<prompt> Longest acting muscle relaxant?DoxacuriumAtracuriumScolineVecuronium  <response>: Ans. a. Doxacurium Ref: Tripathi 6th edition, 345; Lee 12th edition, p. 180-190.Doxacurium is a bisquaternary muscle relaxant having the least rapid onset and the longest action: suitable for longer duration surgeries. It is primarily eliminated by kidney, although hepatic metabolism also occurs. Cardio- vascular chnages are minimal.PROPERTYMUSCLE RELAXANT M.R.Rapid onset of ActionSch overall; Rocuronium non depolarisingShortest ActingSch overall; Mivacuronium non depolarisingLongest ActingDoxacuriumExcreted in LiverRocuronium; VencuroniumNo placenta crossingd-TCHisatminereleased- TC maximum: Atracuroniuin; Mivacuronium; SchLeast Histamine release VlcoroniumMost CArdiostableVicoroniumM.R. used to decrease BPd-TCM.R. Used to maintain BPPancuroniumM.R.Safein asthma Vecronium: CisatracuroniumM.R. Causing epilepsv Atrocuronium; secondary Launodo rubinM.R. Metabolised by Hoffmanns elimination Cisatracuronium: AtracuroniumComparative properties of neuromuscular blocking drugsDrugDose mgkgOnset minDuration minHist. releaseGang blockVagal blockLONG ACTING1.d- Tubocurarilng0.2-0.44-630-60-2.Pancuronium0.04- 0.14-660-120--3.Doxacurium0.03-0.084-860-120--4.Pipecuronium0.05-0.082-850-100---INTERMEDIATE NACTING5.Vecuronium0.08-0.12-430-60--6.Atracurium0.3-0.62-420-35--7.Clsatracurium0.15-0.23-620-40---8.Rocuronium0.6-0.91-225-40---SHORT ACTING9.Mivacurium0.07-0.152-412- 20--10.SUCCILNYLCHOLNE0.5-0.81-1.53-6StSt. 