Weal and flare responses to intradermal rocuronium and cisatracurium in humans{dagger}

Thirty volunteers underwent intradermal skin testing with increasingconcentrations of rocuronium and cisatracurium to evaluate wealand flare responses, and whether either agent would cause mastcell degranulation and sensitization upon re-exposure. We foundthat intradermal injection of rocuronium and cisatracurium atconcentrations >10^–4 M resulted in positive weal (>8 mm)responses, and positive flare responses at >10^–4 and>10^–5 M respectively. Only cisatracurium caused mildto moderate mast cell degranulation, and neither drug causedsignificant in vitro histamine release from whole blood collectedfrom study subjects 4 weeks after skin testing. Skin testingwith rocuronium and cisatracurium should be performed at concentrations<10^–4 and <10^–5 M respectively to avoid false-positiveresponses. The ability of these agents to produce positive wealand flare responses at relatively low concentrations may explainthe high incidence of potential reactions reported. Br J Anaesth 2000; 85: 844–9