The Prevalence of Acute Extrapyramidal Signs and Symptoms in Patients Treated With Clozapine, Risperidone, and Conventional Antipsychotics
J Clin Psychiatry 1998;59(2):69-75
© Copyright 2014 Physicians Postgraduate Press, Inc.
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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.
Method: 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.
Conclusion: 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.