Drug interactions
Primidone + Zonisamide
Severity: Moderate
Primidone and Zonisamide: 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 metabolized to phenobarbital, an enzyme inducer that can lower zonisamide exposure. Reduced anticonvulsant effect and additive sedation may result.
What this interaction means in plain words
Primidone and Zonisamide 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 belongs to Central Nervous System; Zonisamide belongs to Central Nervous System.
Why it happens
Primidone and its metabolite phenobarbital induce CYP3A4, accelerating zonisamide clearance.
What to do
Monitor seizure frequency and sedation, and adjust zonisamide dose to response. Recheck dosing when primidone is started, changed or withdrawn.
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 Zonisamide
- Zonisamide + Zuranolone Major
- Acetazolamide + Zonisamide Moderate
- Amisulpride + Zonisamide Moderate
- Amobarbital + Zonisamide Moderate
- Apalutamide + Zonisamide Moderate
- Asenapine transdermal + Zonisamide Moderate
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 Primidone with Zonisamide?
MediHelp rates the interaction as moderate. Primidone and Zonisamide 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 metabolized to phenobarbital, an enzyme inducer that can lower zonisamide exposure. Reduced anticonvulsant effect and additive sedation may result.
How serious is the interaction between Primidone and Zonisamide?
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 frequency and sedation, and adjust zonisamide dose to response. Recheck dosing when primidone is started, changed or withdrawn.
What other medicines interact with Zonisamide?
MediHelp also lists interactions of Zonisamide with, for example, Zuranolone, Acetazolamide, Amisulpride. The full list is on the Zonisamide page.
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