Doxacurium pharmacodynamics in children during volatile and opioid-based anaesthesia

Abstract

The interaction between doxacurium and halothane, isoflurane or alfentanil has not been studied in children. Using the cumulative dose-response technique and electromyography, we determined ED50 and ED90 of doxacurium during halothane (n = 9), isoflurane (n = 12) or alfentanil (n = 9) based anaesthesia in children aged 2-10 years. Both isoflurane and halothane potentiated the effects of doxacurium compared to alfentanil. The ED50 for doxacurium/halothane was 23.9 micrograms.kg-1 compared to 32.7 micrograms.kg-1 for doxacurium/alfentanil. The ED90 for doxacurium/isoflurane was 32.7 micrograms.kg-1 compared to 48.2 micrograms.kg-1 doxacurium/alfentanil (p < 0.05). There were no significant time course differences between the groups. When equipotent doses of doxacurium were used to provide muscle relaxation the duration of the neuromuscular block was similar in children who received aflentanil, halothane or isoflurane supplementation of N2O/O2 anaesthesia.