Characterization of bencycloquidium bromide, a novel muscarinic M(3) receptor antagonist in guinea pig airways.
ABSTRACT In this study we have investigated the antagonist affinity, efficacy and duration of action of bencycloquidium bromide (BCQB), a selective muscarinic M(3) receptor antagonist, as a possible clinical bronchodilator for the treatment of chronic obstructive pulmonary disease (COPD) and asthma. In competition studies, BCQB showed high affinity toward the M(3) receptor in Chinese hamster ovary (CHO) cells (M(3) pKi=8.21, M(2) pKi=7.21, and M(1) pKi=7.86); pA(2)=8.85, 8.71 and 8.57 in methacholine-induced contraction of trachea, ileum and urinary bladder, 8.19 in methacholine-induced bradycardia of right atrium in vitro, respectively. In function studies, duration of inhibition of carbachol-induced tonic contraction, BCQB and ipratropium had a very similar onset and offset of action, but onset faster and offset slower than that of tiotropium. After treatment with intratracheally instilled or the inhalation route, BCQB protects against methacholine or antigen-induced bronchoconstriction in a dose-dependent manner in the normal and sensitized guinea pigs in vivo. BCQB and ipratropium-induced inhibitory activity was short lasting, as it declined quickly when compared to tiotropium. These results suggest that BCQB bind muscarinic M(3) receptors with high affinity. On this basis we speculate that a putative BCQB-based therapy for COPD might require more than once-a-day administration to be as effective as the currently employed once-daily therapy with tiotropium. Nevertheless, Inhalable M(3)-selective compounds may spare M(2)-cardiac receptors and reduce the risks of cardiovascular events associated with the long-term treatment of these agents.
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ABSTRACT: The relative sensitivity and usefulness of FEV1 and SGaw measurements in determining airway responsiveness to stimuli causing changes in bronchomotor tone depend to a great extent on the population studied. Though neither test provides a great deal of information regarding the site of airway obstruction, when used together they provide a reliable and sensitive indicator of airway responsiveness.Journal of Allergy and Clinical Immunology 01/1980; 64(6 pt 2):592-6. · 12.05 Impact Factor
- Biochemical Pharmacology 01/1974; 22(23):3099-108. · 4.58 Impact Factor
- Bulletin européen de physiopathologie respiratoire 01/1981; 17(4):509-21.