Abametapir and Grazoprevir: 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 recordGrazoprevir
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 put it on your scalp, a little gets into your body and can briefly slow down a liver enzyme called CYP3A4. That enzyme is one of the ways your body clears grazoprevir, a medicine used for hepatitis C. With the enzyme slowed down, grazoprevir can build up to higher levels than usual, which may raise the chance of side effects.
The good news is this is easy to plan around. This effect can last for about two weeks after using the lice lotion. Please talk with your pharmacist or doctor before using both so they can help you time things safely.
Mechanism: Abametapir is a CYP3A4 inhibitor. Grazoprevir is a CYP3A4 substrate, so co-exposure is predicted to raise grazoprevir AUC/Cmax (increased exposure), with rapid onset. Grazoprevir is not a prodrug, so higher exposure means greater pharmacologic and potential toxic effect.
- Direction: increased grazoprevir exposure
- Evidence: theoretical (based on abametapir's CYP3A4 inhibition)
- Severity: major
Management: Avoid CYP3A4 substrates, including grazoprevir, within 2 weeks after a single topical application of abametapir. If concurrent use is unavoidable, avoid abametapir. Consider deferring grazoprevir dosing or arranging closer clinical monitoring per the care team.
What happens
Increased exposure of CYP3A4 substrate
Interaction Deep Dive
Refrain from administering CYP3A4 substrates during the 2-week period following abametapir application. Should this 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
Your care team can manage this safely with timing and monitoring.
- Keep taking your prescribed medicines and do not stop either one on your own.
- Because abametapir's effect on the liver enzyme can last about 2 weeks after application, tell your prescriber and pharmacist that you use or plan to use both.
- Your team may recommend spacing out the lice treatment and grazoprevir, or choosing a different lice treatment, and may monitor you more closely for side effects during this window.
Bring up any new or unusual symptoms with your pharmacist or doctor right away.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Abametapir and Grazoprevir together?
Abametapir can raise grazoprevir levels for up to two weeks after use, so let your pharmacist or doctor coordinate the timing of these two medicines before you use both. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abametapir and Grazoprevir 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 Grazoprevir interaction managed?
Your care team can manage this safely with timing and monitoring. Keep taking your prescribed medicines and do not stop either one on your own. Because abametapir's effect on the liver enzyme can last about 2 weeks after application, tell your prescriber and pharmacist that you use or plan to use both. Your team may recommend spacing out the lice treatment and grazoprevir, or choosing a different… 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 Grazoprevir 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 Grazoprevir
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