Long-Term Assessment of Asenapine vs. Olanzapine in Patients with Schizophrenia or Schizoaffective Disorder

Introduction: We conducted a double-blind 1-year trial of asenapine in patients with schizophrenia or schizoaffective disorder. Methods: Patients were randomized to asenapine (5 or 10 mg BID; n = 913) or olanzapine (10-20 mg QD; n = 312), and monitored regularly. Results: Trial completion rates were 38% with asenapine, 57% with olanzapine; main reasons for discontinuation were withdrawal of consent (22%, 16%) and insufficient response (25%, 14%); fewer discontinuations were due to adverse events (6%, 7%). Mean weight gain was 0.9 kg with asenapine, 4.2 kg with olanzapine. Extrapyramidal symptoms reported as adverse events were more common with asenapine. Mean reductions in PANSS total score with asenapine and olanzapine were -21.0 and -27.5 (P < 0.0001); the exclusion of patients who had previous poor experience with olanzapine may have biased the results in favor of olanzapine. Scores on the subjective well-being on neuroleptics scale and functionality measures were similar between groups. Conclusion: Asenapine was well tolerated over 1 year of treatment, causing less weight gain than olanzapine but more frequent extrapyramidal symptoms. PANSS total score improved with both agents; the improvement was greater with olanzapine than with asenapine using last observations carried forward but not in an observed-case analysis.