Loperamide and Tazemetostat: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Tazemetostat
Loperamide
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
Altered loperamide exposure, an increased risk of loperamide-related adverse reactions and reduced efficacy of loperamide
Interaction Deep Dive
Coadministration of loperamide and tazemetostat (CYP2C8 inhibitor) may increase the exposure of loperamide and may increase a risk for cardiac adverse reactions. Monitor patients for cardiac adverse reactions1. Concomitant use of tazemetostat with loperamide (CYP3A4 substrate) may also reduce loperamide exposure leading to reduced efficacy of loperamide 2.
Why it happens (mechanism)
Inhibition of CYP2C8-mediated metabolism of loperamide; induction of CYP3A4-mediated metabolism of loperamide
Literature reports
3 reports — tap to read
a) In a drug interaction study, coadministration of tazemetostat 800 mg twice daily with oral midazolam (a sensitive CYP3A substrate) in patients decreased midazolam AUC and Cmax by 40% and 21%, respectively 2.
b) In drug interaction studies, When a single 4 mg dose of loperamide hydrochloride was coadministered with 600 mg gemfibrozil, a strong inhibitor of CYP2C8, on day 3 of a 5-day treatment with gemfibrozil twice daily, the mean peak plasma concentration and the systemic exposure to loperamide was increased by 1.6-fold and 2.2-fold, respectively 1
c) When multiple doses of both 100 mg itraconazole and 600 mg gemfibrozil (CYP2C8 inhibitor) twice daily were administered with a single 4 mg dose of loperamide hydrochloride, the mean peak plasma concentration and the systemic exposure to loperamide was increased by 4.2-fold and 12.6-fold, respectively 1.
Common questions
Can I take Loperamide and Tazemetostat together?
Altered loperamide exposure, an increased risk of loperamide-related adverse reactions and reduced efficacy of loperamide Always confirm with your pharmacist or prescriber before making any change.
How serious is the Loperamide and Tazemetostat 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 Loperamide or Tazemetostat 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 (2)
- Product Information: Loperamide hydrochloride oral capsules, loperamide hydrochloride oral capsules. Mylan Pharmaceuticals Inc (per DailyMed), Morgantown, WV, 2022. DailyMed
- Product Information: TAZVERIK(R) oral tablets, tazemetostat oral tablets. Epizyme Inc (per FDA), Cambridge, MA, 2024. DailyMed
Keep reading about Tazemetostat
Keep reading about Loperamide
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:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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