Drug interactions
Isavuconazonium + Ritonavir
Severity: Major
Isavuconazonium and Ritonavir: major interaction.
Last updated Sources: US FDA label
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Ritonavir increases isavuconazole exposure, raising the risk of adverse effects. High-dose ritonavir may also lower exposure to other antiretrovirals taken with it, and isavuconazole itself can alter concentrations of ritonavir-boosted drugs.
What this interaction means in plain words
Isavuconazonium and Ritonavir can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Isavuconazonium belongs to Anti Fungals; Ritonavir belongs to Anti Virals.
Why it happens
Ritonavir inhibits CYP3A4, the main metabolic pathway of isavuconazole, while isavuconazole may induce or modulate other enzymes affecting protease inhibitor levels.
What to do
Avoid the combination with high-dose ritonavir where possible. If it is used, monitor for azole toxicity, including hepatic effects, and track antiretroviral concentrations and virologic response.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
Other interactions of Isavuconazonium
- Amobarbital + Isavuconazonium Contraindicated
- Apalutamide + Isavuconazonium Contraindicated
- Carbamazepine + Isavuconazonium Contraindicated
- Cisapride + Isavuconazonium Contraindicated
- Efavirenz + Isavuconazonium Contraindicated
- Enzalutamide + Isavuconazonium Contraindicated
Other interactions of Ritonavir
- Alfuzosin + Ritonavir Contraindicated
- Amiodarone + Ritonavir Contraindicated
- Avanafil + Ritonavir Contraindicated
- Colchicine + Ritonavir Contraindicated
- Dronedarone + Ritonavir Contraindicated
- Eletriptan + Ritonavir Contraindicated
Frequently asked questions
Can I take Isavuconazonium with Ritonavir?
MediHelp rates the interaction as major. Isavuconazonium and Ritonavir can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Ritonavir increases isavuconazole exposure, raising the risk of adverse effects. High-dose ritonavir may also lower exposure to other antiretrovirals taken with it, and isavuconazole itself can alter concentrations of ritonavir-boosted drugs.
How serious is the interaction between Isavuconazonium and Ritonavir?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination with high-dose ritonavir where possible. If it is used, monitor for azole toxicity, including hepatic effects, and track antiretroviral concentrations and virologic response.
What other medicines interact with Isavuconazonium?
MediHelp also lists interactions of Isavuconazonium with, for example, Amobarbital, Apalutamide, Carbamazepine. The full list is on the Isavuconazonium page.
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