Table 1.

Symbols implemented for deriving theoretical equations of pharmacokinetic parameters.

Symbol	Equation	Description
Symbols corresponding to the EHR model
$\mathrm{\Omega }$	$\mathrm{\Omega }=k_{\mathit{hc}}+{k_{\mathit{hb}}+k}_h$	First-order rate constant accounting for total drug output from the hepatocyte
$\mathrm{\Phi }$	$\mathrm{\Phi }=k_a+{k_{\mathit{gh}}+k}_g$	First-order rate constant accounting for total drug output from the gut
$F_a$	$F_a=k_a/\left(k_a,+,{k_{\mathit{gh}}+k}_g\right)$	Fraction of drug being transferred from the gut to the central compartment
$E_h$	$E_h=k_h/\left(k_{\mathit{hc}},+,{k_{\mathit{hb}}+k}_h\right)$	Fraction of intra-hepatocytic drug submitted to irreversible metabolism
$E_{\mathit{gh}}$	$E_{\mathit{gh}}=k_{\mathit{gh}}/\left(k_a,+,{k_{\mathit{gh}}+k}_g\right)$	Fraction of drug being transferred from the gut to the hepatocyte
$E_{\mathit{hb}}$	$E_{\mathit{hb}}=k_{\mathit{hb}}/\left(k_{\mathit{hc}},+,{k_{\mathit{hb}}+k}_h\right)$	Fraction of intra-hepatocytic drug submitted to hepatobiliary secretion
$E_{\mathit{hc}}$	$E_{\mathit{hc}}=k_{\mathit{hc}}/\left(k_{\mathit{hc}},+,{k_{\mathit{hb}}+k}_h\right)$	Fraction of drug being transferred from the hepatocyte to the central compartment
Symbols corresponding to the EGR model
${\mathrm{\Omega }}^{{}^{\prime }}$	${\mathrm{\Omega }}^{{}^{\prime }}=k_{\mathit{hc}}{+k}_h$	First-order rate constant accounting for total drug output from the hepatocyte
$\mathrm{\Phi }$	$\mathrm{\Phi }=k_a+{k_{\mathit{gh}}+k}_g$	First-order rate constant accounting for total drug output from the gut
$\mathrm{\Theta }$	$\mathrm{\Theta }=k_{\mathit{sc}}+{k_{\mathit{sh}}+k}_s$	First-order rate constant accounting for total drug output from the parietal cells compartment
$E_h$	$E_h=k_h/\left(k_{\mathit{hc}},{+k}_h\right)$	Fraction of intra-hepatocytic drug submitted to irreversible metabolism
$E_s$	$E_s=k_s/(k_s+k_{\mathit{sh}}+k_{\mathit{sc}})$	Fraction of drug in the parietal cells being submitted to gastric secretion

First-order rate constants describing mass transferences: $k_a$ (drug absorption from the gut into the central compartment),$k_{\mathit{gh}}$(hepatic uptake of drug coming from the gut through portal venous blood), $k_g$ (intestinal elimination), $k_{\mathit{cg}}$(drug transference from the systemic circulation to the gut), $k_{\mathit{hc}}$ (drug transference from the hepatocyte to the central compartment), $k_{\mathit{ch}}$ (drug transference from the central compartment to the hepatocyte),$k_h$ (hepatic elimination), $k_{\mathit{hb}}$ (hepatobiliary secretion), $k_{\mathit{cs}}$ (drug transference from the central compartment to the parietal cells), $k_{\mathit{sc}}$ (drug transference from the parietal cells to the central compartment), $k_s$ (drug secretion from parietal cells into gastric lumen) and $k_{\mathit{sh}}$ (hepatic uptake of drug coming from the parietal cells through the gastric vein).