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Tenofovir alafenamide: Drug information

Tenofovir alafenamide: Drug information
2024© UpToDate, Inc. and its affiliates and/or licensors. All Rights Reserved.
For additional information see "Tenofovir alafenamide: Patient drug information" and "Tenofovir alafenamide: Pediatric drug information"

For abbreviations, symbols, and age group definitions show table
ALERT: US 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.

Brand Names: US
  • Vemlidy
Brand Names: Canada
  • Vemlidy
Pharmacologic Category
  • Antihepadnaviral, Reverse Transcriptase Inhibitor, Nucleotide (Anti-HBV)
Dosing: Adult
Chronic hepatitis B

Chronic hepatitis B: Oral: 25 mg once daily.

Treatment duration: Treatment duration for nucleos(t)ide analog-based therapy (eg, tenofovir alafenamide) is variable and influenced by HBeAg status, duration of hepatitis B virus (HBV) suppression, and presence of cirrhosis/decompensation (Ref).

Patients without cirrhosis:

Hepatitis B e antigen (HBeAg)–positive immune-active chronic hepatitis: Treat until HBeAg seroconversion; after seroconversion, prolonged consolidation therapy is often required in patients treated with nucleos(t)ide analogues to prevent hepatitis flares. Optimal duration is unknown; however, consolidation therapy is generally a minimum of 12 months of persistently normal ALT and undetectable serum HBV DNA levels after HBeAg seroconversion (Ref).

HBeAg-negative immune-active chronic hepatitis: Indefinite antiviral therapy is suggested unless there is compelling rationale for discontinuation (risk/benefit decision); treatment discontinuation may be considered in patients with loss of HBsAg; however, there is insufficient evidence to guide decisions in these patients (Ref).

Patients with compensated cirrhosis:

HBeAg-positive immune-active chronic hepatitis: In patients who seroconvert on therapy, continue antiviral therapy indefinitely due to concerns with decompensation and death, unless there is a strong competing rationale for discontinuation (Ref).

HBeAg-negative immune-active chronic hepatitis: Treatment discontinuation is not recommended due to potential for decompensation and death (limited data) (Ref).

Patients with decompensated cirrhosis: For individuals with decompensated cirrhosis, indefinite therapy is recommended regardless of HBV DNA level, HBeAg status, or ALT level (Ref).

Viral breakthrough : For patients with confirmed viral breakthrough (HBV DNA ≥100 units/mL with previously undetectable levels [<10 units/mL] or >1 log increase in HBV DNA compared to nadir), either switch to an alternative antiviral monotherapy agent with a high genetic barrier to resistance or add a second antiviral agent with a complementary resistance profile; consult current clinical practice guidelines for recommended agents (Ref).

Hepatitis B virus reactivation prophylaxis, immunocompromised patients

Hepatitis B virus reactivation prophylaxis , immunocompromised patients (off-label use): Oral: 25 mg once daily (Ref).

Hepatitis B virus reinfection prophylaxis, post liver transplant

Hepatitis B virus reinfection prophylaxis , post liver transplant (with or without hepatitis B immune globulin) (off-label use): Oral: 25 mg once daily (Ref).

Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.

Dosing: Kidney Impairment: Adult

The renal dosing recommendations are based upon the best available evidence and clinical expertise. Senior Editorial Team: Bruce Mueller, PharmD, FCCP, FASN, FNKF; Jason Roberts, PhD, BPharm (Hons), B App Sc, FSHP, FISAC; Michael Heung, MD, MS.

Note: Tenofovir is renally cleared, and exposures are increased in patients with CrCl <30 mL/minute and those receiving hemodialysis (Ref). Close monitoring for adverse effects in the advanced stages of kidney dysfunction is recommended. Kidney function may be estimated using the Cockcroft-Gault formula for dosage adjustment purposes.

Kidney impairment prior to treatment initiation:

Altered kidney function:

CrCl ≥15 mL/minute: No dosage adjustment necessary.

CrCl <15 mL/minute: Use is not recommended.

Hemodialysis, intermittent (thrice weekly): No dosage adjustment necessary; when scheduled dose falls on a dialysis day, administer after dialysis.

CRRT: No dosage adjustment necessary (Ref).

PIRRT (eg, sustained, low-efficiency diafiltration): No dosage adjustment necessary. When scheduled dose falls on PIRRT days, administer after PIRRT (Ref).

Nephrotoxicity during treatment: Discontinue use in patients who develop clinically significant decreases in renal function or evidence of Fanconi syndrome.

Dosing: Hepatic Impairment: Adult

Mild impairment (Child-Pugh class A): No dosage adjustment necessary.

Decompensated cirrhosis (Child-Pugh class B or C): Use is not recommended.

Dosing: Older Adult

Refer to adult dosing.

Dosing: Pediatric

(For additional information see "Tenofovir alafenamide: Pediatric drug information")

Chronic hepatitis B

Chronic hepatitis B (with compensated liver disease):

Children ≥12 years and Adolescents: Oral: 25 mg once daily (manufacturer's labeling). Oral antiviral therapy was continued for 1 to 4 years in trials; hepatitis B e antigen (HBeAg) seroconversion has been suggested as a therapeutic end point followed by an additional 12 months of consolidation (Ref).

Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.

Dosing: Kidney Impairment: Pediatric

Kidney impairment prior to treatment initiation:

Children ≥12 years and Adolescents: There are no dosage adjustments provided in the manufacturer's labeling (has not been studied). Based on experience in adult patients, no dosage adjustment is likely necessary for patients with CrCl ≥15 mL/minute or in those with end-stage renal disease (CrCl <15 mL/minute) receiving chronic hemodialysis (administer after hemodialysis on dialysis days); tenofovir alafenamide is not recommended in adults with CrCl <15 mL/minute who are not receiving chronic hemodialysis. Monitor closely for adverse effects in patients with renal dysfunction.

Nephrotoxicity during treatment:

Children ≥12 years and Adolescents: Discontinue use in patients who develop clinically significant decreases in renal function or evidence of Fanconi syndrome.

Dosing: Hepatic Impairment: Pediatric

Children ≥12 years and Adolescents:

Mild impairment: No dosage adjustment necessary.

Decompensated impairment: Not recommended.

Adverse Reactions

The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified. Reported adverse reactions are for adults, unless otherwise indicated.

>10%:

Nervous system: Headache (12%)

Neuromuscular & skeletal: Decreased bone mineral density (children and adolescents: ≥4% at lumbar spine: 6%; ≥4% whole body: 2%; adults: ≥5% at lumbar spine: 11%; ≥7% at femoral neck: 5%)

1% to 10%:

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

Dermatologic: Skin rash (<5%)

Endocrine & metabolic: Increased LDL cholesterol (grades 3/4: 6%)

Gastrointestinal: Abdominal pain (9%), diarrhea (5%), dyspepsia (5%), flatulence (<5%), increased amylase (grades 3/4: 3%), nausea (6%), vomiting (<5%)

Genitourinary: Glycosuria (grades 3/4: 5%)

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

Nervous system: Fatigue (6%)

Neuromuscular & skeletal: Arthralgia (5%), back pain (6%)

Respiratory: Cough (8%)

Frequency not defined:

Endocrine & metabolic: Decreased HDL cholesterol, increased serum triglycerides

Gastrointestinal: Increased serum lipase

Hepatic: Exacerbation of hepatitis B

Postmarketing:

Dermatologic: Urticaria

Hypersensitivity: Angioedema

Renal: Acute kidney injury, Fanconi syndrome, proximal tubular nephropathy, renal tubular necrosis

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

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).

• Renal toxicity: Renal toxicity (acute renal failure, Fanconi syndrome, and/or proximal renal tubulopathy) has been reported with use of tenofovir alafenamide–containing products; patients with impaired renal function and those with concurrent or recent nephrotoxic therapy (including nonsteroidal anti-inflammatory drug use) are at an increased risk. Discontinue use in patients who develop clinically significant decreases in renal function or evidence of Fanconi syndrome.

Disease-related concerns:

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

• 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.

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.

Warnings: Additional Pediatric Considerations

Through disruption in vitamin D metabolism, decreases in bone mineral density (BMD) have been observed with tenofovir alafenamide (TAF) after 48 weeks of treatment; however, the incidence and negative impact on BMD is less than that observed with tenofovir disoproxil fumarate (TDF). Additionally, TAF is associated with less renal toxicity than TDF but equal antiviral efficacy. A higher incidence of dyslipidemia has been reported with TAF than TDF. Do not use TAF and TDF concomitantly (HHS [pediatric] 2022).

Dosage Forms: US

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

Tablet, Oral:

Vemlidy: 25 mg

Generic Equivalent Available: US

No

Pricing: US

Tablets (Vemlidy Oral)

25 mg (per each): $57.66

Disclaimer: A representative AWP (Average Wholesale Price) price or price range is provided as reference price only. A range is provided when more than one manufacturer's AWP price is available and uses the low and high price reported by the manufacturers to determine the range. The pricing data should be used for benchmarking purposes only, and as such should not be used alone to set or adjudicate any prices for reimbursement or purchasing functions or considered to be an exact price for a single product and/or manufacturer. Medi-Span expressly disclaims all warranties of any kind or nature, whether express or implied, and assumes no liability with respect to accuracy of price or price range data published in its solutions. In no event shall Medi-Span be liable for special, indirect, incidental, or consequential damages arising from use of price or price range data. Pricing data is updated monthly.

Dosage Forms: Canada

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

Tablet, Oral:

Vemlidy: 25 mg

Administration: Adult

Oral: Administer with food.

Administration: Pediatric

Oral: Administer with food.

Use: Labeled Indications

Chronic hepatitis B: Treatment of chronic hepatitis B virus infection in adults and pediatric patients ≥6 years of age and weighing ≥25 kg with compensated liver disease.

Note: Although tenofovir alafenamide as a single agent is not FDA-approved for HIV-1 infection, it is approved for treatment and/or preexposure prophylaxis of HIV-1 infection as part of several fixed-dose combination products; refer to those product monographs for more information.

Use: Off-Label: Adult

Hepatitis B virus reactivation prophylaxis, immunocompromised patients; Hepatitis B virus reinfection prophylaxis, post liver transplant

Medication Safety Issues
Other safety concerns:

TAF is an error-prone abbreviation (mistaken as tenofovir disoproxil fumarate)

Metabolism/Transport Effects

Substrate of BCRP/ABCG2, OAT1/3, OATP1B1/1B3 (SLCO1B1/1B3), P-glycoprotein/ABCB1 (major); Note: Assignment of Major/Minor substrate status based on clinically relevant drug interaction potential; Inhibits MRP2

Drug Interactions

Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the drug interactions program by clicking on the “Launch drug interactions program” link above.

Acyclovir-Valacyclovir: May increase the serum concentration of Tenofovir Products. Tenofovir Products may increase the serum concentration of Acyclovir-Valacyclovir. Risk C: 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. Risk X: Avoid combination

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

Atidarsagene Autotemcel: Antiretroviral Agents may diminish the therapeutic effect of Atidarsagene Autotemcel. Risk X: Avoid combination

Betibeglogene Autotemcel: Antiretroviral Agents may diminish the therapeutic effect of Betibeglogene Autotemcel. Risk X: Avoid combination

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

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

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

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

Cobicistat: May increase the serum concentration of Tenofovir Alafenamide. Risk C: Monitor therapy

Elivaldogene Autotemcel: Antiretroviral Agents may diminish the therapeutic effect of Elivaldogene Autotemcel. Management: Avoid use of antiretroviral medications for at least one month, or for the amount of time required for elimination of the retroviral medication, prior to stem cell mobilization and until the all apheresis cycles are finished Risk X: Avoid combination

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

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

Lovotibeglogene Autotemcel: Antiretroviral Agents may diminish the therapeutic effect of Lovotibeglogene Autotemcel. Risk X: Avoid combination

Lumacaftor and Ivacaftor: May increase the serum concentration of P-glycoprotein/ABCB1 Substrates (High risk with Inhibitors or Inducers). Lumacaftor and Ivacaftor may decrease the serum concentration of P-glycoprotein/ABCB1 Substrates (High risk with Inhibitors or Inducers). Risk C: Monitor therapy

Nirmatrelvir and Ritonavir: May increase the serum concentration of Tenofovir Alafenamide. Risk C: 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 due to a potential risk of acute renal failure. Diclofenac appears to confer the most risk. Risk D: Consider therapy modification

Nonsteroidal Anti-Inflammatory Agents (Topical): May enhance the nephrotoxic effect of Tenofovir Products. Risk C: Monitor therapy

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

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

P-glycoprotein/ABCB1 Inducers: May decrease the serum concentration of Tenofovir Alafenamide. Management: Consider alternatives to the use of P-gp inducers with tenofovir alafenamide. If combined, monitor for reduced tenofovir alafenamide concentrations and efficacy, and for the development of resistance. Risk D: Consider therapy modification

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

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

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

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

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

Ritonavir: May increase the serum concentration of Tenofovir Alafenamide. Risk C: Monitor therapy

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

Tacrolimus (Systemic): Tenofovir Products may enhance the nephrotoxic effect of Tacrolimus (Systemic). Risk C: Monitor therapy

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

Reproductive Considerations

Contraception is not required to initiate or continue antiretroviral therapy.

The Health and Human Services (HHS) perinatal HIV guidelines consider tenofovir alafenamide a preferred nucleoside reverse transcriptase inhibitor in patients with HIV who are not yet pregnant but are trying to conceive.

Tenofovir alafenamide is not effective for preexposure prophylaxis in persons with vaginal exposure to HIV.

Maximum viral suppression sustained below the limits of detection prior to conception is recommended for all persons with HIV who are planning a pregnancy. Optimization of the health of the person who will become pregnant is recommended. Selection of or changes to a specific antiretroviral regimen prior to pregnancy should be done as part of a shared decision-making process. In most cases, recommendations from the HHS perinatal HIV guidelines (based on data obtained from cisgender women) can be applied to transgender and gender diverse people assigned female sex at birth.

Health care providers caring for couples planning a pregnancy when one or both partners are diagnosed with HIV may contact the National Perinatal HIV Hotline (1-888-448-8765) for clinical consultation (HHS [perinatal] 2023).

Pregnancy Considerations

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

No increased risk of overall teratogenic effects has been observed based on limited data collected by the antiretroviral pregnancy.

Maternal antiretroviral therapy (ART) may be associated with adverse pregnancy outcomes, including preterm birth, low birth weight, and small-for-gestational-age infants. Actual risks may be influenced by maternal factors such as disease severity, gestational age at initiation of therapy, and specific ART regimen; therefore, close fetal monitoring is recommended. 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 not diagnosed with HIV but who were exposed to ART in utero or as a neonate and develop significant organ system abnormalities of unknown etiology (particularly of the CNS or heart) should be evaluated for potential metabolic dysfunction.

The Health and Human Services (HHS) perinatal HIV guidelines consider tenofovir alafenamide a preferred nucleoside reverse transcriptase inhibitor (NRTI) for pregnant patients with HIV who are antiretroviral naive, who have had ART therapy in the past but are restarting, or who require a new ART regimen (due to poor tolerance or poor virologic response of current regimen). Patients who become pregnant while taking tenofovir alafenamide may continue if viral suppression is effective and the regimen is well tolerated.

The HHS perinatal HIV guidelines consider tenofovir alafenamide with emtricitabine or lamivudine to be a preferred NRTI backbone for initial therapy in antiretroviral-naive patients who are pregnant. Tenofovir alafenamide is also a preferred component of a regimen when early (acute/recent) HIV infection is detected during pregnancy; genotyping may be required if the person had prior use of long acting cabotegravir for preexposure prophylaxis.

The guidelines also consider tenofovir alafenamide plus emtricitabine or lamivudine a recommended dual NRTI backbone in regimens for patients who are HIV/hepatitis B virus–coinfected and pregnant.

The pharmacokinetics of tenofovir alafenamide are not significantly altered during pregnancy and dose adjustment is not required.

ART is recommended for all pregnant people with HIV to maximize their health, maintain the viral load below the limit of detection, and reduce the risk of perinatal transmission. Selection of or changes to a specific antiretroviral regimen during pregnancy should be done as part of a shared decision-making process. Patients on fully suppressive regimens prior to pregnancy generally may continue the same regimen considering known pregnancy outcomes and pharmacokinetic data. Monitoring of patients who are pregnant is more frequent than in patients who are not pregnant; monitor for appropriate weight gain in patients who are pregnant taking tenofovir alafenamide. ART initiated during pregnancy can be modified after delivery. In most cases, recommendations from the HHS perinatal HIV guidelines (based on data obtained from cisgender women) can be applied to transgender and gender diverse people assigned female sex at birth (HHS [perinatal] 2023).

The American Association for the Study of Liver Diseases (AASLD) chronic hepatitis B treatment guidelines provide recommendations for the management of pregnant patients with hepatitis B infection (not coinfected with HIV). Tenofovir alafenamide is not currently a preferred antiviral for use in pregnant patients due to insufficient data (AASLD [Terrault 2018]). However, studies are ongoing and limited safety and efficacy outcome data are becoming available (Chen 2022; Han 2022; Pan 2021; Zeng 2022).

Data collection to monitor pregnancy and infant outcomes following exposure to ART is ongoing. Health care providers should enroll all patients exposed to antiretroviral medications during pregnancy in the Antiretroviral Pregnancy Registry (1-800-258-4263). Enrollment should be done as early in pregnancy as possible.

Health care providers caring for pregnant patients with HIV and their infants may contact the National Perinatal HIV Hotline (1-888-448-8765) for clinical consultation (HHS [perinatal] 2023).

Breastfeeding Considerations

Tenofovir and tenofovir alafenamide are present in breast milk following administration of tenofovir alafenamide (HHS [perinatal] 2023; Kayes 2022; Li 2021; Yang 2021).

Tenofovir alafenamide is a recommended component of an initial regimen when early (acute/recent) HIV infection is detected in patients who are breastfeeding. Breastfeeding should be interrupted and not continued if infection is confirmed. Breast milk may be expressed and stored while waiting for confirmation.

Maintaining maximum viral suppression during pregnancy and postpartum decreases but does not eliminate the risk of HIV transmission via breast milk. In addition, multiclass-resistant virus has been detected in breastfeeding infants who acquire HIV despite maternal therapy. In the United States, where formula is usually accessible, affordable, safe, and sustainable, and the risk of infant mortality due to diarrhea and respiratory infections is low, the Health and Human Services perinatal HIV guidelines do not recommend breastfeeding for patients with HIV when safer infant feeding options are available. Persons with HIV who maintain an undetectable viral load while taking antiretroviral therapy (ART) should evaluate infant feeding options (formula, banked donor milk, or breastfeeding) as part of a shared decision-making process (if breastfeeding is being considered, see guidelines for measures to reduce the risk of HIV transmission). When the HIV status at delivery is not known, breast milk may be expressed and stored until a negative test is available. If HIV infection is diagnosed after breastfeeding has been initiated, breastfeeding should be discontinued immediately. Breastfeeding is not recommended for persons with HIV who are not taking ART and/or who do not have sustained viral suppression.

Information is available for counseling and managing patients with HIV who are considering breastfeeding (1-888-448-8765). In most cases, recommendations from the HHS perinatal HIV guidelines (based on data obtained from cisgender women) can be applied to transgender and gender diverse people assigned female sex at birth (HHS [perinatal] 2023).

The American Association for the Study of Liver Disease (AASLD) chronic hepatitis B treatment guidelines do not consider antiviral therapy a contraindication to breastfeeding in patients with hepatitis B infection not coinfected with HIV; antivirals are minimally excreted in breast milk and unlikely to cause significant toxicity. However, the unknown risk of low-level exposure to the infant should be discussed with mothers as well as the insufficient long-term safety data in infants born to mothers who took antiviral agents while breastfeeding (AASLD [Terrault 2018]). If nipples are cracked or bleeding, breastfeeding is not recommended (Tran 2016).

Monitoring Parameters

Serum creatinine, estimated CrCl, 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.

Chronic hepatitis B: Hepatitis B virus DNA and ALT (HBV DNA usually done every 3 months until undetectable and then every 3 to 6 months thereafter); hepatitis B e antigen (HBeAg); anti-HBe (in patients who are HBeAg positive to monitor for seroconversion); HBsAg; consider monitoring lactic acid levels (if clinical concern); following discontinuation, monitor for recurrent viremia, ALT flares, seroreversion, and clinical decompensation every 3 months for at least 1 year. As antivirals do not eliminate the risk of hepatocellular carcinoma, continued monitoring for this complication is recommended in at-risk patients (AASLD [Terrault 2018]).

Mechanism of Action

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.

Pharmacokinetics (Adult Data Unless Noted)

Protein binding: 80% to plasma proteins.

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

Bioavailability: Increases ~65% with a high-fat meal

Half-life elimination: 0.51 hours

Time to peak, serum: 0.48 hours

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

Pharmacokinetics: Additional Considerations (Adult Data Unless Noted)

Altered kidney function: In patients with CrCl 15 to 29 mL/minute or with end-stage renal disease requiring dialysis, Cmax and AUC of tenofovir were increased.

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  13. Refer to manufacturer's labeling.
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Topic 110861 Version 112.0

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