Suxamethonium Lidocaine

LIDOCAINE DEPOLARIZING t efficacy of suxamethonium with intravenous lidocaine Uncertain Monitor neuromuscular blockade carefully... 

Procaine and cocaine are esters that are hydrolysed by plasma cholinesterase and may therefore competitively enhance the action of suxamethonium (succinylcholine) (279). Chloroprocaine may have a similar action. Lidocaine also interacts, although the mechanism is not clear unless very high doses are used (280). 

A 22-year-old man had a generalized tonic-clonic convulsion and loss of consciousness after an attempted superior laryngeal nerve block using 2% lidocaine 2 ml (282). The seizure was not terminated by intravenous diazepam 10 mg and he was intubated after intravenous thiopental and suxamethonium. He required two boluses of ephedrine 10 mg to maintain... 

The neuromuscular blockade due to suxamethonium (succinyl-choline) can be increased and prolonged by lidocaine, procaine and possibly procainamide. These local anaesthetics all have some neuromuscular blocking activity and may theoretically also enhance the block produced by competitive neuromuscular blockers. Increased toxicity occurred when mivacurium and prilocaine were given together for regional anaesthesia. 

A patient anaesthetised with fluroxene and nitrous oxide demonstrated 100% blockade with suxamethonium (succinylcholine) and tubocurar-ine. About 50 minutes later when twitch height had fully returned and tidal volume was 400 mL, she was given lidocaine 50 mg intravenously for premature ventricular contractions. She immediately stopped breathing and the twitch disappeared. About 45 minutes later the tidal volume was 450 mL. Later it was found that the patient had a dibucaine number (a measure of cholinesterase activity) of 23%. ... 

Procainamide has been reported to increase the effects of suxamethonium in animals, increase muscle weakness in a myasthenic patient, and reduce plasma cholinesterase activity in healthy subjects. An animal study demonstrated potentiation of the neuromuscular blocking effect of tubocurarine by lidocaine alone and combined with antibiotics having neuromuscular blocking activity (neomycin or polymyxin B). ... 

Information is limited but the interactions of suxamethonium with lidocaine, and suxamethonium with procaine appear to be established and of clinical importance. Be alert for signs of increased blockade and/or recura-risation with apnoea during the recovery period from suxamethonium. 

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