[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [HIV protease inhibitors (PIs)](https://durgical.com/en/pharmacology/classes/hiv-protease-inhibitors/) › Ritonavir

[Pharmacology](https://durgical.com/en/pharmacology/) · [HIV protease inhibitors (PIs)](https://durgical.com/en/pharmacology/classes/hiv-protease-inhibitors/)

# Ritonavir

A protease inhibitor now used mainly as a 'booster': it blocks CYP3A4 and raises other PIs' levels. It has a great many interactions.

Updated 2026-11-01

- Class: [HIV protease inhibitors (PIs)](https://durgical.com/en/pharmacology/classes/hiv-protease-inhibitors/)
- Enzyme: HIV-1 protease
- ATC code: J05AE03
- WHO Model List of Essential Medicines

Also called: RTV

✂**HIV-1 protease**Ritonavir

ⓘ The figure shows ritonavir in the active site of HIV-1 protease.

**Target in 3D:** HIV-1 protease. PDB structure 1HXW (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/1HXW) · Drag to rotate · pinch to zoom

## Mechanism of action

It inhibits HIV protease, but at the low doses used today its main role is different: it is a potent CYP3A4 inhibitor in gut and liver. It slows the metabolism of the partner PI (darunavir, atazanavir, lopinavir), whose levels rise and last longer.

- It inhibits CYP3A4 in gut and liver
- The partner PI is metabolised more slowly
- Its levels rise and last longer

## Pharmacokinetics

**Metabolism**
Liver, by CYP3A and CYP2D6; strongly inhibits CYP3A

## Indications

- Booster of other protease inhibitors in HIV-1 infection [HIV infection and AIDS →](https://durgical.com/en/conditions/hiv-infection-and-aids/)

## Adverse effects

### Common

- Nausea, vomiting, diarrhoea, abdominal pain
- Taste disturbance
- Paraesthesia, including around the mouth
- Raised triglycerides and cholesterol

### Serious (rare, important)

- Serious or fatal interactions from CYP3A inhibition
- Pancreatitis
- Hepatotoxicity
- PR prolongation and AV block

## Contraindications

- Drugs highly dependent on CYP3A with serious risk if raised (for example alfuzosin, simvastatin, lovastatin, ergot drugs and certain sedatives and antiarrhythmics)
- Previous severe hypersensitivity (Stevens-Johnson, toxic epidermal necrolysis)

## Key interactions

**Fluticasone or budesonide**
The steroid builds up: Cushing's syndrome and adrenal suppression

**Simvastatin, lovastatin**
Rhabdomyolysis: contraindicated

**Ergot drugs**
Ergotism with ischaemia: contraindicated

## What is monitored

- Full interaction review at every medication change
- Lipids, glucose and liver tests
- ECG if there is conduction disease

## Administration and safety

- By mouth, with the PI it boosts
- It tastes bitter and metallic: the oral solution may be harder to tolerate
- Keep a full list of medicines and herbal products and review it with pharmacy before any new drug

## Nursing care

- Review all medicines (including steroid inhalers and herbal products) before starting
- Teach to speak up before receiving any new drug, in any service
- Watch for severe abdominal pain (pancreatitis)

## Pregnancy and breastfeeding

Antiretroviral treatment in pregnancy protects the mother and lowers HIV transmission to the baby; the treating team chooses the regimen.

## Memory aid

'RITONAVIR: the booster that sets the others' pace' by blocking CYP3A4.

## Test yourself

Think of the answer, then tap the question to see it.

## What is ritonavir's main use today?

As a pharmacokinetic booster: it inhibits CYP3A4 and raises other PIs' levels.

## A patient on ritonavir uses inhaled fluticasone and develops a moon face. What happened?

Ritonavir blocked fluticasone metabolism by CYP3A: iatrogenic Cushing's syndrome and adrenal suppression.

## Which statins are contraindicated with ritonavir?

Simvastatin and lovastatin, because of the risk of rhabdomyolysis.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/ritonavir/)

## Related drugs

- [Darunavir](https://durgical.com/en/pharmacology/darunavir/)
- [Atazanavir](https://durgical.com/en/pharmacology/atazanavir/)
- [Lopinavir/ritonavir](https://durgical.com/en/pharmacology/lopinavir-ritonavir/)

## Related conditions

- [HIV infection and AIDS](https://durgical.com/en/conditions/hiv-infection-and-aids/)

[← Back to the class: HIV protease inhibitors (PIs)](https://durgical.com/en/pharmacology/classes/hiv-protease-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: [DailyMed - RITONAVIR tablet, film coated](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=11f757f1-cf48-47a8-925e-918359cbd2d4) (DailyMed (U.S. National Library of Medicine), 2026); [Ritonavir: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a696029.html) (MedlinePlus (U.S. National Library of Medicine), 2025); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=J05AE03) (WHO Collaborating Centre for Drug Statistics Methodology, 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 64 (McGraw Hill, 2023).

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

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/ritonavir/