What the FDA labels say about taking them together
Irinotecan and rifabutin
Irinotecan's FDA label of May 12, 2026 names rifabutin in its drug interactions section; the rifabutin label PlainMeds reads does not name irinotecan. The irinotecan label: “Avoid the use of strong CYP3A4 inducers if possible.”
Check it at the source: the irinotecan FDA label on DailyMed (effective May 12, 2026, Pharmacia & Upjohn Company LLC); the rifabutin FDA label on DailyMed (effective September 1, 2026, REMEDYREPACK INC.).
What does the irinotecan label say about rifabutin?
Irinotecan label, drug interactionsThe appropriate starting dose for patients taking these or other strong inducers such as rifampin and rifabutin has not been defined.
Onivyde label (Ipsen Biopharmaceuticals, Inc., March 3, 2025), drug interactionsAvoid the use of strong CYP3A4 inducers (e.g., rifampin, phenytoin, carbamazepine, rifabutin, rifapentine, phenobarbital, St. John's wort) if possible.
Source: FDA drug label (Onivyde, NDA207793), Ipsen Biopharmaceuticals, Inc., effective March 3, 2025 (SPL set c8b58efa-1820-48a4-b70d-62918fc4abfc), via openFDA
Source: FDA drug label (Camptosar), NDA020571 (Pfizer Inc), as published by Pharmacia & Upjohn Company LLC, effective May 12, 2026 (SPL set e518dfc6-7e93-4fee-a66c-51e1ab71c056), via openFDA; the full label on DailyMed
What does the rifabutin label say about irinotecan?
Rifabutin's label (effective September 1, 2026) does not name irinotecan in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Rifabutin), NDA050689 (Pfizer), as published by REMEDYREPACK INC., effective September 1, 2026 (SPL set 25a60937-cbbe-4a50-994f-2ce15203f589), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Irinotecan | Rifabutin | |
|---|---|---|
| Labeled for | Colorectal cancer | n/a |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | n/a | $8.14 per capsule 150 mg capsule |
| Shortage now | A presentation being discontinued | No current entry |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once