Drug Interaction Report

Irinotecan Injection and Paritaprevir: Interaction Details

Name: Irinotecan Injection and Paritaprevir Interaction
Creator: Dr. Brian Staiger, PharmD, BCPS

A pharmacist-reviewed analysis of the Irinotecan Injection and Paritaprevir interaction: the documented clinical effects, severity rating, onset, mechanism, and management considerations, with cited references throughout.

AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature

Paritaprevir

No brand names on record

Irinotecan Injection

Camptosar Camptosar® Onivyde

Medically reviewed by

Dr. Brian Staiger, PharmD, BCPS

Updated Aug 8, 2026

Editorial policy · Data sources

Interaction severity

Major

Potentially serious — often needs a change or close monitoring.

Minor

Moderate

Major

Contraindicated

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.

Of 96 documented Irinotecan Injection interactions, 73 are rated major — including this one.

Worried about symptoms right now? Contact your pharmacist or prescriber, or call Poison Control at 1-800-222-1222 (US). Call 911 for an emergency.

Onset

unspecified

Evidence

theoretical

Severity

Major

What happens

Increased irinotecan exposure and an increased irinotecan active metabolite exposure

Interaction Deep Dive

Avoid coadministration of irinotecan (a CYP3A4 substrate) with a strong CYP3A4 inhibitor unless there are no therapeutic alternatives, as concomitant use may result in an increased exposure to irinotecan or its active metabolite, SN-38. Discontinue strong CYP3A4 inhibitors at least 1 week prior to initiating therapy with irinotecan²¹.

Why it happens (mechanism)

Inhibition of CYP3A4-mediated metabolism of irinotecan

Common questions

Can I take Irinotecan Injection and Paritaprevir together?

Increased irinotecan exposure and an increased irinotecan active metabolite exposure Always confirm with your pharmacist or prescriber before making any change.

How serious is the Irinotecan Injection and Paritaprevir 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 Paritaprevir 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: CAMPTOSAR(R) intravenous injection, irinotecan intravenous injection. Pharmacia & Upjohn Co (per Manufacturer), New York, NY, 2014. DailyMed
Product Information: ONIVYDE(R) intravenous injection, irinotecan liposome intravenous injection. Ipsen Biopharmaceuticals Inc (per FDA), Cambridge, MA, 2024. DailyMed

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Paritaprevir

Keep reading about Paritaprevir

All Paritaprevir interactions (73)

Also serious with: Lovastatin Finerenone Dihydroergotamine Injection Lurasidone

Irinotecan Injection

Keep reading about Irinotecan Injection

All Irinotecan Injection interactions (96) Irinotecan Injection drug information

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HelloPharmacist doesn't license one of the big commercial interaction databases, so what you'll find here is not a complete list of every known drug interaction. Instead, each entry is researched, analyzed, and written up individually — documented from the published literature, reviewed by a pharmacist, and cited so you can check every source yourself.

If a combination isn't listed here, it means we haven't documented it yet — never that it's safe. For screening a full medication list, we recommend pairing this site with a comprehensive tool like the Drugs.com Interaction Checker and, most importantly, a review by your own pharmacist. For a deep, plain-English, fully sourced explanation of a specific documented interaction — that's exactly what we built this for.

This information is for education, not a substitute for professional medical advice. Do not start, stop, or change any medication without talking to your pharmacist or prescriber.