What the FDA labels say about taking them together
Enzalutamide and sirolimus
Enzalutamide's FDA label (Xtandi) of May 25, 2021 names sirolimus in its drug interactions section; the sirolimus labels PlainMeds reads (4) do not name enzalutamide. The enzalutamide label: “Concomitant use of XTANDI with narrow therapeutic index drugs that are metabolized by CYP3A4, CYP2C9 and CYP2C19 should be avoided, as enzalutamide may decrease their exposure.”
Check it at the source: the enzalutamide FDA label on DailyMed (effective July 28, 2026, Astellas Pharma US, Inc.); the sirolimus FDA label on DailyMed (effective January 28, 2026, Glenmark Pharmaceuticals Inc., USA).
What does the enzalutamide label say about sirolimus?
Xtandi label (Astellas Pharma US, Inc., May 25, 2021), drug interactionsConcomitant use of XTANDI with narrow therapeutic index drugs that are metabolized by CYP3A4 (e.g., alfentanil, cyclosporine, dihydroergotamine, ergotamine, fentanyl, pimozide, quinidine, sirolimus and tacrolimus), CYP2C9 (e.g., phenytoin, warfarin) and CYP2C19 (e.g., S-mephenytoin, clopidogrel) should be avoided, as enzalutamide may decrease their exposure.
Source: FDA drug label (Xtandi, NDA213674), Astellas Pharma US, Inc., effective May 25, 2021 (SPL set 381cd215-78c9-4208-8595-7ae7a279b236), via openFDA
Source: FDA drug label (Xtandi), Astellas Pharma US, Inc., effective July 28, 2026 (SPL set b129fdc9-1d8e-425c-a5a9-8a2ed36dfbdf), via openFDA; the full label on DailyMed
What does the sirolimus label say about enzalutamide?
Sirolimus's label (effective January 28, 2026) and its 3 other brand-application labels do not name enzalutamide 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
| Enzalutamide | Sirolimus | |
|---|---|---|
| Labeled for | Prostate cancer | Organ transplant rejection |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | n/a | $0.723 per tablet 1 mg tablet |
| Shortage now | No current entry | 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