title: Microdialysis-HPLC for plasma levodopa and metabolites monitoring in parkinsonian patients.
abstract: We used in vitro microdialysis-HPLC to determine L-3,4-dihydroxyphenylalanine (L-DOPA) and its metabolites in plasma of patients with advanced Parkinson disease. Blood samples and clinical evaluations were obtained 0, 30, 60, 90, 120, and 150 min after oral administration of carbidopa/L-DOPA (25/100 mg, 12.5/125 mg, and 50/200 mg). In vitro recoveries for L-DOPA and metabolites ranged from 22% to 36%. Linear correlation was found between metabolite concentrations in the dialysate and in the surrounding medium. There was a significant positive correlation between L-DOPA dose and plasma concentration of L-DOPA and homovanillic acid (P < 0.04). Clinical response was maximum 60 min after L-DOPA administration. Threshold L-DOPA plasma concentration averaged 7.74 +/- 3.3 mumol/L. Motor effect is longer with the highest L-DOPA peak concentration (P < 0.01). Microdialysis-HPLC is readily applicable, reproducible, and allows monitoring of plasma L-DOPA and metabolites in parkinsonian patients.
authors.affiliation: Service de Neurologie, ULB-Hôpital Erasme, Brussels, Belgium. sdethy@ulb.ac.be
authors.forename: S
authors.initials: S
authors.lastname: Dethy
authors.forename: M A
authors.initials: MA
authors.lastname: Laute
authors.forename: N
authors.initials: N
authors.lastname: Van Blercom
authors.forename: P
authors.initials: P
authors.lastname: Damhaut
authors.forename: S
authors.initials: S
authors.lastname: Goldman
authors.forename: J
authors.initials: J
authors.lastname: Hildebrand
mesh_terms: D000368:Aged; D002230:Carbidopa / Q000008:administration & dosage; D002851:Chromatography, High Pressure Liquid; D006719:Homovanillic Acid / Q000097:blood; D006801:Humans; D007700:Kinetics; D007980:Levodopa / Q000008:administration & dosage / Q000097:blood*; D017551:Microdialysis; D008875:Middle Aged; D010300:Parkinson Disease / Q000097:blood*
chemical_list: D007980:Levodopa; D002230:Carbidopa; D006719:Homovanillic Acid