title: The clinical picture and plasma levodopa metabolite profile of parkinsonian nonresponders. Treatment with levodopa and decarboxylase inhibitor.
abstract: Three parkinsonian patients who were nonresponders to levodopa treatment did not improve when shifted to levodopa-decarboxylase inhibitor combination but, instead, experienced involuntary movements. Their plasma levodopa and metabolite profiles showed unusually high baseline 3-0-methyldopa concentrations that further increased significantly during the decarboxylase inhibitor regimen. All patients had 3-0-methyldopa to levodopa ratios greater than 1, even two hours after therapy. Patients who are responders to levodopa-decarboxylase inhibitor combination or to levodopa alone had 3-0-methyldopa to levodopa ratios of less than 1. We discuss the role of 3-0-methyldopa as a metabolite and the significance of the 3-0-methyldopa to levodopa ratio as a predictor of patients' response to levodopa.
mesh_terms: D000328:Adult; D002230:Carbidopa / Q000009:adverse effects / Q000627:therapeutic use*; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D006834:Hydrazines / Q000627:therapeutic use*; D007980:Levodopa / Q000009:adverse effects / Q000097:blood / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000188:drug therapy*
chemical_list: D006834:Hydrazines; D007980:Levodopa; D002230:Carbidopa