title: Effect of Ethanol on the Metabolic Characteristics of HIV-1 Integrase Inhibitor Elvitegravir and Elvitegravir/Cobicistat with CYP3A: An Analysis Using a Newly Developed LC-MS/MS Method.
abstract: Elvitegravir (EVG), an integrase inhibitor for the treatment HIV infection, is increasingly becoming the part of first-line antiretroviral therapy (ART) regimen. EVG is mainly metabolized through cytochrome P450 (CYP) 3A4. Previously, we have shown that ethanol alters ART-CYP3A4 interactions with protease inhibitors thereby altering their metabolisms. However, as EVG is a fairly new class of drug, its kinetic characteristics and the effect of ethanol on EVG-CYPP3A4 interaction is poorly understood. In this study, we characterized EVG and cobicistat (COBI)-boosted EVG metabolism in human microsomes followed by ethanol-EVG, ethanol-COBI-EVG interaction with CYP3A. First, we developed and validated a simple, sensitive, and robust liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantification of EVG in the human liver microsomes. The lower limit of quantification for the drug was at 0.003 μM (1.34 ng/ml). Extraction yield, matrix effects, drug stability, and calibration curves for the proposed method were validated according to the FDA guidelines. Time dependent kinetics data showed that 20mM ethanol decreases the apparent half-life of EVG degradation by ~50% compared to EVG alone. Our substrate kinetic results revealed that ethanol mildly decreases the catalytic efficiency for EVG metabolism. Inhibition studies demonstrated that EVG inhibits CYP3A4, and 20 mM ethanol causes a decrease in the IC50 of EVG. However, in the presence of COBI we were unable to determine these parameters effectively because COBI, being a strong inhibitor of CYP3A4, blocked the EVG/ethanol-CYP3A4 interactions. Docking studies predicted a shift of EVG or COBI binding to the active site of CYP3A4 in the presence of ethanol. Taken together, these results suggest that ethanol interacts with microsomal CYP3A and alters EVG-CYP3A4 interaction thereby altering EVG metabolism and inhibition of CYP3A4 by EVG. This finding has clinical significance because alcohol use is highly prevalent in HIV population, and there are no separate guidelines for these patients while they are on ART medication.
authors.affiliation: Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America.
authors.forename: Narasimha M
authors.initials: NM
authors.lastname: Midde
authors.affiliation: Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America.
authors.forename: Mohammad A
authors.initials: MA
authors.lastname: Rahman
authors.affiliation: Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America.
authors.forename: Chetan
authors.initials: C
authors.lastname: Rathi
authors.affiliation: Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, Shanghai, China.
authors.forename: Junhao
authors.initials: J
authors.lastname: Li
authors.affiliation: Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America.
authors.forename: Bernd
authors.initials: B
authors.lastname: Meibohm
authors.affiliation: Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, Shanghai, China.
authors.forename: Weihua
authors.initials: W
authors.lastname: Li
authors.affiliation: Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America.
authors.forename: Santosh
authors.initials: S
authors.lastname: Kumar
mesh_terms: D002138:Calibration; D002853:Chromatography, Liquid; D000069547:Cobicistat / Q000378:metabolism*; D051544:Cytochrome P-450 CYP3A / Q000378:metabolism*; D000431:Ethanol / Q000494:pharmacology*; D005615:Freezing; D019427:HIV Integrase / Q000378:metabolism*; D006801:Humans; D019429:Integrase Inhibitors / Q000378:metabolism*; D007700:Kinetics; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism; D062105:Molecular Docking Simulation; D015363:Quinolones / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012015:Reference Standards; D015203:Reproducibility of Results; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry; D013997:Time Factors
chemical_list: D019429:Integrase Inhibitors; D015363:Quinolones; D011994:Recombinant Proteins; D000431:Ethanol; C509700:elvitegravir; D051544:Cytochrome P-450 CYP3A; D019427:HIV Integrase; D000069547:Cobicistat; C514801:p31 integrase protein, Human immunodeficiency virus 1