Intracellular concentrations of non-nucleoside reverse transcriptase inhibitors and its potential role on apoptosis in peripheral blood mononuclear cells

Abstract

Background: Efavirenz (EFV) and nevirapine (NVP) are non-nucleoside reverse transcriptase inhibitors (NNRTIs) that are frequently used in combination with other antiretrovirals for the treatment of HIV-infected persons. Little information is available regarding the intracellular concentrations (ICs) of EFV and NVP in peripheral blood mononuclear cells (PBMCs) and its potential role for cellular toxicity. Methods: PBMCs from healthy adult donors were treated with or without the mean peak steady-state levels (Cmax) of EFV (12.4μM) and NVP (17.0μM) in human plasma during antiretroviral therapy multiplied by 0.5,1.0, 2.0 and 4.0. After 48 hr treatment, ICs of EFV and NVP were measured using liquid chromatoagraphy-ion trap/mass spectrometry. The degree of apoptotic cells and mitochondrial membrane potential in PBMCs were measured by flow cytometry. Results: The mean log ICs of ×1.0 Cmax NVP in PBMCs (2.00 ± 0.23 μM) were significantly lower than the one of ×1.0 Cmax EFV (2.95 ± 0.22 μM) (P < 0.01). Similar significant differences of mean log ICs were observed when the concentration of NNRTIs were ×0.5 Cmax (1.62 ± 0.26 μM vs. 2.87 ±0.13 μM, p < 0.01) and ×2.0 Cmax (1.99 ± 0.39 μM vs. 3.11 ± 0.21 μM, P < 0.01). Furthermore, apoptotic PBMCs were lower than PBMC treated with the concentrations of NVP above the plasma Cmax observed clinically in patients as compared to those treated with comparable concentrations of EFV (P < 0.01). Conclusion: These in vitro data suggest that ICs of NVP in PBMCs are significantly lower than ICs of EFV in PBMC and are also associated with less apoptotic PBMCs. The clinical relevance of this observation remains to be elucidated. © 2011 Saitoh A, et al.