Drug Interaction Report

Trilaciclib and Dofetilide: Interaction Details

A pharmacist-reviewed analysis of the Trilaciclib and Dofetilide 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

Dofetilide

Tikosyn Tikosyn®
+

Trilaciclib

No brand names on record
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.

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

Increased plasma concentrations of dofetilide

Interaction Deep Dive

Avoid concomitant use of trilaciclib (OCT2, MATE2, and MATE-2K inhibitor) with certain OCT2, MATE1, and MATE-2K substrates in which minimal concentration changes may lead to serious or life-threatening toxicities (eg, dofetilide). Concomitant use of trilaciclib and dofetilide may lead to increased concentrations of dofetilide which may lead to serious ventricular arrhythmias associated with QT interval prolongation, including torsades de pointes. If concomitant use is unavoidable, consider the potential benefits of using trilaciclib and dofetilide concurrently against the risk for QT interval prolongation1.

Why it happens (mechanism)

Inhibition of OCT2-, MATE1-, and MATE-2K-mediated drug transport by trilaciclib

Literature reports

2 reports — tap to read

a) Concomitant use of trilaciclib (OCT2, MATE2, and MATE-2K inhibitor) with metformin (OCT2, MATE1, and MATE-2K substrate) resulted in an increase in metformin AUC(infinity) and Cmax by approximately 65% and 81%, respectively. Renal clearance of metformin was decreased by 37% 1.

b) There were no clinically significant differences in topotecan (MATE1 and MATE-2K substrate) pharmacokinetics when used concomitantly with trilaciclib (OCT2, MATE2, and MATE-2K inhibitor) 1.

Common questions

Can I take Trilaciclib and Dofetilide together?

Increased plasma concentrations of dofetilide Always confirm with your pharmacist or prescriber before making any change.

How serious is the Trilaciclib and Dofetilide 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 Trilaciclib or Dofetilide 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: COSELA(TM) intravenous injection, trilaciclib intravenous injection. G1 Therapeutics Inc (per manufacturer), Durham, NC, 2021. DailyMed
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Dofetilide

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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.