Drug interactions
Primidone + Simvastatin
Severity: Moderate
Primidone and Simvastatin: 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 partly to phenobarbital, which induces CYP3A4 and lowers simvastatin concentrations. This can lead to reduced lipid-lowering efficacy.
What this interaction means in plain words
Primidone and Simvastatin 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; Simvastatin belongs to Cardiovascular.
Why it happens
Primidone and its metabolite phenobarbital induce CYP3A4, accelerating simvastatin metabolism.
What to do
Check lipid levels after starting or stopping primidone, and raise the statin dose or choose a statin not dependent on CYP3A4 if control is inadequate.
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 Simvastatin
- Atazanavir + Simvastatin Contraindicated
- Clarithromycin + Simvastatin Contraindicated
- Cobicistat + Simvastatin Contraindicated
- Cyclosporine + Simvastatin Contraindicated
- Cyclosporin + Simvastatin Contraindicated
- Danazol + Simvastatin 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 Primidone with Simvastatin?
MediHelp rates the interaction as moderate. Primidone and Simvastatin 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 partly to phenobarbital, which induces CYP3A4 and lowers simvastatin concentrations. This can lead to reduced lipid-lowering efficacy.
How serious is the interaction between Primidone and Simvastatin?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check lipid levels after starting or stopping primidone, and raise the statin dose or choose a statin not dependent on CYP3A4 if control is inadequate.
What other medicines interact with Simvastatin?
MediHelp also lists interactions of Simvastatin with, for example, Atazanavir, Clarithromycin, Cobicistat. The full list is on the Simvastatin page.
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