Intubating conditions following 1R CIS, 1'R CIS atracurium (51W89). A comparison with atracurium

51W89 besylate, a new intermediate acting non-depolarising muscle relaxant, consisting of a single stereo-isomer of the commercial preparation of atracurium has been assessed in respect of intubating conditions during nitrous oxide-propofol-isoflurane anaesthesia. Intubating conditions at 2 min were acceptable in 67% of patients following a dose of 0.1 mg.kg-1 and in 90% of patients following a dose of 0.15 mg.kg-1. Intubating conditions at 1.5 min were acceptable in 76% of patients following a dose of 0.2 mg.kg-1. In comparison, intubating conditions at 2 min were acceptable in 95% of patients following 0.5 mg.kg-1 of atracurium. The intubating conditions at 2 min following a dose of 0.1 mg.kg-1 51W89 besylate were significantly worse than the other three groups (p < 0.05); however, there was no significant differences between the scores in the other three groups. There was no clinical evidence of histamine release in the groups receiving 51W89 besylate compared to two out of the 19 patients who had cutaneous flushing following the administration of atracurium. Our results suggest that 51W89 besylate provides acceptable intubating conditions at 2 min following a dose of 0.15 mg.kg-1 and may prove to be an acceptable alternative to atracurium if studies in progress confirm its greater cardiovascular stability and reduced propensity to release histamine than its parent compound.