Nicotinic Receptor Agonist

Question 1

Succinylcholine
MOA

Answer 1

Action on nicotinic receptors produces a maintained depolarization of the muscle membrane. This
inactivates the Na+ channels, which propagate the action potential throughout the muscle. Action
potentials fail to spread along the muscle fibers preventing muscle contraction in response to motor
nerve activity
(acts as agonist first before eventually acting as antagonist through receptor desensitization)

Question 2

Succinylcholine
Abs/Distrb/Elim

Answer 2

Given i.v. Hydrolysed by plasma cholinesterase within a few minutes. (A small percentage of people
have an enzyme with much lower activity and action is prolonged.)

Question 3

Succinylcholine
Clinical use

Answer 3

Short-lasting paralysis to aid tracheal intubation and for short operative procedures. Action is not
reversed by anticholinesterases.

Question 4

Succinylcholine
Adverse effects

Answer 4

Hyperkalaemia (with possible cardiac arrhythmia). Hypotension.
Bradycardia.
Muscle pain (resulting from spasm during the initial depolarisation).
Raised intraocular pressure.
Malignant hyperthermia (rarely, when used with halothane).