[Mivacurium]

Mivacurium is a short-acting nondepolarizing muscle relaxant (NDPMR) with a benzyl-isoquinoline structure and rapid, spontaneous reversal. It is hydrolyzed by cholinesterase in plasma and its chemical structure favors histamine release, leading to cutaneous or cardiovascular symptoms, particularly when the dose is increased or when the drug is injected rapidly. Both duration of effect and reversal of mivacurium are less dose dependent than they are with intermediate-duration NDPMRs. In adults the recommended dose for intubation (2 to 3 times the ED95) induces clinically effective blockade lasting 15 to 25 minutes, with spontaneous recovery occurring 10 to 20 minutes later. In children two to 12 years old given the same dose, duration of action is shorter and reversal occurs more rapidly. These properties reduce the likelihood of antagonizing the residual neuromuscular blockade. The duration of successive doses is similar and continuous infusion does not affect reversal. Neuromuscular blockade may be prolonged in patients with low plasma cholinesterase activity, particularly in individuals who are homozygous for the atypical plasma cholinesterase gene. Monitoring is therefore recommended when mivacurium is used. Provided patients have normal plasma cholinesterase activity, mivacurium is indicated for interventions that are short or of unpredictable duration when rapid reversal of neuromuscular blockade is required, or whenever anticholinesterase agents must be avoided.