Abametapir and Elexacaftor: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jun 30, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Abametapir
No brand names on recordElexacaftor
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.
Here's what's going on. Abametapir is a lotion used to treat head lice. Even though you put it on your scalp, a little can get into your body and briefly slow down a liver enzyme called CYP3A4. That enzyme is one of the main ways your body breaks down elexacaftor (part of your cystic fibrosis medicine).
When that enzyme is slowed, elexacaftor can build up higher than usual, which could mean more side effects. This effect is expected to be strongest right after the lice treatment and can linger for about two weeks. The good news: this is very manageable. Please talk with your pharmacist or doctor before using a lice product so they can plan the safest timing for you.
Mechanism: Abametapir is a potent CYP3A4 inhibitor. Elexacaftor is a CYP3A4 substrate, so co-exposure is expected to reduce its clearance and increase systemic exposure (higher AUC/Cmax).
- Direction: increased elexacaftor exposure and potential for enhanced/adverse effects.
- Onset: rapid; inhibition can persist for approximately 2 weeks after a single topical application.
- Evidence: theoretical.
- Management: Avoid CYP3A4 substrates, including elexacaftor, within 2 weeks after applying abametapir. If concurrent use is unavoidable, avoid abametapir. If exposure occurs, monitor for elexacaftor-related adverse effects and individualize per the care team.
What happens
Increased exposure of CYP3A4 substrate
Interaction Deep Dive
Do not administer CYP3A4 substrates during the 2 weeks that follow abametapir application. When avoiding these substrates is not possible, refrain from using abametapir instead1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism by abametapir
How to manage this interaction
The key is timing. Because abametapir can raise elexacaftor levels for about two weeks after it is applied, the documented guidance is to avoid combining them during that window.
- Do not stop your cystic fibrosis medicine on your own. Keep taking it as prescribed.
- Before using any head lice treatment, tell your pharmacist or prescriber that you take elexacaftor.
- Your care team may choose a different lice treatment, adjust timing, or monitor you more closely for side effects.
- If you have already used both, contact your care team and watch for any new or stronger side effects.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Abametapir and Elexacaftor together?
Abametapir can raise elexacaftor levels for about two weeks by blocking the CYP3A4 enzyme, so avoid combining them and check with your pharmacist or doctor before using a lice treatment. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abametapir and Elexacaftor interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "rapid". Effects can appear quickly, often within about 24 hours of combining the drugs.
How is the Abametapir and Elexacaftor interaction managed?
The key is timing. Because abametapir can raise elexacaftor levels for about two weeks after it is applied, the documented guidance is to avoid combining them during that window. Do not stop your cystic fibrosis medicine on your own. Keep taking it as prescribed. Before using any head lice treatment, tell your pharmacist or prescriber that you take elexacaftor. Your care team may choose a differen… Management is individual — always follow your own care team's guidance.
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 Abametapir or Elexacaftor 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: XEGLYZE(TM) topical lotion, abametapir topical lotion. Dr Reddy’s Laboratories Inc (per FDA), Princeton, NJ, 2020. DailyMed
Keep reading about Abametapir
Keep reading about Elexacaftor
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