Time course of action of sugammadex (Org 25969) on rocuronium-induced block in the Rhesus monkey, using a simple model of equilibration of complex formation†  H.D. de Boer, J. van Egmond, F. van de Pol, A. Bom, J.J. Driessen, L.H.D.J. Booij  British Journal of Anaesthesia  Volume 97, Issue 5, Pages 681-686 (November 2006) DOI: 10.1093/bja/ael240 Copyright © 2006 British Journal of Anaesthesia Terms and Conditions

Fig 1 (a) Time courses of the first twitch T1 of a ‘calibrating’ dose of rocuronium (100 μg kg−1) in three different experiments in the same monkey. This calibrating procedure always precedes sugammadex evaluation (part B of the figure). Note the reproducible response to the same dose of rocuronium in three different experiments, separated for at least six weeks. This was common in this monkey population, only few exceptions of small deviations were observed. Time t=0 min corresponds to time of injection of the ‘calibrating’ dose of rocuronium (100 μg kg−1). (b) Tracings of three experiments in the same monkey, corresponding to the first twitch T1 of the TOF sequence as the result of the second dose of rocuronium (100 μg kg−1). This second injection of rocuronium was administered 15, 30 or 60 min after injection of sugammadex 1.0 mg kg−1 in the three experiments. Time t=0 min corresponds to time of injection of sugammadex. It is clear that the effect of sugammadex (preventing block) disappears with time. (c) TOF-ratio as the result of the second dose of rocuronium (100 μg kg−1) at three different time intervals after the administration of sugammadex 1.0 mg kg−1 in three different experiments in the same monkey. British Journal of Anaesthesia 2006 97, 681-686DOI: (10.1093/bja/ael240) Copyright © 2006 British Journal of Anaesthesia Terms and Conditions

Fig 2 Prediction of maximum block by rocuronium 100 μg kg−1 as a function of time interval after the injection of sugammadex 1 mg kg−1. The model assumes exponential decay of the concentration of sugammadex after its injection at t=0. The concentration of free rocuronium follows from the equilibrium constant for its complex formation with sugammadex. The maximum block reached by rocuronium 100 μg kg−1 can then be calculated by the Hill equation, using the free rocuronium concentration. The parameters in the Hill equation are obtained from the tracings obtained from rocuronium (100 μg kg−1) injected before sugammadex and the dose–response relation obtained in earlier experiments. Good agreement between measured and predicted maximum blocks is obtained if the elimination half-life of sugammadex is set at 30 min. British Journal of Anaesthesia 2006 97, 681-686DOI: (10.1093/bja/ael240) Copyright © 2006 British Journal of Anaesthesia Terms and Conditions