Bictegravir and Abametapir: 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 recordBictegravir
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 rub it on your scalp, a little gets into your body, where it can briefly slow down a liver enzyme called CYP3A4. That same enzyme helps clear bictegravir, one of your HIV medicines, out of your body.
When that enzyme is slowed, bictegravir can build up higher than usual, which could raise the chance of side effects. This is based on how the drugs work rather than on real-world reports, but it's taken seriously. The good news is your care team can manage this easily by spacing the treatments out. Please check with your pharmacist or doctor before using the lice lotion.
Mechanism: Abametapir is a topical CYP3A4 inhibitor. Bictegravir is partially metabolized by CYP3A4 (a substrate, not a prodrug), so inhibition is expected to increase bictegravir exposure (AUC/Cmax).
- Direction: Increased bictegravir exposure and potential for enhanced/adverse effects.
- Onset: Rapid; inhibition can persist for up to 2 weeks after a single application.
- Evidence: Theoretical (mechanism-based).
- Severity: Major.
Management: Avoid CYP3A4 substrates such as bictegravir within 2 weeks of abametapir application. If concurrent use is unavoidable, avoid abametapir. Coordinate timing with the prescriber and consider alternative lice therapy.
What happens
Increased exposure of CYP3A4 substrate
Interaction Deep Dive
Refrain from administering CYP3A4 substrates during the 2-week period following abametapir application. Should avoiding these substrates not be practical, then 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 timing. Because abametapir can keep affecting the CYP3A4 enzyme for up to 2 weeks after you apply it, the goal is to keep it separate from your bictegravir.
- Keep taking your HIV medicine as prescribed. Do not stop it on your own.
- Before using any head lice lotion, tell your pharmacist or doctor you take bictegravir.
- Your care team may choose a different lice treatment that doesn't cause this interaction, or advise on timing.
- Report any new or unusual side effects while both are in your system.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Bictegravir and Abametapir together?
Abametapir can raise bictegravir levels by slowing the enzyme that clears it, and this effect can last up to two weeks. Talk to your pharmacist or doctor before using a lice lotion so they can pick a safe option or adjust timing. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Bictegravir and Abametapir 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 Bictegravir and Abametapir interaction managed?
The main strategy here is timing. Because abametapir can keep affecting the CYP3A4 enzyme for up to 2 weeks after you apply it, the goal is to keep it separate from your bictegravir. Keep taking your HIV medicine as prescribed. Do not stop it on your own. Before using any head lice lotion, tell your pharmacist or doctor you take bictegravir. Your care team may choose a different lice treatment tha… 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 Bictegravir or Abametapir 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 Bictegravir
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