Acta Med Okayama
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Vecuronium is hydrolyzed in the body to 3-deacetyl (ORG 7268), 17-deacetyl (ORG NC58), and 3, 17-bis-deacetyl (ORG 7402) derivatives. Interactions of vecuronium and these metabolites were studied in phrenic nerve-hemidiaphragm preparations of rats. As already reported, ORG 7268 had a potent neuromuscular blocking action, and ORG NC58 and ORG 7402 had a weak neuromuscular blocking action. ⋯ Regardless of the mechanism, it should be emphasized that the concentrations of ORG NC58 and ORG 7402 which are necessary to reverse the block are much lower than those which facilitate the block. It is conceivable that this paradoxical reversal of the block occurs in experimental and clinical situations. Therefore, in determining the neuromuscular blocking action of a compound, the "antagonistic" effect of its metabolites should also be considered.