Tenofovirinteractions

Tenofovir disoproxil fumarate increases didanosine concentrations. Dose reduction and close monitoring for didanosine toxicity are warranted. Coadministration decreases atazanavir concentrations. When coadministered with VIREAD, use atazanavir given with ritonavir. Coadministration of VIREAD with certain HIV-1 protease inhibitors or certain drugs to treat HCV increases tenofovir concentrations. Monitor for evidence of tenofovir toxicity. Consult Full Prescribing Information prior to and during treatment for important drug interactions.

7.1 Drugs Affecting

Renal Function Tenofovir is primarily eliminated by the kidneys. Coadministration of VIREAD with drugs that are eliminated by active tubular secretion may increase concentrations of tenofovir and/or the coadministered drug. Some examples include, but are not limited to, acyclovir, cidofovir, ganciclovir, valacyclovir, valganciclovir, aminoglycosides (e.g., gentamicin), and high-dose or multiple NSAIDs. Drugs that decrease renal function may increase concentrations of tenofovir. In the treatment of chronic hepatitis B, VIREAD should not be administered in combination with HEPSERA (adefovir dipivoxil).

7.2 Established and

Significant Interactions Table 12 provides a listing of established or clinically significant drug interactions. The drug interactions described are based on studies conducted with TDF. Table 12 Established and Significant This table is not all inclusive.

Drug Interactions: Alteration in Dose or Regimen May Be Recommended Based on Drug Interaction Trials Concomitant Drug Class: Drug Name Effect on Concentration ↑=Increase, ↓=Decrease Clinical Comment NRTI: didanosine ↑ didanosine Patients receiving VIREAD and didanosine should be monitored closely for didanosine-associated adverse reactions. Discontinue didanosine in patients who develop didanosine-associated adverse reactions. Higher didanosine concentrations could potentiate didanosine-associated adverse reactions, including pancreatitis, and neuropathy. Suppression of CD4+ cell counts has been observed in patients receiving VIREAD with didanosine 400 mg daily. In patients weighing greater than 60 kg, reduce the didanosine dose to 250 mg when it is coadministered with VIREAD. In patients weighing less than 60 kg, reduce the didanosine dose to 200 mg when it is coadministered with VIREAD. When coadministered, VIREAD and Videx EC may be taken under fasted conditions or with a light meal (less than 400 kcal, 20% fat).

HIV-1 Protease Inhibitor s: atazanavir ↓ atazanavir When coadministered with VIREAD, atazanavir 300 mg should be given with ritonavir 100 mg. lopinavir/ritonavir atazanavir/ritonavir darunavir/ritonavir ↑ tenofovir Monitor patients receiving VIREAD concomitantly with lopinavir/ritonavir, ritonavir-boosted atazanavir, or ritonavir-boosted darunavir for TDF-associated adverse reactions. Discontinue VIREAD in patients who develop TDF-associated adverse reactions.

Hepatitis C Antiviral Agents: sofosbuvir/velpatasvir sofosbuvir/velpatasvir/voxilaprevir ↑ tenofovir Monitor patients receiving VIREAD concomitantly with EPCLUSA ® (sofosbuvir/velpatasvir) for adverse reactions associated with TDF. ledipasvir/sofosbuvir Monitor patients receiving VIREAD concomitantly with HARVONI ® (ledipasvir/sofosbuvir) without an HIV-1 protease inhibitor/ritonavir or an HIV-1 protease inhibitor/cobicistat combination, for adverse reactions associated with TDF. In patients receiving VIREAD concomitantly with HARVONI and an HIV-1 protease inhibitor/ritonavir or an HIV-1 protease inhibitor/cobicistat combination, consider an alternative HCV or antiretroviral therapy, as the safety of increased tenofovir concentrations in this setting has not been established. If coadministration is necessary, monitor for adverse reactions associated with TDF.