Understanding Anesthesiology - The Global Regional Anesthesia ...

SUCCINYLCHOLINE CHLORIDE
Class
Depolarizing muscle relaxant; ultra short-acting; Used
for rapid sequence induction.
Mechanism of Action
Succinylcholine (Sch) attaches to nicotinic cholinergic
receptors at the neuromuscular junction. There, it mimics
the action of acetylcholine thus depolarizing the
post-junctional membrane. Neuromuscular blockade
(paralysis) develops because a depolarized postjunctional
membrane cannot respond to subsequent release
of acetylcholine.
Dose
Intubaton: 1-1.5 mg/kg IV or 2.5-4 mg/kg IM
Onset
30-60 seconds after IV administration
2-3 minutes after IM dose
Duration
Duration is 4-6 minutes after IV dose
10-30 minutes after IM dose
Elimination
Hydrolysis by plasma pseudocholinesterase
Effects
CNS
Raised intracranial pressure and raised intraocular pressure.
CVS
Because of cross-reactivity at the muscarinic acetylcholine
receptors, Sch causes vagal cardiac dysrhythmias.
Bradycardia, junctional rhythm and sinus arrest can occur
particularly if a second dose is administered and
particularly in children.
Respiratory
Occasionally leads to bronchospasm and excessive salivation
due to muscarinic effects. Intragastric pressure is
increased thereby theoretically increasing the risk of regurgitation.
Misc.
Most of the other effects are secondary to the depolarization
and subsequent contraction of skeletal muscle.
Sch elevates serum potassium 0.3-0.5 mEq/L in normal
patients It can cause an exaggerated release of potassium
(leading to fatal hyperkalemia) in those with neuromuscular
or muscle disease. Post-operative myalgia
is common particularly in young adults. Succinylcholine
is a potent trigger of malignant hyperthermia.
Contraindications
There is a long list of absolute and relative contraindications
which can be found in any Anesthesia text. A
brief summary follows:
• Malignant Hyperthermia (MH) or presence of conditions
associated with MH.
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