Prediction of hepatic microsomal intrinsic clearance and human clearance values for drugs

Twenty-nine drugs of different structures were used in theoretical QSAR analysis of human hepatic microsomal intrinsic clearance (in vitro T1/2 and in vitro  CL′intCL′int) and whole body clearance (CLblood). The examined compounds demonstrated a wide range of scaled intrinsic clearance values. Constitutional, geometrical, physico-chemical and electronic descriptors were computed for the examined structures by use of the Marvin Sketch 5.1.3_2, the Chem3D Ultra 7.0.0 and the Dragon 5.4 program. Partial least squares regression (PLSR), has been applied for selection of the most relevant molecular descriptors and development of quantitative structure–activity relatioship (QSAR) model for human hepatic microsomal intrinsic clearance (in vitro T1/2).Optimal QSAR models with nine and ten variables, R2 > 0.808 and cross-validation parameter qpre2>0.623, were selected and compared. Since the microsomal in vitro T1/2 data can be used for calculation of in vitro  CL′intCL′int and in vivo CLblood, the developed QSAR model will enable one to analyze the kinetics of cytochrome P450-mediated reactions in term of intrinsic clearance and whole body clearance.A comparison is made between predictions produced from the QSAR analysis and experimental data, and there appears to be generally satisfactory correlations with the literature values for intrinsic clearance data.