Quantification of darunavir and etravirine in human peripheral blood mononuclear cells using high performance liquid chromatography tandem mass spectrometry (LC-MS/MS), clinical application in a cohort of 110 HIV-1 infected patients and evidence of a potential drug-drug interaction

Objectives: To describe the validation of a sensitive high performance liquid chromatography tandem mass spectrometry (LC-MS/MS) method allowing the simultaneous quantification of darunavir (DRV) and etravirine (ETR) in peripheral blood mononuclear cells (PBMCs) and its application in a cohort of HIV-1 infected patients. Methods: Blood samples were obtained from 110 patients. PMBCs were isolated using density gradient centrifugation. Drug extraction from PBMCs was performed with a 60:40 methanol-water (MeOH-H2O) solution containing deuterated IS (DRV-d9 and ETR-d8). The chromatographic separation was performed on a RP18 XBridge (TM) column. Results: The geometric mean (GM) of cell associated concentration ([DRV](CC)) and plasmatic concentration ([DRV](plasma)) were 360.5 ng/mL (CI95%: 294.5-441.2) and 1733 ng/mL (CI95%: 1486-2021), respectively. A geometric mean intracellular (IC)/plasma ratio (GMR) of 0.21 (CI95%: 0.18-0.24) was calculated. Adjusted for dose/body surface area and post-intake time, a statistically significant correlation was observed between [DRV](Plasma) and the eGFR (p = 0.002) and between [DRV](Plasma) and the concomitant use of ETR (p = 0.038). For the 10 patients receiving ETR in addition to DRV, the GMof [ETR](Plasma) (available for 8 out of 10 patients) and [ETR] CC were 492.3 ng/mL and 2951 ng/mL respectively. The GMR of ETR was 7.6 (CI95%: 3.61-13.83). Conclusions: A handy and sensitive high performance LC-MS/MS method allowing the simultaneous quantification of DRV and ETR in PBMCs has been described and successfully applied in the largest cohort of DRV-treated patients reported to date. ETR accumulates more efficiently in PBMCs compared to DRV. We have also highlighted a possible impact of ETR on DRV plasma concentrations requiring further investigations. (C) 2016 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.