Determination of polymyxin B concentration in plasma and its application in critically ill patients / 中国药房

ABSTRACT

OBJECTIVE To establish a method for the determination of polymyxin B concentration in plasma and apply it to clinical practice. METHODS After precipitated with 5% trichloroacetic acid solution， using polymyxin E2 as internal standard， the concentrations of polymyxin B1 and B2 in plasma sample were determined by UPLC-MS/MS. The determination was performed on BEH C18 chromatographic column with water （0.1% formic acid）-acetonitrile （0.1% formic acid） as mobile phase （gradient elution） at the flow rate of 0.5 mL/min. The sample size was 10 µL. The detection was accomplished with electrospray ionization operated in positive ion scanning by multi-reaction monitoring mode. The ion pairs for quantitative analysis were m/z 603.2→101.2 （polymyxin B1）， m/z 595.7→101.1 （polymyxin B2） and m/z 578.5→101.1 （internal standard）. The plasma concentration of polymyxin B in 79 critically ill patients was measured by the above method， the occurrence of acute renal injury （AKI） was recorded and the relationship of polymyxin B concentration in plasma with AKI was analyzed. RESULTS The linear ranges of polymyxin B1 and polymyxin B2 were 200-20 000， 50-5 000 ng/mL （r＞0.995）， and the lower limits of quantification were 200 and 50 ng/mL， respectively. RSDs of intra‐day and inter‐day precision tests were not higher than 12.06%， the average extraction recovery was 103.04%-117.44%， and RSDs of matrix effect test and stability test were all not higher than 7.42%. Steady state trough and peak plasma concentration were （2.54±2.52） and （8.17±5.20） mg/L for 79 clinical patients using polymyxin B. Eighteen patients out of 27 included patients developed AKI， with an incidence of 66.67%. The peak concentration of polymyxin B of patients without AKI was significantly lower than that of patients with AKI （P＜0.05）， but there was no significant difference in the trough concentration between two groups （P＞0.05）. CONCLUSIONS The established UPLC-MS/MS has the advantages of simple operation and high sensitivity， and can be used to monitor the plasma concentration of polymyxin B in patients. The occurrence of AKI is correlated with the peak concentration of polymyxin B.