title: In vitro transport characteristics of EFdA, a novel nucleoside reverse transcriptase inhibitor using Caco-2 and MDCKII cell monolayers.
abstract: 4'-Ethynyl-2-fluoro-2'-deoxyadenosine (EFdA) is a novel nucleoside reverse transcriptase inhibitor with a unique mechanism of action and highly potent activity against both wild-type and clinically relevant drug resistant HIV-1 variants. Furthermore, in vivo efficacy and safety evaluations have shown EFdA to be a promising therapeutic candidate for use in the treatment of HIV infection. However, little is known about the pharmacokinetic and biopharmaceutical properties of EFdA. In this study, we evaluated cellular EFdA transport using Caco-2 and Madin-Darby Canine Kidney II (MDCKII) in vitro cell models. Studies using Caco-2 cell monolayers showed that EFdA efflux ratios were >2.0, suggesting that active drug transport mechanisms may play a role in EFdA flux. ABCB1 transporter (PGP1) inhibition was assessed using the acetomethoxy derivate of calcein (calcein-AM) as a fluorescent probe in both wild-type MDCKII and PGP1 overexpressing MDCKII cells. Nonetheless, our data showed that EFdA is not a substrate of PGP1. Additionally, comparative bidirectional flux of EFdA and Lucifer yellow (LY, a well-known paracellular marker) was studied over a range of EFdA concentrations. In MDCKII monolayers, EFdA had an apparent permeability coefficient (Papp) (a-b) of <1×10(-6)cm/s. The Papp values significantly increased in the presence of the paracellular permeability enhancer, indicating that EFdA primarily permeates via the paracellular route.
authors.affiliation: Magee-Womens Research Institute, University of Pittsburgh, Pittsburgh, PA 15213, USA; Department of Pharmaceutical Sciences, School of Pharmacy, University of Pittsburgh, Pittsburgh, PA 15213, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Department of Microbiology and Molecular Genetics, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Parniak
authors.affiliation: Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, MO 65211, USA.
authors.forename: Stefan G
authors.initials: SG
authors.lastname: Sarafianos
authors.affiliation: Department of Pharmacy and Therapeutics, School of Pharmacy, University of Pittsburgh, Pittsburgh, PA 15213, USA.
authors.forename: Philip E
authors.initials: PE
authors.lastname: Empey
authors.affiliation: Magee-Womens Research Institute, University of Pittsburgh, Pittsburgh, PA 15213, USA; Department of Pharmaceutical Sciences, School of Pharmacy, University of Pittsburgh, Pittsburgh, PA 15213, USA. Electronic address: rohanlc@upmc.edu.
authors.forename: Lisa C
authors.initials: LC
authors.lastname: Rohan
mesh_terms: D000818:Animals; D018938:Caco-2 Cells; D002460:Cell Line; D002463:Cell Membrane Permeability / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003839:Deoxyadenosines / Q000493:pharmacokinetics*; D004285:Dogs; D005456:Fluorescent Dyes; D006801:Humans; D007546:Isoquinolines; D061985:Madin Darby Canine Kidney Cells; D018894:Reverse Transcriptase Inhibitors / Q000493:pharmacokinetics*
chemical_list: D003839:Deoxyadenosines; D005456:Fluorescent Dyes; D007546:Isoquinolines; D018894:Reverse Transcriptase Inhibitors; C017475:lucifer yellow; C558823:islatravir
keywords: Bidirectional flux; Caco-2; EFdA; MDCKII; PGP1