Summary of rituximab CSF concentrations
| . | Wk 1 . | Wk 2 . | Wk 3 . | Wk 4 . | Wk 5 restage . | ||||
|---|---|---|---|---|---|---|---|---|---|
| d 1 . | d 4 . | d 1 . | d 4 . | d 1 . | d 4 . | d 1 . | d 4 . | ||
| 10-mg group (n = 3) | |||||||||
| Predose | LTR | 1.67 | 1.71 | 5.16 | 3 | 4.5 | 3.2 | 5.3 | 3.85 |
| 1 h postdose | 222 | 152 | 248 | 164 | 240 | 154 | 275 | 96 | |
| 2 h postdose | 100 | 98 | |||||||
| 25-mg group (n = 7) | |||||||||
| Predose | LTR | 5.6 | 1.38 | 5.5 | 1.6 | 6.2 | 4.9 | 12.1 | 2.3 |
| 1 h postdose | 757 | 412 | 807 | 392 | 754 | 380 | 705 | 413 | |
| 2 h postdose | 399 | 377 | |||||||
| . | Wk 1 . | Wk 2 . | Wk 3 . | Wk 4 . | Wk 5 restage . | ||||
|---|---|---|---|---|---|---|---|---|---|
| d 1 . | d 4 . | d 1 . | d 4 . | d 1 . | d 4 . | d 1 . | d 4 . | ||
| 10-mg group (n = 3) | |||||||||
| Predose | LTR | 1.67 | 1.71 | 5.16 | 3 | 4.5 | 3.2 | 5.3 | 3.85 |
| 1 h postdose | 222 | 152 | 248 | 164 | 240 | 154 | 275 | 96 | |
| 2 h postdose | 100 | 98 | |||||||
| 25-mg group (n = 7) | |||||||||
| Predose | LTR | 5.6 | 1.38 | 5.5 | 1.6 | 6.2 | 4.9 | 12.1 | 2.3 |
| 1 h postdose | 757 | 412 | 807 | 392 | 754 | 380 | 705 | 413 | |
| 2 h postdose | 399 | 377 | |||||||
The mean 1-h postdose concentrations were 194 ± 79 μg/mL and 580 ± 335 μg/mL for the 10 and 25 mg dose levels. The predose trough concentrations ranged from less than reportable (LTR) to 15.3 μg/mL at the 10-mg dose level and from LTR to 20.5 μg/mL at the 25-mg dose level. Coadministration with methotrexate was associated with a 50% decrease in the rate of rituximab elimination from the intraventricular compartment.