Drug interactions
Ketoconazole + Primidone
Severity: Moderate
Ketoconazole 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, which is partly converted to phenobarbital, induces hepatic and intestinal enzymes and can substantially lower systemic ketoconazole exposure. This may lead to subtherapeutic antifungal levels and treatment failure in systemic infections or in conditions such as Cushing syndrome.
What this interaction means in plain words
Ketoconazole 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.
Ketoconazole belongs to Anti Fungals; Primidone belongs to Central Nervous System.
Why it happens
Induction of CYP3A4 by primidone and its phenobarbital metabolite increases ketoconazole clearance.
What to do
Monitor clinical response and consider ketoconazole levels or an alternative antifungal if efficacy is lost. Prefer a non-inducing anticonvulsant where feasible.
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 Ketoconazole
- Alfuzosin + Ketoconazole Contraindicated
- Alprazolam + Ketoconazole Contraindicated
- Avanafil + Ketoconazole Contraindicated
- Conivaptan + Ketoconazole Contraindicated
- Dihydroergotamine intranasal + Ketoconazole Contraindicated
- Dihydroergotamine + Ketoconazole Contraindicated
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 Ketoconazole with Primidone?
MediHelp rates the interaction as moderate. Ketoconazole 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, which is partly converted to phenobarbital, induces hepatic and intestinal enzymes and can substantially lower systemic ketoconazole exposure. This may lead to subtherapeutic antifungal levels and treatment failure in systemic infections or in conditions such as Cushing syndrome.
How serious is the interaction between Ketoconazole 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 ketoconazole levels or an alternative antifungal if efficacy is lost. Prefer a non-inducing anticonvulsant where feasible.
What other medicines interact with Ketoconazole?
MediHelp also lists interactions of Ketoconazole with, for example, Alfuzosin, Alprazolam, Avanafil. The full list is on the Ketoconazole page.
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