Key points
- Isavuconazole can interact with other medicines, but its interaction profile is often less complex than older azoles.
- It mainly interacts through CYP3A4.
- Some medicines can increase isavuconazole levels, while others can reduce its effectiveness.
- It has an important difference from some other azoles: it can shorten the QT interval.
- It is still essential to check new medicines carefully.
What is isavuconazole?
Isavuconazole is a newer azole antifungal used in invasive aspergillosis and some other serious fungal infections. It is often seen as having a more predictable interaction profile than some older azoles, but it still has important interactions.
Why isavuconazole interacts with other medicines
Isavuconazole is mainly linked to CYP3A4. This means some medicines can become stronger when combined with it, while other medicines can lower isavuconazole levels and reduce its effectiveness.
The interaction groups most likely to matter
Medicines that reduce isavuconazole effectiveness
Some medicines, including rifampicin-type antibiotics and certain anti-seizure drugs, can lower isavuconazole levels and may make treatment ineffective.
Steroids
Some steroid levels may rise with isavuconazole, although the interaction pattern is often less intense than with some older azoles.
Immunosuppressants
Medicines such as tacrolimus and ciclosporin may increase and usually need specialist review and monitoring.
Blood thinners
Some blood thinners may become stronger, increasing bleeding risk.
Statins
Some statin levels may increase, which can raise the risk of muscle side effects.
Important isavuconazole-specific points
QT shortening
Unlike several other azole antifungals, isavuconazole can shorten the QT interval. This is an important difference and should be considered when other heart medicines are being reviewed.
Generally simpler interaction profile
Compared with itraconazole and voriconazole, isavuconazole is often considered a little easier to manage in patients taking several medicines, although checks are still essential.
What patients should do in practice
- Tell your pharmacist or clinician if you are taking isavuconazole.
- Check before starting prescription, over-the-counter, or herbal medicines.
- Ask specifically about anti-seizure drugs, antibiotics, blood thinners, and heart medicines.
- Do not stop or change medicines without advice.
When to seek medical advice
Seek medical advice urgently for severe bleeding, fainting, severe palpitations, severe muscle pain, or rapid worsening after a medicine change.
Important
This page is educational and not a complete interaction database. For a full check, use the BNF interaction checker or speak to a pharmacist or clinician.
References
- BNF: isavuconazole monograph and interactions
- UK isavuconazole SmPCs – not available
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