What the FDA labels say about taking them together
Palbociclib and sirolimus
Palbociclib's FDA label of July 2, 2026 names sirolimus in its drug interactions section; the sirolimus labels PlainMeds reads (4) do not name palbociclib. The palbociclib label: “The dose of the sensitive CYP3A substrate with a narrow therapeutic index may need to be reduced, as IBRANCE may increase its exposure.”
Check it at the source: the palbociclib FDA label on DailyMed (effective July 2, 2026, Pfizer Laboratories Div Pfizer Inc); the sirolimus FDA label on DailyMed (effective January 28, 2026, Glenmark Pharmaceuticals Inc., USA).
What does the palbociclib label say about sirolimus?
Palbociclib label, drug interactionsThe dose of the sensitive CYP3A substrate with a narrow therapeutic index (e.g., alfentanil, cyclosporine, dihydroergotamine, ergotamine, everolimus, fentanyl, pimozide, quinidine, sirolimus, and tacrolimus) may need to be reduced, as IBRANCE may increase its exposure [see Clinical Pharmacology (12.3) ].
Source: FDA drug label (Ibrance), Pfizer Laboratories Div Pfizer Inc, effective July 2, 2026 (SPL set fecbdd7d-b729-41b5-9872-231b8fe104ce), via openFDA; the full label on DailyMed
What does the sirolimus label say about palbociclib?
Sirolimus's label (effective January 28, 2026) and its 3 other brand-application labels do not name palbociclib in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (sirolimus), Glenmark Pharmaceuticals Inc., USA, effective January 28, 2026 (SPL set 57fb4d90-3ccb-4a69-af1e-53be83f7a504), 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
| Palbociclib | Sirolimus | |
|---|---|---|
| Labeled for | Breast cancer | Organ transplant rejection |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | n/a | $0.723 per tablet 1 mg tablet |
| 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