Drug interactions
Diltiazem + Simvastatin
Severity: Major
Diltiazem and Simvastatin: 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 increases simvastatin exposure. This raises the risk of myopathy and rhabdomyolysis.
What this interaction means in plain words
Diltiazem and Simvastatin 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; Simvastatin belongs to Cardiovascular.
Why it happens
Inhibition of CYP3A4 reduces first-pass metabolism of simvastatin.
What to do
Keep simvastatin at or below the labeled maximum dose with diltiazem, or switch to a statin not metabolized by CYP3A4 such as rosuvastatin or pravastatin. Counsel patients to report unexplained muscle symptoms.
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 Simvastatin
- Atazanavir + Simvastatin Contraindicated
- Clarithromycin + Simvastatin Contraindicated
- Cobicistat + Simvastatin Contraindicated
- Cyclosporin + Simvastatin Contraindicated
- Danazol + Simvastatin Contraindicated
- Darunavir + Simvastatin Contraindicated
Frequently asked questions
Can I take Diltiazem with Simvastatin?
MediHelp rates the interaction as major. Diltiazem and Simvastatin 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 increases simvastatin exposure. This raises the risk of myopathy and rhabdomyolysis.
How serious is the interaction between Diltiazem and Simvastatin?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Keep simvastatin at or below the labeled maximum dose with diltiazem, or switch to a statin not metabolized by CYP3A4 such as rosuvastatin or pravastatin. Counsel patients to report unexplained muscle symptoms.
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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