The Simultaneous Assay of Tenofovir and Emtricitabine in Plasma Using LC/MS/MS and Isotopically Labeled Internal Standards

摘要: Abstract An LC/MS/MS assay we published for tenofovir (TFV) plasma levels is a useful tool monitoring the pharmacotherapy of HIV-positive individuals [T. Delahunty, L. Bushman, C.V. Fletcher, J. Chromatogr. B 830 (2006) 6–12]. A new combination therapy consisting TFV pro-drug (300 mg) and another reverse transcriptase inhibitor, emtricitabine (FTC, 200 mg) has become available in convenient once-daily dosage form (Truvada). This widely used medication prompted us to develop validate determine simultaneously FTC concentrations. In view their chemical similarity analytes, stable isotope internal standards (IS) were chosen. These consisted labeled uniformly with 13 C adenine moiety (Iso-TFV) 15 N cytosine (Iso-FTC). Trifluoroacetic acid was added patient's EDTA (containing IS) produce de-proteinated extract after high speed centrifugation. The extracts directly injected into mobile phase (3% acetonitrile/1% acetic acid, aq.) stream flowing at 200 μL/min. Synergi Polar-RP, 2.0 mm × 150 mm, reversed-phase analytical column achieve chromatographic separation. Detection analytes achieved by ESI positive ionization tandem mass spectrometry. precursor/product transitions ( m / z ) ion mode 288/176 293/181 ions Iso-TFV, respectively 248/130 251/133 Iso-FTC, respectively. When analyte/IS abundance ratios plotted against specified concentrations, linearity concentration curves range 10 ng/mL 1500 ng/mL both (250 μL extracted), minimum quantifiable limit analytes. inter- intra-day accuracy precision within ± 20% LLOQ and ± 15% other QC levels. We have expanded method originally designed alone incorporate simultaneous determination latter using IS. been successfully periodic 678 patients being treated therapy.