title: Plasma levels of levodopa and its main metabolites in parkinsonian patients after conventional and controlled-release levodopa-carbidopa associations.
abstract: The paper reports plasma levels of levodopa (LD), its main metabolites [dopamine, dihydroxyphenylacetic acid, homovanillic acid, 3-O-methyldopa (3-O-MD)] and carbidopa in 14 parkinsonian patients first treated with Sinemet and thereafter with Sinemet-CR4. A good relationship was observed between LD plasma levels and pharmacological effects. While the LD area under the curve increased after Sinemet-CR4, the same was not observed with metabolites, except with 3-O-MD. The experiments in volunteer subjects confirmed the increase in 3-O-MD in plasma after Sinemet-CR4. Higher levels were observed also in the CSF with a reduction of LD concentrations. This seems to corroborate the hypothesis of an interference with LD passage through the blood-brain barrier in humans.
authors.affiliation: Institute of Neurology, University of Padua, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Benetello
authors.forename: M
authors.initials: M
authors.lastname: Furlanut
authors.forename: G
authors.initials: G
authors.lastname: Zara
authors.forename: M
authors.initials: M
authors.lastname: Baraldo
authors.forename: E
authors.initials: E
authors.lastname: Hassan
mesh_terms: D015102:3,4-Dihydroxyphenylacetic Acid / Q000097:blood; D000368:Aged; D000978:Antiparkinson Agents / Q000008:administration & dosage* / Q000493:pharmacokinetics; D001812:Blood-Brain Barrier / Q000502:physiology; D002230:Carbidopa / Q000008:administration & dosage* / Q000493:pharmacokinetics; D003692:Delayed-Action Preparations; D004298:Dopamine / Q000097:blood; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D005260:Female; D006719:Homovanillic Acid / Q000097:blood; D006801:Humans; D007980:Levodopa / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D008297:Male; D008875:Middle Aged; D009460:Neurologic Examination / Q000187:drug effects; D010300:Parkinson Disease / Q000097:blood / Q000188:drug therapy*; D014443:Tyrosine / Q000031:analogs & derivatives / Q000493:pharmacokinetics
chemical_list: D000978:Antiparkinson Agents; D003692:Delayed-Action Preparations; D004338:Drug Combinations; C009265:carbidopa, levodopa drug combination; D015102:3,4-Dihydroxyphenylacetic Acid; D014443:Tyrosine; D007980:Levodopa; D002230:Carbidopa; C008404:3-methoxytyrosine; D004298:Dopamine; D006719:Homovanillic Acid