- Phase 4 - Treatment with oral ganciclovir every 8 hours. After at least 4 days on this regimen, patients will be admitted to the hospital for 1 day for blood sampling before the drug dose and then at 0.5, 1, 1.5, 2, 4, 6, and 8 hours after the dose. Kidney function will be estimated by blood tests within 2 days of the blood sampling. If kidney function is not within the normal range, further dosing and blood sampling will be delayed until kidney function returns to normal range.