What the FDA labels say about taking them together
Enzalutamide and phenytoin
Enzalutamide's FDA label (Xtandi) of May 25, 2021 names phenytoin in its drug interactions section; the phenytoin labels PlainMeds reads (2) do not name enzalutamide.
Check it at the source: the enzalutamide FDA label on DailyMed (effective July 28, 2026, Astellas Pharma US, Inc.); the phenytoin FDA label on DailyMed (effective October 15, 2024, Mylan Pharmaceuticals Inc.).
What does the enzalutamide label say about phenytoin?
Xtandi label (Astellas Pharma US, Inc., May 25, 2021), drug interactionsCo-administration of strong CYP3A4 inducers (e.g., carbamazepine, phenobarbital, phenytoin, rifabutin, rifampin, rifapentine) with XTANDI should be avoided if possible.
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 phenytoin label say about enzalutamide?
Phenytoin's label (effective October 15, 2024) and its 1 other brand-application label 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 (Phenytek), Mylan Pharmaceuticals Inc., effective October 15, 2024 (SPL set 0f94c791-8b07-4b41-927e-c9f28bec5f60), 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 | Phenytoin | |
|---|---|---|
| Labeled for | Prostate cancer | Seizures and epilepsy |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | n/a | $0.145 per capsule 100 mg capsule |
| 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