From the Guidelines
Intravenous (IV) muscle relaxers options include succinylcholine, rocuronium, atracurium, cisatracurium, mivacurium, pancuronium, rapacuronium, and vecuronium.
Available Options
- Succinylcholine: a depolarizing muscle relaxant, often used for rapid sequence induction, with a dose varying by age: up to 1 month: 1.8 mg/kg, 1 month to 1 year: 2 mg/kg, 1 to 10 years: 1.2 mg/kg and more than 10 years: 1 mg/kg 1.
- Rocuronium: a non-depolarizing muscle relaxant, with a dose of > 0.9 mg/kg, often used as an alternative to succinylcholine 1.
- Atracurium and cisatracurium: benzylisoquinoline muscle relaxants, recommended for use in cases of renal or hepatic failure due to their organ-independent elimination 1.
Reversal Agents
- Sugammadex: a selective reversal agent for steroidal muscle relaxants, useful for reversing the effects of rocuronium 1.
- Neostigmine: a reversal agent, often used to reverse the effects of non-depolarizing muscle relaxants, with a recommended dose and timing based on the specific muscle relaxant used 1.
Considerations
- The choice of muscle relaxant should be based on the desired duration of muscle relaxation, the risk of difficult intubation, and the presence or risk of a neuromuscular disease 1.
- The risk of anaphylaxis should be considered when choosing a muscle relaxant, with some studies suggesting a lower risk with atracurium and cisatracurium 1.
- The use of muscle relaxants in children requires careful consideration of the dose and potential risks, with succinylcholine and rocuronium being commonly used options 1.
From the Research
Types of Intravenous (IV) Muscle Relaxers
- Succinylcholine: a fast-acting muscle relaxant with a short duration of action, commonly used for rapid-sequence induction 2
- Rocuronium: an alternative to succinylcholine, available in large doses for rapid-sequence induction 2
- Rapacuronium: a muscle relaxant with dose-dependent respiratory side-effects, limiting its usefulness in high doses 2
- Atracurium: an intermediate-acting muscle relaxant, suitable for continuous infusion during prolonged surgical procedures 3, 4, 5
- Vecuronium: an intermediate-acting muscle relaxant with few undesirable side-effects 4
- Doxacurium and pipecuronium: long-acting muscle relaxants, preferred for use when postoperative mechanical ventilation is intended 4
- Mivacurium: a short-acting nondepolarizing muscle relaxant, suitable for clinical applications where rapid recovery is desired 4, 5
- Suxamethonium (curacit): a depolarizing muscle relaxant, introduced into clinical anaesthesia in 1942 6
- Curare compounds: a class of muscle relaxants that interfere with the normal signalling system between nerve and muscle, providing optimal relaxation of skeletal muscles during surgical procedures 6
Characteristics of IV Muscle Relaxers
- Onset time: varies among muscle relaxants, with rocuronium having the shortest onset time 2, 4
- Duration of action: ranges from short-acting (e.g., succinylcholine, mivacurium) to long-acting (e.g., doxacurium, pipecuronium) 2, 4, 5
- Side-effects: vary among muscle relaxants, with some (e.g., suxamethonium) having serious side-effects 2, 6
- Pharmacokinetics: muscle relaxants exhibit multicompartmental behavior, with clearance ranging from total elimination by the kidneys to substantial hepatic clearance 3