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Tenofovir Alafenamide

Medically reviewed by Drugs.com. Last updated on Sep 25, 2019.

Pronunciation

(ten OF oh vir al a FEN a mide)

Index Terms

  • GS-7340
  • Tenofovir Alafenamide Fumarate

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Tablet, Oral:

Vemlidy: 25 mg

Brand Names: U.S.

  • Vemlidy

Pharmacologic Category

  • Antihepadnaviral, Reverse Transcriptase Inhibitor, Nucleotide (Anti-HBV)

Pharmacology

Tenofovir alafenamide, an analog of adenosine 5'-monophosphate, is converted intracellularly by hydrolysis to tenofovir and subsequently phosphorylated to the active tenofovir diphosphate. The active moiety inhibits replication of HBV by inhibiting HBV polymerase.

Metabolism

Tenofovir alafenamide (TAF) is converted intracellularly by hydrolysis to tenofovir, then phosphorylated to the active tenofovir diphosphate.

Excretion

Feces (31.7%) and urine (<1%)

Time to Peak

Serum: 0.48 hours

Half-Life Elimination

Serum: 0.51 hours

Protein Binding

80% to plasma proteins

Use: Labeled Indications

Chronic hepatitis B: Treatment of chronic hepatitis B virus (HBV) infection in adults with compensated liver disease

Contraindications

There are no contraindications listed in the US manufacturer's labeling.

Canadian labeling: Additional contraindications (not in US labeling): Hypersensitivity to tenofovir alafenamide or any component of the formulation

Dosing: Adult

Chronic hepatitis B: Oral: 25 mg once daily

Dosing: Geriatric

Refer to adult dosing.

Administration

Oral: Administer with food.

Storage

Store below 30°C (86°F). Dispense in original container.

Drug Interactions

Acyclovir-Valacyclovir: May increase the serum concentration of Tenofovir Products. Tenofovir Products may increase the serum concentration of Acyclovir-Valacyclovir. Monitor therapy

Adefovir: May diminish the therapeutic effect of Tenofovir Products. Adefovir may increase the serum concentration of Tenofovir Products. Tenofovir Products may increase the serum concentration of Adefovir. Avoid combination

Aminoglycosides: May increase the serum concentration of Tenofovir Products. Tenofovir Products may increase the serum concentration of Aminoglycosides. Monitor therapy

Cabozantinib: MRP2 Inhibitors may increase the serum concentration of Cabozantinib. Monitor therapy

CarBAMazepine: May decrease the serum concentration of Tenofovir Alafenamide. Avoid combination

Cidofovir: May increase the serum concentration of Tenofovir Products. Tenofovir Products may increase the serum concentration of Cidofovir. Monitor therapy

Cladribine: Agents that Undergo Intracellular Phosphorylation may diminish the therapeutic effect of Cladribine. Avoid combination

Cobicistat: May enhance the adverse/toxic effect of Tenofovir Products. More specifically, cobicistat may impair proper tenofovir monitoring and dosing. Monitor therapy

Diclofenac (Systemic): May enhance the nephrotoxic effect of Tenofovir Products. Management: Seek alternatives to this combination whenever possible. Avoid use of tenofovir with multiple NSAIDs or any NSAID given at a high dose. Consider therapy modification

Fosphenytoin-Phenytoin: May decrease the serum concentration of Tenofovir Alafenamide. Avoid combination

Ganciclovir-Valganciclovir: Tenofovir Products may increase the serum concentration of Ganciclovir-Valganciclovir. Ganciclovir-Valganciclovir may increase the serum concentration of Tenofovir Products. Monitor therapy

Nonsteroidal Anti-Inflammatory Agents: May enhance the nephrotoxic effect of Tenofovir Products. Management: Seek alternatives to these combinations whenever possible. Avoid use of tenofovir with multiple NSAIDs or any NSAID given at a high dose. Consider therapy modification

Orlistat: May decrease the serum concentration of Antiretroviral Agents. Monitor therapy

OXcarbazepine: May decrease the serum concentration of Tenofovir Alafenamide. Avoid combination

PHENobarbital: May decrease the serum concentration of Tenofovir Alafenamide. Avoid combination

Primidone: May decrease the serum concentration of Tenofovir Alafenamide. Avoid combination

Rifabutin: May decrease the serum concentration of Tenofovir Alafenamide. Avoid combination

RifAMPin: May decrease the serum concentration of Tenofovir Alafenamide. Avoid combination

Rifapentine: May decrease the serum concentration of Tenofovir Alafenamide. Avoid combination

Sofosbuvir: May increase the serum concentration of Tenofovir Alafenamide. Monitor therapy

St John's Wort: May decrease the serum concentration of Tenofovir Alafenamide. Avoid combination

Tipranavir: May decrease the serum concentration of Tenofovir Alafenamide. Avoid combination

Adverse Reactions

>10%:

Central nervous system: Headache (12%)

Neuromuscular & skeletal: Decreased bone mineral density (5% to 11%)

1% to 10%:

Cardiovascular: Increased serum creatine kinase (grades 3/4: 3%)

Central nervous system: Fatigue (6%)

Dermatologic: Skin rash (<5%)

Endocrine & metabolic: Increased LDL cholesterol (grades 3/4: 6%), glycosuria (grades 3/4: 5%), increased amylase (grades 3/4: 3%)

Gastrointestinal: Abdominal pain (9%), nausea (6%), diarrhea (5%), dyspepsia (5%), flatulence (<5%), vomiting (<5%)

Hepatic: Increased serum alanine aminotransferase (grades 3/4: 8%), increased serum aspartate aminotransferase (grades 3/4: 3%)

Neuromuscular & skeletal: Back pain (6%), arthralgia (5%)

Respiratory: Cough (8%)

<1%, postmarketing, and/or case reports: Angioedema, urticaria

ALERT: U.S. Boxed Warning

Post-treatment severe acute exacerbation of hepatitis B:

Discontinuation of anti-hepatitis B therapy, including tenofovir alafenamide, may result in severe acute exacerbations of hepatitis B. Hepatic function should be monitored closely with both clinical and laboratory follow-up for at least several months in patients who discontinue anti-hepatitis B therapy, including tenofovir alafenamide. If appropriate, resumption of anti-hepatitis B therapy may be warranted.

Warnings/Precautions

Concerns related to adverse effects:

• Lactic acidosis/hepatomegaly: Lactic acidosis and severe hepatomegaly with steatosis, sometimes fatal, have been reported with the use of nucleoside analogs, alone or in combination with other antiretrovirals. Suspend treatment in any patient who develops clinical or laboratory findings suggestive of lactic acidosis or pronounced hepatotoxicity (marked transaminase elevation may/may not accompany hepatomegaly and steatosis).

Disease-related concerns:

• Hepatic impairment: Use is not recommended in patients with Child-Pugh class B or C hepatic impairment.

• Hepatitis B acute exacerbation: [US Boxed Warning]: Discontinuation of anti-hepatitis B therapy may result in severe acute exacerbations of hepatitis B. Monitor clinical and laboratory data closely for several months after treatment discontinuation. If clinically indicated, anti-hepatitis B therapy may be resumed.

• HIV-1 and HBV coinfection: Should not be used as a single agent for the treatment of HIV-1 due to resistance development risk.

• Renal impairment: Use is not recommended in patients with CrCl <15 mL/minute who are not receiving hemodialysis.

• Renal toxicity: Cases of acute renal failure and/or Fanconi syndrome have been reported with use of tenofovir prodrugs; patients with preexisting renal impairment and those taking nephrotoxic agents (including NSAIDs) are at increased risk. Prior to initiation of therapy and during therapy, assess serum creatinine, estimated CrCl, urine protein, and urine glucose in all patients as clinically appropriate; also assess serum phosphorus in patients with chronic kidney disease. Discontinue therapy in patients that develop clinically significant decreases in renal function or evidence of Fanconi syndrome.

Concurrent drug therapy issues:

• Drug-drug interactions: Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information.

Other warnings/precautions:

• HIV testing: HIV antibody testing should be offered to all HBV infected patients prior to treatment initiation. If HIV testing is positive, institute an appropriate antiretroviral (HIV-1) combination regimen.

Monitoring Parameters

Serum creatinine, serum phosphorus (in patients with chronic kidney disease), urine glucose, urine protein (prior to initiation and as clinically indicated during therapy); HIV testing (prior to initiation); hepatic function tests; monitor clinical and laboratory data closely for several months following therapy discontinuation.

Pregnancy Considerations

Tenofovir alafenamide has a low level of transfer across the human placenta.

Data collected by the antiretroviral registry related to the use of tenofovir alafenamide in pregnancy are insufficient to evaluate teratogenicity.

Maternal antiretroviral therapy (ART) may increase the risk of preterm delivery, although available information is conflicting possibly due to variability of maternal factors (disease severity; gestational age at initiation of therapy). An increased risk of stillbirth, low birth weight, and small for gestational age infants has been observed in some but not all studies. Because there is clear benefit to appropriate treatment, maternal ART should not be withheld due to concerns for adverse neonatal outcomes. Long-term follow-up is recommended for all infants exposed to antiretroviral medications; children who develop significant organ system abnormalities of unknown etiology (particularly of the CNS or heart) should be evaluated for potential mitochondrial dysfunction. Cases of lactic acidosis and hepatic steatosis related to mitochondrial toxicity have been reported with use of NRTIs. These adverse events are similar to other rare but life-threatening syndromes which occur during pregnancy (eg, HELLP syndrome). In general nucleoside reverse transcriptase inhibitors are well tolerated and the benefits of use generally outweigh potential risk.

The Health and Human Services (HHS) Perinatal HIV Guidelines note the safety and pharmacokinetic data of tenofovir alafenamide are insufficient to recommend initiation in HIV infected pregnant females who are antiretroviral-naive, who have had ART therapy in the past but are restarting, who require a new ART regimen (due to poor tolerance or poor virologic response of current regimen), and who are not yet pregnant but are trying to conceive. However, females who become pregnant while taking tenofovir alafenamide may continue if viral suppression is effective and the regimen is well tolerated. Pharmacokinetics of tenofovir alafenamide are not significantly altered during pregnancy; dose adjustments are not needed.

Females coinfected with HIV and HBV who are taking tenofovir alafenamide prior to pregnancy and are virally suppressed should be offered a choice to switch to tenofovir disoproxil fumarate or continue with the current regimen.

In general, ART is recommended for all pregnant females with HIV to keep the viral load below the limit of detection and reduce the risk of perinatal transmission. Monitoring during pregnancy is more frequent than in non-pregnant adults. ART should be continued postpartum for all females living with HIV and can be modified after delivery.

Health care providers are encouraged to enroll pregnant females exposed to antiretroviral medications as early in pregnancy as possible in the Antiretroviral Pregnancy Registry (1-800-258-4263 or www.APRegistry.com). Health care providers caring for HIV-infected females and their infants may contact the National Perinatal HIV Hotline (888-448-8765) for clinical consultation (HHS [perinatal] 2018).

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Patient may experience headache, abdominal pain, heartburn, loss of strength and energy, cough, nausea, back pain, joint pain, or diarrhea. Have patient report immediately to prescriber signs of kidney problems (urinary retention, hematuria, change in amount of urine passed, or weight gain), signs of liver problems (dark urine, fatigue, lack of appetite, nausea, abdominal pain, light-colored stools, vomiting, or jaundice), or signs of lactic acidosis (fast breathing, tachycardia, abnormal heartbeat, vomiting, fatigue, shortness of breath, severe loss of strength and energy, severe dizziness, feeling cold, or muscle pain or cramps)(HCAHPS).

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for health care professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience, and judgment in diagnosing, treating, and advising patients.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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