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24 Cards in this Set
- Front
- Back
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What are the 2 types of neuromuscular blockers?
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1. Competitive (non-depolarizing)
2. Depolarizing |
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What is the mechanism of competitive (non-depolarizing) neuromuscular blockers?
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They bind to or interlock with Ach receptors, preventing transmitter function of Ach – no depolarizing activity; No end plate potential
** No muscle contraction because Na+ doesn’t enter cell |
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What is the mechanism of depolarizing neuromuscular blockers?
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* They bind to receptor and allows influx of Na+ causing depolarization of end plate region but does not allow subsynaptic membrane to completely repolarize because remains bound to receptor and renders motor end plate non-responsive
* Length of action depends on amount of plasma cholinesterases because they are metabolized by them * Muscle contraction then paralysis |
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What is the major effect of a neuromuscular blocker?
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Flaccid Muscle Paralysis
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What 3 drugs are competitive (non-depolarizing) neuromuscular blockers?
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1. Atracurium
2. Vecuronium 3. Pancuronium |
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What drug(s) are depolarizing neuromuscular blockers?
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Succinylcholine
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What 2 ways can neuromuscular blockers be metabolized and eliminated?
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1. Liver metabolism and clearance and then renal elimination
2. Hydrolysis by plasma cholinesterases |
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What neuromuscular blocker(s) are metabolized by the liver and eliminated by the kidney?
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1. Vecuronium
2. Pancuronium ***Kidney and liver disease will increase duration of these drugs |
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What neuromuscular blocker(s) are hydrolyized by plasma cholinesterases?
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1. Atracurium (+ spontaneous degradation)
2. Succinylcholine |
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What type of drug is Atracurium?
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Competitive (non-depolarizing) Neuromuscular Blocking Agent
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How is Atracurium metabolized?
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Metabolized by ester hydrolysis, independent of hepatic mechanisms
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What type of drug is Vecuronium?
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Competitive (non-depolarizing) Neuromuscular Blocking Agent
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How is Vecuronium metabolized?
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Partially metabolized, excreted in the bile and urine
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What type of drug is Pancuronium?
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Competitive (non-depolarizing) Neuromuscular Blocking Agent
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How is Pancuronium metabolized?
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40% is metabolized by the kidneys, the rest is by the liver or excreted into the bile
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What type of drug is Succinycholine?
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Depolarizing Neuromuscular Blocking Agent
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How is Succinycholine metabolized?
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Metabolized by plasma psuedocholinesterases, 10% in urine
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What is the effect of a cholinesterase inhibitor on a Non-depolarizing neuromuscular blocker?
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** Reverse effects (increased Ach)
*To a lesser degree for Atracurium because it is metabolized by cholinesterases |
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What is the effect of a cholinesterase inhibitor on a depolarizing neuromuscular blocker?
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Enhanced
(inhibit plasma cholinesterase (blocks metabolism of drug) – prolonged attachment of succinylcholine at receptor) |
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Is there a reversal agent for a Non-depolarizing neuromuscular blocker?
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Cholinesterase inhibitor (i.e. pyridostigmine)
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Is there a reversal agent for a depolarizing neuromuscular blocker?
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None
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Are initial fasciculations present with a Non-depolarizing neuromuscular blocker?
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Absent
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Are initial fasciculations present with a depolarizing neuromuscular blocker?
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Present
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Are neuromuscular blockers considered to be analgesic?
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NO
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