Amitriptyline and Ranolazine: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 2, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Amitriptyline
Ranolazine
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
You've been prescribed amitriptyline (an antidepressant that also helps with things like nerve pain and sleep) and ranolazine (for chest pain, or angina). Here's the plain-English version: ranolazine can slow down the liver enzyme that clears amitriptyline from your body. That means amitriptyline levels can build up higher than usual.
When that happens, you may notice more of amitriptyline's side effects, like drowsiness, dry mouth, or dizziness. Both drugs can also affect your heart's rhythm, so together they may nudge that risk a little higher. The good news: this is something your care team can manage easily by adjusting your dose and keeping an eye on how you're doing. Don't change anything on your own, just talk with your pharmacist or doctor.
Effect: Increased tricyclic exposure. Ranolazine inhibits CYP2D6, the primary enzyme metabolizing amitriptyline, reducing clearance and raising amitriptyline (and metabolite) plasma concentrations. Amitriptyline is an active drug, not a prodrug, so inhibition increases its pharmacologic effect.
- Direction: Elevated TCA exposure, greater anticholinergic/sedative burden.
- Additive risk: Both agents prolong the QT interval; higher TCA levels may compound this.
- Evidence: Theoretical; magnitude not quantified.
- Onset: Unspecified.
- Management: Lower TCA doses may be required. Consider ECG monitoring, correct electrolytes, and monitor for anticholinergic and cardiac effects.
What happens
Increased tricyclic antidepressant exposure
Interaction Deep Dive
When ranolazine is given together with tricyclic antidepressants (which are CYP2D6 substrates) that prolong the QT interval, exposure to the tricyclic antidepressants may rise, and this in turn may heighten QT interval prolongation. As a result, reduced doses of the tricyclic antidepressants may be needed1.
Why it happens (mechanism)
Inhibition of CYP2D6-mediated metabolism by ranolazine
How to manage this interaction
This combination can be managed. Your care team may take a few steps:
- The amitriptyline dose may need to be adjusted and individualized by your prescriber, since ranolazine can raise its levels.
- Your team may monitor you more closely, which can include checking your heart rhythm (ECG) since both drugs can affect the QT interval.
- Watch for increased side effects like strong drowsiness, dry mouth, dizziness, or a racing/irregular heartbeat.
What you should do: Keep taking both medicines exactly as prescribed unless told otherwise. Report any new symptoms, and ask your pharmacist or doctor before making any changes.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) In a drug interaction study, giving ranolazine 750 mg twice daily together with a single dose of immediate release metoprolol (100 mg), a CYP2D6 substrate, produced an 80% increase in metoprolol exposure among extensive CYP2D6 metabolizers, with no requirement to adjust the metoprolol dose. Among extensive metabolizers of dextromethorphan, a CYP2D6 substrate, ranolazine partially inhibits the formation of the principal metabolite dextrorphan 1.
Common questions
Can I take Amitriptyline and Ranolazine together?
Ranolazine can raise amitriptyline levels and add to QT-prolongation risk, so your amitriptyline dose may need lowering and your heart rhythm watched. Keep taking both as prescribed and check with your pharmacist or doctor. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Amitriptyline and Ranolazine interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How is the Amitriptyline and Ranolazine interaction managed?
This combination can be managed. Your care team may take a few steps: The amitriptyline dose may need to be adjusted and individualized by your prescriber, since ranolazine can raise its levels. Your team may monitor you more closely, which can include checking your heart rhythm (ECG) since both drugs can affect the QT interval. Watch for increased side effects like strong drowsiness, dry mouth, d… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Amitriptyline or Ranolazine need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (1)
- Product Information: RANOLAZINE oral extended-release tablets, ranolazine oral extended-release tablets. Viona Pharmaceuticals Inc. (per Dailymed), Cranford, NJ, 2023. DailyMed
Keep reading about Amitriptyline
Keep reading about Ranolazine
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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