title: Simultaneous determination of levodopa, carbidopa, entacapone, tolcapone, 3-O-methyldopa and dopamine in human plasma by an HPLC-MS/MS method.
abstract: BACKGROUND
  In this study, we developed and validated a HPLC-MS/MS method capable of simultaneously determining levodopa, carbidopa, entacapone, tolcapone, 3-O-methyldopa and dopamine in human plasma. RESULTS & METHODOLOGY: Chromatographic separation was achieved using a C8 column with a mobile phase consisting of a gradient of water and acetonitrile:methanol (90:10 v/v), both containing 0.1% formic acid. The developed method was selective, sensitive (LD<7.0 ng ml(-1)), linear (r>0.99), precise (RSD<11.3%), accurate (RE<11.8%) and free of residual and matrix effects. The developed method was successfully applied in plasma patients with Parkinson's disease using Stalevo®.
  
  
  CONCLUSIONS
  The new method can be used for the clinical monitoring of these substances and applied to adjustments in drug dosages.
authors.affiliation: Universidade Federal do Paraná, Department of Pharmacy, 632 Lothário Meissner Avenue, 80210-170, Curitiba - PR, Brazil.
authors.forename: Rômulo Pereira
authors.initials: RP
authors.lastname: Ribeiro
authors.forename: João Cleverson
authors.initials: JC
authors.lastname: Gasparetto
authors.forename: Raquel
authors.initials: R
authors.lastname: de Oliveira Vilhena
authors.forename: Thais Martins
authors.initials: TM
authors.lastname: Guimarães de Francisco
authors.forename: Thais Martins Guimarães
authors.initials: TM
authors.lastname: de Francisco
authors.forename: Cleverson Antônio Ferreira
authors.initials: CA
authors.lastname: Martins
authors.forename: Marco André
authors.initials: MA
authors.lastname: Cardoso
authors.forename: Roberto
authors.initials: R
authors.lastname: Pontarolo
authors.forename: Katherine Athayde Teixeira
authors.initials: KA
authors.lastname: de Carvalho
mesh_terms: D001577:Benzophenones / Q000097:blood* / Q000592:standards; D001774:Blood Chemical Analysis / Q000379:methods*; D002230:Carbidopa / Q000097:blood* / Q000592:standards; D002396:Catechols / Q000097:blood* / Q000592:standards; D002851:Chromatography, High Pressure Liquid / Q000592:standards; D004295:Dihydroxyphenylalanine / Q000031:analogs & derivatives* / Q000097:blood / Q000592:standards; D004298:Dopamine / Q000097:blood* / Q000592:standards; D006801:Humans; D007980:Levodopa / Q000097:blood* / Q000592:standards; D009570:Nitriles / Q000097:blood* / Q000592:standards; D009596:Nitrophenols / Q000097:blood* / Q000592:standards; D011786:Quality Control; D015203:Reproducibility of Results; D053719:Tandem Mass Spectrometry / Q000592:standards; D000077867:Tolcapone; D014443:Tyrosine / Q000031:analogs & derivatives
chemical_list: D001577:Benzophenones; D002396:Catechols; D009570:Nitriles; D009596:Nitrophenols; D014443:Tyrosine; D007980:Levodopa; C071192:entacapone; D004295:Dihydroxyphenylalanine; D000077867:Tolcapone; D002230:Carbidopa; C008404:3-methoxytyrosine; D004298:Dopamine