Drug interactions
Diltiazem + Ranolazine
Severity: Major
Diltiazem and Ranolazine: major interaction.
Last updated Sources: US FDA label
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
Diltiazem markedly raises ranolazine exposure, which increases dose-related QT prolongation, dizziness, nausea and constipation. Labeling limits the ranolazine dose with moderate CYP3A inhibitors.
What this interaction means in plain words
Diltiazem and Ranolazine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Diltiazem belongs to Cardiovascular; Ranolazine belongs to Cardiovascular.
Why it happens
Diltiazem inhibits CYP3A4 (and P-glycoprotein), reducing ranolazine clearance.
What to do
Limit ranolazine to 500 mg twice daily with diltiazem and titrate only per tolerance. Monitor ECG and symptoms such as dizziness and bradycardia.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
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 Ranolazine
- Adagrasib + Ranolazine Contraindicated
- Amobarbital + Ranolazine Contraindicated
- Apalutamide + Ranolazine Contraindicated
- Butabarbital + Ranolazine Contraindicated
- Carbamazepine + Ranolazine Contraindicated
- Clarithromycin + Ranolazine Contraindicated
Frequently asked questions
Can I take Diltiazem with Ranolazine?
MediHelp rates the interaction as major. Diltiazem and Ranolazine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Diltiazem markedly raises ranolazine exposure, which increases dose-related QT prolongation, dizziness, nausea and constipation. Labeling limits the ranolazine dose with moderate CYP3A inhibitors.
How serious is the interaction between Diltiazem and Ranolazine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Limit ranolazine to 500 mg twice daily with diltiazem and titrate only per tolerance. Monitor ECG and symptoms such as dizziness and bradycardia.
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.
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