Isavuconazole !

Triazole for invasive aspergillosis and mucormycosis, given as the prodrug isavuconazonium. Unlike other azoles it shortens the QT interval.

Updated 2026-11-01

Class: Azole antifungals
Enzyme: Lanosterol 14α-demethylase (CYP51, the fungal ERG11 enzyme)
ATC code: J02AC05

Also called: isavuconazonium sulfate (prodrug)

Lanosterol 14α-demethylase (CYP51, the fungal ERG11 enzyme)Isavuconazole

The figure shows isavuconazole bound to CYP51 of the amoeba Acanthamoeba castellanii, the same sterol-demethylase site that the drug blocks in fungi.

Target in 3D: Lanosterol 14α-demethylase (CYP51, the fungal ERG11 enzyme). PDB structure 6UX0 (RCSB PDB, public domain). View the structure at RCSB PDB

Mechanism of action

Isavuconazonium is rapidly hydrolysed in the blood to isavuconazole, which inhibits fungal lanosterol 14α-demethylase like other triazoles. Its broad spectrum includes Aspergillus and the Mucorales. It is both a substrate and an inhibitor of CYP3A4.

The prodrug isavuconazonium becomes isavuconazole
Isavuconazole blocks fungal CYP51
Aspergillus and Mucorales stop growing

Pharmacokinetics

Absorption: Highly bioavailable by mouth; oral and intravenous forms are available, and the intravenous form contains no cyclodextrin.
Distribution: Over 99% protein-bound.
Metabolism: Liver, mainly CYP3A4 and CYP3A5; no dose change for kidney impairment.
Half-life: Very long, several days.

Indications

Invasive aspergillosis. Aspergillosis →
Invasive mucormycosis.

Adverse effects

Common

Nausea, vomiting, diarrhoea, constipation
Fever, headache, cough
Low potassium

Contraindications

Familial short QT syndrome
Allergy to isavuconazonium or other azoles
Use with St John's wort

Key interactions

Strong CYP3A4 inhibitors (for example ketoconazole): Isavuconazole exposure rises several-fold.
Rifampicin and St John's wort: Isavuconazole levels fall sharply and treatment may fail.
Midazolam and sirolimus: Their exposure increases.

What is monitored

Liver tests
Potassium
Heart rhythm in patients with arrhythmia risk

Administration and safety

Capsules are swallowed whole: not opened, chewed, dissolved or crushed.
Doses are written as isavuconazonium sulfate or as isavuconazole: check which the order uses.
Keep capsules in their blister with the desiccant until use.

Nursing care

Ask about a family history of short QT syndrome, arrhythmias or low potassium before starting.
Teach signs of liver injury and allergic reactions and to seek care at once.
Women should avoid pregnancy during treatment and for 28 days after the last dose.

Pregnancy and breastfeeding

May harm the fetus; pregnancy is avoided during treatment and for 28 days afterwards.

Test yourself

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

In which inherited condition is isavuconazole contraindicated, and why?

Familial short QT syndrome, because isavuconazole shortens the QT interval in a dose-related way.

What is isavuconazonium?

The water-soluble prodrug, rapidly hydrolysed to the active isavuconazole.

Besides aspergillosis, which serious mould infection is isavuconazole used for?

Invasive mucormycosis.

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Aspergillosis

← Back to the class: 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: Isavuconazonium: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2024); 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.