Understanding Anesthesiology - The Global Regional Anesthesia ...

Succinylcholine
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 post-junctional
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.
• Pseudocholinesterase deficiency. Deficiency can result as a genetic defect, as a consequence
of various medications or a result of liver disease. The latter two causes are usually
relative while the genetic defect can produce a complete lack of pseudocholinesterase
activity in homozygous individuals. The use of succinylcholine in a patient with pseudocholinestersase
deficiency leads to prolonged paralysis.
• Hyperkalemia.
• Presence of neurologic or muscular condition which would predispose to hyperkalemia
after Sch-induced muscle contraction. Examples include recent paralysis (spinal cord injury
or stroke), amyotrophic lateral sclerosis (ALS), Duchenne’s muscular dystrophy and
recent burn or crush injury. Myotonia congenita or myotonia dystrophica can manifest sustained
contraction with Sch.
Related Glossary Terms
Acetylcholine, Dantrolene, Malignant hyperthermia, Myoglobinuria, Neuromuscular junction,
Non-depolarizing muscle relaxants, Pseudocholinesterase deficiency, Rapid sequence induction,
Ryanodine
Index
Find Term
Chapter 3 - General Anesthesia
Chapter 3 - General Anesthesia
Chapter 3 - General Anesthesia
Chapter 5 - Malignant Hyperthermia
Chapter 6 - Drug Finder
Chapter 6 - Muscle Relaxants