Drug Interaction Report

Lansoprazole and Lonafarnib: Interaction Details

A pharmacist-reviewed analysis of the Lansoprazole and Lonafarnib 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

Lonafarnib

Zokinvy
+

Lansoprazole

Prevacid Prevacid® Prevacid® 24HR Prevacid® SoluTab®
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 94 documented Lansoprazole interactions, 69 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
probable
Severity
Major

What happens

Increased CYP2C19 substrate exposure and an increased risk of CYP2C19 substrate-related adverse effects

Interaction Deep Dive

Avoid concomitant use of lonafarnib (CYP2C19 inhibitor) with CYP2C19 substrates as it may increase the exposure (AUC and Cmax) of the CYP2C19 substrate, which may increase the risk of the CYP2C19 substrate-related adverse reactions. With coadministration of a single oral dose of 40 mg omeprazole (CYP2C19 substrate) with multiple oral doses of lonafarnib 75 mg twice daily for 5 days in healthy subjects, the Cmax and AUC of omeprazole were increased by 28% and 60%, respectively. If coadministration is unavoidable, monitor for adverse reactions and reduce the dosage of the CYP2C19 substrate, if needed1.

Why it happens (mechanism)

Inhibition of CYP2C19-mediated metabolism by lonafarnib

Literature reports

1 report — tap to read

a) In a clinical study, with coadministration of a single oral dose of 40 mg omeprazole (CYP2C19 substrate) with multiple oral doses of lonafarnib 75 mg twice daily for 5 days in healthy subjects, the Cmax and AUC of omeprazole were increased by 28% and 60%, respectively 1.

Common questions

Can I take Lansoprazole and Lonafarnib together?

Increased CYP2C19 substrate exposure and an increased risk of CYP2C19 substrate-related adverse effects Always confirm with your pharmacist or prescriber before making any change.

How serious is the Lansoprazole and Lonafarnib 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.

From our Q&A

Real reader questions about these medications, each personally answered by our pharmacist:

Questions for your pharmacist

  • Does my dose of Lansoprazole or Lonafarnib 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: ZOKINVY(TM) oral capsules, lonafarnib oral capsules. Eiger BioPharmaceuticals Inc (per FDA), Palo Alto, CA, 2024. DailyMed
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Lonafarnib

Keep reading about Lonafarnib

All Lonafarnib interactions (146)
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Lansoprazole

Keep reading about Lansoprazole

All Lansoprazole interactions (94) Lansoprazole drug information
Also serious with: Rilpivirine Ziftomenib Belumosudil Octreotide Injection
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:

Lonafarnib + Activated Charcoal Asarabacca Grapefruit Siberian Cocklebur St. John's Wort Acacia Rigidula Adrafinil African Wild Potato + 152 more
Lansoprazole + Activated Charcoal Grapefruit St. John's Wort Acacia Rigidula Adrafinil African Wild Potato American Elder Artichoke + 145 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.