Drug Interaction Report

GENERALLY AVOID: Generalized seizures have occurred in patients concomitantly receiving ganciclovir with products containing imipenem-cilastatin. The mechanism has not been described, but these agents are individually epileptogenic and may have additive effects on seizure threshold during coadministration.

MANAGEMENT: The manufacturers recommend that concomitant use of ganciclovir or its prodrug, valganciclovir, with imipenem-cilastatin be avoided unless the potential benefits outweigh the risks. Patients receiving this combination should be closely monitored for tremors, mental status changes, and seizures.

ADJUST DOSING INTERVAL: Food increases the bioavailability of ganciclovir from the prodrug, valganciclovir. In 16 HIV-positive subjects, the administration of valganciclovir 875 mg once daily with a high-fat meal containing approximately 600 calories resulted in a 30% increase in the steady-state area under the plasma concentration-time curve (AUC) and a 14% increase in the peak plasma concentration (Cmax) of ganciclovir, with no delay in the time to reach peak plasma concentration (Tmax). The mechanism is unknown.

MANAGEMENT: The manufacturer recommends that valganciclovir be taken with meals.