Following the intravenous administration of 500 and 1000 mg doses of rituximab on two occasions, two weeks apart, mean Cmax values were 183 μ g/ mL (range, 81.8 to 279 μ g/ mL) and 370 μ g/ mL (212 to 637 μ g/ mL), and mean half-lives were 17.9 days (range, 12.3 to 31.3 days) and 19.7 days (range, 12.3 to 34.6 days), respectively.