Accurate prediction of hepatic clearance for low-clearance compounds using micropatterned hepatocyte-stromal cell co-cultures (HepatoPac®)

Generating accurate in vitro intrinsic metabolic stability and clearance data is an important aspect of predicting in vivo human clearance and establishing a safe dosing range in early clinical studies. Primary hepatocytes in suspension are routinely used for determination of metabolic clearance. However, hepatocytes in suspension are only viable for several hours, which is not long enough to appropriately evaluate the metabolic stability of low clearance compounds. Using HepatoPac, a recently developed micropatterned hepatocyte-stromal cell co-culture system which can be used for continuous incubations for up to 7 days, we have successfully determined the metabolic stability of 15 commercially available low clearance drugs (CL < 5 mL/min/kg).  Intrinsic clearance was calculated using the in vitro half-life determined for each compound and hepatic clearance was subsequently calculated using the well-stirred model with and without a correction for protein binding. Without correction for plasma protein binding, hepatic clearance was accurately predicted for only 1 compound, as determined by prediction of clearance within 2-fold of published clinical values. However, with correction for plasma protein binding, hepatic clearance was accurately predicted for 11 compounds.  These results clearly demonstrate the utility of HepatoPac for the prediction of in vivo hepatic clearance of low-clearance compounds.