Pharmacology · HIV entry inhibitors
Enfuvirtide !
An injectable peptide that stops HIV fusing with the cell. It was kept for highly resistant virus and is no longer marketed in the US.
Updated 2026-11-01
Also called: T-20
Mechanism of action
A 36-amino-acid synthetic peptide copied from a region of gp41 itself. It sticks to a groove in gp41's first helical region and stops it folding into the six-helix bundle that fuses the viral envelope with the membrane. It does not act against HIV-2.
- gp41 unfolds after gp120 binds CD4
- Enfuvirtide sticks to its helical region
- The six-helix bundle does not form
- No membrane fusion and no virus entry
Pharmacokinetics
- Absorption
- Subcutaneous injection; good bioavailability by this route
- Metabolism
- As a peptide it is broken down into amino acids; it does not alter other drugs' levels
Indications
- HIV-1 infection in heavily pre-treated people with ongoing viral replication HIV infection and AIDS →
Adverse effects
Common
- Injection-site reactions (pain, redness, hardening, nodules) in almost all patients
- Folliculitis
Contraindications
- Previous hypersensitivity to enfuvirtide
Key interactions
- Other drugs
- No known changes in their concentrations
What is monitored
- Injection sites
- Respiratory symptoms with fever
- Viral load and CD4
Administration and safety
- Subcutaneous; sites are rotated, avoiding areas with a previous reaction
- Reconstituted as the label directs and not shaken hard
- People with bleeding disorders have more risk of bleeding at the site
Nursing care
- Teach injection technique and site rotation
- Check for nodules, redness or local infection
- Teach to seek care for cough with fever or breathing difficulty
Pregnancy and breastfeeding
Antiretroviral treatment in pregnancy protects the mother and lowers HIV transmission to the baby; the treating team chooses the regimen.
Test yourself
Think of the answer, then tap the question to see it.
Which step of HIV entry does enfuvirtide block?
Fusion: it stops gp41 forming the six-helix bundle that joins the viral envelope to the cell membrane.
What is enfuvirtide's most common adverse effect?
Injection-site reactions (pain, redness, nodules), in almost all patients.
Why is enfuvirtide injected rather than taken by mouth?
It is a peptide: it would be digested in the gut.
Related drugs
Related conditions
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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Enfuvirtide Injection: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2025); ATCDDD - ATC/DDD Index (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.