Determination Of Colistin By LC-MS/MS In Human Plasma And Its Application To A Pharmacokinetics Study

Colistin,also named Polymyxin E is a polypeptide antibiotic composed of a variety of different components,the main components of which are colistin A(polymyxin El)and eolistin B(polymyxin E2).Colistin is administered with its inactive prodrug,colistin methanesulphonate sodium,which has a strong effect on most infections caused by Gram-negative aerobacteria.The antibacterial spectrum is mainly Acinetobacter Genus,Pseudomonas aeruginosa,Klebsiella,Enterobacter,Escherichia coli,Salmonella and so on.Colistin was once replaced Colistin methanesulphonate by other antibiotics such as aminoglycosides in the 1970s due to its nephrotoxicity and neurotoxicity.However,in recent years,due to the increase of drug-resistant bacteria and the lack of new anti-drug resistant antibiotics,eolistin has been re-applied to the clinical treatment of critically ill patients again.It is the last line of defense against multidrug-resistant(MDR)Gram-negative bacteria,especially Pseudomonas aeruginosa,Acinetobacter baumannii and Klebsiella pneumoniae.The purpose of this experiment is to establish an analytical method for the determination of Colistin in human plasma,and to apply it to the human pharmacokinetic study of colistin methanesulphonate sodium,to evaluate the drug of colistin in human and provide a basis for the clinical use of colistin.?.Establishment of LC-MS/MS method for determination of colistin in human plasmaThis study established an accurate,sensitive,and reproducible LC-MS/MS method for the determination of Colistin in human plasma.The method uses polymyxin B1 as an internal standard,and the plasma sample is pretreated by protein precipitation.The supernatant is diluted and then eluted by a gradient of Agilent Polaris C18 column(the organic phase is 0.5%formic acid acetonitrile solution,the aqueous phase is 0.5%formic acid aqueous solution,at a flow rate of 0.65 mL/min to 2.4 mL/min)to analyze with Mass Spectrometry.The mass spectrometer is a triple quadrupole mass spectrometer equipped with an ESI ion source,which is detected by positive ionization in multiple reaction monitoring(MRM)mode.The ion pairs of colistin A,colistin B and polymyxin B1(internal standard)for quantitative analysis were m/z 585.6?m/z 101.1,m/z 578.6?m/z 101.1 and m/z 602.5?m/z 241.3,respectively.The linear range is colistin A 20.0?Z000ng/mL,and colistin B 15.0?1500ng/mL.In accordance with FDA and CFDA regulations and guidelines,a complete methodological validation of plasma sample analysis methods was performed for quantitative lower limit,linearity,specificity,precision,accuracy,residual effect,matrix effect,recovery and stability.The results show that each parmeter meets the requirements of relevant regulations.This LC-MS/MS analytical method is applicable to the pharmacokinetic study of colistin.?.Pharmacokinetics of colistin methanesulfate sodium in healthy Chinese subjectsThis test uses a parallel design.Thirty-six subjects(half male and female)were divided into three groups of 6 males and 6 females,each with a low dose of colistin methanesulfate sodium(1.0 mg/kg as colistin activity,equivalent to 30000IU/kg),medium dose(2.5 mg/kg,as colistin activity,equivalent to 75000IU/kg)high dose(4.0 mg/kg,as colistin activity,equivalent to 120,000IU/kg)single-dose pharmacokinetic test.After a single intravenous infusion of colistin methanesulfate sodium at 1.0 mg/kg,2.5 mg/kg,4.0 mg/kg,the Cmax of Colistin was(1.1±0.2),(2.1±0.5),(4.2±0.8)?g/mL,Tmax was 2.0,1.9,1.9h,t1/2 was(3.8±0.3),(3.9± 0.3),(3.9±0.4)h,and AUC0-24 was(5.2 ± 0.9),(11.9±1.3),(24.1 ± 1.9)?g·h/ml,respectively.Intravenous infusion of colistin methanesulfate sodium at 1.0mg/kg?4.0mg/kg dose range,the pharmacokinetic characteristics of the three dose groups are basically the same,the dose does not affect The main pharmacokinetic characteristics of colistin in the human body.The main pharmacokinetic characteristics.Colistin is a linear pharmacokinetic profile in healthy subjects.The experiment established an accurate and reproducible LC-MS/MS method to determine concentration of colistin in human plasma.The method has high specificity and sensitivity,high accuracy,Precision,stability and reliability,and meet the requirements of biological analysis.It can be used for analysis of colistin in a large number of human plasma samples.In the dose range of 1.0mg/kg?4.0mg/kg,the dose level does not affect the main pharmacokinetics of colistin in humans,and colistin has linear pharmacokinetics characteristics in healthy Chinese people.