Establish Methods To Detect Plasma Concentration And Ppb Of Voriconazole,indentify Factors Associated With It's Distribution

BackgroundInvasive fungal infections(IFIs),especially invasive aspergillosis(IA),are major complications due to the use of immunosuppressive agents,broad-spectrum antibiotics and various invasive operations in Intensive care unit(ICU)and immunosuppressive patients.Voriconazole is the first available second-generation triazole with potent activity against a broad spectrum of clinically significant fungal pathogens,including Aspergillus,Candida,and some less common moulds.It became the first-line drug in the treatment of invasive aspergillosis.However,voriconazole has a nonlinear pharmacokinetics,with increasing dose,it shows a superproportional increase in the area under the plasma concentrations-time curve(AUC),the reasons are not clear presently.Voriconazole is extensively metabolized by the hepatic CYP enzymes,mostly by the CYP2C19 isoenzyme and lesser extent by CYP3A4 and CYP2C9,studies had shown that CYP2C19 gene polymorphism,gender,age and other factors will affect the concentration of voriconazole significantly,low blood concentration led to treatment failure,Too high plasma concentration will result in adverse reactions,the impact of the above factors on the final clinical efficacy is not consistent,so future studies are warranted to confirm the pharmacokinetic characteristics of voriconazole.Because of nonlinear kinetics,the plasma concentration varied obviously,Voriconazole extensively distributed into extracellular and intracellular.The plasma protein binding(PPB)is about 58% in healthy subjects.Due to critically illed,basic diseases,poor nutritional status,hypoproteinemia is extremely common ICU patients,whether hypoproteinemia increases free voriconazole are not known.An observational study conducted by Belgian researchers in 2014 showed that PPB of voriconazole was positively correlated with albumin levels,indicating that the concentration of free voriconazole increased when albumin levels were decreased.In the clinical treatment,except for albumin levels,free drug may also be affected by other factors,including bilirubin which competitive inhibit the binding of Voriconazole,When CYP2C19 polymorphism effect the total blood,how does it effect PPB was unknown,To investigate the factors influencing the total plasma concentration,free drug concentration and protein binding of voriconazole,this study aimed to establish methods to detect total concentration and unboud concentration and calculate the PPB of voriconazole,study the in vivo distribution of voriconazole any further and provide reference for clinical therapy.Methods1.We established and verified a reverse phase high performance liquid chromatography(HPLC)to detect the total plasma concentration of voriconazole and the unbound concentration,followed by protein precipitation and ultrafiltration,respectively.The plasma protein binding(PPB)=(total plasma concentration-unbound concentration)/ total blood concentration × 100%.2.To investigate of the main factors affecting the distribution of voriconazole in the pathological body,we enrolled patients use voriconazole for phylaxiology and treatment,to determination of total concentration,unbound drug concentration and PPB The results showed that the CYP2C19 polymorphism was analyzed,the effects of these factors on the three outcome indexes were analyzed,too.Results1.The linear range of unbound drug concentration and total concentration were between 0.20 ~ 12.64 ?g · mL-1 and 0.02 ~ 10.24 ?g · mL-1,respectively.The accuracy and precision were within±15%;both attained the validation requirements of the biological sample analysis guidline.2.To analyze of the main factors influencing the distribution of voriconazole and the pathological distribution,42 cases were included,after the statistical analysis,the results show that was difference in voriconazole total concentration and unbound concentration between two sexes,three CYP2C19 subtype,there was no significant difference in PPB.Multivariate analysis ravealed a positive relation between albumin concentration and PPB,age and bilirubin concentration were not correlated with total concentration?unbound concentration and PPB of voriconazole.Conclusions1.The established method is convenient,selective and accurate,and can be used for the determination of total concentration,unbound concentration and protein binding rate of voriconazole in human plasma.2.The study showed that different sex and CYP2C19 subtypes also affected the total plasma concentration and unbound concentration of voriconazole,and the albumin concentration in patients was positively correlated with the PPB of voriconazole.