Abametapir and Paritaprevir: 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 recordParitaprevir
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.
Abametapir is a lotion used to treat head lice. Even though you rub it on your scalp, some of it can get into your body and briefly block a liver enzyme called CYP3A4. That enzyme is one of the main ways your body breaks down paritaprevir, a hepatitis C medicine.
When that enzyme is slowed down, paritaprevir can build up higher than intended, which may raise the chance of side effects. The good news is this is easy to manage. Let your pharmacist or doctor know you use both, and they can help you time things safely so you stay protected.
Mechanism: Abametapir inhibits CYP3A4. Paritaprevir is a CYP3A4 substrate, so co-use is predicted to increase paritaprevir exposure (AUC/Cmax), potentially raising toxicity risk.
- Direction: increased substrate exposure (neither drug is a prodrug here).
- Onset: rapid.
- Evidence: theoretical, based on abametapir's known CYP3A4 inhibition; enzyme effect may persist.
- Management: Avoid CYP3A4 substrates for 2 weeks following a topical abametapir application. If concurrent paritaprevir therapy cannot be interrupted, avoid using abametapir and consider an alternative lice treatment.
What happens
Increased exposure of CYP3A4 substrate
Interaction Deep Dive
Do not administer CYP3A4 substrates during the 2 week period following abametapir application. Where such avoidance cannot be achieved, refrain from using abametapir1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism by abametapir
How to manage this interaction
This interaction is manageable with planning. Keep taking your paritaprevir as prescribed, and do not start or stop anything on your own.
- Tell your pharmacist or prescriber before using abametapir lice lotion, since it can raise paritaprevir levels for a while.
- Guidance is to avoid CYP3A4 substrates like paritaprevir for about 2 weeks after applying abametapir.
- If you cannot pause paritaprevir, your care team may choose a different lice treatment instead.
- Report any new or stronger side effects promptly.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Abametapir and Paritaprevir together?
Abametapir can raise paritaprevir levels by blocking CYP3A4, so avoid using them together for about 2 weeks after applying the lice lotion, or pick a different lice treatment. Check with your pharmacist or doctor before combining them. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abametapir and Paritaprevir 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 Paritaprevir interaction managed?
This interaction is manageable with planning. Keep taking your paritaprevir as prescribed, and do not start or stop anything on your own. Tell your pharmacist or prescriber before using abametapir lice lotion, since it can raise paritaprevir levels for a while. Guidance is to avoid CYP3A4 substrates like paritaprevir for about 2 weeks after applying abametapir. If you cannot pause paritaprevir, yo… 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 Paritaprevir 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 Paritaprevir
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