Aficamten and Thioridazine: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Thioridazine
No brand names on recordAficamten
No brand names on record
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
Reduced aficamten exposure and reduced efficacy of aficamten
Interaction Deep Dive
Concomitant use of aficamten with moderate/strong CYP3A inducers reduce aficamten exposure, which may reduce aficamten effectiveness. The risk of heart failure due to systolic dysfunction may increase with discontinuation of these inducers. In patients who are on stable therapy with moderate to strong CYP3A inducers, when discontinuing these medications, reduce the dose of aficamten (20 mg to 10 mg; 15 mg to 5 mg; 10 mg to 5 mg). For patients currently receiving aficamten 5 mg, maintain the 5 mg dose. Assess LVEF and LVOT-G 2 to 8 weeks after inducer discontinuation and titrate the dose of aficamten: LVEF greater than or equal to 55%, Valsalva LVOT-G greater than or equal to 30 mmHg: increase the dose by 5 mg (up to the maximum dose of 20 mg once daily). For LVEF greater than or equal to 55%, Valsalva LVOT-G less than 30 mmHg or LVEF less than 55% and greater than or equal to 50%, Valsalva LVOT-G (any): maintain dose. For LVEF less than 50% and greater than or equal to 40%, Valsalva LVOT-G (any): reduce dose by 5 mg (if already on 5 mg, interrupt treatment for at least 7 days). LVEF less than 40%. Valsalva LVOT-G (any): interrupt treatment for 7 days1.
Why it happens (mechanism)
Induction of CYP3A-mediated metabolism of aficamten
Literature reports
1 report — tap to read
a) In a drug interaction study, the observed effect of coadministration of aficamten and rifAMPin, (strong CYP3A inducer) 600 mg once daily was reduced aficamten AUC by 79% 1.
Common questions
Can I take Aficamten and Thioridazine together?
Reduced aficamten exposure and reduced efficacy of aficamten Always confirm with your pharmacist or prescriber before making any change.
How serious is the Aficamten and Thioridazine 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 Aficamten or Thioridazine 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: MYQORZO™ oral tablets, aficamten oral tablets. Cytokinetics, Incorporated (per Manufacturer), South San Francisco, CA, 2025. DailyMed
Keep reading about Thioridazine
Keep reading about Aficamten
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