Anaphylactic reaction suxamethonium

Anaphylactic reactions result from the interaction of antigens with specific IgE antibodies, which have been formed by previous exposure to the antigen. Anaphylactoid reactions are clinically indistinguishable from anaphylaxis but do not result from prior exposure to a triggering agent and do not involve IgE. Intravenous anaesthetics and muscle relaxants can cause anaphylactic or anaphylactoid reactions and, rarely, they are fatal. Muscle relaxants are responsible for 70% of anaphylactic reactions during anaesthesia and suxamethonium accormts for almost half of these. 

Fentanyl 100 pg IV 1 BP, sinus tachycardia, wheezing Scratch tmd IDT Positive whetil and flare to fentanyl tmd suxamethonium Anaphylactic reaction to fentanyl Anaphylactic but could be cross-reaction with MNBDs... 

Generally speaking, all the muscle relaxants discussed here have been reported to produce histamine release when injected intravenously (i.v.). This was shown by an increase in plasma histamine level (Lorenz et al. 1972). The frequency of reaction (significant increase in plasma histamine) was highest with suxamethonium (3 of 8 volunters), followed by alcuronium (alloferin, 2 of 8), and then pancuronium (1 of 7) (Lorenz and Doenicke 1978). However, the latter authors found a poor correlation between the increase in plasma histamine levels and the incidence of clinical manifestations, e.g., such manifestations were more frequent with pancuronium than with suxamethonium. These above findings contradict the low incidence of acute (anaphylactic-like) reactions to pancuronium in practice. 

Assem ESK, Frost PG, Levis RD (1981) Anaphylactic-like reaction to suxamethonium. Anaesthesia 36 405-410... 

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