Abstract
Efavirenz (EFV), an antiretroviral that interacts clinically with co-administered drugs via activation of the pregnane X receptor (PXR), is extensively metabolized by the cytochromes P450. We tested whether its primary metabolite, 8-hydroxyEFV (8-OHEFV) can activate PXR and potentially contribute to PXR-mediated drug–drug interactions attributed to EFV. Luciferase reporter assays revealed that despite only differing from EFV by an oxygen atom, 8-OHEFV does not activate PXR. Corroborating this, treatment with EFV for 72 h elevated the mRNA abundance of the PXR target gene, Cyp3a11, by approximately 28-fold in primary hepatocytes isolated from PXR-humanized mice, whereas treatment with 8-OHEFV did not result in a change in Cyp3A11 mRNA levels. FRET-based competitive binding assays and isothermal calorimetry demonstrated that even with the lack of ability to activate PXR, 8-OHEFV displays an affinity for PXR (IC 50 12.1 μm; K D 7.9 μm) nearly identical to that of EFV (IC 50 18.7 μm; K D 12.5 μm). The use of 16 EFV analogues suggest that other discreet changes to the EFV structure beyond the 8-position are well tolerated. Molecular docking simulations implicate an 8-OHEFV binding mode that may underlie its divergence in PXR activation from EFV.
Original language | English (US) |
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Pages (from-to) | 736-747 |
Number of pages | 12 |
Journal | ChemMedChem |
Volume | 13 |
Issue number | 7 |
DOIs | |
State | Published - Apr 6 2018 |
Keywords
- cytochrome P450
- drug metabolism
- ligand binding
- molecular docking
- nuclear receptors
ASJC Scopus subject areas
- Biochemistry
- Molecular Medicine
- Pharmacology
- Drug Discovery
- Pharmacology, Toxicology and Pharmaceutics(all)
- Organic Chemistry