Doxacurium chloride: a preliminary clinical trial.

The onset, duration of action and reversibility of doxacurium were studied in 27 anaesthetized patients, using doses of 37.5 micrograms kg-1 (1.5 x ED95) and 62.5 micrograms kg-1 (2.5 x ED95). Onset was slow and, whilst tracheal intubation was always possible 3 or 4 min after injection, the conditions were not ideal. With the higher dose a mean 97.6 (SD 5.2)% block of the response of adductor pollicis to ulnar nerve stimulation was obtained in 9.85 (6.17) min and recovery of the integrated EMG response to 20% of control took 102 min (42 min). After these initial doses, when incremental doses were given there was no sign of cumulation of effect. Antagonism of block with edrophonium 1 mg kg-1, whilst fast in onset, was rarely complete; with neostigmine 50 micrograms kg-1 antagonism was satisfactory. No adverse haemodynamic effect was seen, although a gradual onset of bradycardia, which responded to atropine or glycopyrrolate, was noted in 12 of the patients. No histamine release or other adverse effects were noted.