Drug interactions
Ethotoin + Isoniazid
Severity: Moderate
Ethotoin and Isoniazid: moderate 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
Isoniazid inhibits hydantoin metabolism and can raise levels of phenytoin-type anticonvulsants, with toxicity reported mainly with phenytoin. Ethotoin is a related hydantoin so a similar rise in levels is possible, causing ataxia, nystagmus and sedation.
What this interaction means in plain words
Ethotoin and Isoniazid can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Why it happens
Isoniazid inhibits hepatic CYP-mediated metabolism of hydantoin anticonvulsants, extrapolated from phenytoin.
What to do
Monitor for ataxia, nystagmus and sedation and check seizure control; reduce ethotoin dose if signs of toxicity appear.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Isoniazid
Frequently asked questions
Can I take Ethotoin with Isoniazid?
MediHelp rates the interaction as moderate. Ethotoin and Isoniazid can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Isoniazid inhibits hydantoin metabolism and can raise levels of phenytoin-type anticonvulsants, with toxicity reported mainly with phenytoin. Ethotoin is a related hydantoin so a similar rise in levels is possible, causing ataxia, nystagmus and sedation.
How serious is the interaction between Ethotoin and Isoniazid?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for ataxia, nystagmus and sedation and check seizure control; reduce ethotoin dose if signs of toxicity appear.
What other medicines interact with Isoniazid?
MediHelp also lists interactions of Isoniazid with, for example, Bacillus calmette-guerin substrain tice, Benzhydrocodone / acetaminophen, Carbamazepine. The full list is on the Isoniazid page.
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