Objective: To determine the antipsychotic efficacy and extrapyramidal safety of intramuscular (i.m.) olanzapine and i.m. haloperidol during the first 24 hours of treatment of acute schizophrenia.
Method: Patients (n = 311) with acute schizophrenia were randomly allocated (2:2:1) to receive i.m. olanzapine (10.0 mg, n = 131), i.m. haloperidol (7.5 mg, n = 126), or i.m. placebo (n = 54).
Results: After the first injection, i.m. olanzapine was comparable to i.m. haloperidol and superior to i.m. placebo for reducing mean change scores from baseline on the Brief Psychiatric Rating Scale (BRPS) Positive at 2 hours (-2.9 olanzapine, -2.7 haloperidol, and -1.5 placebo) and 24 hours (-2.8 olanzapine, -3.2 haloperidol, and -1.3 placebo); the BPRS Total at 2 hours (-14.2 olanzapine,-13.1 haloperidol, and -7.1 placebo) and 24 hours (-12.8 olanzapine, -12.9 haloperidol, and -6.2 placebo); and the Clinical Global Impressions (CGI) scale at 24 hours (-0.5 olanzapine, -0.5 haloperidol, and -0.1 placebo). Patients treated with i.m. olanzapine had significantly fewer incidences of treatment-emergent parkinsonism (4.3% olanzapine vs 13.3% haloperidol, P = 0.036), but not akathisia (1.1% olanzapine vs 6.5% haloperidol, P = 0.065), than did patients treated with i.m. haloperidol; they also required significantly less anticholinergic treatment (4.6% olanzapine vs 20.6% haloperidol, P < 0.001). Mean extrapyramidal symptoms (EPS) safety scores improved significantly from baseline during i.m. olanzapine treatment, compared with a general worsening during i.m. haloperidol treatment (Simpson-Angus Scale total score mean change: -0.61 olanzapine vs 0.70 haloperidol; P < 0.001; Barnes Akathisia Scale global score mean change: -0.27 olanzapine vs 0.01 haloperidol; P < 0.05).
Conclusion: I.m. olanzapine was comparable to i.m. haloperidol for reducing the symptoms of acute schizophrenia during the first 24 hours of treatment, the efficacy of both being evident within 2 hours after the first injection. In general, more EPS were observed during treatment with i.m. haloperidol than with i.m. olanzapine.