Intramuscular Olanzapine and Intramuscular Haloperidol in Acute Schizophrenia: Antipsychotic Efficacy and Extrapyramidal Safety during the First 24 Hours of Treatment

Abstract

Objective:

To determine the antipsychotic efficacy and extrapyramidal safety of intramuscular (IM) olanzapine and IM 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 IM olanzapine (10.0 mg, n = 131), IM haloperidol (7.5 mg, n = 126), or IM placebo (n = 54).

Results:

After the first injection, IM olanzapine was comparable to IM haloperidol and superior to IM 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 IM 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 IM 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 IM olanzapine treatment, compared with a general worsening during IM 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:

IM olanzapine was comparable to IM 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 IM haloperidol than with IM olanzapine.