4.BH is an 18-year-old man with osteosarcoma of the right tibia currently being treated with cisplatin, doxorubicin, and high-dose methotrexate. Three days after receiving methotrexate, BH is complaining of significant nausea, vomiting, and mucositis, and his urine output has decreased significantly. Comprehensive metabolic panel (CMP) shows that BH’s serum creatinine increased to 3.6 mg/dL. Urine pH was found to be 7.5 and the patient had been receiving a continuous sodium bicarbonate infusion to maintain his urine pH at appropriate levels. A serum methotrexate level after 48 hours was found to be very high at 21 μmol/L. What is the most appropriate treatment for BH’s new acute kidney injury?

A. Immediate hemodialysis

B. Immediate and simultaneous IV glucarpidase and IV leucovorin administration

C. Immediate glucarpidase administration followed by scheduled IV leucovorin 2 hours later

D. Immediate and simultaneous IV furosemide and IV leucovorin administration