The motor response to repeated apomorphine administration in Parkinson's disease.

Seven patients with Parkinson's disease and levodopa-induced motor fluctuations were studied with repeated injections of apomorphine over a 10-h period to explore possible changes in the latency, duration, and quality of motor response with recurrent dopaminergic stimulation. Doses were given when the motor effects induced by the previous dose had just worn off. No significant change in the motor response to repeated boluses of subcutaneous apomorphine was found. Our results do not support the suggestion that rapid changes in receptor sensitivity during repeated intermittent dopaminergic stimulation are a major factor in the pathogenesis of parkinsonian motor fluctuations.