Tenofovir
A nucleotide reverse transcriptase inhibitor, usually given as tenofovir disoproxil, for HIV treatment, HIV prevention and chronic hepatitis B.
Also called tenofovir disoproxil (the prodrug form in most tablets) or TDF (abbreviation for tenofovir disoproxil fumarate).
Drug card
- How it works
- Ending the viral DNA chain as false nucleotides for reverse transcriptase
- Used for
- HIV-1 infection, with other antiretrovirals
- Chronic hepatitis B
- HIV pre-exposure prophylaxis (PrEP)
- Known for
- Kidney injury and Fanconi syndrome
- Loss of bone density
- Its name
- -vir means an antiviral; -fovir means a phosphonate nucleotide antiviral
Study it as a flashcard, and it comes back before you forget it.
Mechanism of action
How does tenofovir work?
Tenofovir disoproxil is a prodrug: removing its ester groups frees tenofovir, an acyclic nucleotide analog of adenosine monophosphate. Cell enzymes add two phosphates, and tenofovir diphosphate competes with dATP for HIV and hepatitis B reverse transcriptase and ends the DNA chain. The kidneys excrete it.
Like other nucleoside reverse transcriptase inhibitors: NRTIs are nucleoside or nucleotide look-alikes. Cell kinases phosphorylate them to their active forms, which compete with natural nucleotides at the active site of HIV reverse transcriptase. Once built into the viral DNA copy they end the chain, so HIV cannot make DNA from its RNA. Some also block the hepatitis B polymerase, and they weakly inhibit human DNA polymerases.
Uses
What is tenofovir used for?
- HIV-1 infection, with other antiretrovirals
- Chronic hepatitis B
- HIV pre-exposure prophylaxis (PrEP)
Side effects
Side effects of tenofovir
- Kidney injury and Fanconi syndromeKnown forSerious
- Loss of bone densityKnown for
- Nausea
- Diarrhea
- Headache
- Rash
- Depression
- Weakness and tiredness
- Lactic acidosis with fatty, enlarged liverSerious
- Severe hepatitis B flare when stoppedSerious
- Immune reconstitution syndromeSerious
Known for marks what an exam expects you to know it for.
Watch for
Cautions and what sets it apart
- Check creatinine clearance before and during treatment, and also phosphate, urine glucose and protein in people at kidney risk.
- Avoid current or recent nephrotoxic drugs, such as high-dose or several NSAIDs.
- Test for HIV before treating hepatitis B, and watch the liver for months after stopping it in hepatitis B.
- Do not combine with other tenofovir-containing products or with adefovir.
Good to know: Tenofovir alafenamide (TAF), a newer prodrug, is turned into tenofovir mainly inside cells; in hepatitis B trials it lowered bone density less than tenofovir disoproxil.
Remember it
A way to remember it
NRTIs are fake bricks: the wall of viral DNA stops where they are laid.
Reverse transcriptase picks up the false nucleotide and builds it into the DNA copy of HIV's RNA, and no further bricks can be added: chain termination.
Written for biofideX
Its name
-vir means antiviral
Sub-stems name the target: -ciclovir, -amivir, -fovir, -tegravir, -navir, -buvir, -virine (NNRTIs). Lamivudine and zidovudine are antivirals without it.
-fovir means phosphonate nucleotide antiviral
Tenofovir and adefovir are phosphonate nucleotide analogues. Tenofovir blocks the reverse transcriptase of both HIV-1 and hepatitis B virus.
- Every drug name stem
Its class
Nucleoside reverse transcriptase inhibitors
Other nucleoside reverse transcriptase inhibitors with a card:
Easily mixed up with non-nucleoside reverse transcriptase inhibitors and antiherpes nucleoside analogues.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- Tenofovir disoproxil fumarate tablets: label (DailyMed)
- Tenofovir (NCI Thesaurus)
- Emtricitabine and tenofovir disoproxil fumarate tablets: label (DailyMed)
- Tenofovir alafenamide tablets: label (DailyMed)
- Tenofovir Alafenamide (NCI Thesaurus)
- HIV and AIDS: fact sheet (WHO)
For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.
Antivirals
Tenofovir is one of 10 drugs practiced together here: their classes, how they work, what they treat and what they're known for.
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