Brexpiprazole and Quinidine: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Brexpiprazole
Quinidine
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 brexpiprazole exposure
Interaction Deep Dive
Concomitant use of brexpiprazole (a CYP2D6 substrate) and a strong CYP2D6 inhibitor may increase brexpiprazole exposure. Drug interaction showed a 5.1-fold increase in AUC values at steady-state is expected when extensive metabolizers of CYP2D6 are administered with both strong CYP2D6 and CYP3A4 inhibitors. Dosage modifications are recommended in patients who are known CYP2D6 poor metabolizers and in patients taking concomitant strong CYP2D6 inhibitors. In patients who are known CYP2D6 poor metabolizers, administer half of the recommended dosage. If concurrent use of brexpiprazole and a strong CYP2D6 inhibitor is required, administer half the usual brexpiprazole dose for the treatment of conditions other than major depressive disorder (MDD) because CYP considerations are already factored into the general MDD dosing recommendations. If brexpiprazole is coadministered with a strong CYP2D6 inhibitor and a strong or moderate CYP3A4 inhibitor, administer a quarter of the recommended brexpiprazole dose. If concurrent inhibitors are discontinued, adjust brexpiprazole to original dosage. In drug interaction studies, coadministration of brexpiprazole and quiNIDine (strong CYP2D6 inhibitor) showed approximately 1.1-fold and 2-fold increase in Cmax and AUC(0 to inf) of brexpiprazole, respectively1.
Why it happens (mechanism)
Inhibition of CYP2D6-mediated metabolism of brexpiprazole
Literature reports
2 reports — tap to read
a) In drug interaction studies, a 5.1-fold increase in AUC values at steady-state is expected when extensive metabolizers of CYP2D6 are administered with both strong CYP2D6 and CYP3A4 inhibitors 1.
b) In drug interaction studies, coadministration of brexpiprazole and quiNIDine (strong CYP2D6 inhibitor) showed approximately 1.1-fold and 2-fold increase in Cmax and AUC(0 to inf) of brexpiprazole, respectively 1.
Common questions
Can I take Brexpiprazole and Quinidine together?
Increased brexpiprazole exposure Always confirm with your pharmacist or prescriber before making any change.
How serious is the Brexpiprazole and Quinidine 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 "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Brexpiprazole or Quinidine 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: REXULTI(R) oral tablets, brexpiprazole oral tablets. Otsuka America Pharmaceutical, Inc. (per Manufacturer), Rockville, MD, 2025. DailyMed
Keep reading about Brexpiprazole
Keep reading about Quinidine
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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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