Drug interactions
Itraconazole + Ritonavir
Severity: Major
Itraconazole 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 strongly inhibits CYP3A4 and raises itraconazole concentrations. Itraconazole may also raise ritonavir levels, and higher itraconazole exposure can increase the risk of toxicity such as edema, heart failure exacerbation and hepatotoxicity.
What this interaction means in plain words
Itraconazole 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.
Itraconazole belongs to Anti Fungals; Ritonavir belongs to Anti Virals.
Why it happens
Inhibition of CYP3A4-mediated itraconazole metabolism by ritonavir, with reciprocal inhibition.
What to do
Limit itraconazole to no more than 200 mg/day with ritonavir. Monitor for itraconazole toxicity and consider measuring itraconazole levels.
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 Itraconazole
- Alfuzosin + Itraconazole Contraindicated
- Alprazolam + Itraconazole Contraindicated
- Avanafil + Itraconazole Contraindicated
- Conivaptan + Itraconazole Contraindicated
- Dihydroergotamine intranasal + Itraconazole Contraindicated
- Dihydroergotamine + Itraconazole 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 Itraconazole with Ritonavir?
MediHelp rates the interaction as major. Itraconazole 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 strongly inhibits CYP3A4 and raises itraconazole concentrations. Itraconazole may also raise ritonavir levels, and higher itraconazole exposure can increase the risk of toxicity such as edema, heart failure exacerbation and hepatotoxicity.
How serious is the interaction between Itraconazole 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: Limit itraconazole to no more than 200 mg/day with ritonavir. Monitor for itraconazole toxicity and consider measuring itraconazole levels.
What other medicines interact with Itraconazole?
MediHelp also lists interactions of Itraconazole with, for example, Alfuzosin, Alprazolam, Avanafil. The full list is on the Itraconazole page.
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