Simultaneous determination of the antiretroviral agents: amprenavir, lopinavir, ritonavir, saquinavir and efavirenz in human peripheral blood mononuclear cells by high-performance liquid chromatography-mass spectrometry

A selective and accurate assay for the simultaneous quantitation of four protease inhibitors (PIs) (amprenavir (APV), lopinavir (LPV), ritonavir (RTV) and saquinavir (SQV)) and a non-nucleoside reverse transcriptase inhibitor (NNRTI) (efavirenz, EFV) in human peripheral blood mononuclear cells using high-performance liquid chromatography-mass chromatography (LC/MS) has been developed and validated. After liquid-liquid extraction, the antiretroviral agents were separated within 15 min. The calibration curves of each drug showed a good linearity in a range of concentration between 2 and 200 ng/3 x 10(6) cells for amprenavir, lopinavir, efavirenz, 1.60 and 128 ng/3 x 10(6) cells for ritonavir and saquinavir. Mean intra- and inter-assay coefficients of variation over the ranges of the standard curves were less than 15% and mean extraction recoveries ranged 88.7-112.1%. The limits of quantification were 2ng/3 x 10(6) cells for amprenavir, lopinavir, efavirenz, 1 ng/3 x 10(6) cells for ritonavir and 1.6 ng/3 x 10(6) cells for saquinavir. This novel LC/MS assay, which provides an excellent method for simultaneous intra-cellular determination of amprenavir, lopinavir, ritonavir, saquinavir and efavirenz in human peripheral blood monormclear cells, could be successfully applied for therapeutic drug monitoring and pharmacokinetic studies. (C) 2004 Elsevier B.V. All rights reserved.