Emtricitabine and Tenofovir Disoproxil Fumarate

Drug class: Antineoplastic Agents

Usage of Emtricitabine and Tenofovir Disoproxil Fumarate

Treatment of HIV Infection

Treatment of HIV-1 infection in adults and pediatric patients weighing ≥17 kg; must use in conjunction with other antiretrovirals.

Dual NRTIs used in conjunction with an HIV integrase strand transfer inhibitor (INSTI), HIV nonnucleoside reverse transcriptase inhibitor (NNRTI), or HIV protease inhibitor (PI) in INSTI-, NNRTI-, or PI-based regimens. Fixed combinations used in certain patient groups to decrease pill burden and improve compliance.

For initial treatment in HIV-infected adults and adolescents, experts state that FTC/TDF is a recommended dual NRTI option for use in most INSTI-, NNRTI-, and PI-based regimens.

For initial treatment in antiretroviral-naive pediatric patients, experts state that FTC/TDF is an alternative dual NRTI option for use in children 2–12 years of age and a preferred dual NRTI option in adolescents ≥12 years of age with SMR 4 or 5.

Also may be used as part of a combination antiretroviral regimen in previously treated patients; select antiretrovirals in new regimen for patients who are experiencing treatment failure based on antiretroviral treatment history and results from current and past resistance testing.

Because both drugs have activity against both HIV and HBV, FTC/TDF is a preferred dual NRTI option for antiretroviral regimens in HIV-infected patients coinfected with HBV.

Most appropriate antiretroviral regimen cannot be defined for every clinical scenario; select regimen based on information regarding antiretroviral potency, potential rate of resistance development, known toxicities, potential for pharmacokinetic interactions, and patient's virologic, immunologic, and clinical characteristics. Guidelines for the management of HIV infection, including specific recommendations for initial treatment in antiretroviral-naive patients and recommendations for changing antiretroviral regimens, are available at [Web].

Preexposure Prophylaxis for Prevention of HIV-1 Infection (PrEP)

FTC/TDF used for PrEP in conjunction with safer sex practices to reduce the risk of sexually acquired HIV-1 in HIV-1-negative at-risk adults and adolescents weighing ≥35 kg.

Adults and adolescents at risk include those with partner(s) known to be infected with HIV-1 or those engaging in sexual activity within a high prevalence area or social network and with ≥1 of the following factors: inconsistent or no condom use, past or current sexually transmitted infections, use of illicit drugs, alcohol Dependence, or partner(s) of unknown HIV-1 status.

PrEP with FTC/TDF not always effective in preventing acquisition of HIV-1 infection; must be used as part of a comprehensive prevention strategy that includes safer sex practices.

Postexposure Prophylaxis following Occupational Exposure to HIV (PEP)

Postexposure prophylaxis of HIV infection following occupational exposure† [off-label] (PEP) in health-care personnel and others exposed via percutaneous injury (e.g., needlestick, cut with sharp object) or mucous membrane or nonintact skin (e.g., chapped, abraded, dermatitis) contact with blood, tissue, or other body fluids that might contain HIV. Used in conjunction with other antiretrovirals.

USPHS recommends 3-drug regimen of raltegravir in conjunction with FTC and TDF as the preferred regimen for PEP following occupational exposures to HIV. Several alternative regimens that include an INSTI, NNRTI, or PI and 2 NRTIs (dual NRTIs) also recommended. Preferred dual NRTI option for PEP regimens is FTC and TDF (may be given as FTC/TDF fixed combination); alternative dual NRTI options are TDF and lamivudine, lamivudine and zidovudine (may be given as lamivudine/zidovudine; Combivir), or zidovudine and emtricitabine.

Management of occupational exposures to HIV is complex and evolving; consult infectious disease specialist, clinician with expertise in administration of antiretroviral agents, and/or National Clinicians’ Postexposure Prophylaxis Hotline (PEPline at 888-448-4911) whenever possible. Do not delay initiation of PEP while waiting for expert consultation.

Postexposure Prophylaxis following Nonoccupational Exposure to HIV (nPEP)

Postexposure prophylaxis of HIV infection following nonoccupational exposure† [off-label] (nPEP) in individuals exposed to blood, genital secretions, or other potentially infectious body fluids that might contain HIV when the exposure represents a substantial risk for HIV transmission. Used in conjunction with other antiretrovirals.

When nPEP indicated in adults and adolescents ≥13 years of age with normal renal function, CDC states preferred regimen is either raltegravir or dolutegravir used in conjunction with FTC/TDF; alternative regimen recommended in these patients is ritonavir-boosted darunavir used in conjunction with FTC/TDF.

Consult infectious disease specialist, clinician with expertise in administration of antiretroviral agents, and/or the National Clinicians’ Postexposure Prophylaxis Hotline (PEPline at 888-448-4911) if nPEP indicated in certain exposed individuals (e.g., pregnant women, children, those with medical conditions such as renal impairment) or if considering a regimen not included in CDC guidelines, source virus is known or likely to be resistant to antiretrovirals, or healthcare provider is inexperienced in prescribing antiretrovirals. Do not delay initiation of nPEP while waiting for expert consultation.

Relate drugs

How to use Emtricitabine and Tenofovir Disoproxil Fumarate

General

Pretreatment Screening

  • Prior to or when initiating FTC/TDF, test patients for HBV infection.
  • Prior to initiation of FTC/TDF, assess Scr, estimated Clcr, urine Glucose, and urine protein in all patients; in patients with chronic kidney disease, also assess serum phosphorus.
  • Immediately prior to initiating FTC/TDF for HIV-1 PrEP, screen for HIV-1 infection. If recent (<1 month) exposures to HIV-1 are suspected or clinical symptoms consistent with acute HIV-1 infection are present, use a test approved or cleared by the FDA as an aid in the diagnosis of acute or primary HIV-1 infection.

    • Patient Monitoring

  • Monitor hepatic function closely with clinical and laboratory follow-up for at least several months after discontinuance of FTC/TDF in patients infected with HBV.
  • On a clinically appropriate schedule, assess Scr, estimated Clcr, urine glucose, and urine protein in all patients; in patients with chronic kidney disease, also assess serum phosphorus.
  • In patients receiving FTC/TDF for PrEP, screen for HIV-1 infection at least once every 3 months and upon diagnosis of any other sexually transmitted infections.
  • Consider bone mineral density (BMD) monitoring in adult and pediatric patients who have a history of pathologic bone fracture or other risk factors for osteoporosis or bone loss.

    • Administration

    Oral Administration

    Administer fixed combination of FTC/TDF orally once daily without regard to food.

    Use in conjunction with other antiretrovirals for treatment of HIV-1; use alone as a complete regimen for PrEP for prevention of sexually transmitted HIV-1.

    Dosage

    FTC/TDF tablets contain Tenofovir" href="/drugs/emtricitabine-and-tenofovir-4889/">Emtricitabine and tenofovir DF; dosage of tenofovir DF expressed in terms of tenofovir DF.

    Pediatric Patients

    Treatment of HIV Infection Oral

    Children weighing ≥35 kg: 1 tablet containing FTC 200 mg and TDF 300 mg once daily.

    Children weighing 17 to <35 kg: Base dosage on weight and use a low-strength fixed-combination tablet. (See Table 1.) Monitor weight periodically and adjust dosage of FTC/TDF accordingly.

    Table 1. Emtricitabine/tenofovir DF Dosage for Treatment of HIV-1 Infection in Children Weighing ≥17 kg1

    Weight (kg)

    Dosage of Emtricitabine/Tenofovir DF given Once Daily

    17 to <22 kg

    1 tablet (emtricitabine 100 mg and tenofovir DF 150 mg)

    22 to <28 kg

    1 tablet (emtricitabine 133 mg and tenofovir DF 200 mg)

    28 to <35 kg

    1 tablet (emtricitabine 167 mg and tenofovir DF 250 mg)

    ≥35 kg

    1 tablet (emtricitabine 200 mg and tenofovir DF 300 mg)

    Preexposure Prophylaxis for Prevention of HIV-1 Infection (PrEP) HIV-1-negative Adolescents at Risk Oral

    Adolescents weighing ≥35 kg: 1 tablet containing FTC 200 mg and TDF 300 mg once daily.

    Adults

    Treatment of HIV Infection Oral

    1 tablet containing FTC 200 mg and TDF 300 mg once daily.

    Preexposure Prophylaxis for Prevention of HIV-1 Infection (PrEP) HIV-1-negative Adults at Risk Oral

    1 tablet containing FTC 200 mg and TDF 300 mg once daily.

    Postexposure Prophylaxis following Occupational Exposure to HIV (PEP)† [off-label] Oral

    1 tablet containing FTC 200 mg and TDF 300 mg once daily. Use in conjunction with a recommended INSTI, NNRTI, or PI.

    Initiate PEP as soon as possible following occupational exposure to HIV (preferably within hours); continue for 4 weeks, if tolerated.

    Postexposure Prophylaxis following Nonoccupational Exposure to HIV (nPEP)† [off-label] Oral

    1 tablet containing FTC 200 mg and TDF 300 mg once daily. Use in conjunction with a preferred or alternative INSTI, NNRTI, or PI.

    Initiate nPEP as soon as possible (within 72 hours) following nonoccupational exposure that represents a substantial risk for HIV transmission and continue for 28 days.

    nPEP not recommended if exposed individual seeks care >72 hours after exposure.

    Special Populations

    Hepatic Impairment

    Treatment of HIV Infection

    FTC not substantially metabolized by liver enzymes; not specifically studied, but clinically important changes in metabolism not expected in patients with hepatic impairment.

    No change in tenofovir pharmacokinetics were observed in patients with moderate to severe hepatic impairment receiving a 300-mg dose of TDF.

    FTC/TDF: Not studied in hepatic impairment.

    Renal Impairment

    Treatment of HIV Infection

    Adults with Clcr 50–80 mL/minute: Use usual dosage.

    Adults with Clcr 30–49 mL/minute: Reduce dosage to 1 tablet (FTC 200 mg and TDF 300 mg) once every 48 hours; monitor clinical response and renal function since dosage not evaluated clinically.

    Adults with Clcr <30 mL/minute (including hemodialysis patients): Do not use.

    Pediatric patients with renal impairment: Data insufficient to make dosage recommendations.

    Preexposure Prophylaxis for Prevention of HIV-1 Infection (PrEP)

    Adults with Clcr ≥60 mL/minute: Use usual dosage.

    Adults with Clcr <60 mL/minute: Do not use.

    If Clcr decreases during use for PrEP, evaluate potential causes and reassess potential risks and benefits of continued use.

    Pediatric patients with renal impairment: Data insufficient to make dosage recommendations.

    Geriatric Patients

    Specific dosage recommendations not available.

    Warnings

    Contraindications

  • Do not use for PrEP of HIV-1 infection in individuals with unknown or positive HIV-1 status.

    • Warnings/Precautions

    Warnings

    Individuals with HBV Infection

    Test all patients for presence of HBV before initiating FTC/TDF.

    Severe acute exacerbations of HBV reported following discontinuance of FTC/TDF in HBV-infected patients. HBV exacerbations have been associated with hepatic decompensation and hepatic failure.

    Offer HBV vaccination to HBV-uninfected individuals.

    Closely monitor hepatic function with both clinical and laboratory follow-up for at least several months after FTC/TDF is discontinued in HBV-infected patients. If clinically appropriate, initiate HBV treatment.

    FTC/TDF is not indicated for treatment of chronic HBV infection.

    Precautions Related to HIV-1 Preexposure Prophylaxis

    Use FTC/TDF for HIV-1 PrEP only in adults or adolescents (≥35 kg) who are HIV-1-negative. COnfirm a negative HIV-1 test immediately prior to initiating PrEP and screen for HIV-1 infection at least once every 3 months and upon diagnosis of any other sexually transmitted infection during PrEP.

    Drug-resistant HIV-1 variants have been identified when FTC/TDF PrEP was used following undetected acute HIV-1 infection. Do not initiate PrEP if signs or symptoms of acute HIV-1 infection are present, unless negative infection status is confirmed.

    Some HIV-1 tests only detect anti-HIV antibodies and may not identify HIV-1 during the acute stage of infection. Prior to initiating PrEP, evaluate HIV-negative individuals for current or recent signs or symptoms consistent with acute viral infections (e.g., fever, fatigue, myalgia, rash) and ask about any potential exposure events within the last month (e.g., unprotected sex, condom broke during sex with a partner of unknown HIV-1 status or unknown viremic status, a recent sexually transmitted infection).

    If recent (<1 month) exposures to HIV-1 are suspected or clinical symptoms consistent with acute HIV-1 infection are present, use a test approved or cleared by the FDA as an aid in the diagnosis of acute or primary HIV-1 infection.

    Time from initiation of FTC/TDF for HIV-1 PrEP to maximal protection against HIV-1 infection unknown.

    Counsel uninfected individuals to strictly adhere to recommended FTC/TDF dosage schedule. Effectiveness in reducing risk of acquiring HIV-1 is strongly correlated with adherence. Some individuals (e.g., adolescents) may benefit from more frequent visits and counseling to support adherence.

    Adverse effects similar to those reported in HIV-infected patients receiving the drugs for treatment of HIV-1 infection.

    Other Warnings/Precautions

    Renal Impairment

    Renal impairment, including cases of acute renal failure and Fanconi syndrome (renal tubular injury with severe hypophosphatemia), reported with use of TDF.

    Assess Scr, estimated Clcr, urine glucose, and urine protein prior to initiating FTC/TDF and monitor during treatment in all patients as clinically appropriate. In patients with chronic kidney disease, also assess serum phosphorus.

    In individuals at risk for renal dysfunction, evaluate renal function if possible manifestations of proximal renal tubulopathy (e.g., persistent or worsening bone pain, pain in extremities, fractures, muscular pain or weakness) occur.

    When used for treatment of HIV-1 infection, dosing interval adjustment of FTC/TDF and close monitoring of renal function are recommended in patients with estimated Clcr 30–49 mL/minute. No safety or efficacy data available in patients with renal impairment who received FTC/TDF using these dosing guidelines; assess potential benefit of FTC/TDF therapy against potential risk of renal toxicity. Use of FTC/TDF for treatment of HIV-1 infection not recommended in patients with estimated Clcr <30 mL/min or patients requiring hemodialysis.

    Use of FTC/TDF for PrEP not recommended in patients with estimated Clcr <60 mL/minute. If a decrease in estimated Clcr is observed while using FTC/TDF for HIV-1 PrEP, evaluate potential causes and reassess potential risks and benefits of continued use.

    Avoid FTC/TDF in patients with concurrent or recent use of a nephrotoxic agent (e.g., high-dose or multiple nonsteroidal anti-inflammatory agents [NSAIAs]). Cases of acute renal failure after initiation of high-dose or multiple NSAIAs reported in HIV-infected patients with risk factors for renal dysfunction who appeared stable on TDF; some patients required hospitalization and renal replacement therapy. Consider alternatives to NSAIAs, if needed, in patients at risk for renal dysfunction.

    Immune Reconstitution Syndrome

    Immune reconstitution syndrome reported in HIV-infected patients receiving multiple-drug antiretroviral therapy, including FTC/TDF.

    During initial treatment, HIV-infected patients who respond to antiretroviral therapy may develop an inflammatory response to indolent or residual opportunistic infections (e.g., Mycobacterium avium complex [MAC], M. tuberculosis, cytomegalovirus [CMV], Pneumocystis jirovecii [formerly P. carinii]); this may necessitate further evaluation and treatment.

    Autoimmune disorders (e.g., Graves' disease, polymyositis, Guillain-Barré syndrome, autoimmune hepatitis) also reported in the setting of immune reconstitution; time to onset is more variable and can occur many months after initiation of antiretroviral therapy.

    Bone Loss and Mineralization Defects

    Decreases in BMD from baseline, increases in several biochemical markers of bone metabolism, and increased serum parathyroid hormone levels and 1,25-vitamin D levels reported during clinical trials of TDF. Effects of tenofovir-associated changes in BMD on long-term bone health and future fracture risk unknown.

    In clinical trials in HIV-1 infected subjects 2 years of age to <18 years of age, bone effects in pediatric and adolescent subjects receiving TDF were similar to those observed in adult subjects, suggesting increased bone turnover. Total body BMD gain was less in the TDF-treated HIV-1 infected pediatric subjects compared with control groups. Similar trends observed in adolescent subjects 12 years of age to <18 years of age treated for chronic HBV infection. Skeletal growth (height) appeared unaffected in pediatric trials.

    Osteomalacia associated with proximal renal tubulopathy, which manifested as bone pain or pain in extremities and may contribute to fractures, reported in patients receiving TDF. Arthralgia and muscle pain or weakness also reported in patients with proximal renal tubulopathy. Consider hypophosphatemia and osteomalacia secondary to proximal renal tubulopathy in patients at risk for renal dysfunction who present with persistent or worsening bone or muscle symptoms while receiving preparations containing TDF.

    Consider BMD monitoring in adult and pediatric patients who have a history of pathologic bone fracture or other risk factors for osteoporosis or bone loss. Although effect of calcium and vitamin D supplementation not studied, such supplementation may be beneficial. If bone abnormalities are suspected, obtain appropriate consultation.

    Lactic Acidosis and Severe Hepatomegaly with Steatosis

    Lactic acidosis and severe hepatomegaly with steatosis (sometimes fatal) reported in patients receiving HIV NRTIs, including FTC and TDF, alone or in combination with other antiretroviral agents.

    Interrupt FTC/TDF treatment in any patient who develops clinical or laboratory findings suggestive of lactic acidosis or pronounced hepatotoxicity (signs of hepatotoxicity may include hepatomegaly and steatosis even in the absence of marked increases in serum aminotransferase concentrations).

    Interactions

    Concomitant use with certain drugs may result in known or potentially clinically important drug interactions, some of which may increase plasma concentrations of concomitant drugs leading to clinically important adverse reactions. (See Interactions.)

    Consider potential for drug interactions prior to and during FTC/TDF therapy; review concomitant drugs during FTC/TDF therapy and monitor for adverse effects.

    Use of Fixed Combinations

    Consider cautions, precautions, contraindications, and interactions associated with each component of FTC/TDF. Consider cautionary information applicable to specific populations (e.g., pregnant or nursing women, individuals with hepatic or renal impairment, geriatric patients) for each drug in the fixed combination.

    FTC/TDF is used in conjunction with other antiretrovirals for the treatment of HIV-1 infection. FTC/TDF is used alone without any other antiretrovirals for PrEP for prevention of HIV-1 infection.

    Specific Populations

    Pregnancy

    Antiretroviral Pregnancy Registry (APR) at 800-258-4263 or [Web].

    Available data from APR show an incidence of major birth defects with first-trimester exposure of 2.3 or 2.1% for FTC or TDF, respectively, compared with a background rate for major birth defects of 2.7% in a US reference population of the Metropolitan Atlanta Congenital Defects Program.

    Experts state that FTC/TDF is a preferred dual NRTI option for use in conjunction with an HIV INSTI or HIV PI for initial treatment of HIV-1 infection in antiretroviral-naive pregnant women, and is a preferred dual NRTI option in pregnant women coinfected with HBV. These experts state that FTC/TDF in conjunction with an HIV NNRTI is an alternative regimen for initial treatment of HIV-1 infection in antiretroviral-naive pregnant women.

    Experts state that the dual NRTI option of FTC/TDF used in conjunction with lopinavir/ritonavir, dolutegravir, raltegravir, or darunavir/ritonavir is among preferred regimens for treatment of HIV type 2 (HIV-2) infection† [off-label] in pregnant women.

    In HIV-1-negative women at risk of acquiring HIV-1, consider methods to prevent HIV-1, including initiating or continuing FTC/TDF PrEP, taking into account the potential increased risk of HIV-1 infection during pregnancy and the increased risk of mother-to-child transmission during acute HIV-1 infection.

    Lactation

    FTC/TDF distributed into human milk in low concentrations.

    Not known whether FTC/TDF affects human milk production or affects the breast-fed infant.

    Instruct HIV-infected women not to breast-feed because of risk of HIV transmission (in HIV-negative infants), risk of development of viral resistance (in HIV-positive infants), and risk of adverse effects in the infant.

    In HIV-uninfected women, consider developmental and health benefits of breast-feeding and mother’s clinical need for FTC/TDF for HIV-1 PrEP along with any potential adverse effects on breast-fed child from FTC/TDF and risk of HIV-1 acquisition due to nonadherence and subsequent mother to child transmission. Advise women not to breast-feed if acute HIV-1 infection is suspected because of the risk of HIV-1 transmission to the infant.

    Pediatric Use

    Safety and efficacy for treatment of HIV-1 infection not established in pediatric patients weighing <17 kg; safety and efficacy for HIV-1 PrEP not established in pediatric patients weighing <35 kg.

    Adverse effects reported in children 3 months to <18 years of age receiving FTC in clinical studies similar to those in adults, with exception of higher frequency of anemia and hyperpigmentation. Adverse effects reported in children 2 to <18 years of age receiving TDF in clinical studies have been similar to those in adults.

    Adverse effects reported in adolescents 15–18 years of age receiving FTC/TDF in clinical trials for HIV-1 PrEP similar to those in adults.

    In clinical trials in HIV-1 infected subjects 2 years of age to <18 years of age, similar bone effects observed in pediatric and adolescent subjects receiving TDF compared with adult subjects, suggesting increased bone turnover. Total BMD gain decreased in TDF-treated HIV-1 infected pediatric subjects compared with control groups. Similar trends observed in adolescent subjects 12 years of age to <18 years of age treated for chronic HBV infection. Skeletal growth (height) appeared unaffected in all pediatric trials.

    Consider BMD monitoring in pediatric patients with history of pathologic bone fracture or other risk factors for osteoporosis or bone loss. Although effects of calcium and vitamin D supplementation not studied, such supplementation may be beneficial. If bone abnormalities are suspected, obtain appropriate consultation.

    Geriatric Use

    Insufficient experience in patients ≥65 years of age to determine whether they respond differently than younger adults.

    Hepatic Impairment

    Not studied in patients with hepatic impairment.

    Renal Impairment

    Assess Scr, estimated Clcr, urine glucose, and urine protein prior to initiating FTC/TDF and routinely monitor during treatment in all patients as clinically appropriate. In patients with chronic kidney disease, also assess serum phosphorus at baseline and during treatment as clinically appropriate.

    Do not use for treatment of HIV-1 in patients with Clcr <30 mL/minute or patients with end-stage renal disease requiring dialysis. Dosage adjustments necessary when used for treatment of HIV-1 infection in those with Clcr 30–49 mL/minute. Do not use for PrEP in HIV-1 uninfected adults with Clcr <60 mL. If Clcr decreases during FTC/TDF PrEP, evaluate potential causes and reassess potential risks and benefits of continued use.

    Common Adverse Effects

    HIV-infected patients (≥10% of patients): Nausea, fatigue, headache, dizziness, depression, insomnia, abnormal dreams, rash.

    PrEP (≥2% of patients): Headache, abdominal pain, decrease in weight.

    What other drugs will affect Emtricitabine and Tenofovir Disoproxil Fumarate

    No pharmacokinetic interactions have been reported between the components of the fixed combination (i.e., FTC, TDF). Administration of FTC 200 mg once daily with TDF 300 mg once daily for 7 days in healthy subjects had no effect on the pharmacokinetics of tenofovir; an increase in FTC minimum concentration of 20% and no change in FTC peak concentration or AUC were observed.

    The following drug interactions are based on studies using FTC or TDF alone or the fixed combination of FTC/TDF or are predicted to occur. Consider interactions associated with each drug in the fixed combination.

    Drugs Affecting or Metabolized by Hepatic Microsomal Enzymes

    FTC is not a substrate of CYP isoenzymes and does not inhibit CYP1A2, 2A6, 2B6, 2C9, 2C19, 2D6, or 3A4.

    Tenofovir is not a substrate of CYP isoenzymes; in in vitro studies does not inhibit CYP isoenzymes 3A4, 2D6, 2C9, or 2E1, but may have a slight inhibitory effect on CYP1A.

    Based on in vitro studies and clinical pharmacokinetic drug-drug interaction trials, pharmacokinetic interactions between FTC/TDF and drugs affecting or metabolized by hepatic microsomal enzymes unlikely.

    Drugs Affecting or Affected by P-glycoprotein Transport

    TDF is a substrate of P-glycoprotein (P-gp). When used concomitantly with an inhibitor of P-gp, increase in tenofovir absorption may occur.

    Drugs Affecting or Affected by Breast Cancer Resistance Protein

    TDF is a substrate of breast cancer resistance protein (BCRP). When used concomitantly with an inhibitor of BCRP, increase in tenofovir absorption may occur.

    Drugs Affecting Renal Function

    FTC and TDF are principally 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, potential pharmacokinetic interactions if FTC/TDF used concomitantly with drugs that reduce renal function or compete for active tubular secretion (e.g., acyclovir, adefovir dipivoxil, aminoglycosides [e.g., gentamicin], cidofovir, ganciclovir, valacyclovir, valganciclovir, high-dose or multiple nonsteroidal anti-inflammatory agents [NSAIAs]); may result in increased concentrations of FTC, TDF, and/or the concomitant drug and increased risk of adverse effects. Avoid concomitant use of FTC/TDF and nephrotoxic drugs.

    Specific Drugs

    Drug

    Interaction

    Comments

    Abacavir

    No evidence of antagonism between FTC or TDF and abacavir

    No effect of FTC/TDF on pharmacokinetics of abacavir

    Adefovir dipivoxil

    Potential increase in concentrations of FTC/TDF and/or adefovir

    Avoid concomitant use of FTC/TDF with nephrotoxic drugs

    Aminoglycosides

    Potential increase in concentrations of FTC/TDF and/or aminoglycoside

    Avoid concomitant use of FTC/TDF with nephrotoxic drugs

    Amprenavir

    No antagonism observed between FTC or TDF and amprenavir

    Atazanavir

    No in vitro evidence of antagonistic antiretroviral effects between FTC and atazanavir

    Pharmacokinetic interaction: TDF decreases atazanavir concentrations; atazanavir also may increase tenofovir concentrations

    When used concomitantly with FTC/TDF, use atazanavir (300 mg) given with ritonavir (100 mg); monitor patients receiving FTC/TDF concomitantly with ritonavir-boosted atazanavir for tenofovir-associated adverse reactions

    Discontinue FTC/TDF in patients who develop tenofovir-associated adverse reactions

    Darunavir/ritonavir

    Pharmacokinetic interaction: Ritonavir-boosted darunavir increases tenofovir concentrations

    Monitor patients receiving FTC/TDF concomitantly with ritonavir-boosted darunavir for tenofovir-associated adverse reactions; discontinue FTC/TDF in patients who develop tenofovir-associated adverse reactions

    Delavirdine

    No evidence of antagonism between FTC or TDF and delavirdine

    Didanosine

    Pharmacokinetic interaction: TDF increases didanosine concentrations; may result in didanosine toxicity (e.g., pancreatitis, neuropathy)

    No evidence of antagonism between TDF and didanosine

    Closely monitor patients receiving FTC/TDF and didanosine concomitantly for didanosine-associated adverse reactions

    Patients weighing >60 kg: Reduce didanosine dosage to 250 mg when it is used concomitantly with FTC/TDF

    Patients (adult or pediatric) weighing <60 kg: Data not available to recommend an adjusted dosage for didanosine in patients receiving FTC/TDF

    When used concomitantly, FTC/TDF and delayed-release didanosine capsules (Videx EC) may be taken under fasted conditions or with a light meal (<400 kcal, 20% fat)

    Discontinue didanosine in patients who develop didanosine-associated adverse reactions

    Efavirenz

    No evidence of antagonism between FTC or TDF and efavirenz

    No clinically important pharmacokinetic interactions between TDF and efavirenz

    Elbasvir and grazoprevir

    Fixed combination of elbasvir and grazoprevir (elbasvir/grazoprevir): Clinically important pharmacokinetic interactions with emtricitabine not expected

    Entecavir

    Pharmacokinetic interaction unlikely

    Etravirine

    No in vitro evidence of antagonistic antiretroviral effects between FTC and etravirine

    Indinavir

    No clinically important pharmacokinetic interactions between FTC and indinavir

    No antagonism observed between TDF and indinavir

    Lamivudine

    No potential benefit of concomitant use with FTC

    Do not use concomitantly

    Ledipasvir/sofosbuvir

    Pharmacokinetic interaction: Increased tenofovir concentrations

    Monitor patients receiving FTC/TDF concomitantly with ledipasvir/sofosbuvir without an HIV-1 protease inhibitor/ritonavir or HIV-1 protease inhibitor/cobicistat combination for adverse reactions associated with tenofovir

    Patients receiving FTC/TDF concomitantly with ledipasvir/sofosbuvir and an HIV-1 protease inhibitor/ritonavir or an HIV-1 protease inhibitor/cobicistat combination: Consider alternative HCV or antiretroviral therapy, as safety of increased tenofovir concentrations in this setting not established; if coadministration necessary, monitor for adverse reactions associated with tenofovir

    Lopinavir/ritonavir

    Pharmacokinetic interaction: Increased tenofovir concentrations

    Monitor patients receiving FTC/TDF concomitantly with lopinavir/ritonavir for tenofovir-associated adverse reactions; discontinue FTC/TDF in patients who develop tenofovir-associated adverse reactions

    Maraviroc

    No in vitro evidence of antagonistic antiretroviral effects between FTC and maraviroc

    Methadone

    No clinically important pharmacokinetic interactions expected between TDF and methadone

    Nelfinavir

    No antagonism observed between FTC or TDF and nelfinavir

    No clinically important pharmacokinetic interactions between TDF and nelfinavir

    Nevirapine

    No evidence of antagonism between FTC or TDF and nevirapine

    NSAIAs

    Potential increase in concentrations of FTC/TDF and/or NSAIA, especially with high-dose or multiple NSAIA use

    Consider alternatives to NSAIAs, if needed, in patients at risk for renal dysfunction

    Nucleoside and nucleotide antiviral agents (acyclovir, cidofovir, ganciclovir, valacyclovir, valganciclovir)

    Potential for increased concentrations of FTC/TDF and/or antiviral agent due to competition for active tubular secretion and/or reduced renal function

    Famciclovir: No clinically important pharmacokinetic interactions between FTC and famciclovir

    Ribavirin: No clinically important pharmacokinetic interactions between TDF and ribavirin

    Avoid concomitant use of FTC/TDF with nephrotoxic drugs

    Oral contraceptives

    No clinically important pharmacokinetic interactions expected between TDF and oral contraceptives

    Rilpivirine

    Pharmacokinetic interactions unlikely

    No in vitro evidence of antagonistic antiretroviral effects between FTC and rilpivirine

    Ritonavir

    No antagonism observed between FTC or TDF and ritonavir

    Saquinavir

    No antagonism observed between FTC or TDF and saquinavir

    Saquinavir/ritonavir

    Pharmacokinetic interaction: Potential for increased tenofovir and/or saquinavir concentrations; not expected to be clinically important

    Dosage adjustments not required

    Simeprevir

    Clinically important interactions with FTC not expected

    Sofosbuvir

    Clinically important interactions with FTC or TDF not expected

    Sofosbuvir/velpatasvir

    Pharmacokinetic interaction: increased tenofovir concentrations

    Monitor for tenofovir-associated adverse effects

    Sofosbuvir/velpatasvir/voxilaprevir

    Pharmacokinetic interaction: increased tenofovir concentrations

    Monitor for tenofovir-associated adverse effects

    Stavudine

    No clinically important pharmacokinetic interaction between FTC and stavudine

    No antagonism observed between FTC or TDF and stavudine

    Tacrolimus

    Clinically important interactions between tacrolimus and FTC/TDF unlikely

    Tipranavir

    In vitro evidence of additive antiretroviral effects between FTC and tipranavir observed

    Tipranavir/ritonavir

    Potential pharmacokinetic interaction; variable effects on tenofovir and tipranavir pharmacokinetics observed

    Zidovudine

    No antagonism observed between FTC or TDF and zidovudine

    No clinically important pharmacokinetic interactions between FTC and zidovudine

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