Abametapir and Osilodrostat: 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 recordOsilodrostat
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.
Abametapir is a lotion used to treat head lice. Even though it goes on your scalp, a little gets into your body and can temporarily block a liver enzyme (called CYP3A4) that helps break down many medicines.
Osilodrostat (Isturisa) is one of those medicines. If that enzyme is slowed down, osilodrostat can build up higher than expected, which may increase side effects. This is based on how the drugs work rather than reports of harm, but it is worth taking seriously. The good news: this is easy to plan around. Talk with your pharmacist or doctor about the timing of these two so your care team can keep you safe.
Mechanism: Abametapir is a CYP3A4 inhibitor. Osilodrostat is a CYP3A4 substrate, so co-exposure is expected to increase osilodrostat AUC/Cmax with a rapid onset.
Direction: Increased osilodrostat exposure (neither agent is activated by this pathway, so effects and adverse events are amplified, not reduced).
Evidence: Theoretical, but rated major due to abametapir's known potent, prolonged CYP3A4 inhibition.
- Avoid CYP3A4 substrates, including osilodrostat, for 2 weeks after abametapir application.
- If concurrent therapy is unavoidable, avoid abametapir.
- If exposure occurs, monitor for exaggerated osilodrostat effects (hypocortisolism, QT prolongation).
What happens
Increased exposure of CYP3A4 substrate
Interaction Deep Dive
For a period of 2 weeks following abametapir application, refrain from administering CYP3A4 substrates. Should that not be possible, abametapir itself should be avoided 1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism by abametapir
How to manage this interaction
The main strategy here is separation in time, because abametapir's enzyme-blocking effect can last a while.
- The documented guidance is to avoid CYP3A4 substrates like osilodrostat for 2 weeks after applying abametapir.
- If avoiding osilodrostat during that window is not feasible, the recommendation is to avoid using abametapir and consider another lice treatment.
- Do not start or stop either medicine on your own.
Before using abametapir, tell your pharmacist or prescriber that you take osilodrostat so your care team can plan the safest timing or choose an alternative.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Abametapir and Osilodrostat together?
Abametapir can raise osilodrostat levels by blocking the enzyme that clears it, so avoid osilodrostat for 2 weeks after abametapir, or skip the abametapir. Ask your pharmacist or doctor to plan the timing. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abametapir and Osilodrostat 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 Osilodrostat interaction managed?
The main strategy here is separation in time, because abametapir's enzyme-blocking effect can last a while. The documented guidance is to avoid CYP3A4 substrates like osilodrostat for 2 weeks after applying abametapir. If avoiding osilodrostat during that window is not feasible, the recommendation is to avoid using abametapir and consider another lice treatment. Do not start or stop either medicin… 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 Osilodrostat 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 Osilodrostat
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