Assessment of the Potential for Displacement Interactions with Sugammadex

Methods: Isothermal titration calorimetry (ITC) was used to determine the binding affinity (estimated by association rate constant [k_ass]) between sugammadex and 300 commonly prescribed drugs. The screening included drugs commonly used in or shortly after anaesthesia, commonly prescribed drugs such as antidepressants and cardiovascular drugs, drugs (both steroidal and nonsteroidal) acting on steroidal receptors (such as the corticosteroids hydrocortisone, prednisolone and dexamethasone), and the selective estrogen receptor modulator toremifene. The model took into account the population pharmacokinetic-pharmacodynamic relationships of sugammadex, rocuronium and vecuronium, the binding affinities of the NMBAs and other compounds as determined by ITC, and the relationship between the free concentration of NMBA with sugammadex in the presence of a third complexed compound. Using the model, the critical concentrations of a con-comitantly administered compound required to result in a train-of-four (TOF) ratio of <0.9, indicating reoccurrence of neuromuscular blockade, for each plasma concentration of sugammadex and NMBA were calculated. For compounds with a k_ass value of ≥2.5 ×10⁴ mol/L likely to be administered during sugammadex reversal, the combinations of k_ass and maximum plasma drug concentration (C_max) were entered into a graph, consisting of a critical line established using a conservative approach, and those compounds above this critical line potentially resulting in a TOF ratio <0.9 were subsequently identified. Clinical validation was performed in a post hoc analysis of data from ten sugammadex studies, in which the impact of various drugs administered perioperatively on neuromuscular recovery was assessed for up to 1 hour after sugammadex administration.

Results: ITC analysis demonstrated that the binding affinity of rocuronium and vecuronium for sugammadex was very high, with k_ass values of 1.79 × 10⁷ mol/L and 5.72 × 10⁶ mol/L, respectively. Only three compounds (flucloxacillin, fusidic acid and toremifene) were found to have critical combinations of k_ass and C_max, and thus the potential for displacement. Sugammadex was administered to 600 patients for reversal of rocuronium- or vecuronium-induced blockade in the ten analysed studies, in which 21 co-administered drugs were selected for analysis. No reoccurrence of blockade occurred in any patient.