LAUSR

The main objective was to investigate the effect of albumin (ALB) and/or alpha-1-acid glycoprotein (AGP) on the hepatic clearance (CLh) of the drugs that bind, extensively, to both proteins. Isolated perfused livers from male Sprague Dawley rats (IPRL) were performed for perampanel (PER) and fluoxetine (FLU), using physiological solutions in four scenarios (n= 3 rats/scenario/drug): 1) without plasma proteins (WO), 2) with bovine ALB (40 g/L), 3) with bovine AGP (1 g/L), and 4) with mixture of both proteins (MIX). PER is poorly to moderately metabolized (hepatic extraction= 0.2-0.7), while FLU is highly metabolized (hepatic extraction= 0.8-0.99). The metabolic kinetics were fitted to the Michaelis-Menten model. For the PER, the parameters were Vmax= 90, 20.9 and 19.75 (nmol/min/g liver) and Km= 17, 20.8 and 18.24 (μM) for the scenarios WO, with ALB and with MIX, respectively. For PER with AGP, saturation was not observed. As for FLU, the parameters were Vmax= 65.5, 18.83, 34.5 and 15.3 (nmol/min/g liver) and Km= 1.5, 2.4, 0.69 and 6.31 (μM) in all four scenarios, respectively. In conclusion, a protein-mediated hepatic uptake likely occurred only at low free concentrations for both drugs (i.e., therapeutic concentrations) in the presence of plasma proteins (except for the scenario of PER with AGP).