Drug absorption VIII: Kinetics of GI absorption of methotrexate.


The absorption of methotrexate from the lumen of the rat small intestine, in situ, was found to obey Michaelis--Menten kinetics. The values of Vmax and Km for the absorption process were 4.78 X 10(-7) M/min and 1.49 X 10(-5) M, respectively.