title: Alternative method for determination of pyrimethamine in plasma by high-performance liquid chromatography.
abstract: A rapid, selective, sensitive and reproducible reversed-phase high-performance liquid chromatography (HPLC) procedure for the quantitative determination of pyrimethamine (PYR) in plasma is described. The procedure involved the two-step extraction of PYR and the internal standard, quinine (QN) with acetonitrile and dichloromethane at basic pH. Chromatographic separation consisted of the mobile phase (methanol-water containing 0.005 M octanesulfonic acid, 50:50, v/v) running through the column (Techopak-10 C18) at a flow-rate of 1.6 ml/min. Detection was at UV wavelength of 240 nm. The mean recoveries of PYR and QN at a concentration range of 50 and 500 ng/ml were 98.9 and 89%, and 94.7 and 96% for PYR and QN. The within-day coefficients of variation were 2.1-5.1% for PYR and 5.9% for QN. The day-to-day coefficients of variation were 2.1-4.1% for PYR and 5% for QN. The minimum detectable concentrations for PYR and QN in plasma were 3 and 10 ng/ml. The method was found to be suitable for use in clinical pharmacokinetic study.
authors.affiliation: Clinical Pharmacology Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
authors.forename: K
authors.initials: K
authors.lastname: Na-Bangchang
authors.forename: P
authors.initials: P
authors.lastname: Tan-ariya
authors.forename: R
authors.initials: R
authors.lastname: Ubalee
authors.forename: B
authors.initials: B
authors.lastname: Kamanikom
authors.forename: J
authors.initials: J
authors.lastname: Karbwang
mesh_terms: D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D015394:Molecular Structure; D011739:Pyrimethamine / Q000097:blood*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D011739:Pyrimethamine