Drug interactions
Phenytoin + Secobarbital
Severity: Moderate
Phenytoin and Secobarbital: 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
Barbiturates have variable effects on phenytoin levels, with induction lowering and competition for metabolism sometimes raising them. Both drugs also cause CNS depression, and changes in either can affect seizure control or cause toxicity.
What this interaction means in plain words
Phenytoin and Secobarbital 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 belongs to Central Nervous System; Secobarbital belongs to Central Nervous System.
Why it happens
Barbiturate induction of CYP2C9/2C19 may increase phenytoin clearance, with possible competitive metabolic inhibition and additive CNS depression.
What to do
Monitor serum phenytoin concentrations when starting, stopping or changing the barbiturate dose. Adjust the phenytoin dose accordingly and watch for sedation.
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 Secobarbital
- Calcium / magnesium / potassium / sodium oxybates + Secobarbital Contraindicated
- Doravirine + Secobarbital Contraindicated
- Elbasvir / grazoprevir + Secobarbital Contraindicated
- Elvitegravir / cobicistat / emtricitabine / tenofovir df + Secobarbital Contraindicated
- Isavuconazonium + Secobarbital Contraindicated
- Lonafarnib + Secobarbital Contraindicated
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 Phenytoin with Secobarbital?
MediHelp rates the interaction as moderate. Phenytoin and Secobarbital 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. Barbiturates have variable effects on phenytoin levels, with induction lowering and competition for metabolism sometimes raising them. Both drugs also cause CNS depression, and changes in either can affect seizure control or cause toxicity.
How serious is the interaction between Phenytoin and Secobarbital?
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 serum phenytoin concentrations when starting, stopping or changing the barbiturate dose. Adjust the phenytoin dose accordingly and watch for sedation.
What other medicines interact with Secobarbital?
MediHelp also lists interactions of Secobarbital with, for example, Calcium / magnesium / potassium / sodium oxybates, Doravirine, Elbasvir / grazoprevir. The full list is on the Secobarbital page.
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