New England Journal of Medicine (06/18/92) Vol. 326, No. 25, P. 1701
The more toxic side effects and decreased anti-HIV activity of the
combination of ganciclovir and zidovudine (AZT) to treat cytomegalovirus
(CMV) retinitis could explain the poorer performance of the combination
as compared with foscarnet in the study published in the Jan. 23 issue of
the New England Journal of Medicine, writes Susan W. Cox and Britta
Wahren of the National Bacteriological Laboratory in Stockholm, Sweden.
Foscarnet has not only been shown to act synergistically with AZT against
the HIV, but also the combination of foscarnet and AZT have reduced
toxicity as compared with either drug alone. But ganciclovir has
demonstrated increased toxicity synergistically in combination with AZT.
Moreover, recent studies in the laboratory have shown that ganciclovir
may antagonize the anti-HIV effect of zidovudine, which explains the
apparently decreased anti-HIV effect of the combination of ganciclovir
and AZT, conclude the researchers.