Anaphylactoid skin reactions after intravenous regional anaesthesia using 0.5% prilocaine with or without preservative--a double-blind study.

Abstract

Methylparaben, the preservative of various local anaesthetic solutions, is a potential allergen. In a double-blind study, 0.5% prilocaine with (Citanest, n = 100) or without (n = 100) methylparaben were compared for the occurrence of skin reactions after intravenous regional anaesthesia of the arm in surgical patients. Skin reactions were registered after the deflation of the tourniquet cuff, and intradermal tests were performed with 0.5% prilocaine, 0.1% methylparaben and saline in all patients. Seventeen patients in the Citanest group and four patients in the methylparaben-free prilocaine group developed erythematous skin reactions in the exposed arm after deflation of the tourniquet cuff (P < 0.05, between the groups). The skin symptoms disappeared within an hour and were always restricted to the region which had been anaesthetised. None of the affected patients had positive intradermal tests. The observed skin reactions are probably non-IgE-mediated anaphylactoid reactions in which the presence of methylparaben in the local anaesthetic solution plays a major role.