Prescription medicine
Istradefylline Brand names: Nourianz
Istradefylline (Nourianz) is a prescription medicine with an FDA approval on record since 2019. No generic is listed in FDA's NDC Directory.
- No generic listed
Check it at the source: the istradefylline FDA label on DailyMed (effective May 20, 2025, Kyowa Kirin, Inc.); the NDA 22075 record on Drugs@FDA; every istradefylline label on DailyMed.
Highlights of the record
FDA label of May 20, 2025; NDC Directory, Drugs@FDA and Orange Book, October 8, 2026
Used for
From the label: indications and usageNOURIANZ is indicated as adjunctive treatment to levodopa/carbidopa in adult patients with Parkinson's disease (PD) experiencing "off" episodes.
Forms and strengths
- 20 mg
- 40 mg
Film-coated tablet.
On the market
- Earliest approval on file
- August 27, 2019 Nourianz, Kyowa Kirin; Drugs@FDA’s file, where older or withdrawn approvals can be missing
- Generic approvals
- No generic approved
- Labelers listed (NDC)
- 1 of which 0 under generic applications, 1 under brand applications, repackagers included
- Last listed patent
- January 28, 2028 Nourianz tablets; not a generic launch date
Supply and safety
- Pharmacy cost (NADAC)
- Not in the survey
- Shortage (FDA)
- No current entry
- Recalls by its makers (FDA)
- No recall recorded
- FAERS reports
- 5,920 through July 30, 2026
What is istradefylline used for?
From the label: indications and usageNOURIANZ is indicated as adjunctive treatment to levodopa/carbidopa in adult patients with Parkinson's disease (PD) experiencing "off" episodes. NOURIANZ is an adenosine receptor antagonist indicated as adjunctive treatment to levodopa/carbidopa in adult patients with Parkinson's disease (PD) experiencing "off" episodes ( 1 ).
Conditions named in the indications of istradefylline's FDA labels, with every medicine labeled for each:
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
Is there a generic for istradefylline (Nourianz)?
No generic istradefylline is approved (Drugs@FDA, October 8, 2026).
The Orange Book lists 2 patents for Nourianz tablets, the last expiring on January 28, 2028. A patent or exclusivity date is not the date a generic goes on sale: court cases and settlements move it either way.
- 2019 earliest approval on file
- 2028 last listed patent
Source: Drugs@FDA, FDA NDC Directory and the Orange Book (openFDA bulk files, October 8, 2026)
What does the istradefylline label say about other medicines?
The istradefylline label names 10 other medicines in its interaction, contraindication or warning sections. The sentences are the labels' own; a label lists what its studies and reports found, not every interaction.
| Medicine named | Section | What the label says |
|---|---|---|
| Atorvastatin | drug interactions | Coadministration of NOURIANZ 20 mg with a CYP3A4 substrate (midazolam) did not affect the CYP3A4 substrate exposure, while concomitant administration of NOURIANZ 40 mg increased the CYP3A4 substrate (atorvastatin) C max and AUC inf by 1.5-fold [see Clinical Pharmacology (12.3) ]. |
| Carbamazepine | drug interactions | Therefore, it is recommended to avoid use of NOURIANZ with strong CYP3A4 inducers (e.g., carbamazepine, rifampin, phenytoin, St. John's wort) [see Dosage and Administration (2.3) ]. |
| Clarithromycin | drug interactions | Therefore, the recommended maximum dosage of NOURIANZ in patients concomitantly using strong CYP3A4 inhibitors (e.g., itraconazole, ketoconazole, clarithromycin) is 20 mg once daily [see Dosage and Administration (2.2) ]. |
| Digoxin | drug interactions | 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 [see Clinical Pharmacology (12.3) ]. |
| Itraconazole | drug interactions | Therefore, the recommended maximum dosage of NOURIANZ in patients concomitantly using strong CYP3A4 inhibitors (e.g., itraconazole, ketoconazole, clarithromycin) is 20 mg once daily [see Dosage and Administration (2.2) ]. |
| Ketoconazole | drug interactions | Drugs on NOURIANZ Strong CYP3A4 Inhibitors Coadministration of NOURIANZ with a strong CYP3A4 inhibitor (ketoconazole) increased istradefylline AUC inf by 2.5-fold [see Clinical Pharmacology (12.3) ]. |
| Levodopa | warnings and precautions | Dyskinesia NOURIANZ in combination with levodopa may cause dyskinesia or exacerbate pre-existing dyskinesia. |
| Midazolam | drug interactions | Coadministration of NOURIANZ 20 mg with a CYP3A4 substrate (midazolam) did not affect the CYP3A4 substrate exposure, while concomitant administration of NOURIANZ 40 mg increased the CYP3A4 substrate (atorvastatin) C max and AUC inf by 1.5-fold [see Clinical Pharmacology (12.3) ]. |
| Phenytoin | drug interactions | Therefore, it is recommended to avoid use of NOURIANZ with strong CYP3A4 inducers (e.g., carbamazepine, rifampin, phenytoin, St. John's wort) [see Dosage and Administration (2.3) ]. |
| Rifampin | drug interactions | Strong 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 do FAERS reports show for istradefylline?
The FDA Adverse Event Reporting System holds 5,920 reports that list istradefylline among the medicines taken, through July 30, 2026, each a report of something that happened, not proof the medicine caused it; 928 are coded as a death and 763 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is.
Reports received each year
The most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026
What else is labeled for the same conditions as istradefylline?
13 other medicines are given the same way (oral) and in the same FDA class as istradefylline or labeled mainly for the same use (parkinson's disease), the same class first. Parkinson's disease lists all 19 medicines labeled for it, by any route. The first 8 are below. They are listed as records, not as substitutes: whether one can replace another is a prescriber's decision.
| Medicine | Shared indication | Generic labelers (oral) | Pharmacy cost | Shortage |
|---|---|---|---|---|
| Ropinirole | Parkinson's disease | 27 labelers | $0.046 per tablet 0.25 mg tablet | No current entry |
| Pramipexole | Parkinson's disease | 22 labelers | $0.0452 per tablet 0.25 mg tablet | No current entry |
| Carbidopa and levodopa | Parkinson's disease | 33 labelers | $0.0759 per tablet 25-100 tablet | No current entry |
| Benztropine | Parkinson's disease | 19 labelers | $0.0753 per tablet 1 mg tablet | A presentation being discontinued |
| Rasagiline | Parkinson's disease | 14 labelers | $0.521 per tablet 0.5 mg tablet | No current entry |
| Carbidopa and entacapone and levodopa | Parkinson's disease | 4 labelers | $0.695 per tablet 25-100-200 mg tablet | No current entry |
| Trihexyphenidyl | Parkinson's disease | 8 labelers | $0.0884 per tablet 2 mg tablet | No current entry |
| Entacapone | Parkinson's disease | 11 labelers | $0.325 per tablet 200 mg tablet | No current entry |
Every medicine labeled for the same conditions as istradefylline
Source: FDA drug labels (indications), NDC Directory, NADAC of October 7, 2026, FDA shortages (October 8, 2026)
What next?
- Alternatives to istradefylline
- 13 medicines for the same use
- Istradefylline side effects
- the label's list beside FAERS reports
- Check an interaction
- what two or more labels say about each other