OBJECTIVE

The objective of this study was to determine the relationship between the plasma polymyxin B concentration and renal function in elderly patients.

METHODS

This prospective, case-control, observational study included elderly patients who received polymyxin B therapy and were divided into an acute kidney injury (AKI) group and a non-AKI group based on their renal function. We monitored the pharmacokinetics and pharmacodynamics of polymyxin B, including the minimum plasma concentration (C), mean blood drug concentration at steady state (C), and area under the concentration-time curve across 24 h at steady state (AUC) in both study groups. The plasma polymyxin concentration was determined using high-performance liquid chromatography-tandem mass spectrometry.

RESULTS

The loading doses, C, C, and AUC were significantly higher in the AKI group than in the non-AKI group ( < 0.05). Receiver-operating characteristic curve analysis showed that the optimal cutoff values for predicting AKI were 2.94 mg/L for C, 4.14 mg/L for C, and 99.35 mg·h/L for AUC, with corresponding sensitivities and specificities ranging from 78.57% to 82.14%.

CONCLUSION

Monitoring plasma polymyxin B concentrations is essential in elderly patients. Keeping the C below 2.94 mg/L, the C below 4.14 mg/L, and the AUC below 99.35 mg h/L may help prevent AKI in this population.