Irinotecan Injection and Conivaptan: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Conivaptan
Irinotecan 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 CYP3A substrate exposure
Interaction Deep Dive
Avoid concomitant use of conivaptan (strong CYP3A inhibitor) with drugs eliminated primarily by CYP3A-mediated metabolism, as this may result in increased exposure of the CYP3A substrate. Conivaptan increased the AUC of CYP3A substrates midazolam, simvastatin, and amLODIPine. The CYP3A substrate may be initiated no sooner than 1 week after completion of conivaptan therapy1.
Why it happens (mechanism)
Inhibition of CYP3A-mediated substrate metabolism by conivaptan
Literature reports
3 reports — tap to read
a) The strong CYP3A inhibitor conivaptan 40 mg/day IV increased the AUC of midazolam, a CYP3A substrate, by approximately 100% with a 1 mg IV dose and by 200% with a 2 mg oral dose 1.
b) Conivaptan 30 mg/day IV tripled the AUC of simvastatin, a CYP3A substrate 1.
c) Conivaptan 40 mg orally twice daily doubled the AUC and half-life of amLODIPine, a CYP3A substrate 1.
Common questions
Can I take Irinotecan Injection and Conivaptan together?
Increased CYP3A substrate exposure Always confirm with your pharmacist or prescriber before making any change.
How serious is the Irinotecan Injection and Conivaptan interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
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 Irinotecan Injection or Conivaptan 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: VAPRISOL(R) intravenous injection, conivaptan HCl intravenous injection. Cumberland Pharmaceuticals Inc. (per manufacturer), Nashville, TN, 2014.
Keep reading about Conivaptan
Keep reading about Irinotecan Injection
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