Mivacurium is an antagonist of nicotinic acetylcholine receptors (nAChRs) and muscarinic M2 and M3 receptors (ED50s = 0.08, 0.3, and 0.1 mg/kg for ex vivo human skeletal muscle nAChRs, guinea pig cardiac M2 receptors, and guinea pig bronchial M3 receptors, respectively). It inhibits acetylcholine-induced activation of neuronal nAChRs (IC50s = 69.04, 3.71, 1.52, and 2.90 for human α3β2-, α3β4-, α4β2-, and α7-containing nAChRs expressed in Xenopus oocytes). Mivacurium also inhibits adult human muscular α1β1εδ-containing nAChRs (IC50 = 3.69 nM in Xenopus oocytes expressing the human recombinant receptor). In vivo, mivacurium inhibits bradycardia and bronchoconstriction induced by vagal stimulation or acetylcholine in guinea pigs. It also induces neuromuscular blockade (ED95 = 80 μg/kg) in sheep with a more rapid onset time than atracurium and vecuronium . Formulations containing mivacurium have been used for pediatric anesthesia.