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# Tenofovir alafenamide

A newer tenofovir prodrug: it enters cells before activation, leaves little tenofovir in blood, and so harms kidney and bone less.

Updated 2026-11-01

- Class: [Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs)](https://durgical.com/en/pharmacology/classes/nucleoside-nucleotide-reverse-transcriptase-inhibitors/)
- Enzyme: HIV-1 reverse transcriptase
- ATC code: J05AF13

Also called: TAF

✂**HIV-1 reverse transcriptase**Tenofovir alafenamide

ⓘ The figure shows tenofovir diphosphate, the active form that tenofovir alafenamide also produces, as the incoming nucleotide in HIV-1 reverse transcriptase.

**Target in 3D:** HIV-1 reverse transcriptase. PDB structure 1T05 (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/1T05) · Drag to rotate · pinch to zoom

## Mechanism of action

It circulates mostly as intact prodrug; once inside lymphocytes and liver cells it becomes tenofovir and then tenofovir diphosphate, which ends the DNA chain of HIV and hepatitis B virus. Because free plasma tenofovir is much lower than with disoproxil, less reaches the kidney tubule and bone.

- It circulates as intact prodrug
- Inside the cell it becomes tenofovir diphosphate
- It ends the viral DNA chain
- Little free tenofovir reaches kidney and bone

## Pharmacokinetics

**Absorption**
Oral; the hepatitis B product is taken with food

**Distribution**
Concentrates inside cells; little free tenofovir in plasma

## Indications

- HIV-1 infection, within combinations with other antiretrovirals [HIV infection and AIDS →](https://durgical.com/en/conditions/hiv-infection-and-aids/)
- Chronic hepatitis B [Viral hepatitis →](https://durgical.com/en/conditions/viral-hepatitis/)

## Adverse effects

### Common

- Headache
- Nausea
- Tiredness

### Serious (rare, important)

- Severe hepatitis B flare after stopping
- Kidney injury (less frequent than with disoproxil)
- Lactic acidosis with hepatic steatosis (class effect)

## Contraindications

- Hypersensitivity to tenofovir alafenamide

## Key interactions

**St John's wort**
Lowers levels and can cause treatment failure

**NSAIDs**
Higher kidney risk; avoided or monitored

## What is monitored

- HIV and hepatitis B tests before starting
- Kidney function
- Liver tests for months if stopped in hepatitis B

## Administration and safety

- By mouth
- Do not swap with tenofovir disoproxil without an explicit order: the names look alike but the products are not equivalent
- If the person has untreated HIV, the hepatitis-B-only product can induce HIV resistance

## Nursing care

- Confirm HIV and hepatitis B tests
- Teach not to run out of medicine (hepatitis B flare risk)
- Ask about anti-inflammatories and herbal products

## Pregnancy and breastfeeding

Antiretroviral treatment in pregnancy protects the mother and lowers HIV transmission to the baby; the treating team chooses the regimen.

## Memory aid

'TAF = Tenofovir Activated Far inside': active inside cells, little left in blood.

## Test yourself

Think of the answer, then tap the question to see it.

## Why is tenofovir alafenamide less nephrotoxic than disoproxil?

It is activated mainly inside cells and leaves much less free plasma tenofovir, which is what harms the kidney tubule.

## Which two infections does tenofovir alafenamide treat?

HIV-1 infection (in combinations) and chronic hepatitis B.

## What is the risk of using the hepatitis B product in someone with untreated HIV?

That HIV is exposed to a single drug and develops resistance.

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## Related drugs

- [Tenofovir disoproxil](https://durgical.com/en/pharmacology/tenofovir-disoproxil/)
- [Emtricitabine](https://durgical.com/en/pharmacology/emtricitabine/)
- [Bictegravir](https://durgical.com/en/pharmacology/bictegravir/)

## Related conditions

- [HIV infection and AIDS](https://durgical.com/en/conditions/hiv-infection-and-aids/)
- [Viral hepatitis](https://durgical.com/en/conditions/viral-hepatitis/)

[← Back to the class: Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs)](https://durgical.com/en/pharmacology/classes/nucleoside-nucleotide-reverse-transcriptase-inhibitors/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [Tenofovir alafenamide: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a602018.html) (MedlinePlus (U.S. National Library of Medicine), 2025); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=J05AF13) (WHO Collaborating Centre for Drug Statistics Methodology, 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 64 (McGraw Hill, 2023).

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Representative model, for educational purposes only.

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