- Phase 2 - Treatment with oral valganciclovir once a day for 7 to 21 days at a dose approximately equivalent to intravenous ganciclovir. Sometime between 4 and 21 days on this dose, patients will have blood sampling in the morning before taking the drug and then at 0.5, 1, 1.5, 2, 4, 6, 8, 12, and 24 hours after the dose.