Drug interactions
Diazepam intranasal + Phenytoin
Severity: Moderate
Diazepam intranasal and Phenytoin: 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
Phenytoin induces enzymes that metabolize diazepam, which may reduce its effect in seizure rescue. Diazepam can also variably change phenytoin levels, and both depress the CNS.
What this interaction means in plain words
Diazepam intranasal and Phenytoin 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
Phenytoin induces CYP2C19 and CYP3A4, increasing diazepam clearance, with additive CNS depression.
What to do
Monitor seizure control and sedation, and be prepared to use further rescue measures if diazepam is ineffective. Check phenytoin levels if changes in toxicity or control occur.
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 Phenytoin
- Artemether / lumefantrine + Phenytoin Contraindicated
- Bictegravir + Phenytoin Contraindicated
- Cabotegravir + Phenytoin Contraindicated
- Doravirine + Phenytoin Contraindicated
- Elbasvir / grazoprevir + Phenytoin Contraindicated
- Elvitegravir / cobicistat / emtricitabine / tenofovir df + Phenytoin Contraindicated
Frequently asked questions
Can I take Diazepam intranasal with Phenytoin?
MediHelp rates the interaction as moderate. Diazepam intranasal and Phenytoin 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. Phenytoin induces enzymes that metabolize diazepam, which may reduce its effect in seizure rescue. Diazepam can also variably change phenytoin levels, and both depress the CNS.
How serious is the interaction between Diazepam intranasal and Phenytoin?
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 seizure control and sedation, and be prepared to use further rescue measures if diazepam is ineffective. Check phenytoin levels if changes in toxicity or control occur.
What other medicines interact with Phenytoin?
MediHelp also lists interactions of Phenytoin with, for example, Artemether / lumefantrine, Bictegravir, Cabotegravir. The full list is on the Phenytoin page.
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