Abametapir and Diltiazem: 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 recordDiltiazem
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 helps break down many medicines. Diltiazem, your blood pressure and heart medicine, is cleared by that same enzyme.
So for a short time after using the lotion, diltiazem may build up more than usual. That could make its effects stronger, like a slower heart rate or lower blood pressure (feeling dizzy or lightheaded). The good news is this is easy to plan around. Talk with your pharmacist or doctor before using the lice lotion so they can guide the timing.
Mechanism: Abametapir is a CYP3A4 inhibitor. Diltiazem is a CYP3A4 substrate (and itself a moderate CYP3A4 inhibitor), so co-exposure is expected to raise diltiazem exposure (increased AUC/Cmax).
- Direction: Increased diltiazem effect (enhanced negative chronotropic/hypotensive effects).
- Onset: Rapid; enzyme inhibition can persist for up to ~2 weeks after a single topical application.
- Evidence: Theoretical, based on abametapir's labeled CYP3A4 inhibition.
- Management: Avoid CYP3A4 substrates within 2 weeks of abametapir; if unavoidable, avoid abametapir. Monitor HR and BP if co-use occurs.
What happens
Increased exposure of CYP3A4 substrate
Interaction Deep Dive
Following the application of abametapir, refrain from using CYP3A4 substrates for a period of 2 weeks. Should avoiding these substrates not be practical, abametapir itself should not be used 1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism by abametapir
How to manage this interaction
Keep taking your diltiazem as prescribed. The concern is only about adding the abametapir lice lotion during the same time window.
- Before using abametapir, tell your pharmacist or prescriber that you take diltiazem so they can plan the safest timing.
- The labeling advises avoiding CYP3A4 medicines like diltiazem for about 2 weeks after applying abametapir; if that is not workable, the alternative is to avoid the abametapir.
- If both are used together, your team may monitor your heart rate and blood pressure more closely.
- Report dizziness, lightheadedness, or an unusually slow heartbeat.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Abametapir and Diltiazem together?
Abametapir can briefly boost diltiazem levels, so the labeling says to avoid diltiazem for about 2 weeks after the lice lotion, or skip the lotion. 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 Diltiazem 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 Diltiazem interaction managed?
Keep taking your diltiazem as prescribed. The concern is only about adding the abametapir lice lotion during the same time window. Before using abametapir, tell your pharmacist or prescriber that you take diltiazem so they can plan the safest timing. The labeling advises avoiding CYP3A4 medicines like diltiazem for about 2 weeks after applying abametapir; if that is not workable, the alternative i… 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.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Abametapir or Diltiazem 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 Diltiazem
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