title: Preformulation studies of EFdA, a novel nucleoside reverse transcriptase inhibitor for HIV prevention.
abstract: 4'-Ethynyl-2-fluoro-2'-deoxyadenosine (EFdA) is a novel nucleoside analog of great interest because of its superior activity against wild-type and multidrug-resistant HIV-1 strains, and favorable safety profiles in vitro and in vivo. The aim of this work was to provide preformulation information of EFdA important for delivery system development. A simple, accurate and specific reverse-phase high performance liquid chromatographic (RP-HPLC) method with UV detection was developed for quantification of EFdA. In addition, physicochemical characterizations including pH solubility profile, octanol/water partition coefficient (Log Po/w), DSC analysis, field emission scanning electron microscopy, and stability studies under various conditions were conducted. EFdA existed in planar or flake shape, with a melting point of ∼130 °C, and had a pH dependent solubility. The log Po/w value of EFdA was -1.19. The compound was stable upon exposure to pH levels from 3 to 9 and showed good stability at elevated temperature (65 °C). In vitro cytotoxicity assessments were performed in two different epithelial cell lines. In cell-based studies, the EFdA selectivity index (50% cytotoxic concentration [CC50] values/50% effective concentration [EC50]) was found to be greater than 1 × 10(3). Permeability studies using cell- and tissue-based models showed that EFdA had an apparent permeability coefficient (Papp) <1 × 10(-6)cm/s and that the paracelluar pathway was the dominant transport route for EFdA. Overall, EFdA possesses favorable characteristics for further formulation development.
authors.affiliation: Magee Womens Research Institute, University of Pittsburgh , Pittsburgh, PA , USA .
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Michael A
authors.initials: MA
authors.lastname: Parniak
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Mitsuya
authors.forename: Stefan G
authors.initials: SG
authors.lastname: Sarafianos
authors.forename: Phillip W
authors.initials: PW
authors.lastname: Graebing
authors.forename: Lisa C
authors.initials: LC
authors.lastname: Rohan
mesh_terms: D019380:Anti-HIV Agents / Q000737:chemistry* / Q000494:pharmacology*; D018938:Caco-2 Cells; D045744:Cell Line, Tumor; D002626:Chemistry, Pharmaceutical / Q000379:methods; D003839:Deoxyadenosines / Q000737:chemistry* / Q000494:pharmacology*; D016503:Drug Delivery Systems / Q000379:methods; D004847:Epithelial Cells / Q000187:drug effects; D015497:HIV-1 / Q000187:drug effects*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D010539:Permeability; D018894:Reverse Transcriptase Inhibitors / Q000737:chemistry* / Q000494:pharmacology*; D012995:Solubility; D044366:Transition Temperature
chemical_list: D019380:Anti-HIV Agents; D003839:Deoxyadenosines; D018894:Reverse Transcriptase Inhibitors; C558823:islatravir
keywords: Caco-2 cells; EFdA; permeability; preformulation; solubility; transport