Pacritinib 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
Pacritinib
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 your medicines can affect the timing of your heartbeat. Amitriptyline (Elavil) and pacritinib (Vonjo) can each stretch out a part of the heart's electrical cycle called the QT interval. When they are taken together, that effect can add up, which can slightly raise the chance of an irregular heartbeat.
This concern is based mostly on how these drugs work rather than on lots of real-world reports, so please don't be alarmed. The good news is your care team knows how to handle this. They may check your heart with an EKG, watch your blood minerals like potassium, and adjust doses as needed. Please talk with your doctor or pharmacist before changing anything.
Effect: Additive QTc prolongation with increased risk of ventricular arrhythmia (including torsades de pointes) when amitriptyline is combined with pacritinib.
Mechanism: Pharmacodynamic (additive), not PK based. Both agents independently prolong the QT interval.
- Direction/magnitude: Additive QTc effect; exact magnitude undefined.
- Evidence: Theoretical; severity graded major.
- Management: Avoid coadministration where possible. Avoid pacritinib if baseline QTc greater than 480 msec. Obtain baseline and periodic ECGs, correct hypokalemia/hypomagnesemia. If QTc exceeds 500 msec or increases 60 msec from baseline, hold pacritinib; resume per resolution timeline (same dose if resolved within 1 week, reduced dose if longer).
What happens
An increased risk of QT interval prolongation
Interaction Deep Dive
Do not combine pacritinib with any agent recognized for prolonging the QTc interval. When drugs that prolong the QT interval are taken together, they can compound the QTc-prolonging action of pacritinib, thereby heightening the likelihood of cardiac arrhythmias. Pacritinib should not be given to patients whose baseline QTc exceeds 480 msec. Should QT interval prolongation surpass 500 msec, or rise by more than 60 msec above baseline, pacritinib should be withheld. Pacritinib may be resumed at the same dose if the QTc prolongation returns to 480 msec or less, or to baseline, within 1 week. If resolution requires longer than 1 week, resume pacritinib at a lowered dose. Where coadministration cannot be avoided, correct hypokalemia both before and throughout pacritinib therapy, and address QTc prolongation through pacritinib interruption along with electrolyte management1.
Why it happens (mechanism)
Additive QT interval prolongation
How to manage this interaction
Both drugs can affect your heart's rhythm, so your care team will usually manage this carefully rather than simply combining them without a plan.
- Keep taking both medicines as prescribed unless your doctor tells you otherwise.
- Your team may order an EKG before and during treatment to watch your QT interval.
- They may check and correct blood minerals like potassium and magnesium.
- Doses may be adjusted and individualized, and pacritinib may be paused if your heart tracing changes too much.
Tell your pharmacist or prescriber about all your medicines, and report fainting, dizziness, or a racing or irregular heartbeat right away.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Pacritinib and Amitriptyline together?
Combining amitriptyline and pacritinib can add to QT prolongation and raise arrhythmia risk, so this pairing is usually avoided; if both are needed, your team will monitor your EKG and electrolytes closely. Do not change either medicine on your own. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Pacritinib 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 Pacritinib and Amitriptyline interaction managed?
Both drugs can affect your heart's rhythm, so your care team will usually manage this carefully rather than simply combining them without a plan. Keep taking both medicines as prescribed unless your doctor tells you otherwise. Your team may order an EKG before and during treatment to watch your QT interval. They may check and correct blood minerals like potassium and magnesium. Doses may be adjust… 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 Pacritinib 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: VONJO(R) oral capsules, pacritinib oral capsules. CTI BioPharma Corp (per FDA), Seattle, WA, 2024. DailyMed
Keep reading about Amitriptyline
Keep reading about Pacritinib
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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