What the FDA labels say about taking them together
Digoxin and istradefylline
Istradefylline's FDA label of May 20, 2025 names digoxin in its drug interactions section; the digoxin labels PlainMeds reads (3) do not name istradefylline. The istradefylline label: “P-glycoprotein (P-gp) Substrates Coadministration of NOURIANZ with a P-gp substrate (digoxin) increased the P-gp substrate C max and AUC inf by 33% and 21%, respectively.”
Check it at the source: the digoxin FDA label on DailyMed (effective December 5, 2024, Advanz Pharma (US) Corp.); the istradefylline FDA label on DailyMed (effective May 20, 2025, Kyowa Kirin, Inc.).
What does the digoxin label say about istradefylline?
Digoxin's label (effective December 5, 2024) and its 2 other brand-application labels do not name istradefylline in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (LANOXIN), Advanz Pharma (US) Corp., effective December 5, 2024 (SPL set d91e3646-4c63-4512-ab22-db39c085c4dc), via openFDA; the full label on DailyMed
What does the istradefylline label say about digoxin?
Istradefylline label, drug interactionsP-glycoprotein (P-gp) Substrates Coadministration of NOURIANZ with a P-gp substrate (digoxin) increased the P-gp substrate C max and AUC inf by 33% and 21%, respectively [see Clinical Pharmacology (12.3) ].
Source: FDA drug label (NOURIANZ), Kyowa Kirin, Inc., effective May 20, 2025 (SPL set a7d008cb-b273-4049-a5d2-9c6902910d58), 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
| Digoxin | Istradefylline | |
|---|---|---|
| Labeled for | Heart failure, Atrial fibrillation | Parkinson's disease |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.133 per tablet 125 mcg tablet | n/a |
| 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