Drug interactions
Ethosuximide + Primidone
Severity: Moderate
Ethosuximide and Primidone: 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
Primidone is metabolised to phenobarbital, a CYP3A4 inducer that can lower ethosuximide concentrations. Reports also describe variable effects on primidone levels, so seizure control may fluctuate.
What this interaction means in plain words
Ethosuximide and Primidone 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.
Ethosuximide belongs to Central Nervous System; Primidone belongs to Central Nervous System.
Why it happens
Phenobarbital derived from primidone induces hepatic CYP3A4, increasing ethosuximide clearance.
What to do
Monitor ethosuximide serum levels and seizure control when starting or changing primidone. Raise the ethosuximide dose as needed.
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 Ethosuximide
- Benzhydrocodone / acetaminophen + Ethosuximide Major
- Buprenorphine long-acting + Ethosuximide Major
- Buprenorphine subdermal implant + Ethosuximide Major
- Buprenorphine transdermal + Ethosuximide Major
- Calcium / magnesium / potassium / sodium oxybates + Ethosuximide Major
- Ethosuximide + Fentanyl intranasal Major
Other interactions of Primidone
- Lorlatinib + Primidone Contraindicated
- Lurasidone + Primidone Contraindicated
- Primidone + Ranolazine Contraindicated
- Primidone + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
- Primidone + Voriconazole Contraindicated
- Abiraterone + Primidone Major
Frequently asked questions
Can I take Ethosuximide with Primidone?
MediHelp rates the interaction as moderate. Ethosuximide and Primidone 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. Primidone is metabolised to phenobarbital, a CYP3A4 inducer that can lower ethosuximide concentrations. Reports also describe variable effects on primidone levels, so seizure control may fluctuate.
How serious is the interaction between Ethosuximide and Primidone?
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 ethosuximide serum levels and seizure control when starting or changing primidone. Raise the ethosuximide dose as needed.
What other medicines interact with Ethosuximide?
MediHelp also lists interactions of Ethosuximide with, for example, Benzhydrocodone / acetaminophen, Buprenorphine long-acting, Buprenorphine subdermal implant. The full list is on the Ethosuximide page.
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