Drug interactions
Ethotoin + Voriconazole
Severity: Major
Ethotoin and Voriconazole: major interaction.
Last updated
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
Ethotoin is a hydantoin related to phenytoin, which strongly lowers voriconazole levels. Voriconazole may in turn raise hydantoin concentrations. The combination could cause loss of antifungal efficacy and hydantoin toxicity, though data for ethotoin itself are limited.
What this interaction means in plain words
Ethotoin and Voriconazole 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.
Why it happens
Hydantoins are suspected to induce voriconazole metabolism via CYP enzymes, while voriconazole inhibits CYP2C9/2C19 metabolism of hydantoins; this is extrapolated from phenytoin.
What to do
Avoid the combination where possible; if used, monitor voriconazole trough levels and for ataxia, nystagmus or sedation, and adjust doses accordingly.
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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Other interactions of Voriconazole
- Avanafil + Voriconazole Contraindicated
- Butabarbital + Voriconazole Contraindicated
- Carbamazepine + Voriconazole Contraindicated
- Conivaptan + Voriconazole Contraindicated
- Dihydroergotamine intranasal + Voriconazole Contraindicated
- Dihydroergotamine + Voriconazole Contraindicated
Frequently asked questions
Can I take Ethotoin with Voriconazole?
MediHelp rates the interaction as major. Ethotoin and Voriconazole 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. Ethotoin is a hydantoin related to phenytoin, which strongly lowers voriconazole levels. Voriconazole may in turn raise hydantoin concentrations. The combination could cause loss of antifungal efficacy and hydantoin toxicity, though data for ethotoin itself are limited.
How serious is the interaction between Ethotoin and Voriconazole?
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 where possible; if used, monitor voriconazole trough levels and for ataxia, nystagmus or sedation, and adjust doses accordingly.
What other medicines interact with Voriconazole?
MediHelp also lists interactions of Voriconazole with, for example, Avanafil, Butabarbital, Carbamazepine. The full list is on the Voriconazole page.
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