Flecainide and Taletrectinib: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Flecainide
Taletrectinib
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.
What happens
Increased risk of QT interval prolongation and torsade de pointes
Interaction Deep Dive
Avoid concomitant use of taletrectinib with other drugs with a known potential to prolong the QTc interval, such as antiarrhythmics as it may increase the risk of QTc interval prolongation, which can increase the risk for ventricular tachyarrhythmias (eg, torsades de pointes) or sudden death. If concomitant use cannot be avoided, adjust the frequency of monitoring as recommended. Withhold taletrectinib if the QTc interval is more than 500 msec or the change from baseline is more than 60 msec causes QTc interval prolongation. Monitor ECGs and electrolytes prior to administration of taletrectinib, and then periodically thereafter as clinically indicated during treatment. Adjust the frequency of monitoring based on risk factors such as known long QT syndromes, clinically significant bradyarrhythmias, severe or uncontrolled heart failure, and concomitant medications associated with QTc interval prolongation. Administer taletrectinib on an empty stomach. Withhold, then resume at the same or reduced dose, or permanently discontinue taletrectinib based on severity1.
Why it happens (mechanism)
Additive QT interval prolongation
Literature reports
1 report — tap to read
a) In the pooled safety population, of the 351 patients who underwent at least one post baseline ECG assessment, 13% experienced an increase in QTcF (QT interval corrected per Fridericia formula) of more than 60 msec compared to baseline after receiving taletrectinib and 2.6% had an increase in QTcF to more than 500 msec. Overall, 3.4% of patients had Grade more than and equal to 3 QTc interval prolongation. The median time from the first dose of taletrectinib to the onset of ECG QT prolongation was 22 days (range: 1 day to 38.7 months). QTc prolongation led to dose interruption and dose reduction, each in 2.8% of patients treated with taletrectinib 1.
Common questions
Can I take Flecainide and Taletrectinib together?
Increased risk of QT interval prolongation and torsade de pointes Always confirm with your pharmacist or prescriber before making any change.
How serious is the Flecainide and Taletrectinib 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 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 Flecainide or Taletrectinib 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: IBTROZI(TM) oral capsules, taletrectinib oral capsules. Nuvation Bio Inc. (per Manufacturer), Burlington, MA, 2025. DailyMed
Keep reading about Flecainide
Keep reading about Taletrectinib
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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