serum disappearance curves in dogs after the intravenous injection of radioactive methotrexate , 5-methyltetrahydrofolate , 5-formyltetrahydrofolate , and folic acid followed first-order kinetics with half-disappearance times ranging from 1.3 to 9 hr respectively .
C0023413
5-formyltetrahydrofolate
C0016410
folic acid