- Course III: Patients receive intrathecal methotrexate, vincristine IV, and methotrexate IV over 3 hours on days 1, 8, and 15 and oral methotrexate every 6 hours for 4 doses beginning 6 hours after starting methotrexate IV on days 1, 2, 8, 9, 15, and 16. Patients receive leucovorin calcium IV 6 hours after the last oral methotrexate dose on days 2, 9, and 16 and oral leucovorin calcium beginning 12 hours after leucovorin calcium IV for at least 4 doses on days 3, 4, 10, 11, 17, and 18.