The use of diamox in the sequential methotrexate-5-fluorouracil therapy of advanced gastrointestinal cancer

Acetazolamide for acute kidney injury in patients undergoing high dose methotrexate therapy: a systematic review and meta-analysis

BACKGROUND

Urine alkalization is one of the standard treatments to prevent acute kidney injury in patients receiving high-dose methotrexate. Carbonic anhydrase inhibitors are promising adjuvants/substitutes with advantages such as faster urine alkalization time and prevention of fluid overload. However, there is limited and contradictory evidence on its efficacy and safety. We aimed to compare the efficacy and safety of carbonic anhydrase inhibitors to standard treatments in adult patients receiving high-dose methotrexate.

METHODS

The protocol was registered at PROSPERO (CRD42022352802) in August 2021. We evaluated the use of carbonic anhydrase inhibitors in combination with standard treatment compared to standard treatment alone. We excluded articles irrelevant to the efficacy and safety of acetazolamide in patients receiving high dose methotrexate and/or did not provide sufficient data regarding doses, recruitment criteria, and follow-up period. Two authors performed the data extraction independently.

RESULTS

Among 198 articles retrieved, six observational studies met all eligibility criteria. Four studies with five datasets (totaling 558 patients/cycles) had enough data to be included in the meta-analysis. We independently report the results from the two remaining studies. The results did not show a significant difference between acetazolamide versus standard treatment in acute kidney injury (AKI) rate (OR = 0.79, 95% CI 0.48-1.29, P = 0.34, I2 = 0%). Regarding the time to urine pH goal, there was no significant time difference between the two groups (Mean Difference = 0.07, 95% CI - 1.9 to 2.04, P = 0.95, I2 = 25%). Furthermore, our meta-analysis showed that acetazolamide did not reduce length of stay (Mean Difference = 0.75, 95% CI - 0.8 to 2.31, P = 0.34, I2 = 0%). In one study, the only reported side effect of acetazolamide was hypokalemia (nearly 50% in the acetazolamide group).

CONCLUSIONS

This systematic review showed no significant difference between acetazolamide and standard care treatment regarding urine alkalinization time and AKI rate in adult patients receiving high dose methotrexate. We suggest performing a large blinded, randomized, controlled trial to evaluate the potential benefits of this low-cost medication.

Assessing the impact of adding acetazolamide to oral or intravenous sodium bicarbonate as compared with intravenous bicarbonate monotherapy as urinary alkalinization in adults receiving high-dose methotrexate

PURPOSE

High-dose methotrexate (HD-MTX) requires urine alkalinization to pH ≥ 7 for adequate excretion to prevent toxicity. Due to shortages of IV sodium bicarbonate (IV-NaHCO3), few reports have demonstrated utility of oral bicarbonate (PO-NaHCO3); however, the addition of acetazolamide (Acet) has not been well described. Our study compares outcomes between alkalinization methods of IV-NaHCO3 monotherapy versus IV-NaHCO2 + Acet and PO-NaHCO3 + Acet.

METHODS

A single-center, IRB exempt, retrospective review was conducted from Jan 2016 to Sept 2019 of adults receiving HD-MTX ≥ 500 mg/m². The primary outcome was time from start of alkalinization to pH ≥ 7. Secondary outcomes included time from start of alkalinization to initiation of HD-MTX, time to MTX clearance, length of stay (LOS), percentage of urine pH assessments < 7, and incidence of MTX toxicity. Statistical analysis was performed using SAS9.4 with alpha 0.05.

RESULTS

Overall demographics (n = 196 HD-MTX cycles for 55 patients) include a mean age 55 years, HD-MTX dose ~ 5400 mg/m², and 69% with a diagnosis of lymphoma. Adjusting for baseline demographic differences among groups, median time from first dose alkalinization to pH ≥ 7 and to start of HD-MTX was longer for those receiving IV-NaHCO3 (n = 41) vs either IV-NaHCO3 + Acet (n = 70) or PO-NaHCO3 + Acet (n = 76) (p = 0.0001). HD-MTX clearance to a level < 0.1 μmol/L was not improved with the addition of Acet. No difference existed among groups for pH results < 7, LOS, or incidence of MTX toxicity (p > 0.05).

CONCLUSIONS

Addition of Acet to NaHCO3 reduces time to pH ≥ 7 and initiation of HD-MTX but does not appear to improve LOS, MTX toxicities, or time to MTX clearance.

Acetazolamide for alkalinisation of urine in patients receiving high-dose methotrexate

Acetazolamide, 500 mg 6 hourly, has been used to alkalinise the urine in patients receiving high dose methotrexate. A urinary pH of greater than 7.5 was achieved in every cycle (13 cycles in 10 patients). In 6 cycles a single supplementary dose of sodium bicarbonate was necessary. Plasma methotrexate levels fell satisfactorily at 24 and 48 h. Acetazolamide is a simple and effective method of achieving urinary alkalinisation with advantages over oral and intravenous bicarbonate.