Emtricitabine and Tenofovir Alafenamide Fumarate (Monograph)

Drug class: HIV Nucleoside and Nucleotide Reverse Transcriptase Inhibitors


Emtricitabine and Tenofovir Alafenamide Fumarate (Systemic) is also contained as an ingredient in the following combinations:
Emtricitabine and Tenofovir Alafenamide Fumarate

Medically reviewed by Drugs.com on Apr 10, 2024. Written by ASHP.

Introduction

Antiretroviral; fixed combination of emtricitabine and tenofovir alafenamide fumarate (emtricitabine/tenofovir alafenamide fumarate; FTC/TAF). Emtricitabine (FTC) is an HIV nucleoside reverse transcriptase inhibitor (NRTI), and tenofovir alafenamide fumarate (TAF) is an HIV nucleotide reverse transcriptase inhibitor.

Uses for Emtricitabine and Tenofovir Alafenamide Fumarate

Treatment of HIV Infection

Treatment of HIV-1 infection in adults, adolescents, and pediatric patients weighing ≥35 kg; must use in conjunction with other antiretrovirals.

Treatment of HIV-1 infection in pediatric patients weighing ≥14 kg and <35 kg in conjunction with other antiretroviral agents, excluding protease inhibitors that require a CYP3A inhibitor.

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/TAF 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/TAF is a preferred dual NRTI option for initial treatment regimens in antiretroviral-naive children ≥6 years of age in early puberty (SMR 1–3) weighing ≥25 kg as part of an NNRTI- or INSTI-based regimen and in such patients weighing ≥35 kg as part of a PI-, NNRTI-, or INSTI-based regimen. These experts state that FTC/TAF is a preferred dual NRTI option in antiretroviral-naive 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/TAF 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/TAF used for PrEP in conjunction with safer sex practices to reduce the risk of sexually acquired (excluding receptive vaginal sex) HIV-1 in at-risk HIV-1-negative adults and adolescents weighing ≥35 kg.

Individuals must have a negative HIV-1 test immediately prior to initiating FTC/TAF for PrEP.

Efficacy of FTC/TAF for HIV-1 PrEP in individuals at risk of acquiring HIV-1 from receptive vaginal sex not established.

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 with any of these risk factors.

PrEP with FTC/TAF 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.

Related/similar drugs

Biktarvy, Descovy, Truvada, emtricitabine / tenofovir, Atripla, cabotegravir, Apretude

Emtricitabine and Tenofovir Alafenamide Fumarate Dosage and Administration

General

Pretreatment Screening

• Prior to or when initiating emtricitabine/tenofovir alafenamide fumarate (FTC/TAF), test patients for hepatitis B virus (HBV) infection.

• Prior to initiation of FTC/TAF, assess S_cr, estimated Cl_cr, urine glucose, and urine protein in all patients; in patients with chronic kidney disease, also assess serum phosphorus.

• Immediately prior to initiating FTC/TAF for HIV-1 preexposure prophylaxis (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/TAF in patients infected with HBV.

• On a clinically appropriate schedule, assess S_cr, estimated Cl_cr, urine glucose, and urine protein in all patients; in patients with chronic kidney disease, also assess serum phosphorus.

• In patients receiving FTC/TAF for PrEP, screen for HIV-1 infection at least once every 3 months and upon diagnosis of any other sexually transmitted infections.

Administration

Oral Administration

Administer fixed combination of FTC/TAF 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/TAF tablets contain emtricitabine and tenofovir alafenamide fumarate; dosage of tenofovir alafenamide fumarate expressed in terms of tenofovir alafenamide.

Fixed-combination tablets of FTC/TAF contain emtricitabine 200 mg and tenofovir alafenamide 25 mg or emtricitabine 120 mg and tenofovir alafenamide 15 mg.

Pediatric Patients

Treatment of HIV Infection

Oral

Pediatric patients ≥35 kg: 1 tablet of FTC/TAF (emtricitabine 200 mg, tenofovir alafenamide 25 mg) once daily.

Pediatric patients 14 to <35 kg: Base dosage on weight; use a low-strength fixed-combination tablet (emtricitabine 120 mg, tenofovir alafenamide 15 mg) in those weighing <25 kg. (See Table 1.)

This dosing information applicable to pediatric patients with estimated Cl_cr ≥30 mL/minute who are not receiving an HIV protease inhibitor that is administered with either ritonavir or cobicistat.

Safety and efficacy of concomitant use of FTC/TAF with an HIV-1 protease inhibitor that is administered with either ritonavir or cobicistat not established in pediatric patients weighing <35 kg.

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

HIV-1-negative Adolescents at Risk

Oral

Adolescents weighing ≥35 kg with estimated Cl_cr ≥30 mL/minute: 1 tablet of FTC/TAF (emtricitabine 200 mg, tenofovir alafenamide 25 mg) once daily.

Adults

Treatment of HIV Infection

Oral

1 tablet of FTC/TAF (emtricitabine 200 mg, tenofovir alafenamide 25 mg) once daily.

This dosage recommendation applies to adults weighing ≥35 kg who have an estimated Cl_cr greater than or equal to 30 mL/minute or who have Cl_cr <15 mL/minute and are receiving chronic hemodialysis.

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

HIV-1-negative Adults at Risk

Oral

1 tablet of FTC/TAF (emtricitabine 200 mg, tenofovir alafenamide 25 mg) once daily.

This dosage recommendation applicable to adults weighing ≥35 kg who have an estimated Cl_cr greater than or equal to 30 mL/minute or who have Cl_cr <15 mL/minute and are receiving chronic hemodialysis.

Special Populations

Renal Impairment

Treatment of HIV Infection

Cl_cr ≥30 mL/minute: Use usual dosage.

Cl_cr 15 to <30 mL/minute: Use not recommended.

Cl_cr <15 mL/minute (adults receiving hemodialysis): Use usual dosage. On days of hemodialysis, administer daily dose of FTC/TAF after completion of hemodialysis.

Cl_cr <15 mL/minute (not receiving hemodialysis): Use not recommended.

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

Cl_cr ≥30 mL/minute: Use usual dosage.

Cl_cr 15 to <30 mL/minute: Use not recommended.

Cl_cr <15 mL/minute (adults receiving hemodialysis): Use usual dosage.

Cl_cr <15 mL/minute (not receiving hemodialysis): Use not recommended.

Hepatic Impairment

Treatment of HIV Infection

Mild (Child-Pugh class A) or moderate (Child-Pugh class B) hepatic impairment: Use usual dosage.

Severe hepatic impairment (Child-Pugh class C): Not studied.

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

Mild (Child-Pugh class A) or moderate (Child-Pugh class B) hepatic impairment: Use usual dosage.

Severe hepatic impairment (Child-Pugh class C): Not studied.

Geriatric Patients

Specific dosage recommendations not available.

Cautions for Emtricitabine and Tenofovir Alafenamide Fumarate

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/TAF.

Severe acute exacerbations of HBV reported following discontinuance of preparations containing FTC and/or TDF in HBV-infected patients. HBV exacerbations have been associated with hepatic decompensation and hepatic failure. Such reactions could occur with FTC/TAF.

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/TAF is discontinued in HBV-infected patients. If clinically appropriate, initiate HBV treatment.

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

Precautions Related to HIV-1 Preexposure Prophylaxis

Use FTC/TAF for HIV-1 PrEP only in at-risk 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 may emerge if FTC/TAF PrEP is used in individuals with undetected acute HIV-1 infection. Do not initiate FTC/TAF 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 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 diagnosis of acute or primary HIV-1 infection.

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

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

Other Warnings/Precautions

Immune Reconstitution Syndrome

Immune reconstitution syndrome reported in HIV-infected patients receiving multiple-drug antiretroviral therapy, including regimens containing FTC, a component of FTC/TAF.

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.

Renal Impairment

Renal impairment, including cases of acute renal failure, proximal renal tubulopathy, and Fanconi syndrome (renal tubular injury with severe hypophosphatemia), reported with use of preparations containing TAF, a component of FTC/TAF. Most of these cases characterized by potential confounding factors; however, these factors may have predisposed patients to tenofovir-related renal toxicity.

Individuals with impaired renal function and those receiving nephrotoxic agents (e.g., nonsteroidal anti-inflammatory agents [NSAIAs]) are at increased risk of developing renal-related adverse reactions.

Measure S_cr, estimated Cl_cr, urine glucose, and urine protein prior to initiating FTC/TAF and 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.

Discontinue FTC/TAF in individuals who develop a clinically important decrease in renal function or evidence of Fanconi syndrome.

Use of FTC/TAF not recommended in patients with estimated Cl_cr of 15 to <30 mL/minute or in patients with an estimated Cl_cr <15 mL/minute who are not receiving chronic hemodialysis.

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/TAF 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).

Use of Fixed Combinations

Consider cautions, precautions, contraindications, and interactions associated with each component of FTC/TAF. 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/TAF is used in conjunction with other antiretrovirals for the treatment of HIV-1 infection. FTC/TAF 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 no difference in overall risk of major birth defects for FTC or TAF compared with background rate of 2.7% for major birth defects in a US reference population of the Metropolitan Atlanta Congenital Defects Program. An incidence of major birth defects with first-trimester exposure of 2.6 or 4.2%, and with second- or third-trimester exposure of 2.7 or 3%, reported for FTC or TAF, respectively. No congenital abnormalities reported among 117 infants exposed to TAF after 24 weeks' gestation in mothers with HBV.

Experts state that FTC/TAF 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 a preferred dual NRTI option in pregnant women coinfected with HBV. These experts state that FTC/TAF 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/TAF 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.

FTC/TAF has not been demonstrated to be effective for PrEP in people with receptive vaginal exposure to HIV-1. In HIV-1-negative women at risk of acquiring HIV-1, consideration should be given to 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 distributed into human milk; not known whether TAF is distributed into human milk. Tenofovir is distributed into human milk following administration of TDF.

Not known whether FTC/TAF 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.

Pediatric Use

Safety and efficacy for treatment of HIV-1 infection not established in pediatric patients weighing <14 kg; safety and efficacy for HIV-1 PrEP not established in pediatric patients weighing <35 kg.

Safety and efficacy of concomitant use of FTC/TAF with an HIV-1 protease inhibitor administered with either ritonavir or cobicistat not established in pediatric patients weighing <35 kg.

Adverse effects reported in children 6 to <18 years of age weighing ≥25 kg receiving FTC/TAF in clinical studies for treatment of HIV-1 infection similar to those in adults, with exception of a decrease in mean CD4⁺ cell count observed in virologically-suppressed subjects between the ages of 6 to <12 years of age.

Waning adherence to daily oral PrEP regimen following switch from monthly to quarterly clinic visits reported in at-risk adolescents; therefore, adolescents receiving FTC/TAF PrEP may benefit from more frequent visits and counseling.

Geriatric Use

No differences in safety or efficacy observed in patients ≥65 years of age compared with younger adults.

Hepatic Impairment

Not studied in patients with severe hepatic impairment.

No dosage adjustment required in patients with mild or moderate hepatic impairment.

Renal Impairment

Assess S_cr, estimated Cl_cr, urine glucose, and urine protein prior to initiating FTC/TAF 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.

No dosage adjustment required in patients with Cl_cr ≥30 mL/minute.

No dosage adjustment required in adults with estimated Cl_cr <15 mL/minute (end-stage renal disease) who are receiving chronic hemodialysis. On days of hemodialysis, administer the daily dose of FTC/TAF after completion of hemodialysis treatment.

Use not recommended in patients with severe renal impairment (estimated Cl_cr of 15 to <30 mL/minute) or in patients with end-state renal disease (estimated Cl_cr <15 mL/minute) who are not receiving hemodialysis.

Safety and efficacy of concomitant use of FTC/TAF with an HIV-1 protease inhibitor that is administered with either ritonavir or cobicistat not established in adults with Cl_cr <15 mL/ minute, with or without hemodialysis.

Common Adverse Effects

HIV-infected patients (≥10% of patients): Nausea.

PrEP (≥5% of patients): Diarrhea.

Drug Interactions

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.

TAF minimally metabolized by CYP3A. TAF is not an inhibitor of CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, or UGT1A1; TAF is a weak inhibitor of CYP3A in vitro but is not an inhibitor or inducer of CYP3A in vivo.

Pharmacokinetic interactions between FTC/TAF and drugs affecting or metabolized by hepatic microsomal enzymes unlikely.

Drugs Affecting or Affected by P-glycoprotein Transport

TAF is a substrate of P-glycoprotein (P-gp). When used concomitantly with drugs that strongly affect P-gp, changes in tenofovir absorption may occur.

Inhibitors of P-gp: May increase absorption and plasma concentrations of tenofovir.

Inducers of P-gp: May decrease absorption of tenofovir, resulting in decreased plasma concentrations and possible loss of therapeutic effect and development of resistance.

Drugs Affecting Breast Cancer Resistance Protein

TAF is a substrate of breast cancer resistance protein (BCRP). When used concomitantly with drugs that strongly affect BCRP, changes in tenofovir absorption may occur.

Inhibitors of BCRP: May increase absorption and plasma concentrations of tenofovir.

Drugs Affecting Renal Function

FTC and tenofovir are principally excreted by the kidneys by a combination of glomerular filtration and active tubular secretion.

Drugs that reduce renal function or compete for active tubular secretion: Potential increased concentrations of FTC, TAF, and/or concomitant drug; possible increased risk of adverse effects.

Nephrotoxic drugs: Avoid concomitant use.

Specific Drugs

Emtricitabine and Tenofovir Alafenamide Fumarate Pharmacokinetics

Absorption

Bioavailability

Following oral administration of the individual components of FTC/TAF, peak plasma concentrations of FTC and tenofovir occur at 3 hours and 1 hour, respectively.

Food

No clinically important effect of food on FTC or tenofovir absorption.

Relative to fasting, administration of FTC/TAF components with high-fat meal (approximately 800 kcal, 50% fat) decreased peak concentration and AUC of FTC by 26 and 9%, respectively, compared with administration in the fasting state; a 15% decrease in tenofovir peak concentration and 75% increase in tenofovir AUC were observed.

Distribution

Extent

FTC: Distributed into human milk.

TAF: Not known whether distributed into human milk. Tenofovir distributed into human milk following administration of TDF.

Plasma Protein Binding

FTC: <4 %.

Tenofovir alafenamide: Approximately 80%.

Elimination

Metabolism

FTC: Intracellularly, phosphorylated and converted by cellular enzymes to the active metabolite, emtricitabine 5′-triphosphate.

Tenofovir alafenamide: Prodrug of tenofovir; hydrolyzed intracellularly in peripheral blood mononuclear cells (PBMCs) and macrophages by cathepsin A to form tenofovir; subsequently metabolized to active metabolite (tenofovir diphosphate). In vitro studies indicate tenofovir alafenamide also converted to tenofovir by carboxylesterase 1 (CES1) in hepatocytes. Metabolism accounts for >80% of elimination following oral administration; minimally metabolized via CYP3A.

Elimination Route

FTC: 70% in urine, 13.7% in feces. Eliminated by glomerular filtration and active tubular secretion. Removed by hemodialysis (approximately 30% of dose over a 3-hour dialysis period starting within 1.5 hours of FTC dosing [blood flow rate of 400 mL/minute and dialysate flow rate of 600 mL/minute]); not known whether removed by peritoneal dialysis.

Tenofovir alafenamide: 31.7% in feces and minimally (<1%) in urine. Tenofovir is eliminated by glomerular filtration and active tubular secretion. Efficiently removed by hemodialysis with an extraction coefficient of approximately 54%.

Half-life

FTC: 10 hours.

Tenofovir alafenamide: 0.51 hours; active metabolite (tenofovir diphosphate) half-life within PBMCs is 150–180 hours.

Special Populations

Pediatric patients ≥6 years of age weighing ≥25 kg: No clinically important differences in pharmacokinetics observed.

Geriatric patients: Pharmacokinetics of FTC and TAF not fully evaluated in patients ≥65 years of age; however, no clinically relevant effect of age on exposures of TAF observed in patients up to 75 years of age.

Renal impairment: Clinically important effects on pharmacokinetics of FTC and TAF not observed in subjects with mild or moderate renal impairment.

Severe renal impairment: FTC/TAF not recommended in individuals with severe renal impairment (estimated Cl_cr 15 to <30 mL/minute) or in individuals with end-stage renal disease not receiving chronic hemodialysis. Clinically important effects on pharmacokinetics of FTC and TAF not observed in those with end-stage renal disease (Cl_cr <15 mL/minute) receiving chronic hemodialysis.

Hepatic impairment: Pharmacokinetics of FTC not studied in patients with hepatic impairment; clinically important changes in metabolism not expected. Clinically relevant changes in tenofovir pharmacokinetics not observed in subjects with mild (Child-Pugh class A) or moderate (Child-Pugh class B) hepatic impairment. Pharmacokinetics of FTC/TAF not fully evaluated in subjects infected with hepatitis B and/or C virus.

Race/gender: Based on population pharmacokinetic analyses, no clinically meaningful effects on pharmacokinetics.

Stability

Storage

Oral

Tablets

25°C (excursions permitted to 15–30°C). Store in original container; keep tightly closed.

Actions and Spectrum

• Antiretroviral; fixed combination of FTC (an HIV NRTI), and TAF (an HIV nucleotide reverse transcriptase inhibitor).

• FTC inactive until converted intracellularly to an active 5′-triphosphate metabolite.

• TAF inactive until it undergoes cathepsin A hydrolysis in vivo to tenofovir and is subsequently phosphorylated by cellular kinases to the active metabolite (tenofovir diphosphate).

• FTC and TAF are active in vitro against HIV-1 and HIV-2. Also have some activity against HBV.

• Inhibit replication of HIV by interfering with viral RNA-directed DNA polymerase (reverse transcriptase).

• HIV-1 with reduced susceptibility to FTC and TAF have been produced in vitro and have emerged during therapy.

• HIV resistant to FTC or TAF may be cross-resistant to some other NRTIs (e.g., lamivudine, abacavir, didanosine).

Advice to Patients

• Importance of advising patients to read the FDA-approved patient labeling (medication guide).

• Critical nature of compliance with therapy for HIV-1 infection and importance of remaining under the care of a clinician. Importance of taking as prescribed; do not alter or discontinue antiretroviral regimen without consulting clinician. Importance of advising patients that missing doses may result in development of resistance.

• Importance of using FTC/TAF in conjunction with other antiretrovirals for treatment of HIV-1 infection—not for monotherapy.

• Advise patients receiving FTC/TAF in conjunction with other antiretrovirals for treatment of HIV-1 infection that early initiation of antiretroviral therapy and sustained decreases in plasma HIV RNA have been associated with reduced risk of progression to acquired immunodeficiency syndrome (AIDS) and death. Advise patients that effective antiretroviral regimens can decrease HIV concentrations in blood and genital secretions and strict adherence to such regimens in conjunction with risk-reduction measures may decrease, but cannot absolutely eliminate, the risk of secondary transmission of HIV to others. Importance of continuing to practice safer sex (e.g., using latex or polyurethane condoms to minimize sexual contact with body fluids) and reducing high-risk behaviors (e.g., reusing or sharing needles).

• Advise HIV-negative individuals taking FTC/TAF for HIV-1 PrEP of the importance of confirming that they are HIV-1-negative before starting PrEP, importance of regular HIV-1 testing (at least every 3 months or more frequently for some individuals [e.g., adolescents]) during PrEP, importance of strictly adhering to recommended dosage schedule and not missing any doses, and importance of using a complete prevention strategy that also includes other measures (e.g., consistent condom use, testing for other sexually transmitted infections such as syphilis, chlamydia, and gonorrhea that may facilitate HIV-1 transmission, reducing sexual risk behavior). Advise uninfected individuals that PrEP does not protect all individuals from acquiring HIV-1 and to report any symptoms of acute HIV-1 infection (e.g., fever, headache, fatigue, arthralgia, vomiting, myalgia, diarrhea, pharyngitis, rash, night sweats, cervical and inguinal adenopathy) immediately to a clinician. Advise patients that HIV-1 resistance substitutions may emerge in individuals with undetected HIV-1 infection who are taking FTC/TAF, because FTC/TAF alone does not constitute a complete regimen for HIV-1 treatment.

• Inform patients that testing for HBV infection is recommended before antiretroviral therapy is initiated. Also advise patients that severe acute exacerbations of HBV infection have been reported following discontinuance of emtricitabine and/or tenofovir disoproxil fumarate in HIV-infected patients coinfected with HBV and may occur with discontinuance of FTC/TAF. Advise patients with HBV not to discontinue FTC/TAF without consulting their clinician.

• Inform patients that in some patients with advanced HIV infection, signs and symptoms of inflammation from previous infections may occur soon after antiretroviral therapy is initiated. These symptoms may be due to an improvement in immune response, enabling the body to fight infections that may have been present with no obvious symptoms. Advise patients with HIV-1 infection to inform their clinician immediately if symptoms of possible infection occur.

• Advise patients that cases of renal impairment, including acute renal failure, have been reported. Advise patients to avoid FTC/TAF with concurrent or recent use of nephrotoxic agents (e.g., high-dose or multiple NSAIAs).

• Advise patients that cases of lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported with the use of drugs similar to FTC/TAF. Importance of contacting clinician and suspending treatment if recommended if symptoms suggestive of lactic acidosis or pronounced hepatotoxicity (e.g., unusual muscle pain, shortness of breath or fast breathing, cold or blue hands and feet, dizziness or lightheadedness, fast or abnormal heartbeat, nausea, vomiting, unusual/unexpected stomach discomfort, weakness or unusual tiredness) occur.

• Importance of informing clinician of existing or contemplated concomitant therapy, including prescription (e.g., other antiviral agents) and OTC drugs and dietary or herbal products (e.g., St. John's wort).

• Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed. Advise patients of pregnancy registry. Advise HIV-infected women not to breast-feed.

• Importance of advising patients of other important precautionary information. (See Cautions.)

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

Reload page with references included

Frequently asked questions

• Truvada vs Descovy: How do they compare for HIV and PrEP?
• What is the difference between Biktarvy and Descovy?

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