title: Activities of 3'-azido-3'-deoxythymidine nucleotide dimers in primary lymphocytes infected with human immunodeficiency virus type 1.
abstract: The relative antiviral potencies of five nucleotide heterodimers of 3'-azido-3'-deoxythymidine (AZT), 3'-azido-3'-deoxythymidilyl-(5',5')-2'-3'-dideoxy-5'-adenylic acid (AZT-P-ddA), 3'-azido-3'-deoxythymidilyl-(5',5')-2',3'-dideoxy-5'-inosinic acid (AZT-P-ddI), and the corresponding 2-cyanoethyl congeners AZT-P(CyE)-ddA and AZT-P(CyE)-ddI, were determined in primary human peripheral blood mononuclear cells infected with human immunodeficiency virus type 1. The homodimer 3'-azido-3'-deoxythymidilyl-(5',5')-3'-azido-3'-deoxythymidilic acid (AZT-P-AZT) was also included for comparison. The potencies of the compounds were AZT-P-ddA greater than or equal to AZT-P-ddI greater than AZT-P(CyE)-ddA greater than or equal to AZT-P(CyE)-ddI greater than or equal to AZT greater than AZT-P-AZT. Whereas AZT-P-ddA and AZT-P-ddI had in vitro therapeutic indices greater than that of AZT, the homodimer of AZT had a low therapeutic index. AZT-P-ddI exhibited the lowest toxicity in peripheral blood mononuclear, Vero, or CEM cells. Combination studies between AZT and 2',3'-dideoxyinosine (ddI) at nontoxic concentrations indicated a synergistic interaction at a drug ratio of 1:100. At higher ratios (1:500 and 1:1,000), the interactions were synergistic only at concentrations that produced up to 75% virus inhibition. At higher levels of antiviral effects, this combination was antagonistic, as determined by the multiple drug effect analysis method. AZT-P-ddI was about 10-fold less toxic than AZT to human granulocyte-macrophage progenitor cells. However, no significant difference was apparent when the compounds were evaluated against cells of the erythroid lineage. The greater antiviral activity and lower toxicity of this compound could not be attributed to the extracellular decomposition of the dimer in media at physiological temperature and pH. However, in acidic solutions, AZT-P-ddI decomposed in a pH-dependent manner. Advanced preclinical studies with this heterodimer of two clinically effective antiretroviral agents should be considered.
authors.affiliation: Veterans Affairs Medical Center, Decatur, Georgia 30033.
authors.forename: R F
authors.initials: RF
authors.lastname: Schinazi
authors.forename: J P
authors.initials: JP
authors.lastname: Sommadossi
authors.forename: V
authors.initials: V
authors.lastname: Saalmann
authors.forename: D L
authors.initials: DL
authors.lastname: Cannon
authors.forename: M Y
authors.initials: MY
authors.lastname: Xie
authors.forename: G C
authors.initials: GC
authors.lastname: Hart
authors.forename: G A
authors.initials: GA
authors.lastname: Smith
authors.forename: E F
authors.initials: EF
authors.lastname: Hahn
mesh_terms: D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D003114:Colony-Forming Units Assay; D004355:Drug Stability; D015672:Erythroid Precursor Cells / Q000187:drug effects; D006098:Granulocytes / Q000187:drug effects; D015658:HIV Infections / Q000188:drug therapy*; D015497:HIV-1; D006801:Humans; D008264:Macrophages / Q000187:drug effects; D011740:Pyrimidine Dimers / Q000627:therapeutic use*; D013601:T-Lymphocytes / Q000187:drug effects*; D015215:Zidovudine / Q000031:analogs & derivatives* / Q000627:therapeutic use
chemical_list: D011740:Pyrimidine Dimers; D015215:Zidovudine