Skeletal muscle relaxants
A. Pancuronium
B. Doxacurium
C. Mivacurium
D. Atracurium
ANSWER
C. Mivacurium
——————
A. Pancuronium
B. Doxacurium
C. Mivacurium
D. Atracurium
ANSWER
D. Atracurium
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unique feature of atracurium is inactivation in plasma by spontaneous nonenzymatic degradation which is called Hofmann elimination in addition to that by cholinesterases.
A. Cisatracurium
B. Doxacurium
C. Mivacurium
D. Laudanosine
ANSWER
D. Laudanosine
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Primary metabolite of Hofmann elimination of atracurium is laudanosine which does not have any neuromuscular blocking activity but acts as a central nervous system (CNS) stimulant.
A. Succinylcholine
B. Doxacurium
C. Decamethonium
D. Dantrolene sodium
ANSWER
D. Dantrolene sodium
——————
A. Diazepam
B. Propranolol
C. Quinidine
D. High dose of corticosteroids
ANSWER
D. High dose of corticosteroids
——————
Diazepam, propranolol and quinidine intensify competitive block, while high dose of corticosteroids reduces it.
A. 25
B. 45
C. 75
D. 95
ANSWER
B. 45 %
——————
Nonenzymatic degradation (Hofmann elimination) accounts for 45% of the metabolism of atracurium.
Hoffman elimination is a temperature and pH-dependent process and is slowed by acidosis and hypothermia.
The remainder is metabolized via ester hydrolysis by non-specific esterases in the plasma that are unrelated to pseudocholinesterase.
In-Shorts
| Neuromuscular blocking agents | Skeletal muscle relaxants – act peripherally |
|---|---|
| Nondepolarizing blockers | Competitive blockers |
| Long acting | d-Tubocurarine, Pancuronium, Doxacurium, Pipecuronium |
| Intermediate acting | Vecuronium, Atracurium, Cisatracurium, Rocuronium, Rapacuronium |
| Short acting | Mivacurium |
| Depolarizing blockers | Succinylcholine, Decamethonium |
Depolarizing agents – are nicotinic receptor agonists which mimic Ach, block muscle contraction by depolarizing to such an extent that it desensitizes the receptor and it can no longer initiate an action potential and cause muscle contraction.
Ex – succinylcholine
Nondepolarizing agents – block the agonist, acetylcholine, from binding to nicotinic receptors and activating them, thereby preventing depolarization.
Ex- tubocurarine
