Isavuconazole: Uses, Interactions and Safety

Uses

Isavuconazole treats invasive aspergillosis and, in the European indication, mucormycosis when amphotericin B is inappropriate. It is delivered as the prodrug isavuconazonium sulfate. These serious infections need specialist diagnosis and follow-up; the capsule and intravenous products have different age and weight eligibility requirements.

Administration

Capsules are swallowed whole and may be taken with or without food. Intravenous treatment requires preparation, dilution and infusion by professionals. The prescriber chooses the form and duration and may switch between suitable products. Do not interpret the amount of prodrug salt as the same numerical amount of active isavuconazole.

Safety

Unlike many other azole antifungals, isavuconazole shortens the QT interval. It is contraindicated in familial short QT syndrome. Liver tests may be needed. Severe rash, jaundice, fainting, palpitations or an allergic reaction require urgent assessment. Breathlessness, dizziness or low blood pressure during an infusion should be reported immediately.

Interactions

Isavuconazole moderately inhibits CYP3A4 and can raise concentrations of tacrolimus, ciclosporin and other susceptible medicines. Digoxin, dabigatran, colchicine and metformin may need monitoring or adjustment. Rifampicin, rifabutin, carbamazepine and phenytoin are prohibited combinations because antifungal exposure can fall substantially. High-dose ritonavir is also prohibited; this restriction should not be applied blindly to every ritonavir regimen.

Pregnancy and breastfeeding

Pregnancy use is reserved for severe or potentially life-threatening infection when the expected benefit outweighs fetal risk. Effective contraception should be discussed. The European information advises stopping breastfeeding during treatment.

Adverse effects

Nausea, vomiting, diarrhoea, abdominal pain, headache, rash, low potassium and abnormal liver tests are reported. Turkish medical-society teaching material corroborates the active ingredient, oral and intravenous routes and QT shortening; it does not establish Turkish marketing authorisation or current availability.

Sources

• CRESEMBA: EMA product information, summary of product characteristics
• Turkish infectious-disease society: invasive aspergillosis update
• KERENDIA: EMA Summary of Product Characteristics
• Lurasidone 18.5 mg film-coated tablets: SmPC
• XTANDI (enzalutamide): EMA product information
• ERLEADA (apalutamide): EMA product information
• INSPRA (eplerenone): US prescribing information