Lorcainide 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
Lorcainide
No brand names on record
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) is an antidepressant, and lorcainide is a heart rhythm medicine. Each one on its own can slightly stretch out a part of your heartbeat called the QT interval. When you take them together, those effects can add up, which in rare cases could lead to a dangerous irregular heartbeat.
This concern is based on how these drugs work rather than on specific studies, so please don't panic. If you've been prescribed both, keep taking them as directed and talk with your pharmacist or doctor. Your care team can watch your heart closely or adjust things to keep you safe.
Effect: Additive QT prolongation, increasing the theoretical risk of torsades de pointes and cardiac arrest.
Mechanism: Both agents independently prolong the QTc interval. Lorcainide is a Class I antiarrhythmic; amitriptyline is a TCA with known QT effects. The interaction is pharmacodynamic (additive), not primarily metabolic.
- Direction: Enhanced cardiotoxicity (increased combined QT effect).
- Onset: Unspecified.
- Evidence: Theoretical; no formal interaction studies.
- Management: Coadministration not recommended. If unavoidable, obtain baseline and follow-up ECGs, monitor electrolytes (K+, Mg2+), and dose should be individualized by the care team.
What happens
An increased risk of cardiotoxicity (QT prolongation, torsades de pointes, cardiac arrest)
Interaction Deep Dive
At recommended therapeutic doses, Class I antiarrhythmics have demonstrated the ability to lengthen the QTc interval. Although no formal studies of drug interactions have been performed, giving Class I antiarrhythmics together with other agents recognized to prolong the QTc interval, such as tricyclic antidepressants, is not advised345.
Why it happens (mechanism)
Additive effects on QT prolongation
How to manage this interaction
Combining these two is generally not recommended because their heart-rhythm effects can add together.
- Keep taking both exactly as prescribed unless your doctor tells you otherwise. Do not stop either one on your own.
- Ask your pharmacist or prescriber whether this combination is right for you, or whether an alternative to one drug might be safer.
- Your care team may check your heart with an ECG and review your blood minerals (like potassium and magnesium), and may monitor you more closely.
- Report symptoms like fainting, dizziness, palpitations, or a racing/irregular heartbeat right away.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
2 reports — tap to read
a) Electrocardiographic changes documented in patients taking therapeutic doses of tricyclic antidepressants include an elevated heart rate, lengthened PR interval, delays in intraventricular conduction, a longer corrected QT interval (QTc), and flattened T waves 1.
b) A 68-year-old man with agitated major depression was started on desipramine 125 mg per day, which yielded a subtherapeutic serum concentration of 442 nmol/L (therapeutic range = 500 to 1000 nmol/L). Raising the dose to 175 mg daily led to an excellent clinical response without adverse effects. He then developed atrial fibrillation and flutter. Digoxin 0.25 mg daily was added to his regimen, and desipramine was stopped. His arrhythmia was controlled with the addition of propafenone 150 mg twice daily plus 300 mg at bedtime. Desipramine 150 mg daily was restarted, at which time he had dry mouth, sedation, and shakiness; the desipramine serum level was found to be 2092 nmol/L. Desipramine was withheld for five days, the adverse effects resolved, and desipramine was reintroduced at 75 mg daily. The desipramine serum level was then measured at 1130 nmol/L 2.
Common questions
Can I take Lorcainide and Amitriptyline together?
Taking amitriptyline and lorcainide together can add to each drug's effect on your heart rhythm, so this combination is generally avoided. Check with your doctor or pharmacist before changing anything. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Lorcainide 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 Lorcainide and Amitriptyline interaction managed?
Combining these two is generally not recommended because their heart-rhythm effects can add together. Keep taking both exactly as prescribed unless your doctor tells you otherwise. Do not stop either one on your own. Ask your pharmacist or prescriber whether this combination is right for you, or whether an alternative to one drug might be safer. Your care team may check your heart with an ECG and… 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 Lorcainide 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 (5)
- Marshall JB & Forker AD: Cardiovascular effects of tricyclic antidepressant drugs: therapeutic usage, overdose, and management of complications. Am Heart J 1982; 103:401-414. PubMed
- Katz MR: Raised serum levels of desipramine with the antiarrhythmic propafenone (letter). J Clin Psychiatry 1991; 52:432-433.
- Product Information: Tambocor(R) flecainide acetate. 3M Pharmaceuticals, Northridge, CA, 1998.
- Larochelle P, Belanger L, Lemire F, et al: Dose-response effect of propafenone in patients with ventricular arrhythmias. Curr Ther Res 1984; 36:959-969. DOI
- Scagliotti D, Strasberg B, Hai HA, et al: Aprindine-induced polymorphous ventricular tachycardia. Am J Cardiol 1982; 49:1297-1300. PubMed
Keep reading about Amitriptyline
Keep reading about Lorcainide
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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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