Aztec is the tradename for a sustained release formulation of the licensed anti-HIV drug AZT. It has been developed by Verex Laboratories Inc.

Verex have conducted a trial comparing the standard formulation of AZT versus Aztec. The results suggested that Aztec caused fewer side-effects and that the development of AZT-resistant HIV strains may also have been reduced. These effects may be explained by the fact that the sustained release formulation maintains relatively constant blood levels of AZT while the standard formulation results in blood levels that peak soon after a dose is taken, perhaps causing more side-effects, then drop before the next dose is taken, perhaps allowing the development of resistance.

Verex are not allowed to market Aztec themselves because AZT is still under patent to Glaxo Wellcome, and Glaxo Wellcome have declined to take up an option to develop Aztec. They dispute Verexs claims that Aztec is a significant advance over the standard version of AZT.

Key research

Hollister enrolled 190 HIV-positive adults with CD4 counts between 200 and 500 and no AIDS-defining illness in a 24 week study comparing standard AZT (200 mg three times daily) versus Aztec (300 mg twice daily). Effects on immunological and virological markers were similar in both arms. Seven AZT recipients and three Aztec recipients discontinued due to drug-related side-effects. Aztec recipients had significantly less nausea/vomiting, headache and fatigue during the first month. 10/76 (13.2%) of the AZT group developed the 215 mutation associated with resistance to AZT, versus 1/72 (1.4%) of the Aztec group.

References

Hollister AS et al. Sustained-release zidovudine shows equal surrogate marker efficacy, reduced development of resistance, and fewer side-effects in the treatment of HIV infection. Eleventh International Conference on AIDS, Vancouver, abstract We.B.3134, 1996.