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[Pharmacology](https://durgical.com/en/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

## Key points

- Maraviroc only works if the virus uses CCR5: a tropism test is done first.
- Maraviroc acts on a human protein, not a viral one.
- Enfuvirtide is injected subcutaneously; almost all patients have injection-site reactions.
- Enfuvirtide has been linked to more pneumonia.

## Drugs in this class

- [**Maraviroc** Blocks 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](https://durgical.com/en/pharmacology/maraviroc/)
- [**Enfuvirtide** An 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](https://durgical.com/en/pharmacology/enfuvirtide/)

## 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.

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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: Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 64 (McGraw Hill, 2023); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=J05AX) (WHO Collaborating Centre for Drug Statistics Methodology, 2026); [DailyMed - MARAVIROC tablet, film coated](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=c35f72dc-d90e-43f8-9899-f7d1da89460d) (DailyMed (U.S. National Library of Medicine), 2026).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/classes/hiv-entry-inhibitors/