3. 4. 5. Evaluate patient for presence of third spaces (ascites, pleural or cardiac effusions). If present, the site mus

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3 4 5 Evaluate Patient For Presence Of Third Spaces Ascites Pleural Or Cardiac Effusions If Present The Site Mus 1 (381.51 KiB) Viewed 34 times

3. 4. 5. Evaluate patient for presence of third spaces (ascites, pleural or cardiac effusions). If present, the site must be drained before methotrex- ate infusion is initiated. Urine pH on admission. Must obtain urine pH 7 or greater prior to start of therapy; repeat urine pH every 4h until urine pH is 7 or greater. Methotrexate levels exactly 24 hours, 48 hours, 72 hours after infusion completed, and then every am until level is less than 0.1 micromo- lar for normal methotrexate clearance or less than 0.05 for delayed clearance. Daily labs: urine pH, CMP, IV Fluids: Patient needs to be well hydrated before starting methotrexate: Administer NS 1 Lover 2 hours x 1 L-OR- 6. 7. 8. Maintenance IV Fluids:D5 1/4NS IL with sodium bicarbonate 100 mEq at 200 mL/hr to continue until leucovorin is discontinued [total fluids of 2.5-3 L/m2/day]. -OR- to continue until leucovorin is discontinued. 9. Acetazolamide (Diamox) 500 mg immediate release PO every 4h x 2 doses. If urine pH is greater than or equal to 7, do not administer acetazolamide. 10. Drug Interactions: avoid PPIs (use ranitidine), penicillins, cephalosporins, probenecid, trimethoprim, NSAIDs and other nephrotoxic meds 11. Antiemetics: Granisetron 2 mg PO plus dexamethasone 12 mg PO prior to methotrexate Prochlorperazine 10 mg PO every 4 hours prn nausea Promethazine 12.5 mg IV every 6 hours prn vomiting 12. Methotrexate g/m2/dose = g IV over 4 hours Typical dosage range: 3.5 g/m2 to 8 g/m2 depending on indication and renal function. Subsequent dose adjustments are required based on delayed methotrexate clearance and/or toxicities. Modify initial methotrexate dose if calculated creatinine clearance (CrCl) is below 100 mL/min. For example, if est. CrCl is 75 mL/min, reduce methotrexate dose 25%; if CrCl is 50 mL/min, reduce dose 50%. 13. Leucovorin 25 mg PO every 6 hours, beginning 24 hours after the start of methotrexate infusion. Continue until methotrexate level is less than 0.1 micromolar for normal methotrexate clearance or less than 0.05 for delayed clearance. Notify Oncology Fellow before changing leucovorin dose. Time after MTX infusion completed MTX level (micromolar) Change in leucovorin dose greater than 10 to less than 50 Increase to 50 mg IV every 6h 24 hours 50 or greater Increase to 150 mg IV every 3h greater than 1 to less than 5 Increase to 50 mg IV every 6h 48 hours 5 or greater Increase to 150 mg IV every 3h 72 hours greater than 0.1 Increase to 50 mg IV every 6h If the leucovorin dose has been increased to 50 mg IV every 6hrs, continue this dose until the methotrexate level less than 0.1 micromolar. If the patient has severe delayed methotrexate clearance or develops acute renal injury (doubling of baseline creatinine), increase leu- covorin dose to 150 mg IV every 3h. Continue dose until methotrexate level is less than 1, then reduce leucovorin dose to 25 mg IV every 6hrs until the methotrexate level is less than 0.05. Hydration, urinary pH 7.0 or greater, and close monitoring of fluid and electrolyte status should continue until the serum methotrexate level has fallen less than 0.05 and renal injury has resolved.