Mx. Qian et al., COMPARISON OF RATES OF INTRACELLULAR METABOLISM OF ZIDOVUDINE IN HUMAN AND PRIMATE PERIPHERAL-BLOOD MONONUCLEAR-CELLS, Antimicrobial agents and chemotherapy, 38(10), 1994, pp. 2398-2403
3'-Azido-3'-deoxythymidine (AZT) is a drug of choice for the treatment
of AIDS. On the basis of pharmacokinetic data, the nonhuman primate M
acaca nemestrina has been shown to be a suitable animal model for use
in the study of the disposition of AZT. However, since AZT is activate
d to its metabolite, the AZT triphosphate (AZTTP), intracellularly, we
investigated the intracellular activation of AZT in peripheral blood
mononuclear cells (PBMCs) of healthy and simian immunodeficiency virus
-infected macaques and compared it with that in PBMCs obtained from hu
man volunteers. At 5 mu M extracellular AZT, both human and macaque PB
MCs rapidly convert AZT to AZT monophosphate (AZTMP) (84% of total pho
sphorylated products) in 4 h. Increases in AZTMP levels of 7.7- and 12
-fold were observed in human and macaque PBMCs, respectively, when the
extracellular AZT concentration increased from 0.45 to 14.4 mu M. Sim
ilar ratios of AZT metabolites, AZT diphosphate (AZTDP)/AZTTP (0.7 to
1.4), AZTMP/AZTDP (3 to 14), and AZTMP/AZTTP (3 to 19), over the same
AZT concentration range were observed in both human and macaque PBMCs,
suggesting that these cells have similar capacities to phosphorylate
AZT. Simian immunodeficiency virus-infected macaque PBMCs showed a fiv
efold increase in intracellular AZT and AZTMP levels and a twofold inc
rease in AZTDP and AZTTP levels (picomoles per 107 cells) when compare
d with those in the uninfected cells (at 4 h with 0.9 mu M extracellul
ar concentration). This increase in AZT metabolite levels has also bee
n reported for human immunodeficiency virus-infected PBMCs. Collective
ly, given the similarities in phosphorylation profiles between healthy
and infected human and macaque PBMCs, we conclude that the macaque is
a suitable animal model for use in the study of factors that can affe
ct the in vivo phosphorylation of AZT.