Remoxipride in Parkinson's disease: differential response in patients with dyskinesias fluctuations versus psychosis.

Remoxipride is a novel substituted benzamide that more effectively blocks mesolimbic than striatal D2 dopamine receptors. We used remoxipride in the management of nine patients with Parkinson's disease (PD) who were experiencing visual hallucinations due to dopaminergic therapy. Remoxipride was begun in a dose of 25 mg three times daily and gradually increased to 75-225 mg/d (mean 161 mg). The psychiatric status improved in eight patients. Little or no change in the severity of parkinsonism was noted in five, a mild increase in two, and a moderate increase in two. Because one patient with moderately severe levodopa-induced dyskinesias experienced a reduction in the abnormal movements without a substantial increase in parkinsonism, we began a trial of remoxipride for disabling peak-dose dyskinesias. The trial was abandoned after every one of the first four patients entered experienced an immediate, severe, and prolonged increase in off periods with single 10- to 25-mg doses. This striking differential response to an atypical neuroleptic with weak striatal D2 antagonist properties indicates that different states of postsynaptic dopamine receptor sensitivity or synaptic dopamine levels may be associated with various disease- and treatment-related problems found in late-stage PD.