Interactions between valtrex(valacyclovir) and Viread (tenofovir)
valacyclovir and tenofovir (Moderate Drug-Drug)
MONITOR: Theoretically, coadministration of tenofovir disoproxil fumarate with other drugs that are eliminated by active tubular secretion may result in increased plasma concentrations of tenofovir and/or the coadministered drug(s). The mechanism is competitive inhibition of renal excretion. Drugs that are thought to undergo active tubular secretion include metformin, cimetidine, ranitidine, procainamide, flecainide, quinidine, triamterene, midodrine, cidofovir, acyclovir, valacyclovir, ganciclovir, and valganciclovir.
MANAGEMENT: Patients receiving tenofovir disoproxil fumarate in combination with other drugs that undergo active tubular secretion should be monitored for excessive pharmacologic effects of one or both drugs, and the dosages of the drugs adjusted if necessary.
