Decrease the Dose of Ganciclovir in Renal Insufficiency
Angela D. Shoher MD
Ganciclovir is an antiviral agent similar to acyclovir. It is active against all herpes viruses but is especially effective for Cytomegalovirus (CMV). Ganciclovir is often used in the intensive care unit (ICU) to prevent CMV disease in transplant patients and is also effective for chronic suppression of CMV retinitis in immunocompromised patients. It is an acyclic guanine nucleoside analog that acts by inhibiting viral DNA synthesis. One form used in ICU patients is valganciclovir, which is the L-valyl ester prodrug of ganciclovir. Valganciclovir is well absorbed, is hydrolyzed to ganciclovir rapidly, and produces levels comparable to intravenous (IV) ganciclovir. The plasma half-life is about 2 to 4 hours in patients with normal renal function. More than 90% of ganciclovir is eliminated unchanged by renal excretion. The half-life may be significantly increased in patients with severe renal failure and thus requires dosing based on renal function.
What to Do
For the treatment of CMV retinitis in a patient with normal renal function (creatinine clearance >70), the recommended dosage for induction is 5 mg/kg intravenously every 12 hours for 2 to 3 weeks. Maintenance dosing after the induction period is 5 mg/kg intravenously once per day 7 days a week or 6 mg/kg once per day 5 days a week. Oral ganciclovir is not predictably absorbed, so for patients taking oral valganciclovir, the recommended dose is 900 mg by mouth twice a day. Reinduction is recommended for patients who experience progression of CMV retinitis while on maintenance dosing. To prevent CMV disease in transplant patients with normal renal function, the dosage is also 5 mg/kg every 12 hours for 2 to 3 weeks, followed by daily dosing for intravenous maintenance. The oral maintenance regimen is also 1,000 mg three times a day with food. Oral valganciclovir maintenance is 900 mg per day. For patients in renal failure, see Table 249.1 for dosing guidelines.