What the FDA labels say about taking them together
Palbociclib and quinidine
Palbociclib's FDA label of July 2, 2026 names quinidine in its drug interactions section; the quinidine label PlainMeds reads does 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 quinidine FDA label on DailyMed (effective February 1, 2018, Sun Pharmaceutical Industries, Inc.).
What does the palbociclib label say about quinidine?
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 quinidine label say about palbociclib?
Quinidine's label (effective February 1, 2018) does 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 (Quinidine Gluconate), Sun Pharmaceutical Industries, Inc., effective February 1, 2018 (SPL set 5023f053-fcc4-4c2c-aa59-9ec198ad185e), 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 | Quinidine | |
|---|---|---|
| Labeled for | Breast cancer | Atrial fibrillation |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | n/a | $4.92 per tablet 324 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