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New method for the simultaneous estimation of intrinsic hepatic clearance and protein binding by matrix inhibition
Author(s) -
Uchimura Takahide,
Kato Motohiro,
Tachibana Tatsuhiko,
Arai Shinichi,
Nabuchi Yoshiaki,
Saito Kimitoshi,
Kinoshita Haruki
Publication year - 2008
Publication title -
biopharmaceutics and drug disposition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.419
H-Index - 58
eISSN - 1099-081X
pISSN - 0142-2782
DOI - 10.1002/bdd.583
Subject(s) - microsome , chemistry , free fraction , incubation , int , microsoma , chromatography , matrix (chemical analysis) , plasma protein binding , biochemistry , in vitro , computer science , operating system
The purpose of this study was to develop a method for estimating the hepatic clearance ( CL h ) without using a protein binding test. This method allows the simultaneous evaluation of the intrinsic hepatic clearance ( CL int ) with a correction for microsomal binding, and the free fraction in the serum ( fu ). It uses the decrease in metabolic velocity achieved by decreasing the free fraction of a compound in the incubation mixture ( fu inc ) by the addition of serum, and by changing the microsomal protein concentration. This method is denoted as the ‘matrix inhibition method’, because it uses the inhibition of the metabolic velocity by the incubation matrix. The metabolic rates of eight compounds (diazepam, imipramine, warfarin, and compounds A–E) were evaluated under several incubation conditions using rat serum and microsomes. The correlation of CL int evaluated using the method and using equilibrium dialysis after the CL int was corrected for microsomal binding was r = 0.968. The correlation of fu · CL int was r = 0.996. Although the method required a high enough fu and fu microsomes difference among the reaction conditions for each compound, it could evaluate CL int and fu simultaneously and easily by adding additional reaction conditions to the metabolic stability tests performed in ADME screening. Copyright © 2007 John Wiley & Sons, Ltd.