Decreased intestinal absorption of methotrexate in the rat following repeated oral dosing.
The absorption of methotrexate (MTX) following single and repeated oral administrations was investigated in the rat and compared with that after intravenous injections. The absorption of intermediate dose MTX was poor (14.7%), both after single gift (25 mg X kg-1) and when given repeatedly at 72-hour intervals (3 X 25 mg X kg-1). Repeated oral administration did not produce higher plasma concentrations of MTX in spite of decreased elimination as a result of impaired renal clearance. It is concluded from these experiments that repeated oral administration of MTX when spaced 72 hours apart leads to a deterioration of the already incomplete intestinal absorption of the drug in the rat.
D000284:Administration, Oral; D000818:Animals; D005260:Female; D007275:Injections, Intravenous; D007408:Intestinal Absorption; D008727:Methotrexate / Q000008:administration & dosage / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D008727:Methotrexate