Does O-methyl-dopa play a role in levodopa-induced dyskinesias?

Clinically scored levodopa-induced dyskinesias were correlated with plasma dopa and O-methyl-dopa levels determined every hour during one day in 30 Parkinsonian-treated patients. In patients treated with a combination of L-dopa and a peripheral decarboxylase inhibitor (PDI), those with dyskinesias have very high plasma O-methyl-dopa levels compared with those who have no dyskinesias. In contrast, no significantly different plasma dopa levels are found in these two subgroups of patients, leaving open the question of the possible involvement of such elevated plasma O-methyl-dopa levels in favouring dyskinesias.