A 6 year old boy taken for ophthalmic examination under anaesthesia. His father told that he has lower limb weakness & his elder brother died at 14 years of age. Which anaethetic drug has to be avoided-

Ans. is 'a' i.e., Succinylcholine Succinylcholine SCh is a depolarising skeletal muscle relaxant. It causes sustained paial depolarization of muscle end plate --> intially produce twitching and fasciculation followed by flaccid paralysis. It is the shoest and fastest acting skeletal muscle relaxant. It is the only muscle relaxant which stimulate autonomic ganglia and vagus. SCh is the most commonly used muscle relaxant for passing endotracheal tube (mivacurium and rocuronium are alternatives). SCh is rapidly hydrolysed by plasma cholinesterase, some patients have genetically determined abnormality or deficiency of pseudocholinesterase, in them, SCh causes phase II block. It can cause muscle fasiculations and soreness, change in BP and HR, arrythmia, histamine release and IC efflux from muscles. Dangerous hyperkalemia can occur in patients with burn, crush injury, muscular dystrophy, GB. Syndrome, paraplegia or hemiplagia, mysthenia gravis and rhabdomyolysis contraindicated in such patients. o It can accentuate malignant hypehermia caused by halothane. SCh causes increase in all pressures --> inraocular, intracranial, BP, and intrabdominal --> contraindicated in glaucoma, head injury.