Tenofovir-DF should be avoided with concurrent or recent use of a nephrotoxic agent. Since tenofovir-DF is primarily eliminated by the kidneys, coadministration of tenofovir-DF with drugs that reduce renal function or compete for active tubular secretion may increase serum concentrations of tenofovir and/or increase the concentrations of other renally eliminated drugs. Some examples include, but are not limited to, cidofovir, acyclovir, valacyclovir, ganciclovir, valganciclovir, aminoglycosides (e.g., gentamicin), and high-dose or multiple NSAIDs.