title: Levodopa consumption reduces dopaminergic receptor responsiveness in Parkinson's disease.
abstract: In seven patients with Parkinson's disease with daily motor fluctuations, we found that the same subcutaneous apomorphine dose that improved motor function when given in the morning after a normal night without taking levodopa failed to turn patients "on" during afternoon and evening "off" periods, and on a different morning after receiving levodopa during the night. No significant changes in levodopa or 3-O-methyldopa plasma levels that could explain these variations were detected. These findings suggest that increased daily levodopa consumption may reduce striatal responsiveness to dopaminergic stimulation.
authors: Department of Neurology, University of Navarra, Pamplona, Spain.
authors: J
authors: J
authors: Vaamonde
authors: M R
authors: MR
authors: Luquin
authors: J A
authors: JA
authors: Obeso
mesh_terms: D000368:Aged; D001058:Apomorphine / Q000008:administration & dosage; D002230:Carbidopa / Q000627:therapeutic use; D004351:Drug Resistance; D005260:Female; D006801:Humans; D007279:Injections, Subcutaneous; D007980:Levodopa / Q000009:adverse effects* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000188:drug therapy / Q000378:metabolism* / Q000503:physiopathology; D011597:Psychomotor Performance / Q000187:drug effects; D011954:Receptors, Dopamine / Q000187:drug effects*
chemical_list: D011954:Receptors, Dopamine; D007980:Levodopa; D002230:Carbidopa; D001058:Apomorphine