Drug Interaction Report

Irinotecan Injection and Cobicistat: Interaction Details

A pharmacist-reviewed analysis of the Irinotecan Injection and Cobicistat 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

Cobicistat

Tybost
+

Irinotecan Injection

Camptosar Camptosar® Onivyde
Dr. Brian Staiger, PharmD, BCPS
Medically reviewed by
Dr. Brian Staiger, PharmD, BCPS
Updated Aug 8, 2026
Editorial policy · Data sources
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Interaction severity
Contraindicated
These should generally not be used together.
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, 14 are rated contraindicated — 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
Contraindicated

What happens

Increased irinotecan exposure and an risk of increased irinotecan active metabolite exposure

Interaction Deep Dive

Coadministration of cobicistat and irinotecan is contraindicated due to potential for increased irinotecan toxicity3. Coadministration of irinotecan (CYP3A4 substrate) with cobicistat (strong CYP3A4 inhibitor) may result in an increased exposure to irinotecan or its active metabolite, SN-38. Discontinue cobicistat at least 1 week prior to initiating therapy with irinotecan 2145.

Why it happens (mechanism)

Inhibition of CYP3A4-mediated metabolism of irinotecan; inhibition of BCPR-mediated efflux transport of irinotecan; inhibition of OATP1B1-mediated efflux transport of irinotecan

Common questions

Can I take Irinotecan Injection and Cobicistat together?

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

How serious is the Irinotecan Injection and Cobicistat interaction?

It is rated contraindicated. These should generally not be used together.

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 Cobicistat 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 (5)

  1. Product Information: CAMPTOSAR(R) intravenous injection, irinotecan intravenous injection. Pharmacia & Upjohn Co (per Manufacturer), New York, NY, 2014. DailyMed
  2. Product Information: ONIVYDE(R) intravenous injection, irinotecan liposome intravenous injection. Ipsen Biopharmaceuticals Inc (per FDA), Cambridge, MA, 2024. DailyMed
  3. Product Information: TYBOST(R) oral tablets, cobicistat oral tablets. Gilead Sciences Inc (per FDA), Foster City, CA, 2025. DailyMed
  4. Product Information: PREZCOBIX® PED oral tablets for suspension, darunavir cobicistat oral tablets for suspension. Janssen Products, LP (per FDA), Horsham, PA, 2026. DailyMed
  5. Product Information: PREZCOBIX® oral tablets, darunavir cobicistat oral tablets. Janssen Products, LP (per FDA), Horsham, PA, 2026. DailyMed
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Cobicistat

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Irinotecan Injection

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All Irinotecan Injection interactions (96) Irinotecan Injection drug information
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Beyond drug–drug

These medications also interact with supplements

Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:

Cobicistat + Activated Charcoal Adrafinil Cannabidiol (cbd) Cannabinol (cbn) Cannabis Coffee Charcoal Delta-9-tetrahydrocannabinol (thc) Ergot + 22 more

major · moderate · minor — check everything you take with our drug–supplement interaction checker.

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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.