Table II.

Summary of the fixed parameters for the hepatocyte model that was fitted to the time course data of the uptake for PTV and RSV in SHH (lot HH1045)

Parameter (unit)	Values used		Description
	PTV	RSV
VMed (μL/mg protein)	1000		The actual volume of medium was normalized to mg protein in cells.
VCell (μL/mg protein)	2.28		From the previous report (7)
CMed(t = 0) (μM)	0.0692	0.0957	Extrapolated from the drug concentrations in medium at the two earliest time points (0.25 and 1.25 min; Uptake Study #1)
XAds(t = 0) (pmol/mg protein)	1.55	0.981	Extrapolated from the uptake amount at the two earliest time points (0.25 and 1.25 min;; Uptake Study #1)
KAds	44.7	97.6	Estimated by (CMed(t = 0)·VMed)/XAds(t = 0) (Uptake Study #1)
k-1(Ads) (/min)	10		Chosen based on the assumption of the rapid equilibrium; sensitivity analysis performed to ensure that the selected value is reasonable
PSdif,inf (μL/min/mg protein)	15.6	0.822	Chosen as a half of the uptake clearance in the presence of rifamycin SV (30 μM; based on the projection that rifamycin SV (30 μM) likely inhibited the uptake by OATP1Bs to a partial extent; Uptake Study #2)
tx (min)	20		Chosen based on the visual inspection of the threshold time in drug-free pre-incubation, beyond which a decline in the uptake clearance was observed (Uptake Study #2; sensitivity analysis performed by varying the values from 20 to 180 min)
kloss (/min)	0.03		Chosen based on the slope of the decline in the uptake clearance (Uptake Study #2)
fu,h·CLmet (μL/min/mg protein)	0.0176	0.0005	For the lot HH1045, there was a decline in the total amount recovered (a sum of the drug amounts detected in cells and medium). The assumption was made that the observed decline is from the metabolic loss. The fu,h·CLmet value was thus calculated as follows: the rate of the presumed metabolic loss (the slope of the decline in the total drug amount recovered from 60 to 180 min) divided by the intracellular drug concentration at 120 min (at the midpoint between 60 and 180 min).
fu,h·PSeff (μL/min/mg protein)	0.484	0.118	The assumption was made that the steady-state was reached at 180 min with the uptake clearance corresponding to < PSact,inf remaining after a partial loss + PSdif,inf > (estimated from the uptake clearance values at 180 min from Uptake Study #2). By assuming the steady-state (i.e., $\frac{\mathrm{d}}{\mathrm{dt}}{X}_{\text{Cell}}$=0), the following equation was rearranged to calculate fu,h·PSeff: $\frac{\mathrm{d}}{\mathrm{dt}}{X}_{\text{Cell}}=\left({\mathrm{PS}}_{\mathrm{act},inf}+{\mathrm{PS}}_{\mathrm{dif},inf}\right)\bullet C_{\mathrm{Med}}-\left(f_{\mathrm{u},\mathrm{h}}\bullet {\mathrm{PS}}_{\mathrm{eff}}+f_{\mathrm{u},\mathrm{h}}\bullet {\mathrm{CL}}_{\mathrm{met}}\right)\bullet \frac{X_{\text{Cell}}}{V_{\text{Cell}}}$ At the steady-state, $f_{\mathrm{u},\mathrm{h}}\bullet {\mathrm{PS}}_{\mathrm{eff}}=\frac{\left({\mathrm{PS}}_{\mathrm{act},inf}+{\mathrm{PS}}_{\mathrm{dif},inf}\right)}{C_{\text{cell}}/C_{\mathrm{Med}}}-f_{\mathrm{u},\mathrm{h}}\bullet {\mathrm{CL}}_{\mathrm{met}}$