Efavirenz, emtricitabine, and tenofovir disoproxil

Consult Full Prescribing Information prior to and during treatment for important potential drug interactions. ( 4 , 5.4 , 7 ) HIV-1 protease inhibitors: Coadministration of efavirenz, emtricitabine and tenofovir disoproxil fumarate with either lopinavir/ritonavir or darunavir and ritonavir increases tenofovir concentrations. Monitor for evidence of tenofovir toxicity. Coadministration of efavirenz, emtricitabine and tenofovir disoproxil fumarate with either atazanavir or atazanavir and ritonavir is not recommended. ( 7.3 )

7.1 Efavirenz Efavirenz has been shown in vivo to induce CYP3A and CYP2B6. Other compounds that are substrates of CYP3A or CYP2B6 may have decreased plasma concentrations when coadministered with EFV. Drugs that induce CYP3A activity (e.g., phenobarbital, rifampin, rifabutin) would be expected to increase the clearance of EFV, resulting in lowered plasma concentrations [see Dosage and Administration (2.2) ] . There is limited information available on the potential for a pharmacodynamic interaction between EFV and drugs that prolong the QTc interval. QTc prolongation has been observed with the use of EFV [see Clinical Pharmacology (12.2) ] .

Consider alternatives to efavirenz, emtricitabine and tenofovir disoproxil fumarate when coadministered with a drug with a known risk of Torsade de Pointes.

7.2 Drugs Affecting Renal Function FTC and tenofovir are primarily eliminated by the kidneys [see Clinical Pharmacology (12.3) ] . Coadministration of efavirenz, 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 [see Warnings and Precautions (5.7) ] . Drugs that decrease renal function may increase concentrations of FTC and/or tenofovir.

7.3 Established and Potentially Significant Drug Interactions Other important drug interaction information for efavirenz, emtricitabine and tenofovir disoproxil fumarate is summarized in Table 3. The drug interactions described are based on trials conducted with either efavirenz, emtricitabine and tenofovir disoproxil fumarate, the components of efavirenz, emtricitabine and tenofovir disoproxil fumarate tablets (EFV, FTC, or TDF) as individual agents, or are potential drug interactions [see Clinical Pharmacology (12.3) ] . Table 3 Established and Potentially Significant a Drug Interactions Concomitant Drug Class: Drug Name Effect Clinical Comment a. This table is not all inclusive.

HIV antiviral agents Protease inhibitor: atazanavir ↓atazanavir ↑tenofovir Coadministration of atazanavir with efavirenz, emtricitabine and tenofovir disoproxil fumarate is not recommended. The combined effect of EFV plus TDF on atazanavir plasma concentrations is not known. There are insufficient data to support dosing recommendations for atazanavir or atazanavir/ritonavir in combination with efavirenz, emtricitabine and tenofovir disoproxil fumarate. Protease inhibitor: fosamprenavir calcium ↓amprenavir Fosamprenavir (unboosted): Appropriate doses of fosamprenavir and efavirenz, emtricitabine and tenofovir disoproxil fumarate with respect to safety and efficacy have not been established.

Fosamprenavir/ritonavir: An additional 100 mg/day (300 mg total) of ritonavir is recommended when efavirenz, emtricitabine and tenofovir disoproxil fumarate is administered with fosamprenavir/ritonavir once daily. No change in the ritonavir dose is required when efavirenz, emtricitabine and tenofovir disoproxil fumarate is administered with fosamprenavir plus ritonavir twice daily. Protease inhibitor: indinavir ↓indinavir The optimal dose of indinavir, when given in combination with EFV, is not known. Increasing the indinavir dose to 1,000 mg every 8 hours does not compensate for the increased indinavir metabolism due to EFV.

Protease inhibitor: darunavir/ritonavir lopinavir/ritonavir ↑tenofovir ↓lopinavir ↑tenofovir Monitor patients receiving efavirenz, emtricitabine and tenofovir disoproxil fumarate concomitantly with ritonavir-boosted darunavir for TDF-associated adverse reactions. Discontinue efavirenz, emtricitabine and tenofovir disoproxil fumarate in patients who develop TDF-associated adverse reactions. Do not use once daily administration of lopinavir/ritonavir. Dose increase of lopinavir/ritonavir is recommended for all patients when coadministered with EFV.

Refer to the Full Prescribing Information for lopinavir/ritonavir for guidance on coadministration with EFV- or tenofovir-containing regimens, such as efavirenz, emtricitabine and tenofovir disoproxil fumarate. Patients should be monitored for tenofovir-associated adverse reactions. Discontinue efavirenz, emtricitabine and tenofovir disoproxil fumarate in patients who develop TDF-associated adverse reactions.

Protease inhibitor: ritonavir ↑ritonavir ↑efavirenz When ritonavir 500 mg every 12 hours was coadministered with EFV 600 mg once daily, the combination was associated with a higher frequency of adverse clinical experiences (e.g., dizziness, nausea, paresthesia) and laboratory abnormalities (elevated liver enzymes). Monitoring of liver enzymes is recommended when efavirenz, emtricitabine and tenofovir disoproxil fumarate is used in combination with ritonavir. Protease inhibitor: saquinavir ↓saquinavir Appropriate doses of the combination of EFV and saquinavir/ritonavir with respect to safety and efficacy have not been established.

CCR5 co-receptor antagonist: maraviroc ↓maraviroc Refer to the full prescribing information for maraviroc for guidance on coadministration with efavirenz, emtricitabine and tenofovir disoproxil fumarate. NRTI: didanosine ↑didanosine Patients receiving efavirenz, 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 efavirenz, emtricitabine and tenofovir disoproxil fumarate. In patients weighing less than 60 kg, reduce the didanosine dose to 200 mg when it is coadministered with efavirenz, emtricitabine and tenofovir disoproxil fumarate. When coadministered, efavirenz, 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).

NNRTI: Other NNRTIs ↑ or ↓ efavirenz and/or NNRTI Combining two NNRTIs has not been shown to be beneficial. Efavirenz, emtricitabine and tenofovir disoproxil fumarate contains EFV and should not be coadministered with other NNRTIs. Integrase strand transfer inhibitor: raltegravir ↓ raltegravir The clinical significance of this interaction has not been directly assessed. Hepatitis C antiviral agents boceprevir ↓ boceprevir Plasma trough concentrations of boceprevir were decreased when boceprevir was coadministered with EFV, which may result in loss of therapeutic effect. The combination should be avoided.

elbasvir/grazoprevir ↓ elbasvir ↓ grazoprevir Coadministration of efavirenz, emtricitabine and tenofovir disoproxil fumarate with elbasvir/grazoprevir is contraindicated [ see Contraindications (4) ] because it may lead to loss of virologic response to elbasvir/grazoprevir. glecaprevir/pibrentasvir ↓ glecaprevir ↓ pibrentasvir Coadministration of efavirenz, emtricitabine and tenofovir disoproxil fumarate is not recommended because it may lead to reduced therapeutic effect of glecaprevir/pibrentasvir.

ledipasvir/sofosbuvir ↑ tenofovir Patients receiving efavirenz, emtricitabine and tenofovir disoproxil fumarate and HARVONI ® (ledipasvir/sofosbuvir) concomitantly should be monitored for adverse reactions associated with TDF. simeprevir ↓ simeprevir ↔ efavirenz Concomitant administration of simeprevir with EFV is not recommended because it may result in loss of therapeutic effect of simeprevir. sofosbuvir/velpatasvir sofosbuvir/velpatasvir/ voxilaprevir ↑ tenofovir ↓ velpatasvir ↓ voxilaprevir Coadministration of EFV-containing regimens and EPCLUSA ® (sofosbuvir/velpatasvir) or VOSEVI ® (sofosbuvir/velpatasvir/voxilaprevir) is not recommended.

Other agents Anticoagulant: warfarin ↑ or ↓ warfarin Plasma concentrations and effects potentially increased or decreased by EFV. Anticonvulsants: carbamazepine ↓ carbamazepine ↓ efavirenz There are insufficient data to make a dose recommendation for efavirenz, emtricitabine and tenofovir disoproxil fumarate. Alternative anticonvulsant treatment…

8.1 Pregnancy Antiretroviral Pregnancy Registry There is a pregnancy exposure registry that monitors pregnancy outcomes in adults and adolescents exposed to efavirenz, emtricitabine and tenofovir disoproxil fumarate during pregnancy. Healthcare providers are encouraged to register patients by calling the Antiretroviral Pregnancy Registry (APR) at (800) 258-4263. Risk Summary There are retrospective case reports of neural tube defects in infants whose mothers were exposed to EFV-containing regimens in the first trimester of pregnancy. Prospective pregnancy data from the APR are not sufficient to adequately assess this risk.

Although a causal relationship has not been established between exposure to EFV in the first trimester and neural tube defects, similar malformations have been observed in studies conducted in monkeys at doses similar to the human dose (see Data) . In addition, fetal and embryonic toxicities occurred in rats at a dose 10 times less than the human exposure at the recommended clinical human dose (RHD) of EFV. Because of the potential risk of neural tube defects, EFV is not recommended for use in the first trimester of pregnancy. Avoid pregnancy while receiving efavirenz, emtricitabine and tenofovir disoproxil fumarate and for 12 weeks after discontinuation.

Advise pregnant patients of the potential risk to a fetus. Available data from the APR show no increase in the overall risk of major birth defects for EFV, FTC, or TDF compared with the background rate for major birth defects of 2.7% in a U.S. reference population of the Metropolitan Atlanta Congenital Defects Program (MACDP) (see Data) . The rate of miscarriage is not reported in the APR. The estimated background rate of miscarriage in clinically recognized pregnancies in the U.S. general population is 15 to 20%. The background risk of major birth defects and miscarriage for the indicated population is unknown. The APR uses the MACDP as the U.S.

reference population for birth defects in the general population. The MACDP evaluates mothers and infants from a limited geographic area and does not include outcomes for births that occurred at less than 20 weeks’ gestation. In animal reproduction studies, no adverse developmental effects were observed when FTC and TDF were administered separately at doses/exposures ≥60 (FTC), ≥14 (TDF) and 2.7 (tenofovir) times those at the RHD of efavirenz, emtricitabine and tenofovir disoproxil fumarate ( see Data ). Data Human Data Efavirenz: There are retrospective postmarketing reports of findings consistent with neural tube defects, including…

8.3 Females and Males of Reproductive Potential Pregnancy Testing Perform pregnancy testing in adults and adolescents of childbearing potential before initiation of efavirenz, emtricitabine and tenofovir disoproxil fumarate because of potential risk of neural tube defects [see Use in Specific Populations (8.1) ] .

Contraception Advise adults and adolescents of childbearing potential to use effective contraception during treatment with efavirenz, emtricitabine and tenofovir disoproxil fumarate and for 12 weeks after discontinuing efavirenz, emtricitabine and tenofovir disoproxil fumarate due to the long half-life of EFV, a component of efavirenz, emtricitabine and tenofovir disoproxil fumarate tablets. Hormonal methods that contain progesterone may have decreased effectiveness. Always use barrier contraception in combination with other methods of contraception [see Drug Interactions (7.1 , 7.3) ].