Clinical Pharmacology of Doxacurium Chloride (BW A938U) in Children

The neuromuscular effects of doxacurium were studied in 26 children during halothane-nitrous oxide-oxygen anesthesia. Neuromuscular blockade was measured using electromyography activity of the adductor pollicis muscle after supra maximal stimulation of the ulnar nerve at 2 Hz for 2seconds at 10-second intervals. To estimate the cumulative dose-response relation, nine patientsreceived incremental doses of doxacurium (2.5–10 μg/kg); nine patients received 27.5 μg/kg (the estimated ED95); eight patients received 50μg/kg (1.8 × ED95). The ED25, EDM, ED75′ and ED95 (estimated from linear regression plots of log dose vs probit of effect) were 11.5, 14.8, 19.0, and 27.3 fJ-g/kg, respectively. Clinical duration (T25) was 27.8 ± 10.3 (mean ± SD) minutes at 1 × ED95 and 50.6 ± 15.6 minutes at 1.8 × ED95. Timeto recovery of the train-of-four ratio to 0.75 was 63.1 ± 32.9 minutes at 1 × ED95 and 108,5 ± 25.7 minutes at 1.8 × ED95. There were no significant changes in heart rate or mean arterial pressure after bolus administration of any dose ofdoxacurium.