<prompt> Which of the following agent is associated with maximum histamine release?d-TubocurarineCisatracuriumPancroniumRocuronium  <response>: Ans. is a i.e., d-Tubocurarine Important facts about MRs Longest acting Neuromuscular blocker - Pancuronium duration of action 120-180 minutes. Goodman Gilman 11the p. 222 Note: In some books pipecuronium or Doxacurium have given as the longer activity. Shortest and fastest acting neuromuscular blocker - Succinylcholine suxamethonium - duration of action 5-8 minutes. Shortest acting competitive nondepolarizing neuromuscular blocker - Mivacurium duration of action 12- 18 minutes. Fastest acting nondepolarizing blocker - Rocuronium can be used for endotracheal intubation as an alternative to Sch. Histamine release is caused by - D-TC maximum tendency, succinylcholine, mivacurium, doxacurium,atracurium, tubocurarine - can cause bronchoconstriction. Virtually no histamine release. -- Pancuronium. Vagal block is caused by - PancuroniumMaximal, recuronium, Gallamine. Vagal stimulation is caused by - succinylcholine can cause bradycardia. Ganglion block is caused by - d-Tc Maximum, Metocurine, Alcuronium. Ganglion stimulation is caused by - Succinylcholine Most commonly used muscle relaxant for routine surgery - vecuronium. Most potent skeletal muscle relaxant - Doxacurium. Least potent skeletal muscle relaxant - Succinylcholine Gallamine was least potent but it is not used now. Least potent nondepolarising muscle relaxant - Rocuronium. MR of choice for - intubation - Sch 1st choice, Rapacuroium 2nd choice, Rocuronium 3rd choice. Mivacurium is the only non-depolarizing blocker that is metabolized by plasma cholinesterase. Gallamine was the most nephrotoxic NM blocker - was contraindicated in renal failure. Due to its nephrotoxic and tetratogenic potential it has been withdrawn. Recuronium produces pain on injection. 