Figure 1.

Schematic illustration of the PK model for tesofensine and M1 after i.v. and oral administration. The subscripts tesofensine and M1 denote the respective parameter of the parent compound and the metabolite. D represents the doses administered orally or intravenously; F, the fraction of dose available to gut enterocytes; K_a, the first-order absorption rate constants and C, the concentrations in the central compartments. V_m are the maximum rates and K_m, the amounts yielding 50% V_m, where the subscripts FP, MET and EL denote the first-pass, the metabolism and elimination processes.