Fig. 1. Schematic representation of the pharmacokinetic–pharmacodynamic (PK-PD) interaction model for rocuronium and sugammadex. ( A ) PK model for rocuronium alone; ( B ) PK-PD model for rocuronium alone; ( C ) PK interaction model; ( D ) PK-PD interaction model; Clroc = rocuronium clearance; Clsug = sugammadex clearance; EC50 = concentration at 50% of maximum effect; Emax = maximum effect; K1 = association rate constant; K2 = dissociation rate constant; Kd = equilibrium dissociation constant; ke0 = distribution rate constant between first peripheral and biophase (effect) compartment; NMB = neuromuscular blockade; V1 = volume of central compartment; V2 = volume of first peripheral compartment; V3 = volume of second peripheral compartment.