Drug interactions
Olanzapine + Primidone
Severity: Moderate
Olanzapine 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, partly converted to phenobarbital, induces hepatic enzymes and can lower olanzapine concentrations, possibly reducing antipsychotic efficacy. Both drugs are also sedating, so additive drowsiness can occur.
What this interaction means in plain words
Olanzapine 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.
Olanzapine belongs to Central Nervous System; Primidone belongs to Central Nervous System.
Why it happens
Enzyme induction (including CYP1A2 and UGT) by primidone and phenobarbital increases olanzapine clearance, plus additive CNS depression.
What to do
Monitor clinical response and consider increasing olanzapine dose, with levels if available. Check for sedation and reduce olanzapine if primidone is stopped.
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 Olanzapine
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 Olanzapine with Primidone?
MediHelp rates the interaction as moderate. Olanzapine 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, partly converted to phenobarbital, induces hepatic enzymes and can lower olanzapine concentrations, possibly reducing antipsychotic efficacy. Both drugs are also sedating, so additive drowsiness can occur.
How serious is the interaction between Olanzapine 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 clinical response and consider increasing olanzapine dose, with levels if available. Check for sedation and reduce olanzapine if primidone is stopped.
What other medicines interact with Olanzapine?
MediHelp also lists interactions of Olanzapine with, for example, Amisulpride, Amoxapine, Apomorphine. The full list is on the Olanzapine page.
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