[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Azole antifungals](https://durgical.com/en/pharmacology/classes/azole-antifungals/) › Posaconazole

[Pharmacology](https://durgical.com/en/pharmacology/) · [Azole antifungals](https://durgical.com/en/pharmacology/classes/azole-antifungals/)

# Posaconazole

Broad triazole that prevents Aspergillus and Candida infections in severely immunocompromised patients and treats aspergillosis.

Updated 2026-11-01

- Class: [Azole antifungals](https://durgical.com/en/pharmacology/classes/azole-antifungals/)
- Enzyme: Lanosterol 14α-demethylase (CYP51, the fungal ERG11 enzyme)
- ATC code: J02AC04

✂**Lanosterol 14α-demethylase (CYP51, the fungal ERG11 enzyme)**Posaconazole

ⓘ The figure shows posaconazole bound to CYP51 from Candida albicans.

**Target in 3D:** Lanosterol 14α-demethylase (CYP51, the fungal ERG11 enzyme). PDB structure 5FSA (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/5FSA) · Drag to rotate · pinch to zoom

## Mechanism of action

Posaconazole blocks fungal lanosterol 14α-demethylase, so methylated sterol precursors accumulate and ergosterol is depleted, weakening the fungal membrane. It covers Aspergillus and Candida and has more activity than other azoles against the moulds that cause mucormycosis. It is a strong CYP3A4 inhibitor.

- Posaconazole blocks fungal CYP51
- Ergosterol is depleted and methylated sterols build up
- Mould and yeast growth stops

## Pharmacokinetics

**Absorption**
Delayed-release tablets can be given with or without food; the oral suspension needs food and is not substitutable with the tablets.

**Distribution**
Large volume of distribution and over 98% protein-bound.

**Elimination**
Mostly in the stool, largely unchanged.

**Half-life**
Long, about a day.

## Indications

- Prevention of invasive Aspergillus infections in severely immunocompromised patients (stem cell transplant with graft-versus-host disease, haematological cancers with prolonged neutropenia). [Aspergillosis →](https://durgical.com/en/conditions/aspergillosis/)
- Prevention of invasive Candida infections in the same patients. [Candidiasis: oral, oesophageal and invasive →](https://durgical.com/en/conditions/candidiasis-oral-oesophageal-and-invasive/)
- Treatment of invasive aspergillosis; alternative in mucormycosis when amphotericin B is not tolerated. [Aspergillosis →](https://durgical.com/en/conditions/aspergillosis/)

## Adverse effects

### Common

- Diarrhoea
- Fever
- Nausea

### Serious (rare, important)

- QT prolongation and torsade de pointes
- Hepatic toxicity, including hepatitis
- Pseudoaldosteronism: hypertension and low potassium
- Calcineurin-inhibitor toxicity (nephrotoxicity, leukoencephalopathy) when combined
- Breakthrough fungal infections with severe diarrhoea or vomiting

## Contraindications

- Hypersensitivity to posaconazole or other azoles
- Sirolimus
- QT-prolonging CYP3A4 substrates such as pimozide and quinidine
- Statins cleared mainly by CYP3A4 (atorvastatin, lovastatin, simvastatin)
- Ergot alkaloids; venetoclax at initiation in chronic lymphocytic leukaemia

## Key interactions

**Sirolimus**
Contraindicated: sirolimus levels rise about nine-fold.

**Cyclosporine and tacrolimus**
Levels rise; dose reduction and frequent level checks.

**Midazolam**
Levels rise about five-fold: prolonged sedation.

**Vincristine**
Neurotoxicity (seizures, neuropathy, paralytic ileus); azoles are reserved for when no alternative exists.

**Statins cleared by CYP3A4**
Contraindicated: rhabdomyolysis.

## What is monitored

- Liver tests at the start and during treatment
- Potassium, magnesium and calcium; blood pressure
- Calcineurin-inhibitor levels if used together
- ECG in patients with arrhythmia risk

## Administration and safety

- Tablets, oral suspension, powder for suspension and injection have different strengths and doses and are not substitutable: check the exact form ordered.
- Delayed-release tablets are swallowed whole (not divided, crushed or chewed), with or without food.
- Correct electrolyte disturbances before and during treatment.

## Nursing care

- Report severe diarrhoea or vomiting: absorption falls and breakthrough infection can occur.
- Check blood pressure and potassium (pseudoaldosteronism).
- Teach signs of liver injury and palpitations or fainting.
- Watch sedation when benzodiazepines are also used.

## Pregnancy and breastfeeding

Animal studies showed skeletal malformations; used in pregnancy only if the benefit justifies the risk.

## Memory aid

«POSAconazole = PrOphylaxis + Superior Against mucor among azoles».

## Test yourself

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

## What is the main labelled use of posaconazole delayed-release tablets?

Prevention of invasive Aspergillus and Candida infections in severely immunocompromised patients, such as stem cell transplant recipients with graft-versus-host disease.

## Why is sirolimus contraindicated with posaconazole?

Posaconazole strongly inhibits CYP3A4 and sirolimus levels rise about nine-fold, causing toxicity.

## Can the oral suspension be swapped for the tablets at the same dose?

No. The formulations are dosed differently and are not substitutable.

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

## Related drugs

- [Voriconazole](https://durgical.com/en/pharmacology/voriconazole/)
- [Isavuconazole](https://durgical.com/en/pharmacology/isavuconazole/)
- [Itraconazole](https://durgical.com/en/pharmacology/itraconazole/)

## Related conditions

- [Aspergillosis](https://durgical.com/en/conditions/aspergillosis/)
- [Candidiasis: oral, oesophageal and invasive](https://durgical.com/en/conditions/candidiasis-oral-oesophageal-and-invasive/)

[← Back to the class: Azole antifungals](https://durgical.com/en/pharmacology/classes/azole-antifungals/)

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 - POSACONAZOLE tablet, delayed release](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=e0e8023a-3c82-e455-a57b-ccc0206ad156) (DailyMed (U.S. National Library of Medicine), 2026); [Posaconazole: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a607036.html) (MedlinePlus (U.S. National Library of Medicine), 2025); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 61 (McGraw Hill, 2023).

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Representative model, for educational purposes only.

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