Establishment and application of a method for the determination of plasma protein binding rate of imatinib and its metabolite / 中国药房

ABSTRACT

OBJECTIVE To establish a method for the determination of plasma protein binding rate of imatinib and its metabolite（N-desmethyl imatinib ）and apply it to patients with gastrointestinal stromal tumor （GIST）.METHODS Using imatinib - d8 as the internal standard ，after being deproteinized methanol ，the sample was determined by equilibrium dialysis combined with liquid chromatography -tandem mass spectrometry . The free concentrations of imatinib and its metabolites in plasma of GIST patients were detected by the same method . RESULTS The protein binding rates of imatinib with albumin ，α1-acid glycoprotein and globulin at 120 ng/mL and 4 000 ng/mL were （92.5±1.0）% and（91.7±0.4）%，（56.6±2.0）% and（62.6±2.6）%，（56.3±3.1）% and （68.0±8.6）% ，respectively. The protein binding rates of N-desmethyl imatinib with albumin ，α1-acid glycoprotein and globulin at 60 ng/mL and 2 000 ng/mL were （90.6±3.5）% and（91.3±1.5）%，（54.1±5.1）% and（63.7±1.3）%，（56.2±7.6）% and（67.5±7.3）%，respectively. Compared with the low concentration group of imatinib （120 ng/mL）and its metabolite （60 ng/mL），the plasma protein binding rate of high concentration of imatinib （4 000 ng/mL）and its metabolite （2 000 ng/mL）with α1-acid glycoprotein and globulin was significantly increased （P＜ Δ基金项目 国家自然科学基金资助项目（No.81503160）；江苏省 0.05），but there was no signifi -cant difference with albumin 卫生健康发展研究中心 2021年度开放课题（No.JSHD2021004）；江苏 （P＞0.05）. In blank plasma ，the protein binding rates of imatinib（4 000 ng/mL）at high concentration and its metabolites（2 000 ng/mL）were significantly lower than those of low （120， 60 ng/mL） and medium （750， 375 ng/mL）concentration （P＜0.01）. Average protein binding rates of imatinib and its metabolite in plasma of GIST patients were （99.0±0.3）% and（99.2±0.3）%，respectively；the correlation coefficients between the concentrations of imatinib and its metabolites and the protein binding rates were －0.298 5 and －3.332 3，respectively（all P＜0.05）. CONCLUSIONS The method for determining the plasma protein binding rates of imatinib and its metabolites is successfully established . The plasma protein binding rates of imatinib and its metabolites in patients with GIST are negatively correlated with drug concentration .