Paradoxial response to dopaminergic agents in parkinsonism.

A patient with the classical stigmata of parkinsonism was treated on three separate occasions with levodopa, a combination of levodopa and carbidopa, and lergotrile mesylate, a direct-acting dopamine-receptor agonist. All three treatment regimens resulted in dose-related increases in parkinsonian features. To our knowledge, this response has not been previously described. Lergotrile did not alter CSF homovanillic acid concentration. It is suggested that this rare paradoxical motor response to dopaminergic agents may be associated with dysfunction of the postsynaptic dopamine receptor site.