Oral sodium bicarbonate a feasible alternative for high-dose MTX urine alkalinization

Oral sodium bicarbonate with Lactated Ringer’s solution (LR) is a good option for urine alkalization to ease nephrotoxicity caused by high-dose methotrexate (MTX; doses ≥500 mg/m²), suggests a study. Moreover, the total dose of sodium bicarbonate used is lower in the oral than the intravenous (IV) cohort, with no additional delays in clearance.

“A shortage of IV sodium bicarbonate in 2017 prompted Alberta Children’s Hospital (ACH) and Stollery Children’s Hospital (SCH) to adopt an alternative protocol including oral sodium bicarbonate and IV hydration with LR,” the authors said.

This retrospective chart review was performed for ACH and SCH inpatients who received high-dose MTX between January and December 2017. The proportion of cycles with delayed high-dose MTX clearance within the IV and oral cohorts was the primary outcome. Secondary ones included sodium bicarbonate administered until clearance, sodium bicarbonate required to reach pH ≥7, time to reach pH ≥7, time to clearance, and time to discharge.

The authors also reported adverse effects associated with delayed clearance or sodium bicarbonate administration.

A total of 112 MTX cycles were included, of which 50 and 62 are from the IV and oral cohorts, respectively. Clearance delays beyond protocol expectations occurred in 10 cycles (8.9 percent), five from each cohort (p=0.72).

No statistically significant differences were observed between the two cohorts, except for the amounts of sodium bicarbonate required until clearance (383 vs 277 mmol/m²; p=0.005) and to reach pH ≥7 (52 vs 40 mmol/m²; p=0.004) which were lower in the oral cohort.

Incidences of adverse effects were similar between cohorts.

“MTX is a cytotoxic antimetabolite. IV hydration and urine alkalinization with sodium bicarbonate can mitigate nephrotoxicity associated with high-dose MTX,” the authors said.