RT Journal Article SR Electronic T1 Bronchodilator Activity of (3R)-3[[[ (3-fluorophenyl) [(3,4,5trifluorophenyl)methyl]amino] oxy]carbonyl]-1-[2-oxo-2-(2-thienyl)ethyl]-1-azoniabicyclo[2.2.2]octane bromide (CHF5407) a Potent, Long-Acting and Selective Muscarinic M3 Receptor Antagonist JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP jpet.110.170035 DO 10.1124/jpet.110.170035 A1 Gino Villetti A1 Fiorella Pastore A1 marco bergamaschi A1 franco Bassani A1 Pier Tonino Bolzoni A1 Loredana Battipaglia A1 gabriele amari A1 andrea rizzi A1 maurizio delcanale A1 roberta volta A1 valentina cenacchi A1 francesca cacciani A1 massimiliano zaniboni A1 ferruccio berti A1 giuseppe rossoni A1 selena harrison A1 paola petrillo A1 enza santoro A1 roberta scudellaro A1 fabio mannini A1 Pierangelo Geppetti A1 roberta razzetti A1 riccardo patacchini A1 maurizio civelli YR 2010 UL http://jpet.aspetjournals.org/content/early/2010/08/30/jpet.110.170035.abstract AB The novel quaternary ammonium salt, CHF5407, showed subnanomolar affinities for human muscarinic M1, M2 and M3 receptors, and dissociated very slowly (t1/2 = 166 min from hM3 receptors (t1/2 = 166 min) with a large part of the receptorial complex (54%) remaining undissociated at 32h from radioligand washout. In contrast, [3H]-CHF5407 dissociated quickly from hM2 receptors (t1/2=31 min), whereas [3H]-tiotropium dissociated slowly from both hM3 (t1/2=163 min) and hM2 receptor (t1/2=297 min). In the guinea-pig isolated trachea and human isolated bronchus, CHF5407 produced a potent (pIC50=9.0-9.6) and long-lasting (up to 24h) inhibition of M3-receptor mediated contractile responses to carbachol. In the guinea-pig electrically-driven left atrium, the M2 receptor-mediated inhibitory response to carbachol was recovered more quickly in CHF5407-pretreated, than in tiotropium-pretreated preparations. CHF5407, administered intratracheally (i.t.) to anaesthetized guinea pigs, potently inhibited acetylcholine (Ach)-induced bronchoconstriction with an ED50 value of 0.15 nmoles/kg. The effect was substained over a period of 24 h, with a residual 57% inhibition 48 h after antagonist administration at 1 nmoles/kg. In conscious guinea pigs, inhaled CHF5407 inhibited Ach-induced bronchoconstriction for at least 24 h as did tiotropium at similar dosages. Cardiovascular parameters in anaesthetised guinea pigs were not significantly changed by CHF5407, up to 100 nmoles/kg i.v. and up to 1000 nmoles/kg i.t. In conclusion, CHF5407 shows a prolonged antibronchospastic activity both in vitro and in vivo, due to a very slow dissociation from M3 receptors. In contrast, CHF5407 is markedly short-acting at M2 receptors, a behaviour not shared by tiotropium.