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

We compared onset and offset of action and tracheal intubatingconditions after rapacuronium and rocuronium in 60 patientsin a randomized, assessor-blinded study. Following inductionof anaesthesia with propofol 2.5 mg kg^–1, eitherrapacuronium 1.5 mg kg^–1 (n=30) or rocuronium0.6 mg kg^–1 (n=30) was administered to facilitatetracheal intubation. Anaesthesia was maintained with eithera propofol infusion (100 µg kg^–1 min^–1)or sevoflurane (1% end-tidal) with 66% nitrous oxide (N₂O),n=15 in each subgroup. Neuromuscular monitoring was performedusing an electromyographic (EMG) device (Datex Relaxograph).The lag times (mean 42 (SD 11) s and 44 (16) s), maximumblock (99 (2)% and 98 (3)%) and intubating conditions at 60 s(good-to-excellent in 86% and 84% of patients) were similarfor rapacuronium and rocuronium, respectively. The onset timeof rapacuronium was shorter than rocuronium (87 (20) vs 141(65) s, P<0.001), and the degree of block at 60 swas greater (69 (26) vs 50 (27)%, P<0.05). Twenty-five percent recovery was shorter with rapacuronium than rocuroniumduring 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^–1had a more rapid onset, similar intubating conditions, and shorterrecovery times than rocuronium 0.6 mg kg^–1. Br J Anaesth 2000; 85: 246–50