Pharmacokinetics of Ceftazidime-Avibactam in Combination with Aztreonam (COMBINE) in a Phase 1, Open-Label Study of Healthy Adults

Antimicrob Agents Chemother. 2022 Dec 20;66(12):e0093622. doi: 10.1128/aac.00936-22. Epub 2022 Nov 17.


Scant pharmacokinetic (PK) data are available on ceftazidime-avibactam (CZA) and aztreonam (ATM) in combination, and it is unknown if CZA-ATM exacerbates alanine aminotransferase (ALT)/aspartate aminotransferase (AST) elevations relative to ATM alone. This phase 1 study sought to describe the PK of CZA-ATM and assess the associations between ATM exposures and ALT/AST elevations. Subjects (n = 48) were assigned to one of six cohorts (intermittent infusion [II] CZA, continuous infusion [CI] CZA, II ATM, CI ATM [8 g/daily], II CZA with II ATM [6 g/daily], and II CZA with II ATM [8 g/daily]), and study product(s) were administered for 7 days. A total of 19 subjects (40%) had ALT/AST elevations, and most (89%) occurred in the ATM/CZA-ATM cohorts. Two subjects in the CI ATM cohort experienced severe ALT/AST elevations, which halted the study. All subjects with ALT/AST elevations were asymptomatic with no other signs of liver injury, and all ALT/AST elevations resolved without sequalae after cessation of dosing. In the population PK (PopPK) analyses, CZA-ATM administration reduced total ATM clearance by 16%, had a negligible effect on total ceftazidime clearance, and was not a covariate in the avibactam PopPK model. In the exposure-response analyses, coadministration of CZA-ATM was not found to augment ALT/AST elevations. Modest associations were observed between ATM exposure (maximum concentration of drug in serum [Cmax] and area under the concentration-time curve [AUC]) and ALT/AST elevations in the analysis of subjects in the II ATM/CZA-ATM cohorts. The findings suggest that administration of CZA-ATM reduces ATM clearance but does not exacerbate AST/ALT elevations relative to ATM alone. The results also indicate that CI ATM should be used with caution.

Keywords: aztreonam; ceftazidime-avibactam; clinical trials; pharmacokinetics.

Publication types

  • Clinical Trial, Phase I
  • Research Support, Non-U.S. Gov't
  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • Anti-Bacterial Agents / pharmacokinetics
  • Anti-Bacterial Agents / therapeutic use
  • Azabicyclo Compounds / pharmacokinetics
  • Aztreonam* / therapeutic use
  • Ceftazidime* / pharmacokinetics
  • Drug Combinations
  • Humans
  • Microbial Sensitivity Tests
  • beta-Lactamase Inhibitors / pharmacokinetics


  • avibactam, ceftazidime drug combination
  • Ceftazidime
  • Aztreonam
  • beta-Lactamase Inhibitors
  • Azabicyclo Compounds
  • Drug Combinations
  • Anti-Bacterial Agents