Succinylcholine
Anectine / Quelicin
neuromuscular blockerIV · IM (for laryngospasm when no IV access)Onset: 45–60 secondsDuration: 8–12 minutes
Mechanism of Action
Depolarizing neuromuscular blocking agent. Structurally mimics acetylcholine. Binds and persistently activates nicotinic receptors at neuromuscular junction → initial muscle fasciculations → sustained depolarization → flaccid paralysis (phase I block).
Dosing
Adult
RSI: 1–1.5 mg/kg IV. Laryngospasm: 0.5–1 mg/kg IV or 3–4 mg/kg IM
Pediatric
RSI: 1.5–2 mg/kg IV (higher dose needed; faster metabolism). IM: 4 mg/kg (max 150 mg)
Indications
- Rapid Sequence Intubation (RSI) — drug of choice for conditions where rapid paralysis and airway recovery are needed
- Laryngospasm (IV or IM)
Contraindications
- History or family history of malignant hyperthermia
- Denervation injuries >72 hours (spinal cord injury, burns, prolonged immobility → up-regulation of extra-junctional receptors → hyperkalemia)
- Hyperkalemia (K+ >5.5 mEq/L)
- Crush injury or rhabdomyolysis
- Myopathies (Duchenne muscular dystrophy, myotonias)
- Penetrating eye injuries (raises intraocular pressure — relative contraindication)
Side Effects
- Hyperkalemia (0.5–1 mEq/L increase normally; massive in denervation/burn patients)
- Bradycardia (especially pediatric patients — second dose)
- Increased intraocular pressure
- Increased intragastric pressure (fasciculations)
- Malignant hyperthermia (trigger in susceptible patients)
- Myalgia (from fasciculations)
- Prolonged block in pseudocholinesterase deficiency
Monitoring Parameters
- End-tidal CO2 confirmation of intubation
- SpO2
- ECG (bradycardia, arrhythmias from hyperkalemia)
- Serum potassium (in at-risk patients)
- Train-of-four (TOF) monitoring not typically needed for RSI
Drug Interactions
- Cholinesterase inhibitors (neostigmine, organophosphates) — prolong block
- Pseudocholinesterase deficiency (genetic — prolongs duration to hours)
- Non-depolarizing NMBs given before succinylcholine reduce fasciculations
Clinical Pearls
- Fastest-onset NMB → drug of choice for RSI when rapid recovery needed (failed airway scenario)
- No reversal agent (unlike rocuronium — reversed by sugammadex)
- Contraindicated >72 hours after burns, crush injury, stroke, SCI (up-regulation of extra-junctional receptors)
- Pretreatment with atropine 0.02 mg/kg before pediatric dose prevents bradycardia
- Malignant hyperthermia: stop succinylcholine, give dantrolene 2.5 mg/kg IV
- NOT for long-term ICU paralysis (depolarizing agent — only RSI use)
Mnemonic
💡 SUCKS for: Succinylcholine Used for Crash airway — but watch for K+ elevation, Sux in burns
NBRC High-Yield
- Depolarizing NMB — fastest onset (45–60 sec), drug of choice for RSI
- Contraindicated in burns/SCI/denervation >72 hours (fatal hyperkalemia risk)
- Duration 8–12 min; NO reversal agent
- Malignant hyperthermia trigger: stop drug, give dantrolene
- Causes fasciculations then paralysis
- Rocuronium (+ sugammadex reversal) is alternative when succinylcholine is contraindicated