Simultaneous Spatial Mapping of Emtricitabine, Tenofovir, and Efavirenz in Mouse Tissue Using MALDI Mass Spectrometry Imaging

Abstract

Emtricitabine (FTC), tenofovir (TFV; prescribed as the tenofovir disoproxil fumarate prodrug) and efavirenz (EFV) inhibit human immunodeficiency virus (HIV) replication and are currently used in combination for HIV treatment. FTC and TFV are nucleotide analog reverse transcriptase inhibitors whereas EFV is a non‐nucleoside analog. Despite the clinical importance of these drugs as commonly used antiretrovirals, their spatial distributions within tissues including those susceptible to HIV infection are poorly understood. Therefore, in this study, we employed a Matrix‐Assisted Laser Desorption/Ionization Mass Spectrometry Imaging (MALDI MSI) method to detect, identify and localize FTC, TFV and EFV in mouse tissues following in vivo dosing. For this study, brain and liver were obtained from mice (n=3) 24 h following oral administration of FTC‐TFV‐EFV. Tissue samples were embedded with OCT medium and 20‐micron tissue sections were utilized for tissue imaging experiments. MALDI matrix α‐cyano‐4‐hydroxycinnamic acid was employed to facilitate the ionization and detection of all three compounds, FTC, TFV and EFV. FTC and EFV were detected as their sodium adducts, [M+Na]+ at m/z 270.0319 ± 5 ppm and 338.0166 ± 5 ppm, respectively; while, TFV yielded its protonated molecular ion, [M+H]+ at m/z 288.0856 ± 5 ppm. When collision‐induced dissociation fragmentation experiments were performed using an FTC‐TFV‐EFV mixture, FTC, TFV and EFV exhibited major fragment ions at m/z 130.0409, 270.0746, and 272.0430 corresponding to C4H5FN3O+, C9H13N5O3P+, and C13H10ClF3N+ structural moieties, respectively. Tissue spatial distribution profiles of FTC, TFV and EFV generated using their corresponding ions (sodium adducts and molecular ions) exhibited differences in their distribution across tissue sections. Interestingly, ion intensity of TFV was greater in liver tissue sections than FTC and EFV. In addition, relative homogeneity in distribution of an endogenous lipid species, PC (16:0/OH) indicated that the distribution patterns observed for above molecules were distinct. In order to correlate the tissue distributions of FTC, TFV, and EFV with their lipophilicities, Log P values were calculated. In conclusion, the above results demonstrate the differential spatial distribution of FTC, TFV and EFV in mouse brain and liver following in vivo dosing. Further, results from this study provide important insights into the disposition of FTC, TFV and EFV.Support or Funding InformationThis work was funded by NIH grants U19AI113127, UM1 AI068613 and R01AI128781This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.