Neuromuscular Blocking Agents

Introduction

• Skeletal muscle relaxants — drugs that reduce muscle tone or produce paralysis by acting either peripherally at the neuromuscular junction (NMJ) / muscle fibre, or centrally in the cerebrospinal axis.
• Neuromuscular blocking agents (NMBAs) — the peripherally acting, NMJ-blocking subset used chiefly with general anaesthetics to relax skeletal muscle for surgery and to facilitate endotracheal intubation; being charged quaternary compounds they do not cross the blood–brain barrier, so they lack CNS activity, analgesia or sedation.
• Two clinical classes — depolarising (only succinylcholine in general use) and non-depolarising / competitive (tubocurarine, the aminosteroids and the benzylisoquinoliniums).
• Historical note — curare = South-American arrow poison; Claude Bernard localised its action to the NMJ; Griffith & Johnson introduced curare for surgical relaxation in 1942.