Newer Muscle Relaxants

NEWER MUSCLE RELAXANTS

Gantacurium belongs to a new class of nondepolar-izing neuromuscular blockers called chlorofuma-rates. It is provided as a lyophilized powder, because it is not stable as an aqueous solution; therefore, it requires reconstitution prior to administration. In preclinical trials, gantacurium demonstrated an ultrashort duration of action, similar to that of suc-cinylcholine. Its pharmacokinetic profile is explained by the fact that it undergoes nonenzymatic degrada-tion by two chemical mechanisms: rapid formation of inactive cysteine adduction product and ester hydrolysis. At a dose of 0.2 mg/kg (ED₉₅), the onset of action has been estimated to be 1-2 min, with a duration of blockade similar to that of succinyl-choline. Its clinical duration of action ranged from 5-10 min; recovery can be accelerated by edropho-nium, as well as by the administration of exogenous cysteine. Cardiovascular effects suggestive of his-tamine release were observed following the use of three times the ED₉₅ dosage.

AV002 (CW002) is another investigational nondepolarizing agent. It is a benzylisoquinolinium fumarate ester-based compound with an intermedi-ate duration of action that undergoes metabolism and elimination similar to that of gantacurium.