Co-Administration Dosing of Ceftazidime–Avibactam and Aztreonam in Patients with Varying Renal Function for Carbapenem-Resistant Enterobacterales Infections via Monte Carlo Simulation

BACKGROUND: For infections caused by metallo-β-lactamase (MBL)-producing carbapenem-resistant Enterobacterales (CRE), ceftazidime-avibactam (CZA) alone is inactive because avibactam does not inhibit MBLs. Co-administration with aztreonam can restore activity but requires simultaneous delivery and harmonization of non-aligned renal dose adjustments. Pharmacodynamic (PD) targets for MBL producers may also differ from those for serine β-lactamase producers. This study aimed to define practical CZA plus aztreonam dosing regimens across renal function strata using Monte Carlo simulation. MATERIALS AND METHODS: >80 mg/L was applied as a neurotoxicity risk threshold. RESULTS: >80 mg/L) remained low across renal strata. CONCLUSION: Co-administration of CZA and aztreonam using renal-adjusted doses provides a practical and effective strategy for MBL-CRE infections. This approach ensures high joint PTA attainment while maintaining a low neurotoxicity risk across all renal function strata.