The neuromuscular blocking effect of doxacurium chloride during isoflurane anaesthesia

Doxacurium, a new long-acting neuromuscular blocking drug, was administered to 45 patients to assess the neuromuscular profile of this drug during isoflurane anaesthesia. Using a mechanical force-displacement transducer to assess neuromuscular block, the ED₅₀ and ED₉₅ for doxacurium during 60% nitrous oxide and 0.7% end-tidal isoflurane concentrations were estimated to be 9 and 16 μg kg^-1, respectively. When doxacurium was administered during a stable level of isoflurane anaesthesia, neuromuscular blocking doses were reduced by one-third in comparison to neuromuscular requirements during nitrous oxide and narcotic anaesthesia. As with other non-depolarizing blocking agents, the onset of neuromuscular blockade with doxacurium was accelerated during isoflurane anaesthesia.