ABSTRACT
Objective To establish a rapid LC- MS/MS method for the simultaneous quantitative determination of lopinavir (LPV) and ritonavir (RTV) in human plasma. Methods Plasma samples were prepared by protein precipitation and separated by a Thermo Hypersil GOLD column (2.1 mm×100 mm, 5 mm) with the mobile phase consisting of methanol and water (0.1% formic acid) at a flow rate of 0.2 ml/min. Detection of LPV, RTV and the internal standard (IS) MS 275 was performed using selected reaction moni-toring (SRM) of the transitions m/z 629.3→155.0, m/z 721.3→268.0 and m/z 377.1→359.2 in positive ion mode, respectively. Re-sults The calibration curve was linear in the range of 20-1000 ng/ml (r0.994) for LPV and RTV. The intra and inter-day precision and accuracy values met the set acceptance criteria. Conclusion The method is rapid, sensitive and accurate for the therapeutic drug monitoring of LPV and RTV simultaneously in clinic and pharmacokinetic studies.