Ampicillin sulbactam impacts serum potassium level comparable to piperacillin tazobactam

Ampicillin/sulbactam (ABPC/SBT) and piperacillin/tazobactam (PIPC/TAZ) are important beta-lactam/beta-lactamase inhibitor combinations. Recently, PIPC/TAZ has been reported to decrease serum potassium level (SPL). To test the hypothesis that ABPC/SBT also has the same impact, we evaluated the change in SPL by ABPC/SBT administration and compared with that by PIPC/TAZ. A retrospective, observational propensity-score matched cohort study was performed using data between 2020 and 2022. After subject selection, multiple regression analysis was conducted to identify risk factors associated with decrease in SPL. Baseline SPL, duration of ABPC/SBT or PIPC/TAZ administration, and female sex were identified as significant risk factors. Using the factors that potentially influence SPL, propensity score matching was performed, and the decrease in SPL was compared between the propensity score-matched cohorts (ABPC/SBT: n = 59, PIPC/TAZ: n = 59). The change in SPL was not significantly different between the two cohorts (- 0.28 ± 0.47 mEq/L vs. - 0.35 ± 0.51 mEq/L, P = 0.443). In addition, the percent decrease in SPL (10.7 ± 7.0% vs. 11.0 ± 9.7%, P = 0.822) and the incidence of hypokalemia (25.4% vs. 27.1%, P = 1.000) were not significantly different. ABPC/SBT decreases SPL comparable to PIPC/TAZ, with a clinically significant effect. Careful monitoring of SPL is necessary when patients with identified risk factors are treated with ABPC/SBT or PIPC/TAZ.