Ganciclovir

Ganciclovir is an antiviral medication used to treat and prevent cytomegalovirus (CMV) infections, especially in immunocompromised people such as organ transplant recipients and individuals with advanced HIV infection. It is a nucleoside analogue that, once phosphorylated inside cells to ganciclovir triphosphate, inhibits CMV DNA polymerase and terminates viral DNA synthesis.

Ganciclovir can be administered intravenously or as the oral prodrug valganciclovir, which has greater oral bioavailability and is rapidly converted to ganciclovir. The drug is primarily cleared by the kidneys, and renal function dictates dose adjustments. The elimination half-life is longer in renal impairment.

Clinical uses include induction and maintenance therapy for CMV retinitis and prevention of CMV disease in transplant recipients. Valganciclovir is widely used for CMV prophylaxis and treatment in these settings, and ganciclovir remains a cornerstone in managing CMV disease in other immunocompromised patients.

Dosing regimens vary by indication and route. For CMV retinitis in adults, intravenous ganciclovir induction is typically 5 mg/kg every 12 hours for 14–21 days, then 5 mg/kg once daily for maintenance, adjusted for renal function. Valganciclovir induction commonly involves 900 mg taken twice daily for 14–21 days, followed by 900 mg once daily for maintenance. Prophylaxis dosing and renal adjustments depend on eGFR.

Adverse effects are principally hematologic, with neutropenia, anemia, and thrombocytopenia risk increasing on therapy. Other risks include nephrotoxicity, hepatotoxicity, GI symptoms, and rare CNS effects. Pregnancy should be avoided if possible, as ganciclovir is teratogenic in animal studies and humans are advised to use contraception. Drug interactions include increased hematologic toxicity with zidovudine. Resistance can arise from UL97 or UL54 mutations.