title: Quantitative determination of pravastatin and R-416, its main metabolite in human plasma, by liquid chromatography-tandem mass spectrometry.
abstract: A quantitative method was developed and validated for rapid and sensitive analysis of pravastatin and R-416, the main metabolite of pravastatin, in human plasma. The analytes were extracted from plasma samples by a solid phase extraction method using a Bond Elut C(8). The method involved the use of liquid chromatography coupled with atmospheric pressure chemical ionization (APCI) and selected reaction monitoring (SRM) mass spectrometry. A pravastatin analog, R-122798, was used as the internal standard (I.S.). Separation of pravastatin, R-416 and the I.S. was accomplished using a reverse-phase column (C(18)). The components eluted were ionized by the APCI source (negative ion) and subsequently detected by a highly selective triple quadrupole mass spectrometer in the SRM mode. Linear standard curves were obtained from 0.1 ng/mL (lower limit of quantification, LLOQ) to 100 ng/mL. The intra-assay precisions (coefficient of variation) for the samples at the LLOQ were 1.8% for pravastatin and 1.6% for R-416. The intra-assay accuracy values were 95.8-107.6% for pravastatin, and 92.6-109.0% for R-416, respectively. Precision and accuracy of quality control (QC) samples were determined at concentrations of 0.5, 10 and 80 ng/mL for all analytes. The intra- and inter-assay precision calculated from QC samples were within 10% for pravastatin and within 11% for R-416. The overall recoveries for pravastatin and R-416 were 75.7-82.1% and 68.6-74.3%, respectively. Pravastatin and R-416 were stable in human plasma for 3 weeks at -20 degrees C in a freezer, up to 6h at room temperature, and up to 48 h at 6 degrees C. This assay method was successfully used to evaluate the pravastatin and R-416 levels in healthy volunteers following oral administration of Mevalotin.
authors.affiliation: Drug Metabolism and Pharmacokinetics Research Laboratories, Sankyo Co., Ltd., 1-2-58, Hiromachi, Shinagawa-ku, Tokyo 140-8710, Japan. kawaba@shina.sankyo.co.jp
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Kawabata
authors.forename: Naozumi
authors.initials: N
authors.lastname: Samata
authors.forename: Yoko
authors.initials: Y
authors.lastname: Urasaki
mesh_terms: D002853:Chromatography, Liquid / Q000379:methods; D006538:Heptanoic Acids / Q000097:blood*; D006801:Humans; D008297:Male; D013058:Mass Spectrometry / Q000379:methods; D009281:Naphthalenes / Q000097:blood*; D017035:Pravastatin / Q000097:blood* / Q000493:pharmacokinetics / Q000031:analogs & derivatives; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D006538:Heptanoic Acids; D009281:Naphthalenes; C500699:R-416 (pravastatin metabolite); D017035:Pravastatin