Amprenavir and Dihydroergotamine Injection: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Amprenavir
No brand names on recordDihydroergotamine Injection
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.
What happens
Increased dihydroergotamine exposure and an increased risk of ergotism (nausea, vomiting, peripheral vasospasm, and peripheral ischemia)
Interaction Deep Dive
Serious and/or life-threatening reactions, such as peripheral vasospasm and peripheral tissue ischemia, can occur with increased plasma concentrations of dihydroergotamine, therefore, the concurrent use of dihydroergotamine and amprenavir/fosamprenavir is contraindicated12. Dihydroergotamine and amprenavir are both metabolized by cytochrome P450 3A4 (CYP3A4) enzymes, and amprenavir is known to inhibit CYP3A4. The resultant inhibition of dihydroergotamine metabolism can result in increased plasma concentrations of dihydroergotamine 2.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism of dihydroergotamine
Common questions
Can I take Amprenavir and Dihydroergotamine Injection together?
Increased dihydroergotamine exposure and an increased risk of ergotism (nausea, vomiting, peripheral vasospasm, and peripheral ischemia) Always confirm with your pharmacist or prescriber before making any change.
How serious is the Amprenavir and Dihydroergotamine Injection interaction?
It is rated contraindicated. These should generally not be used together.
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 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 Amprenavir or Dihydroergotamine Injection 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 (2)
- Product Information: LEXIVA(R) oral tablets, oral suspension, fosamprenavir calcium oral tablets, oral suspension. ViiV Healthcare (per FDA), Research Triangle Park, NC, 2019. DailyMed
- Product Information: Agenerase(R), amprenavir oral solution. GlaxoSmithKline, Research Triangle Park, NC, 2004.
Keep reading about Amprenavir
Keep reading about Dihydroergotamine Injection
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