13) from baseline to 3-month endpoint (PANSS total, p = .012; PANSS general, p = .068; PANSS negative, p = .098; CGI-Improvement, p = .007; CGI-Severity, p = .026; GAF, p = .015). Side effect rating scales showed no statistical differences between the 2 groups (AIMS, Barnes Akathisia Scale, AMDP-5, vital signs). The depot control group showed no statistical superiority in any measure except weight change (p = .0005). After 3 months, all olanzapine patients preferred olanzapine to their previous depot medications and chose to continue on olanzapine treatment.

Conclusion: Clinicians may expect clinical improvement when switching chronically psychotic patients from traditional depot antipsychotic drugs to oral olanzapine. Switching may be completed within a 4-week period with relative compliance being maintained and patients preferring oral olanzapine to their previous depot medications.