In several studies
ganciclovir has been found to raise the maximum
serum levels and AUC of
didanosine by roughly 70%, even when the drugs are given 2 hours apart. Other studies have suggested that the
efficacy of
ganciclovir may be reduced by
didanosine. Valganciclovir is a prodrug of
ganciclovir and would therefore be expected to interact similarly.
The manufacturers say that the implications of these pharmacokinetic changes is unclear. Until more is known it would seem prudent to monitor concurrent use for
didanosine toxicity. Also monitor for
ganciclovir efficacy.