Influence of suxamethonium on the potency of ORG NC 45 in anaesthetized patients

The non-depolarizing neuromuscular block produced by Org NC 45 was potentiated by the previous administration of suxamethonium 1 mg kg-1, shown by twitch depression of 91.3 +/- 2.4% when the same dose of Org NC 45 was administered after recovery from suxamethonium compared with the control value of 71.9 +/- 6.5%. The recovery index was also prolonged from 8.1 +/- 0.3 to 10.4 +/- 1.0 min after suxamethonium. The dose-response curves for Org NC 45 showed a 1.66 potentiation factor for ED50 and 1.73 for ED95, caused by the previous administration of suxamethonium. This interaction is likely to occur in the plasma.