In medicine, a muscle relaxant is a drug that causes skeletal muscle contraction to cease. Muscle relaxants are used to facilitate surgery, to enable tracheal intubation and to facilitate mechanical ventilation.

Muscles relaxants typically work by blocking the effect of acetylcholine (ACh) at the neuromuscular junction.

Receptor blockers

Substances that compete with ACh, for the receptors on a muscle cell can be either depolarising, or non-depolarising.

Depolarising muscle relaxants activate the muscle briefly, before blocking it.

• Succinylcholine (BE) or Suxamethonium (AE)

Non-depolarising relaxants block the ACh receptors without activating them.

• Curare
• Atracurium and Cisatracurium
• Vecuronium
• Rocuronium
• Mivacurium
• Curare-based molecules, e.g. tubocurarine, pancuronium bromide.

Other mechanisms

Botulinum toxin, marketed as Botox for facial wrinkle removal, works by stopping the release of ACh from the presynaptic neuron.

Central acting muscle relaxants

• Benzodiazepines

Acting on smooth muscle

• Amyl nitrite

See also

• Paralysis