No difference in the effect of biperiden and amantadine on parkinsonian- and tardive dyskinesia-type involuntary movements: a double-blind crossover, placebo-controlled study in medicated chronic schizophrenic patients.

BACKGROUND

There are few objective guidelines for the clinician in the choice of antiparkinsonian drugs, even though these drugs are a heterogeneous group. We compared the effect of biperiden (M1 selective anticholinergic) and amantadine (dopaminergic) on neuroleptic-induced parkinsonian extrapyramidal symptoms (EPS) and tardive dyskinesia (TD)-type involuntary movements.

METHOD

Thirty-two schizophrenic (DSM-III-R) inpatients on long-term stable antipsychotic and trihexyphenidyl treatment entered the study. Antipsychotics were kept constant, but trihexyphenidyl was replaced by placebo under single-blind conditions for 1 week, and the the patients were randomly assigned to either amantadine 100 mg b.i.d. or biperiden 2 mg b.i.d. treatment under double-blind conditions for 2 weeks. After a second 1-week placebo period, the test drugs were crossed over under double-blind conditions. Assessments of tardive dyskinesia (Abnormal Involuntary Movement Scale [AIMS]) and of parkinsonian extrapyramidal side effects (Simpson-Angus Neurologic Rating Scale) were made pretreatment and posttreatment.

RESULTS

Twenty-six patients completed all study procedures. Amantadine and biperiden were equally effective in relieving neuroleptic-induced EPS and did not exacerbate TD-type movements. AIMS scores during treatment were significantly lower than during placebo period. The findings were similar in patients with diagnosable TD.

CONCLUSION

Amantadine and biperiden have similar effects on neuroleptic-induced EPS and TD and may ameliorate mild TD.