DRUGS ACTING ON PERIPHERAL NERVOUS
SYSTEM
✽ Which of the following drugs is a
nondepolarizing neuromuscular blocker
(a) Succinylcholine
(b) Vecuronium
(c) Decamethonium
(d) Dantrolene sodium
ANSWER:
[ b ]
✽ The site of
action of d-tubocurarine is
(a) Spinal internuncial neurone
(b) Motor nerve ending
(c) Muscle end-plate
(d) Sodium channels in the muscle fibre
ANSWER:
[ c ]
✽ At the muscle
end-plate, d-tubocurarine reduces the
(a) Number of Na+ channels
(b) Duration for which the Na+ channels remain open
(c) Ion conductance of the open Na+ channel
(d) Frequency of Na+ channel opening
ANSWER:
[ d ]
✽ Depolarizing neuromuscular blockers differ
from competitive blockers in the following attributes except
(a) They induce contraction of isolated frog rectus abdominis muscle
(b) Ether anaesthesia intensifies block produced by them
(c) Tetanic nerve stimulation during partial depolarizing block produces
well sustained contraction
(d) Neostigmine does not reverse block produced by them
ANSWER:
[ b ]
✽ Succinylcholine produces spastic paralysis in
(a) Rabbits
(b) Frogs
(c) Birds
(d) Patients with atypical pseudocholinesterase
ANSWER:
[ c ]
✽ The fall in
blood pressure caused by d-tubocurarine is due to
(a) Reduced venous return
(b) Ganglionic blockade
(c) Histamine release
(d) All of the above
ANSWER:
[ d ]
✽ Select the skeletal muscle relaxant that is
commonly used for endotracheal intubation despite causing histamine release, K+
efflux from muscles and cardiovascular changes
(a) Pipecuronium
(b) Succinylcholine
(c) Pancuronium
(d) Cisatracurium
ANSWER:
[ b ]
✽ Neuromuscular blocking drugs do not produce
central actions because
(a) They do not cross the blood-brain barrier
(b) Nicotinic receptors are not present in the brain
(c) They are sequestrated in the periphery by tight binding to the
skeletal muscles
(d) They do not ionise at the brain pH
ANSWER:
[ a ]
✽ Pancuronium
differs from tubocurarine in that
(a) It is a depolarizing blocker
(b) Its action is not reversed by neostigmine
(c) It can cause rise in BP on rapid I.V. injection
(d) It causes marked histamine release
ANSWER:
[ c ]
✽ Which of the following drugs undergoes
‘Hofmann’ elimination
(a) Succinylcholine
(b) Pancuronium
(c) Vecuronium
(d) Atracurium
ANSWER:
[ d ]
✽ The neuromuscular blocker that does not need
reversal of action by neostigmine at the end of the operation is
(a) d-Tubocurarine
(b) Doxacurium
(c) Pipecuronium
(d) Mivacurium
ANSWER:
[ d ]
✽ The most rapidly acting nondepolarizing
neuromuscular blocking agent which can be used as an alternative to
succinylcholine for tracheal intubation is
(a) Rocuronium
(b) Pancuronium
(c) Doxacurium
(d) Pipecuronium
ANSWER:
[ a ]