Ibalizumab
HIV entry inhibitors
HIV entry inhibitors
A monoclonal antibody against the CD4 receptor, infused every two weeks for adults with multidrug-resistant HIV.
Quick facts
- Group
- HIV entry inhibitors
- Target
- CD4 receptor (domain 2)
- Used for
- HIV-1 infection
- Key effects
- Diarrhoea · Dizziness · Nausea
- Monitor
- HIV viral load · Vital signs during
- ATC
- J05AX23
No doses: the clinician sets them by the current guideline.
Mechanism of action
The figure shows the ibalizumab antibody fragment bound to human CD4.
Ibalizumab is a humanised monoclonal antibody that binds domain 2 of CD4 on T cells. It does not stop gp120 from attaching to CD4, but it blocks the shape change of the gp120-CD4 complex that is needed for fusion and entry. Its binding site is away from the MHC class II site, so normal CD4 immune function is preserved. Resistance develops if it is used without other active drugs.
- Ibalizumab binds domain 2 of CD4
- gp120 still attaches to CD4
- The post-attachment shape change is blocked
- HIV cannot fuse and enter
Indications
- HIV-1 infection in heavily treatment-experienced adults with multidrug resistance who are failing their regimen, with other antiretrovirals HIV infection and AIDS →
Adverse effects
Common
- Diarrhoea
- Dizziness
- Nausea
- Rash
Contraindications
- Hypersensitivity to ibalizumab
Key interactions
- Other medicines
- No drug-drug interactions are expected (an antibody, not metabolised by CYP)
What is monitored
- HIV viral load
- Vital signs during and after each infusion
- New signs of infection early in treatment
Administration and safety
- Intravenous infusion by a health professional every two weeks
- The patient is observed during the infusion and for a period afterwards
- Missed infusions are rescheduled promptly to avoid resistance
Pregnancy and breastfeeding
Human data are limited; benefit and risk are weighed with the HIV team.
Nursing care
- Monitor for fever, rash or breathing difficulty during the infusion
- Keep the infusion schedule and record each dose
- Teach to report new infection symptoms
- Reinforce adherence to the oral background regimen
Pharmacokinetics
- Absorption
- Intravenous only
- Half-life
- Long enough for infusions every two weeks
Test yourself
Think of the answer, then tap the question to see it.
Where does ibalizumab bind?
Domain 2 of the human CD4 receptor.
Does ibalizumab prevent gp120 from attaching to CD4?
No. It blocks the conformational change after attachment that is needed for entry.
Why are drug interactions not expected with ibalizumab?
It is a monoclonal antibody and is not handled by CYP enzymes.
Connections
← Back to the class: HIV entry 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: Ibalizumab-uiyk Injection: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); Crystal structure of HIV-1 primary receptor CD4 in complex with a potent antiviral antibody (RCSB Protein Data Bank, 2010); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.