Switching Clozapine Responders to Olanzapine

Background: Clozapine is an atypicalantipsychotic indicated for the management of severely illpatients with schizophrenia who have failed to respond adequatelyto standard drug treatment. The significant risk ofagranulocytosis and seizure associated with clozapine has led tothe restrictions in its use. Additionally, drug-induced sedation,sialorrhea, enuresis, and weight gain are often cited asproblematic consequences of clozapine treatment. Our primaryobjective was to determine the effectiveness and safety of amethod of slow cross-titration from clozapine to olanzapine amongpatients responsive to clozapine treatment but experiencingmedication-induced adverse events.

Method: Changes in symptomatology, mood,subjective response, and safety were examined in 20 outpatientsmeeting DSM-IV criteria for schizophrenia or schizoaffectivedisorder who converted from clozapine to olanzapine. Patientswere considered clozapine-responsive as evidenced by improvedsocial function and decreased symptoms with clozapine therapy;however, they were interested in alternative pharmacologictreatment because of clozapine-related side effects.

Results: Equivalent efficacy of olanzapine toclozapine was found in 90% of the patients (18/20) in the studygroup, without rehospitalization or suicidal behavior in any ofthe patients. Also notable was a reduction in drug-induced sideeffects and improved subjective response to pharmacotherapy.

Conclusion: The successful conversion fromclozapine to olanzapine has the potential to provide greatbenefits for the patient, including reducing drug-induced sideeffects while maintaining symptom control. These preliminaryresults suggest that further research on converting clozapineresponders to olanzapine is warranted.