Ans. is 'a' i.e., Succinylcholine o History suggestive of some type of muscle dystrophy,o Sch can cause dangerous hyperkalemia in Muscular dystrophy.Succinylcholineo SCh is a depolarising skeletal muscle relaxant.o It causes sustained partial depolarization of muscle end plate - intially produce twitching and fasciculation followed by flaccid paralysis.o It is the shortest and fastest acting skeletal muscle relaxant.o It is the only muscle relaxant which stimulate autonomic ganglia and vagus.o SCh is the most commonly used muscle relaxant for passing endotracheal tube (mivacurium and rocuronium are alternatives).o SCh is rapidly hydrolysed by plasma cholinesterase, some patients have genetically determined abnormality or deficiency of pseudocholinesterase, in them, SCh causes phase II block,o It can cause muscle fasiculations and soreness, change in BP and HR, arrythmia, histamine release and K+ efflux from muscles.o 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 hyperthermia caused by halothane.o SCh causes increase in all pressures - inraocular, intracranial, BP, and intrabdominal - contraindicated in glaucoma, head injury.