Which of the following agent is associated with maximum histamine release?

Ans. is 'a' i.e., d-Tubocurarine Important facts about MRs* Longest acting Neuromuscular blocker - Pancuronium (duration of action 120-180 minutes). (Goodman & Gilman 11th/e 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 - Pancuronium(Maximal), 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 Due to its nephrotoxic and tetratogenic potential it has been withdrawn.* Recuronium produces pain on injection.