Tenofovir alafenamide (TAF) is a newer-generation antiviral medicine used to treat HIV infection and chronic hepatitis B. It belongs to a class of medicines called nucleotide reverse transcriptase inhibitors, and is a more targeted prodrug of the same active molecule found in tenofovir disoproxil fumarate, designed to reduce kidney and bone side effects. It is a prescription-only medicine.

• Therapeutic Class: Antiviral medicine (antiretroviral / anti-hepatitis B agent).

• Pharmacological Class: Nucleotide analog reverse transcriptase inhibitor.

• Drug Family: Acyclic nucleotide phosphonates (newer prodrug class).

• ATC Classification: J05AF13 (Tenofovir alafenamide).

Approved: HIV-1 infection, in combination with other antiretroviral agents, in adults and pediatric patients weighing at least 14 kg (formulation-dependent); chronic hepatitis B infection in adults and adolescents with compensated liver disease.

Commonly used for: People living with HIV as part of combination therapy, and people with chronic hepatitis B needing long-term antiviral suppression, particularly where kidney or bone health is a specific concern.

Off-label use (only under medical guidance): Not typically used off-label, given its defined approved indications.

●       Oral tablets: 25 mg (as a standalone hepatitis B treatment, brand Vemlidy), with lower doses used within various fixed-dose HIV combination products.

Tenofovir alafenamide is a prodrug engineered to be more stable in the bloodstream, delivering tenofovir more efficiently and directly into infected cells (such as liver cells for hepatitis B, or immune cells for HIV) at a much lower overall dose than tenofovir disoproxil fumarate. Once inside these cells, it is converted to its active form and blocks the viral reverse transcriptase enzyme in the same way, stopping the virus from replicating — but with substantially lower circulating drug levels in the rest of the body.

• Standard dose (hepatitis B, standalone): 25 mg taken orally once daily, with food.

• Condition-wise dose (HIV combination products): Dosing varies by the specific fixed-dose combination product (e.g., Descovy, Biktarvy), each taken once daily as directed.

• Route: Oral, once daily; the standalone hepatitis B tablet is taken with food to improve absorption.

• Renal impairment: Generally usable without dose adjustment down to a lower creatinine clearance threshold than tenofovir disoproxil fumarate, though specific product labelling should be checked.

• Missed dose: Take as soon as remembered unless close to the next dose; don't double up.

• Overdose: Limited clinical data at doses beyond recommended; would be managed with supportive care and monitoring.

• Common: Nausea, fatigue, and headache.

• Serious: Lactic acidosis and severe hepatomegaly with steatosis (rare), and — though less pronounced than with tenofovir disoproxil fumarate — some effect on kidney function and bone density can still occur.

• Emergency symptoms: Unusual muscle pain or weakness, rapid breathing, unusual tiredness, or signs of liver problems (yellowing of skin/eyes, dark urine).

• Recovery advice: Because this formulation generally has a milder effect on kidneys and bones compared with the older tenofovir prodrug, routine monitoring is still recommended but effects are typically less pronounced.

• Pregnancy: Used when clearly needed, including as part of standard HIV treatment regimens during pregnancy, under medical guidance.

• Breastfeeding: Discussed with the treating doctor, in line with broader HIV/hepatitis B and breastfeeding guidance.

• Liver disease: Approved for use in patients with compensated liver disease; not established in decompensated (severe) liver disease.

• Kidney disease: Generally usable with less dose-adjustment need than tenofovir disoproxil fumarate, though specific product guidance should be followed.

• Elderly: Used with routine monitoring; considered to have a more favourable kidney/bone safety profile in this age group compared with the older prodrug.

• Children: Approved from various weight thresholds depending on the specific combination product; standalone hepatitis B use approved in adults and certain adolescents.

●       P-glycoprotein inducers (e.g., rifampin, St. John's Wort, certain anti-seizure medicines): can significantly reduce tenofovir alafenamide levels and effectiveness; co-administration is not recommended.

●       P-glycoprotein inhibitors: can increase tenofovir alafenamide levels; used with monitoring.

●       Other tenofovir-containing products: should not be combined to avoid duplicate dosing.

●       Other nephrotoxic drugs: caution advised, though the interaction risk is generally considered lower than with tenofovir disoproxil fumarate.

●       Kidney function tests periodically, though less frequently emphasized than with the older tenofovir prodrug.

●       Hepatitis B virus testing before starting, and hepatic function monitoring if discontinued in coinfected patients.

●       HIV viral load and CD4 count (for HIV treatment) or hepatitis B viral markers (for HBV treatment) to monitor response.

●       Weight and metabolic parameters, as some tenofovir alafenamide-containing regimens have been associated with weight gain in research.

Tenofovir disoproxil fumarate (the older prodrug, generally more affordable but with more kidney/bone impact), Entecavir (for hepatitis B specifically).

Used as a standalone tablet for chronic hepatitis B (Vemlidy), and as a component of several fixed-dose combination HIV regimens (e.g., with emtricitabine, and various third agents) — not combined with other tenofovir-containing products.

●       HIV / Antiretroviral Medicines

●       Hepatitis B Medicines

●       Nucleotide Reverse Transcriptase Inhibitors

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1.  https://www.gilead.com/-/media/files/pdfs/medicines/liver-disease/vemlidy/vemlidy_pi.pdf

2. https://www.sciencedirect.com/science/article/pii/S2468125316300243

The information on this page is for educational purposes only and is not a substitute for medical advice. Please consult your doctor to know if this treatment is appropriate for your condition.