Ribociclib and Amitriptyline: 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
Ribociclib
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.
Both of these medicines can affect your heart's rhythm. Amitriptyline (Elavil), an older antidepressant, and ribociclib (Kisqali), a breast cancer medicine, can each stretch out a part of your heartbeat called the QT interval. When you take them together, that effect can add up and, in rare cases, lead to a dangerous irregular heartbeat.
The good news is that this risk is manageable. Your care team can keep an eye on your heart with an ECG and adjust things as needed. Please don't stop or change either medicine on your own. Just talk with your doctor or pharmacist so they can make sure this combination is safe for you.
Effect: Additive QT interval prolongation with concurrent amitriptyline (a TCA with known QT-prolonging potential) and ribociclib (a CDK4/6 inhibitor with a documented QT effect).
- Mechanism: Additive/pharmacodynamic QT prolongation; neither is a prodrug.
- Direction: Increased arrhythmia risk (TdP potential).
- Evidence: Theoretical; severity rated major.
- Management: Avoid coadministration if possible. If unavoidable, obtain baseline ECG and electrolytes, monitor ECG at initiation and periodically. Follow ribociclib dose-interruption/reduction thresholds: interrupt if QTcF >480 ms; permanently discontinue if QTcF >500 ms or >60 ms change with syncope/TdP/serious arrhythmia.
What happens
An increased risk of QT interval prolongation
Interaction Deep Dive
Do not give ribociclib together with drugs recognized as capable of prolonging the QT interval, since this combination may worsen QT interval prolongation. Should simultaneous use be unavoidable, obtain ECG monitoring at the start of therapy, throughout concurrent use, and whenever otherwise indicated. If QTcF (QT interval corrected using the Fridericia formula) prolongation exceeds 480 ms but remains at or below 500 ms: For early breast cancer, hold ribociclib until the QTcF returns to below 480 ms, then restart at the identical dose. For advanced or metastatic breast cancer, hold ribociclib until the QTcF drops below 480 ms, then decrease to the next lower dose level; if QTcF greater than 480 ms happens again, hold ribociclib until QTcF falls below 480 ms and then restart at the next lower dose level. If QTcF prolongation is greater than 500 ms: hold ribociclib until QTcF returns to under 480 ms, then resume at the next lower dose level; should QTcF greater than 500 ms recur, stop ribociclib. Discontinue ribociclib permanently if the QTcF interval prolongation is either above 500 ms or a change of more than 60 ms from baseline together with any of the following: torsade's de pointes, polymorphic ventricular tachycardia, syncope, or signs/symptoms of serious arrhythmia. Ribociclib should be discontinued if a dose reduction to below 200 mg/day becomes necessary1.
Why it happens (mechanism)
Additive QT interval prolongation
How to manage this interaction
What your care team may do:
- Where possible, they may choose an alternative to one of these medicines to avoid combining two QT-prolonging drugs.
- If both are needed, they will typically check an ECG before starting, during treatment, and as needed.
- They may interrupt, lower, or in some cases adjust the ribociclib dose based on your ECG results, individualized by your team.
- They may check and correct electrolytes (like potassium and magnesium).
What you can do: Keep taking both exactly as prescribed unless told otherwise. Report fainting, dizziness, palpitations, or a racing/irregular heartbeat right away, and confirm the plan with your pharmacist or prescriber.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Ribociclib and Amitriptyline together?
Amitriptyline and ribociclib can both prolong the QT interval, so together they raise the risk of a dangerous heart rhythm; your care team will try to avoid the combination or monitor your heart with ECGs and adjust ribociclib if needed. Don't change either medicine on your own. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Ribociclib and Amitriptyline 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 Ribociclib and Amitriptyline interaction managed?
What your care team may do: Where possible, they may choose an alternative to one of these medicines to avoid combining two QT-prolonging drugs. If both are needed, they will typically check an ECG before starting, during treatment, and as needed. They may interrupt, lower, or in some cases adjust the ribociclib dose based on your ECG results, individualized by your team. They may check and correc… 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 Ribociclib or Amitriptyline 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: KISQALI(R) oral tablets, ribociclib oral tablets. Novartis Pharmaceuticals Corporation (per FDA), East Hanover, NJ, 2025. DailyMed
Keep reading about Amitriptyline
Keep reading about Ribociclib
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