DOXACURIUM PHARMACODYNAMICS IN CHILDREN DURING VOLATILE AND OPIOID-BASED ANESTHESIA

The interaction between doxacurium and halothane, isoflurane or alfent anil has not been studied in children. Using the cumulative dose-respo nse technique and electromyography, we determined ED(50) and ED(90) of doxacurium during halothane (n = 9), isoflurane (n = 12) or alfentani l (n = 9) based anaesthesia in children aged 2-10 years. Both isoflura ne and halothane potentiated the effects of doxacurium compared to alf entanil. The ED(50) for doxacurium/halothane was 23.9 mu g.kg(-1) comp ared to 32.7 mu g.kg(-1) for doxacurium/alfentanil. The ED(90) for dox acurium/isoflurane was 32.7 mu g.kg(-1) compared to 48.2 mu g.kg(-1) d oxacurium/alfentanil (p < 0.05). There were no significant time course differences between the groups. When equipotent doses of doxacurium w ere used to provide muscle relaxation the duration of the neuromuscula r block was similar in children who received aflentanil, halothane or isoflurane supplementation of N2O/O-2 anaesthesia.