- Regimen A: Patients receive methotrexate IV over 24 hours on day 1. Cytarabine is administered IV over 2 hours every 12 hours on days 2 and 3. Filgrastim (G-CSF) is administered subcutaneously (SC) daily beginning on day 4 and continuing until blood counts recover. Treatment repeats every 21 days for up to 8 courses.