Onset/offset characteristics and intubating conditions of rapacuronium: a comparison with rocuronium

We compared onset and offset of action and tracheal intubating conditions a fter rapacuronium and rocuronium in 60 patients in a randomized, assessor-b linded study. Following induction of anaesthesia with propofol 2.5 mg kg(-1 ), either rapacuronium 1.5 mg kg(-1) (n=30) or rocuronium 0.6 mg kg(-1) (n= 30) was administered to facilitate tracheal intubation. Anaesthesia was mai ntained with either a propofol infusion (100 mu g kg(-1) min(-1)) or sevofl urane (1% end-tidal) with 66% nitrous oxide (N2O), n=15 in each subgroup. N euromuscular monitoring was performed using an electromyographic (EMG) devi ce (Datex Relaxograph). The lag times (mean 42 (SD 11) s and 44 (16) s), ma ximum block (99 (2)% and 98 (3)%) and intubating conditions at 60 s (good-t o-excellent in 86% and 84% of patients) were similar for rapacuronium and r ocuronium, respectively. The onset time of rapacuronium was shorter than ro curonium (87 (20) vs 141 (65) s, P<0.001), and the degree of block at 60 s was greater (69 (26) vs 50 (27)%, P<0.05). Twenty-five per cent recovery wa s shorter with rapacuronium than rocuronium during propofol (15.0 (3.2) vs 39.1 (14.2) min, P<0.001) and sevoflurane (15.1 (4.2) vs 47.8 (19.0) min, P <0.001) anaesthesia. We conclude that rapacuronium 1.5 mg kg(-1) had a more rapid onset, similar intubating conditions, and shorter recovery times tha n rocuronium 0.6 mg kg(-1).