Drug interactions
Diltiazem + Primidone
Severity: Moderate
Diltiazem 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 converted to phenobarbital and induces CYP3A4, which can lower diltiazem concentrations. Reduced diltiazem effect may lead to loss of blood pressure or angina and rate control.
What this interaction means in plain words
Diltiazem 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.
Diltiazem belongs to Cardiovascular; Primidone belongs to Central Nervous System.
Why it happens
Induction of CYP3A4 by primidone and its metabolite phenobarbital increases diltiazem clearance.
What to do
Monitor blood pressure, heart rate and symptoms and increase the diltiazem dose if needed, or choose an alternative agent. Reassess if primidone is stopped because diltiazem levels will rise.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Diltiazem and Primidone, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 7 days on the web. No card needed.
Other interactions of Diltiazem
- Diltiazem + Flibanserin Contraindicated
- Diltiazem + Ivabradine Contraindicated
- Diltiazem + Lomitapide Contraindicated
- Diltiazem + Lonafarnib Contraindicated
- Acebutolol + Diltiazem Major
- Alfentanil + Diltiazem 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 Diltiazem with Primidone?
MediHelp rates the interaction as moderate. Diltiazem 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 converted to phenobarbital and induces CYP3A4, which can lower diltiazem concentrations. Reduced diltiazem effect may lead to loss of blood pressure or angina and rate control.
How serious is the interaction between Diltiazem 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 blood pressure, heart rate and symptoms and increase the diltiazem dose if needed, or choose an alternative agent. Reassess if primidone is stopped because diltiazem levels will rise.
What other medicines interact with Diltiazem?
MediHelp also lists interactions of Diltiazem with, for example, Flibanserin, Ivabradine, Lomitapide. The full list is on the Diltiazem page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
