Dopaminergic agonist Ro 8-4650 in Parkinson's disease. II. Patients not treated with dopa.

An isoquinolone derivative Ro 8-4650 (rac-4-(3,4-dichlorophenyl)-1,2,3,4-tetrahydro-7-methoxy-2-methylisoquinoline hydrochloride) with dopaminergic properties was studied in a randomized crossover trial. The group studied comprised 37 patients with idiopathic parkinsonism, not previously treated with levodopa or dopamin agonists. The trial drug was significantly more effectve than placebo, but the clinical improvement, according to the Webster rating scale, was small. No significant difference was observed as regards involuntary movements, but the trial drug led to more frequent minor side effects. It can be concluded that the trial drug, despite its proven effect in Parkinson's disease, has only limited clinical value.