Olanzapine as alternative therapy for patients with haloperidol-induced extrapyramidal symptoms: Results of a multicenter, collaborative trial in Latin America

Conventional antipsychotic agents can induce extrapyramidal symptoms (EPS) that may be alleviated by switching patients to novel agents such as olanza pine. Patients with schizophrenia and related disorders (ICD-10) who were t aking haloperidol (N = 94; mean dose = 12.7 mg/day) and had EPS (Simpson-An gus Scale [SAS] > 3) were directly switched to 6 weeks of open-label olanza pine treatment (mean dose = 11.4 mg/day). There were significant mean impro vements (p < 0.001 for all measurements) from baseline to endpoint on the S AS (-9.69 +/- 5.33; percentage change, 87.2%), the Barnes Akathisia Scale ( -1.00 +/- 1.19; percentage change, 82.5%), and the Abnormal Involuntary Mov ement Scale (-1.48 +/- 2.89; percentage change, 81.1%), and anticholinergic use decreased from 47.9% to 12.8% (mean baseline to endpoint change: -1.52 +/- 1.91-mg equivalents of benztropine; p < 0.001). Significant mean basel ine to endpoint improvements (p <less than> 0.001 for all measurements) wer e observed on the Positive and Negative Syndrome Scale (PANSS; -25.28 +/- 1 8.67; percentage change, 30.3%), the PANSS-extracted Brief Psychiatric Rati ng Scale (0-6 scale, -13.41 +/- 10.16; percentage change, 54.4%), and the C linical Global Impressions Severity scale (-1.16 +/- 1.19; percentage chang e, 26.4%). Spontaneously reported treatment- emergent adverse events with a greater than 5% incidence were somnolence (16.0%), increased appetite (14. 9%), weight gain (11.7%), headache (8.5%), anxiety (7.4%), dizziness (6.4%) , and insomnia (5.3%). Criteria for a successful switch were met by 90.5% o f patients. Psychotic symptom exacerbation was experienced by 30.9% of pati ents at any time during the study and by 11.7% of patients at endpoint. Res ults suggest that a direct switch to olanzapine is a therapeutic option whe n patients with haloperidol-induced EPS are unable to tolerate a more gradu al switch.