The pharmacokinetics of vancomycin in patients with severe acute pancreatitis

The aim of this study was to evaluate the pharmacokinetics of vancomycin in patients with severe acute pancreatitis (SAP). Sixty-seven patients with SAP were included. The FPIA method was used to measure vancomycin serum trough concentrations, and the pharmacokinetic parameters were calculated using the Bayesian estimator. Comparisons of mean values were analyzed using SPSS 11.0. The average daily dose of vancomycin was 15.0 +/- 3.7 mg/kg (q 12 h). Sixty-seven trough concentrations were collected. Compared with the recommended standard vancomycin trough concentration (15 mg/L), SAP patients had significantly lower vancomycin trough concentrations (6.1 +/- 3.0 mg/L; p < 0.0001) while the volume of distribution (Vd) and clearance (CL) of vancomycin were significantly increased. Multiple regression analysis revealed that vancomycin trough concentration was strongly correlated not only with age and albumin but also with the duration from SAP onset to vancomycin therapy (p < 0.0001). Stepwise regression analysis revealed that the duration was the most important variable for vancomycin trough concentration (r (2) = 0.456). The relationships between vancomycin trough concentrations and the duration were further evaluated after the 67 patients were stratified into two groups according to the duration from SAP onset to vancomycin therapeutic drug monitoring (TDM) within or over 4 weeks. Early group had much lower trough concentrations compared to late group, and the CL was also significantly increased in the early group. Of these 67 patients, 24 patients made vancomycin dosage adjustment (increased to 18.5 +/- 3.9 mg/kg, q 12 h) and the average trough concentrations increased to 12.6 +/- 3.8 mg/L. The serum trough concentration of vancomycin was significantly reduced in SAP patients. Higher dosage regimens are needed to ensure the clinical effect.