Comparison of Sodium Bicarbonate and Lactated Ringers Hydration for High-dose Methotrexate Chemotherapy in Children

Background: High-dose methotrexate is part of the treatment of pediatric cancers. To reduce the risk of toxicity, supportive measures, including hydration and alkalinization, are recommended. At our institution, we switched from intravenous sodium bicarbonate to Lactated Ringers during a worldwide shortage. Procedure: This was a retrospective cohort of children who received high-dose methotrexate from January 1, 2016 to August 31, 2018. The primary outcome was the prevalence of delayed methotrexate clearance. Secondary outcomes were proportion of cycles with delayed methotrexate clearance, time to methotrexate clearance, adverse events, risk factors for delayed clearance, and association between hydration type and delayed clearance. Results: Eighty-two patients, with a total of 325 methotrexate cycles, were included. Forty-four patients received sodium bicarbonate, 31 received Lactated Ringers, and 7 received both. There was no difference in the prevalence of delayed methotrexate clearance between those who received sodium bicarbonate and Lactated Ringers (64% vs. 68%). The proportion of cycles with delayed methotrexate clearance, time to methotrexate clearance, and adverse events were similar between groups. Cancer type, methotrexate dose, and vomiting were associated with delayed clearance. Conclusions: Our study suggests that Lactated Ringers may be used in place of sodium bicarbonate for intravenous hydration during high-dose methotrexate.