Emtricitabineinteractions

Tenofovir disoproxil fumarate increases didanosine concentrations. Dose reduction and close monitoring for didanosine toxicity are warranted.

Coadministration decreases atazanavir concentrations. When coadministered with emtricitabine and tenofovir disoproxil fumarate, use atazanavir given with ritonavir.

Coadministration of emtricitabine and tenofovir disoproxil fumarate 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 FTC and tenofovir are primarily excreted by the kidneys by a combination of glomerular filtration and active tubular secretion. No drug-drug interactions due to competition for renal excretion have been observed; however, coadministration of emtricitabine and tenofovir disoproxil fumarate with drugs that are eliminated by active tubular secretion may increase concentrations of FTC, tenofovir, and/or the coadministered drug. Some examples include, but are not limited to, acyclovir, adefovir dipivoxil, cidofovir, ganciclovir, valacyclovir, valganciclovir, aminoglycosides (e.g., gentamicin), and high-dose or multiple NSAIDs. Drugs that decrease renal function may increase concentrations of FTC and/or tenofovir.

7.2 Established and

Significant Interactions Table 7 provides a listing of established or clinically significant drug interactions. The drug interactions described are based on studies conducted with either emtricitabine and tenofovir disoproxil fumarate, the components of emtricitabine and tenofovir disoproxil fumarate tablets (FTC and TDF) as individual agents and/or in combination, or are predicted drug interactions that may occur with emtricitabine and tenofovir disoproxil fumarate. Table 7 Established and Significant a Drug Interactions: Alteration in Dose or Regimen May Be Recommended Based on Drug Interaction Trials Concomitant Drug Class: Drug Name Effect on Concentration b Clinical Comment NRTI: didanosine c ↑ didanosine Patients receiving emtricitabine and tenofovir disoproxil fumarate 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 TDF with didanosine 400 mg daily. In patients weighing greater than 60 kg, reduce the didanosine dose to 250 mg when it is coadministered with emtricitabine and tenofovir disoproxil fumarate. Data are not available to recommend a dose adjustment of didanosine for adult or pediatric patients weighing less than 60 kg. When coadministered, emtricitabine and tenofovir disoproxil fumarate and Videx EC may be taken under fasted conditions or with a light meal (less than 400 kcal, 20% fat).

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

Hepatitis C Antiviral Agents: sofosbuvir/velpatasvir c sofosbuvir/velpatasvir/ voxilaprevir c ledipasvir/sofosbuvir c ↑ tenofovir Monitor patients receiving emtricitabine and tenofovir disoproxil fumarate concomitantly with EPCLUSA ® (sofosbuvir/velpatasvir) or VOSEVI ® (sofosbuvir/velpatasvir/voxilaprevir) for adverse reactions associated with TDF. Monitor patients receiving emtricitabine and tenofovir disoproxil fumarate 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 emtricitabine and tenofovir disoproxil fumarate 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. a. This table is not all inclusive. b. ↑=Increase, ↓=Decrease. c. Indicates that a drug-drug interaction trial was conducted.