Learning objectives
- Describe the mechanism of action of succinylcholine
- Describe the side effects of succinylcholine
- Prevent and manage succinylcholine-induce myalgias
Background
- Succinylcholine is a depolarizing neuromuscular blocking agent
- It is considered the standard drug for rapid sequence intubation
Mechanisms
- Acts as an acetylcholine receptor agonist
- Not metabolized by acetylcholinesterase, leading to persistent depolarization of the muscle fibers
- Effect: Desensitization of motor endplate to acetylcholine resulting in paralysis
Adverse effects
- Paralysis of the diaphragm
- Arrhythmias
- Autonomic symptoms
- Hypotension
- Flushing
- Tachycardia
- Hyperkalemia
- Muscle fasciculation
- Jaw rigidity
- Apnea
- Bradycardia
- Increased intraocular pressure
- Excessive salivation
- Hypersensitivity reactions
- Malignant hyperthermia
- Myoglobinuria/myoglobinemia
- Myalgia
- Myalgia has a high incidence (50-90%) and may last for several days, inducing significant discomfort
Protective factors
- Children
- Age >50
- Female
- Pregnancy
- Better muscular fitness
Risk factors
- Minor procedures
- Early ambulation
Prevention
- Avoid succinylcholine use
- Use a higher dose of succinylcholine (1.5 mg/kg causes less myalgias than 1 mg/kg)
- Low-dose nondepolarizing muscle relaxants (e.g., 0.04 mg/kg rocuronium 2 min before succinylcholine), use cautiously (risk of potentially serious side effects)
- Lidocaine (1.5 mg/kg just before succinylcholine)
- Magnesium
- Non-steroidal anti-inflammatory drugs (e.g., 75 mg diclofenac 20 min before surgery)
Management
- Postoperative muscle stretching exercises
- High-dose vitamin C
Suggested reading
- Gulenay M, Mathai JK. Depolarizing Neuromuscular Blocking Drugs. [Updated 2022 Nov 17]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK532996/
- Schreiber JU, Lysakowski C, Fuchs-Buder T, Tramèr MR. Prevention of succinylcholine-induced fasciculation and myalgia: a meta-analysis of randomized trials. Anesthesiology. 2005;103(4):877-884.
Clinical updates
Kumar et al. (Cureus, 2024) report in a randomized, double-blind trial of 80 ASA I–II adults that propofol (2 mg/kg) is more effective than thiopentone (5 mg/kg) in reducing both the severity of succinylcholine-induced fasciculations and postoperative myalgia when patients are premedicated with oral gabapentin 600 mg. Propofol significantly reduced myalgia at 2, 6, and 12 hours postoperatively and shortened the overall duration of myalgia to ≤ 12 hours, with no increase in adverse effects or rescue opioid use. These findings provide contemporary evidence supporting the choice of induction agent (propofol over thiopentone), combined with gabapentin premedication, as an effective preventive strategy for succinylcholine-associated myalgias.
