 | C4X-106116 | N/A | Impurity | |
| Istradefylline Impurity 16 |
| C4X-106117 | N/A | Impurity | |
| Istradefylline Impurity 17 (Mixture of Diastereomers) |
| C4X-106118 | 146946-10-3 | Impurity | |
| Istradefylline Impurity 18 |
 | C4X-106119 | 155272-03-0 | Impurity | |
| Istradefylline Impurity 19 |
 | C4X-10612 | 160434-48-0 | Impurity | |
| Istradefylline Impurity 2 |
| C4X-106120 | 1785764-26-2 | Impurity | |
| Istradefylline Impurity 20 |
| C4X-106121 | 41740-15-2 | Impurity | |
| Istradefylline Impurity 21 |
 | C4X-106122 | 1453190-01-6 | Impurity | |
| Istradefylline Impurity 22 |
| C4X-106123 | 187393-68-6 | Impurity | |
| Istradefylline Impurity 23 |
| C4X-106124 | 155270-98-7 | Impurity | |
| Istradefylline Impurity 24 |
