Anticholinergic antiparkinsonian therapy in outpatients treated with neuroleptic drugs: a prescription survey.

Extrapyramidal adverse effects (EPAs) due to neuroleptic treatment are routinely treated with anti-cholinergic antiparkinsonian drugs (APDs). We studied the use of these drugs in the general population exposed to neuroleptic drugs to improve our knowledge of the epidemiology of EPAs. We selected all the neuroleptic and antiparkinsonian drug prescriptions delivered in the province of Rome (ca. 3,750,000 inhabitants) from 1986 to 1989. During the study period, 10.6% of neuroleptic-treated subjects were concurrently prescribed anticholinergic antiparkinsonian drugs. The influence of different factors on APD prescriptions was evaluated through a logistic regression model. The highest probability of receiving APDs was associated with trifluperidol treatment (odds ratio = 5.0, using chlorpromazine as baseline); among the commonly prescribed neuroleptics, sulpiride, levosulpiride and tiapride chlorydrate had the lowest probability of coprescription with APDs (odds ratios less than 0.1). The probability of being prescribed anticholinergic antiparkinsonian drugs decreased with age and increased with the amount of neuroleptics prescribed. This study surveys a very large sample using a population-based approach, whereas the same topics have previously only been studied in limited inpatient populations.