Similarities between Neurologic Effects of L-Dopa and of Apomorphine

Abstract

L-DOPA is a precursor for the biosynthesis of both melanins and catecholamines. Both groups of substances are diminished within the Parkinsonian brain.1 2 3 L-dopa administration might therefore increase both melanins and catecholamines.4 The side effects of L-dopa were assigned to dopamine instead of melanin5 because they paralleled the effects of apomorphine, which has chemical similarities to dopamine6 and activates dopaminergic receptors in laboratory animals.6 7 8 The therapeutic effects of L-dopa might also be assigned to dopamine if they could be duplicated by apomorphine.4 , 9 , 10 We have found that subcutaneous administration of apomorphine to patients with selected neurologic disorders has temporarily changed the neurologic . . .