Drug Interaction Report

Theoretically, the concomitant administration of memantine and other drugs that undergo active renal tubular secretion may result in altered plasma levels of both drugs. The clinical significance is unknown. When hydrochlorothiazide/triamterene and memantine were coadministered in a clinical study, the bioavailability of hydrochlorothiazide decreased by 20% and there was no change in memantine or triamterene bioavailability.

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.