title: The prevalence of acute extrapyramidal signs and symptoms in patients treated with clozapine, risperidone, and conventional antipsychotics.
abstract: BACKGROUND
  Acute extrapyramidal side effects (EPS) are a common phenomenon of treatment with conventional antipsychotics. Previous studies found that clozapine has little propensity to cause EPS, while risperidone produces some EPS, but at levels lower than those of conventional antipsychotics.
  
  
  METHODS
  We compared the prevalence and severity of EPS in patients treated with clozapine, risperidone, or conventional antipsychotics for at least 3 months. Our main hypothesis was that there would be differences between the three treatment groups with regard to akathisia, measured with the Barnes Akathisia Scale, and extrapyramidal motor side effects (rigidity, rigidity factor, tremor, salivation), measured with the Simpson-Angus scale. Secondarily, we were interested in possible differences between the three groups with respect to the anticholinergic comedication and the subjective impression of the patients, measured with the van Putten scale.
  
  
  RESULTS
  We studied 106 patients (41 patients treated with clozapine, 23 patients with risperidone, and 42 patients treated with conventional antipsychotics). The sample was 57.5% male and had a mean +/- SD age of 36.6 +/- 9.3 years. The mean dose of antipsychotics calculated in chlorpromazine equivalents was 425.6 +/- 197.1 mg/day in the clozapine group, 4.7 +/- 2.1 mg/day in the risperidone group, and 476.5 +/- 476.9 mg/day in the group treated with conventional antipsychotics. The point-prevalence of akathisia was 7.3% in the clozapine group, 13% in the risperidone group, and 23.8% in the group treated with conventional antipsychotics. The point-prevalence of rigidity and cogwheeling respectively was 4.9% and 2.4% in the clozapine group, 17.4% and 17.4% in the risperidone group, and 35.7% and 26.2% in the group treated with conventional antipsychotics.
  
  
  CONCLUSIONS
  Our results indicate that risperidone is superior to conventional neuroleptics in that it causes fewer EPS. In comparison to clozapine, risperidone produces EPS levels that are intermediate between clozapine and conventional antipsychotic drugs.
authors.affiliation: Department of Biological Psychiatry, Innsbruck University Clinics, Austria.
authors.forename: C H
authors.initials: CH
authors.lastname: Miller
authors.forename: F
authors.initials: F
authors.lastname: Mohr
authors.forename: D
authors.initials: D
authors.lastname: Umbricht
authors.forename: M
authors.initials: M
authors.lastname: Woerner
authors.forename: W W
authors.initials: WW
authors.lastname: Fleischhacker
authors.forename: J A
authors.initials: JA
authors.lastname: Lieberman
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D017109:Akathisia, Drug-Induced / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology; D000553:Ambulatory Care; D014150:Antipsychotic Agents / Q000009:adverse effects* / Q000627:therapeutic use; D001480:Basal Ganglia Diseases / Q000139:chemically induced* / Q000175:diagnosis / Q000453:epidemiology*; D003024:Clozapine / Q000009:adverse effects* / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011358:Product Surveillance, Postmarketing; D011618:Psychotic Disorders / Q000188:drug therapy; D018967:Risperidone / Q000009:adverse effects* / Q000627:therapeutic use; D012559:Schizophrenia / Q000188:drug therapy; D012720:Severity of Illness Index
chemical_list: D014150:Antipsychotic Agents; D003024:Clozapine; D018967:Risperidone