Drug Interaction Report

Dofetilide and Mobocertinib: Interaction Details

A pharmacist-reviewed analysis of the Dofetilide and Mobocertinib interaction: the documented clinical effects, severity rating, onset, mechanism, and management considerations, with cited references throughout.

AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature

Mobocertinib

Exkivity
+

Dofetilide

Tikosyn Tikosyn®
Dr. Brian Staiger, PharmD, BCPS
Medically reviewed by
Dr. Brian Staiger, PharmD, BCPS
Updated Aug 8, 2026
Editorial policy · Data sources
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Interaction severity
Major
Potentially serious — often needs a change or close monitoring.
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.

Of 454 documented Dofetilide interactions, 288 are rated major — including this one.
Worried about symptoms right now? Contact your pharmacist or prescriber, or call Poison Control at 1-800-222-1222 (US). Call 911 for an emergency.
Onset
unspecified
Evidence
theoretical
Severity
Major

What happens

Decreased plasma concentrations of the CYP3A substrate, which may result in serious therapeutic failure; QT interval prolongation

Interaction Deep Dive

Coadministration of mobocertinib (QT prolonging CYP3A inducer) with a CYP3A substrate may decrease plasma concentrations of CYP3A substrates, which may lead to serious therapeutic failure. Coadministration of mobocertinib with oral or IV midazolam (a CYP3A substrate) decreased the AUC of midazolam by 32% and 16%, respectively. Additionally coadministration of mobocertinib with drugs known to prolong the corrected QT (QTc) interval may increase the risk of QTc interval prolongation, including torsades de pointes, which can be fatal. Avoid concomitant use of mobocertinib with CYP3A substrates where minimal concentration changes may lead to serious therapeutic failures and are also known to prolong the QTc interval. If concomitant use is unavoidable, monitor the QTc interval more frequently with ECGs and increase the CYP3A substrate dosage as recommended1.

Why it happens (mechanism)

Induction of the metabolism of CYP3A substrates by mobocertinib; additive prolongation of the QT interval

Literature reports

1 report — tap to read

a) Coadministration of mobocertinib 160 mg once daily with oral or IV midazolam (a CYP3A substrate) decreased the AUC of midazolam by 32% and 16%, respectively 1.

Common questions

Can I take Dofetilide and Mobocertinib together?

Decreased plasma concentrations of the CYP3A substrate, which may result in serious therapeutic failure; QT interval prolongation Always confirm with your pharmacist or prescriber before making any change.

How serious is the Dofetilide and Mobocertinib 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 Dofetilide or Mobocertinib 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)

  1. Product Information: EXKIVITY(TM) oral capsules, mobocertinib oral capsules. Takeda Pharmaceuticals America Inc (per FDA), Lexington, MA, 2021.
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Mobocertinib

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Dofetilide

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All Dofetilide interactions (454) Dofetilide drug information
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Beyond drug–drug

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:

Dofetilide + Activated Charcoal American Hellebore Arsenic Cesium Ephedra Grapefruit Sida Cordifolia St. John's Wort + 138 more

major · moderate · minor — check everything you take with our drug–supplement interaction checker.

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This information is for education, not a substitute for professional medical advice. Do not start, stop, or change any medication without talking to your pharmacist or prescriber.