neuromuscular blocker

Succinylcholine

Anectine / Quelicin

Route: IV · IM (for laryngospasm when no IV access)
Onset: 45–60 seconds
Duration: 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

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

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

All Drugs

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

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

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)