Drug Interaction Report

Dacomitinib and Pitolisant: Interaction Details

A pharmacist-reviewed analysis of the Dacomitinib and Pitolisant 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

Dacomitinib

Vizimpro Vizimpro®
+

Pitolisant

Wakix Wakix®
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 56 documented Dacomitinib interactions, 43 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

Increased pitolisant exposure

Interaction Deep Dive

Pitolisant is primarily metabolized by CYP2D6 and coadministration with the strong CYP2D6 inhibitor PARoxetine increased pitolisant exposure by 2.2-fold in a pharmacokinetic study. For patients on a stable dose of pitolisant, reduce the pitolisant dose by half when initiating a strong CYP2D6 inhibitor. If used concomitantly in patients currently receiving a strong CYP2D6 inhibitor, initiate pitolisant at 8.9 mg once daily and increase after 7 days to a maximum dosage of 17.8 mg once daily. For pediatric patients (6 years and older) weighing less than 40 kg, initiate pitolisant at 4.45 mg once daily and increase after 7 days to a maximum recommended dosage of 8.9 mg once daily. For pediatric patients (6 years and older) weighing more than or equal to 40 kg, initiate pitolisant at 4.45 mg once daily and increase after 7 days to a maximum recommended dosage of 8.9 mg once daily. May increase after another 7 days to a maximum recommended dosage of 17.8 mg once daily1.

Why it happens (mechanism)

Inhibition of CYP2D6-mediated metabolism of pitolisant

Literature reports

1 report — tap to read

a) In a drug interaction study, coadministration of pitolisant with PARoxetine (strong CYP2D6 inhibitors) may increase pitolisant Cmax and AUC by 1.47-fold and 2.21-fold, respectively 1.

Common questions

Can I take Dacomitinib and Pitolisant together?

Increased pitolisant exposure Always confirm with your pharmacist or prescriber before making any change.

How serious is the Dacomitinib and Pitolisant 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.

Questions for your pharmacist

  • Does my dose of Dacomitinib or Pitolisant 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: WAKIX® oral tablets, pitolisant oral tablets. Harmony Biosciences LLC (per FDA), Plymouth Meeting, PA, 2026. DailyMed
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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:

Dacomitinib + Activated Charcoal Coffee Charcoal European Mandrake Fever Bark Glucomannan Guar Gum Gum Arabic Iboga + 12 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.