Clinical Efficacy and Safety of Vancomycin Based on Unbound Vancomycin Concentration Monitoring

Objective: To monitor total trough concentration (Cmin_total) and unbound trough concentration (Cmin_free) of vancomycin in clinical samples and analyze the factors influencing them, and to assess their correlation with clinical efficacy and acute kidney injury (AKI).

Methods: Plasma samples were processed by protein precipitation, followed by hollow-fiber centrifugal ultrafiltration to separate unbound vancomycin from plasma. Thereafter, Cmin_total and Cmin_free were determined using high-performance liquid chromatography. Clinical data of patients were collected. Factors affecting vancomycin Cmin_total, Cmin_free, and their correlation with clinical efficacy and nephrotoxicity were investigated.

Results: A total of 146 samples from 105 included patients were collected. Cmin_total and Cmin_free of vancomycin ranged from 0.62 to 56.08 mcg·mL-1 and 0.61-38.51 mcg·mL-1, respectively. Cmin_total and Cmin_free were correlated (r = 0.8899), influenced by basal creatinine and cystatin C. Higher level of Cmin_free (˃8.6 mcg·mL-1) and nephrotoxic drugs concomitant were risk factors of vancomycin-associated AKI (P < 0.05); Cmin_total and Cmin_free thresholds of vancomycin-associated AKI were 15.35 and 6.83 mcg·mL-1, respectively.

Conclusions: vancomycin Cmin_total and Cmin_free, higher Cmin_total and Cmin_free were correlated and higher concentrations of both may increase the risk of AKI.