Abrocitinib and Lonafarnib: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 10, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Lonafarnib
Abrocitinib
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. Lonafarnib (Zokinvy) can slow down a liver enzyme called CYP2C19. Your body uses that same enzyme to break down abrocitinib (Cibinqo), your eczema medicine. When lonafarnib slows the enzyme, abrocitinib can build up higher than usual in your blood.
More abrocitinib in your system can mean a bigger chance of its side effects, like nausea, headache, or effects on your blood counts and infection risk. The good news is that this is manageable. Your care team may lower your abrocitinib dose or watch you more closely. Please don't stop or change either medicine on your own, just talk with your pharmacist or doctor first.
Mechanism: Lonafarnib inhibits CYP2C19; abrocitinib is a CYP2C19 substrate (neither is a prodrug), so its metabolism is reduced and exposure rises.
- Direction: Increased abrocitinib AUC and Cmax, raising risk of dose-related adverse effects (GI upset, headache, cytopenias, infection risk).
- Magnitude reference: With omeprazole (CYP2C19 substrate), lonafarnib 75 mg BID x5 days increased Cmax ~28% and AUC ~60%.
- Evidence/onset: Probable; onset unspecified.
- Management: Avoid combination if possible. If unavoidable, monitor for adverse reactions and reduce the abrocitinib dose as needed, individualized by the care team.
What happens
Increased CYP2C19 substrate exposure and an increased risk of CYP2C19 substrate-related adverse effects
Interaction Deep Dive
Because lonafarnib acts as a CYP2C19 inhibitor, giving it together with CYP2C19 substrates should be avoided, since doing so can raise the exposure (both AUC and Cmax) of the substrate and thereby heighten the likelihood of adverse reactions tied to that substrate. In healthy subjects, when a single 40 mg oral dose of omeprazole (a CYP2C19 substrate) was given alongside lonafarnib 75 mg administered orally twice daily over 5 days, omeprazole's Cmax rose by 28% and its AUC by 60%. When the combination cannot be avoided, watch for adverse reactions and, if necessary, lower the dose of the CYP2C19 substrate1.
Why it happens (mechanism)
Inhibition of CYP2C19-mediated metabolism by lonafarnib
How to manage this interaction
The combination is best avoided, but if you need both, your care team can manage it.
- Keep taking both medicines exactly as prescribed unless your prescriber tells you otherwise.
- Your team may reduce your abrocitinib dose and individualize it for you.
- They may monitor you more closely for side effects such as nausea, headache, or changes in blood counts.
- Report any new or worsening symptoms, especially signs of infection, unusual bruising, or feeling unwell, to your pharmacist or doctor.
Ask your pharmacist to review this combination so it can be tailored safely to you.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) In a clinical study involving healthy subjects, a single 40 mg oral dose of omeprazole (a CYP2C19 substrate) was given together with repeated oral doses of lonafarnib 75 mg twice daily over 5 days, and this resulted in increases of 28% in the Cmax and 60% in the AUC of omeprazole 1.
Common questions
Can I take Abrocitinib and Lonafarnib together?
Lonafarnib can raise abrocitinib levels and side-effect risk by blocking the CYP2C19 enzyme, so this combination should be avoided when possible; if used together, your care team may lower the abrocitinib dose and watch you more closely. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abrocitinib 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 is the Abrocitinib and Lonafarnib interaction managed?
The combination is best avoided, but if you need both, your care team can manage it. Keep taking both medicines exactly as prescribed unless your prescriber tells you otherwise. Your team may reduce your abrocitinib dose and individualize it for you. They may monitor you more closely for side effects such as nausea, headache, or changes in blood counts. Report any new or worsening symptoms, especi… 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.
Questions for your pharmacist
- Does my dose of Abrocitinib 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)
- Product Information: ZOKINVY(TM) oral capsules, lonafarnib oral capsules. Eiger BioPharmaceuticals Inc (per FDA), Palo Alto, CA, 2024. DailyMed
Keep reading about Lonafarnib
Keep reading about Abrocitinib
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.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist