Muscle RelaxantsMuscle RelaxantsWhat are they used for?Facilitate intubation of the tracheaFacilitate mechanical ventilationOptimized surgical working conditionsMuscle Relaxantsow skeletal muscle relaxation can be achieved?igh doses of volatile anestheticsRegional anesthesia!dministration of neuromuscular blocking agents"roper patient positioning on the operating tableMuscle RelaxantsMuscle relaxants must not be given without ade#uate dosage of analgesic and hypnotic drugs$nappropriately given % a patient is paralyzed but not anesthetizedMuscle Relaxantsow do they work?&euromuscular 'unctionNerve terminalMotor endplate of a muscleSynaptic cleft&erve stimulationRelease of !cetylcholine (!ch)"ostsynaptic events&euromuscular *unction (&M*)+inding of !ch to receptors on muscle end,plateMuscle Relaxants-epolarizing muscle relaxant Succinylcholine&ondepolarizing muscle relaxantsShort actingIntermediate actingLong acting-epolarizing Muscle Relaxant.uccinylcholineWhat is the mechanism of action?Physically resemble AchAct as acetylcholine receptor agonistNot metabolized locally at NMJMetabolized by pseudocholinesterase in plasma Depolarizing action persistsAch!ontinuous end"plate depolarization causes muscle rela#ation-epolarizing Muscle Relaxant.uccinylcholineWhat is the clinical use of succinylcholine?Most often used to facilitate intubationWhat is intubating dose of succinylcholine?/,/01 mg2kgOnset 34,54 seconds6 duration 1,/4 minutes-epolarizing Muscle Relaxant.uccinylcholineWhat is phase $ neuromuscular blockade?Sustained opening of receptor channels in depolarized post"$untional membrane cannot respond to further AchWhat is phase $$ neuromuscular blockade?%esemble bloc&ade produced by nondepolarizing muscle rela#antSuccinylcholine infusion or dose'"( mg)&g-epolarizing Muscle Relaxant.uccinylcholine-oes it has side e7ects? 8ardiovascularFasciculationMuscle pain$ncrease intraocular pressure$ncrease intragastric pressure$ncrease intracranial pressureyperkalemia Malignant hyperthermia&ondepolarizing Muscle RelaxantsWhat is the mechanism of action?!ompete *ith Ach at the binding sitesDo not depolarized the motor endplateAct as competitive antagonist+#cessive concentration causing channel bloc&adeAct at presynaptic sites, prevent movement of Ach to release sites&ondepolarizing Muscle Relaxants9ong actingPancuronium$ntermediate actingAtracurium-ecuronium%ocuronium!isatracurium.hort actingMivacurium&ondepolarizing Muscle Relaxants"ancuroniumAminosteroid compound.nset '"( minutes, duration /0"10 minutesIntubating dose 0203"0245 mg)&g+limination mainly by &idney 63(78, liver 64(78Side e9ects : hypertension, tachycrdia, dysrhythmia,&ondepolarizing Muscle Relaxants:ecuroniumAnalogue of pancuronium much less vagolytic e9ect and shorter duration than pancuronium.nset '"( minutes duration 50"'( minutesIntubating dose 0203"0245 mg)&g+limination ;07 by &idney, /07 by liver &ondepolarizing Muscle Relaxants!tracuriumMetabolized by +ster hydrolysis