Apomorphine test for dopaminergic responsiveness: A dose assessment study

Abstract

The clinical diagnosis of idiopathic Parkinson's disease (IPD) remains difficult and is supported by a favorable response to levodopa, while failure to respond represents an exclusion criterion. Recently, the response to subcutaneous apomorphine has been suggested as a tool in predicting levodopa responsiveness in parkinsonian syndromes. We administered apomorphine at doses of 10, 50, and 100 μg/kg dose. Because of the high frequency of side effects with the dose of 100 μg/kg, 50 μ/kg seems more useful. After an adequate period of levodopa/carbidopa therapy (12‐month follow‐up), 29 patients improved; 25 of these had demonstrated a positive response to the apomorphine test. The final diagnosis of IPD, made on the basis of an exhaustive clincal and neuroradiological evaluation and on the response to chronic levodopa therapy, was in good agreeement with the response to the apomorphine test (predictivity of diagnosis, 86.4%). Our data indicate that subcutaneous apomorphine at the dose of 50 μg/kg is a useful tool in the differential diagnosis of parkinsonian syndromes.