Dopamine excretion and vulnerability to drug-induced Parkinsonism. Schizophrenic patients.

Before and during a standardized course of trifluoperazine therapy, 18 schizophrenic patients underwent repeated examinations for extrapyramidal motor signs, clinical psychopathology, and urinary excretion of free and conjugated forms of dopamine and its metabolites. Patients excreting more free dopamine and metabolites, or showing less complete conjugation, before drug treatment, were much less likely than others to develop parkinsonian akinesia and rigidity during drug treatment. Neither catatonic rigidity nor akinesia before treatment was predictive of a parkinsonian response to trifluoperazine, but pretreatment tremor may have been. The severity of schizophrenic psychopathology was unrelated to dopamine excretion. This study of schizophrenic patients, and our previous research in Parkinson's disease, suggest that urinary dopamine excretion may reflect dopaminergic function of the extrapyramidal motor system in both conditions.