title: Simplified micromethod for the HPLC measurement of diclofenac in plasma.
abstract: A simple and sensitive micromethod based on HPLC is described for the measurement of diclofenac in 200 microliters plasma. A single extraction with dichloromethane in acidic medium was an essential clean-up step. Diclofenac and its internal standard (cyclohexendiphenyl propionic acid) was eluted at 3.3 and 6.5 min from a 4-micron C18 reverse-phase column using a mobile phase consisting of 0.75 M sodium acetate buffer, pH 5.0, and acetonitrile (55:45, v/v) at a flow rate of 0.9 ml/min with detection at 282 nm. The method, validated on the basis of parameters evaluated for the confidence limits of diclofenac measurements in spiked plasma, presented 1 ng/ml sensitivity, 10-10,000 ng/ml linearity, and 3.5% and 5.7% intra- and interassay precision, respectively. Peak plasma diclofenac levels ranging from 177 to 841 ng/ml and from 276 to 1008 ng/ml were obtained for two slow-release formulations. A wide range (1 ng/ml-3 micrograms/ml) was observed for plasma diclofenac levels of volunteers during a 24-h study period.
authors.affiliation: Centro Avançado de Estudos em Farmacologia Clínica, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, Brasil.
authors.forename: S R
authors.initials: SR
authors.lastname: Santos
authors.forename: H
authors.initials: H
authors.lastname: Donzella
authors.forename: M A
authors.initials: MA
authors.lastname: Bertoline
authors.forename: M D
authors.initials: MD
authors.lastname: Pereira
authors.forename: C E
authors.initials: CE
authors.lastname: Omosako
authors.forename: V
authors.initials: V
authors.lastname: Porta
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004008:Diclofenac / Q000097:blood*; D006801:Humans; D012680:Sensitivity and Specificity; D013997:Time Factors
chemical_list: D004008:Diclofenac