title: Simultaneous quantitation of levodopa and 3-O-methyldopa in human plasma by HPLC-ESI-MS/MS: application for a pharmacokinetic study with a levodopa/benserazide formulation.
abstract: A sensitive and simple method was developed for the quantitation of levodopa and its metabolite 3-O-methyldopa, in human plasma, after oral administration of tablet formulations containing levodopa (200 mg) and benserazide (50 mg). The analytes were extracted by a protein precipitation procedure, using carbidopa as an internal standard. A mobile phase consisting of 0.2% formic acid and acetonitrile (94:6, v/v) was used and chromatographic separation was achieved using ACE C(18) column (50 mm×4.6 mm i.d.; 5 μm particle size). Selected reaction monitoring was performed using the fragmentation transitions m/z 198→m/z 107, m/z 212→m/z 166 and m/z 227→m/z 181 for levodopa, 3-O-methyldopa and carbidopa, respectively. Calibration curves were constructed over the range 50.0-6000.0 ng/mL for levodopa and 25.0-4000.0 ng/mL for 3-O-methyldopa. The method shown to be specific, precise, accurate and provided recovery rates higher than 85% for all analytes. No matrix effect was detected in the samples. The validated method was applied in a pharmacokinetic study with a levodopa/benserazide tablet formulation in healthy volunteers.
authors.affiliation: Instituto de Ciências Farmacêuticas, Alameda Coronel Eugênio Jardim 53, 74175-100 Goiânia, GO, Brazil. isaccesar@bol.com.br
authors.forename: Isabela da Costa
authors.initials: Ida C
authors.lastname: César
authors.forename: Ricardo Martins Duarte
authors.initials: RM
authors.lastname: Byrro
authors.forename: Fabiana Fernandes de Santana e Silva
authors.initials: FF
authors.lastname: Cardoso
authors.forename: Iram Moreira
authors.initials: IM
authors.lastname: Mundim
authors.forename: Leonardo de Souza
authors.initials: Lde S
authors.lastname: Teixeira
authors.forename: Enikson Pontes
authors.initials: EP
authors.lastname: da Silva
authors.forename: Sandro Antônio
authors.initials: SA
authors.lastname: Gomes
authors.forename: Ricardo Rodrigues
authors.initials: RR
authors.lastname: Bonfim
authors.forename: Gerson Antônio
authors.initials: GA
authors.lastname: Pianetti
mesh_terms: D001545:Benserazide / Q000097:blood* / Q000493:pharmacokinetics; D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D007980:Levodopa / Q000097:blood* / Q000493:pharmacokinetics; D008750:Methyldopa / Q000097:blood* / Q000493:pharmacokinetics; D011786:Quality Control; D015203:Reproducibility of Results; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013607:Tablets; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D013607:Tablets; D007980:Levodopa; D008750:Methyldopa; D001545:Benserazide