What the FDA labels say about taking them together
Istradefylline and rifampin
Istradefylline's FDA label of May 20, 2025 names rifampin in its drug interactions section; the rifampin label PlainMeds reads does not name istradefylline. The istradefylline label: “Strong CYP3A4 Inducers Coadministration of NOURIANZ with a strong CYP3A4 inducer (rifampin) decreased istradefylline C max and AUC inf by 45% and 81%, respectively.”
Check it at the source: the istradefylline FDA label on DailyMed (effective May 20, 2025, Kyowa Kirin, Inc.); the rifampin FDA label on DailyMed (effective February 11, 2026, Lupin Pharmaceuticals, Inc.).
What does the istradefylline label say about rifampin?
Istradefylline label, drug interactionsStrong CYP3A4 Inducers Coadministration of NOURIANZ with a strong CYP3A4 inducer (rifampin) decreased istradefylline C max and AUC inf by 45% and 81%, 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
What does the rifampin label say about istradefylline?
Rifampin's label (effective February 11, 2026) does 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 (rifampin), Lupin Pharmaceuticals, Inc., effective February 11, 2026 (SPL set b56004f0-f23d-47f6-80c7-39884fccbccc), 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
| Istradefylline | Rifampin | |
|---|---|---|
| Labeled for | Parkinson's disease | n/a |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | n/a | $0.679 per capsule 300 mg capsule |
| Shortage now | No current entry | In shortage |
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