Omeprazole and Nirogacestat: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 2, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Omeprazole
Nirogacestat
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.
Here's what's going on. Omeprazole (Prilosec) lowers the acid in your stomach. Nirogacestat (Ogsiveo), a medicine used for desmoid tumors, needs an acidic stomach to dissolve and get absorbed properly. When your stomach acid is reduced, less nirogacestat gets into your body, so it may not work as well against your tumor.
This one matters because it can quietly weaken your cancer treatment. The good news is your care team can plan around it, whether by adjusting timing, choosing a different stomach medicine, or watching your response closely. Please don't stop either drug on your own, just talk with your oncologist or pharmacist first.
Effect: Reduced nirogacestat exposure and potential loss of efficacy.
Mechanism: Omeprazole raises gastric pH; nirogacestat is poorly soluble at pH 6 or greater, so acid suppression decreases its dissolution and absorption (lower AUC/Cmax). Nirogacestat may also induce metabolism of CYP2C19 substrates.
- Direction: Decreased nirogacestat serum concentrations, reduced antitumor effect.
- Evidence: Probable. Severity: Major. Onset unspecified.
- Management: Avoid coadministration with PPIs where possible. If unavoidable, prefer short-acting antacids and stagger dosing (nirogacestat 2 hours before or 2 hours after antacid). Monitor treatment response.
What happens
Reduced nirogacestat/CYP2C19 substrate exposure and reduced efficacy of nirogacestat/CYP2C19 substrate
Interaction Deep Dive
Do not co-administer nirogacestat with agents that function both as CYP2C19 substrates and proton pump inhibitors. Because nirogacestat lowers the exposure of CYP2C19 substrates, the resulting reduction in their concentrations can substantially diminish their efficacy. When such combined use is unavoidable, nirogacestat dosing can be separated from antacids (for example, give nirogacestat 2 hours prior to or 2 hours following antacid administration). At a pH of 6 or higher, nirogacestat has poor solubility. Agents that reduce gastric acid may lower serum nirogacestat exposure, potentially decreasing the drug's effectiveness1.
Why it happens (mechanism)
Reduced gastric acidity; induction of CYP2C19-substrate metabolism by nirogacestat
How to manage this interaction
Keep taking both exactly as prescribed until your care team weighs in. This combination can lower how much nirogacestat your body absorbs, which may reduce its effectiveness.
- Your oncology team may prefer to avoid a proton pump inhibitor like omeprazole during nirogacestat treatment, or switch you to a different acid-reducing approach.
- If an acid reducer is truly needed, an antacid may be used with careful timing (nirogacestat given about 2 hours before or 2 hours after the antacid).
- Tell your pharmacist and prescriber about every heartburn or acid medicine you take, even over-the-counter ones.
Your team can tailor the plan and monitor your response so treatment stays on track.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
2 reports — tap to read
a) Taking multiple doses of nirogacestat (150 mg twice daily) together with a drug that is a sensitive substrate of CYP2C19 lowers the plasma concentrations of those substrates 1.
b) Giving nirogacestat at the same time as proton pump inhibitors (for example, omeprazole) is anticipated to decrease nirogacestat concentrations 1.
Common questions
Can I take Omeprazole and Nirogacestat together?
Omeprazole lowers stomach acid and can reduce how well nirogacestat is absorbed, weakening your cancer treatment; ask your oncology team before combining them so they can adjust the plan. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Omeprazole and Nirogacestat 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 is the Omeprazole and Nirogacestat interaction managed?
Keep taking both exactly as prescribed until your care team weighs in. This combination can lower how much nirogacestat your body absorbs, which may reduce its effectiveness. Your oncology team may prefer to avoid a proton pump inhibitor like omeprazole during nirogacestat treatment, or switch you to a different acid-reducing approach. If an acid reducer is truly needed, an antacid may be used wit… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Omeprazole or Nirogacestat 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: OGSIVEO(TM) oral tablets, nirogacestat oral tablets. SpringWorks Therapeutics, Inc. (per FDA), Stamford, CT, 2023. DailyMed
Keep reading about Omeprazole
Keep reading about Nirogacestat
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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