Dopaminergic responsiveness to apomorphine after chronic treatment with subcutaneous lisuride infusion in Parkinson's disease.

The aim of this study was to assess whether or not continuous infusion of lisuride in combination with intermittent levodopa-carbidopa administration was associated with tolerance. Intravenous apomorphine was given to four patients before initiation of chronic treatment with subcutaneous lisuride infusion and oral levodopa. The study was repeated under identical conditions after a mean of 18 months of treatment. In no case was the motor response induced by apomorphine infusion reduced as compared to baseline assessment. Choreic dyskinesias accompanying the "on" state were enhanced in all patients. These findings suggest that chronic continuous infusion of a dopamine agonist like lisuride, associated with oral levodopa, is not accompanied by tolerance or down-regulation of striatal dopaminergic receptors.