Safety and efficacy of a urine alkalinization protocol developed for high-dose methotrexate patients during intravenous bicarbonate shortage.

PURPOSE: Urinary alkalinization with intravenous sodium bicarbonate is standard during high-dose methotrexate administration. Due to a national intravenous sodium bicarbonate shortage, a urinary alkalinization protocol involving hyperhydration with intravenous fluids, oral bicarbonate, and intravenous or oral acetazolamide was utilized from 10 April to 30 May 2017 ("shortage protocol"). This study compared outcomes between protocols.

METHODS: A single-center, retrospective chart review was conducted for adults who received methotrexate ≥500 mg/m2 on ≥ two occasions, at least once during each protocol, between 19 February and 19 July 2017.

RESULTS: Eighteen patients (50% male), median age 65 years, received 76 total high-dose methotrexate cycles. Shortage protocol was used in 37 cycles (48.7%). Mean time to methotrexate clearance did not differ between groups (p = ns). Mean time to urinary alkalinization and duration of hospitalization were not statistically different (p = 0.49 and 0.23, respectively). Average total bicarbonate administered per 24 hours was higher in standard protocol (p < 0.05), but hydration rates were similar (p = 0.73). Creatinine clearance and urine output on days 1 and 2 post-high-dose methotrexate did not significantly differ (creatinine clearance day 1, p = 0.27; creatinine clearance day 2, p = 0.55; urine output day 1, p = 0.62; urine output day 2, p = 0.60). Interruptions in alkalinization were significantly higher during shortage (0.41 ± 0.75 instances of urine pH < 7 during standard vs. 1.3 ± 1.7 under shortage, p < 0.05).