Pharmacology · Class
HIV entry inhibitors !
Drugs that stop HIV entering the cell, either by covering the CCR5 co-receptor or by preventing the viral envelope from fusing with the membrane.
Updated 2026-11-01
What they are
A mixed group acting before the virus gets in: maraviroc (antagonist of the human CCR5 co-receptor) and enfuvirtide (a peptide that inhibits gp41-mediated fusion). They are kept for people with virus resistant to many drugs.
Mechanism of action
To enter, HIV gp120 binds CD4 and then a co-receptor (CCR5 or CXCR4); gp41 then folds into a six-helix bundle that pulls the membranes together and fuses them. Maraviroc occupies CCR5 so gp120 no longer recognises it; enfuvirtide sticks to gp41 and prevents the six-helix bundle from forming.
Target: Human CCR5 co-receptor; HIV gp41 glycoprotein
Drugs in this class
- MaravirocBlocks the human CCR5 co-receptor HIV uses to enter. It only works if the patient's virus uses CCR5, which is checked…Human CCR5 chemokine receptor
- EnfuvirtideAn injectable peptide that stops HIV fusing with the cell. It was kept for highly resistant virus and is no longer…HIV-1 envelope glycoprotein gp41
Others in the class
- Fostemsavir (gp120 attachment inhibitor)
- Ibalizumab (anti-CD4 antibody)
Test yourself
Think of the answer, then tap the question to see it.
Which test is done before maraviroc, and why?
A tropism test: maraviroc only blocks entry of virus that uses CCR5, not virus that uses CXCR4.
Which viral structure does enfuvirtide prevent from forming?
The gp41 six-helix bundle, needed to fuse the viral envelope with the cell membrane.
What is special about maraviroc's target compared with other antiretrovirals?
It is a human protein (the CCR5 chemokine receptor), not a viral enzyme or protein.
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 64 (McGraw Hill, 2023); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); DailyMed - MARAVIROC tablet, film coated (DailyMed (U.S. National Library of Medicine), 2026).
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Representative model, for educational purposes only.