Cimetropium Bromide is a mAChR antagonist used for long-term treatment of irritable bowel syndrome.

Cimetropium decreases the labeled ACh release induced by electrical field stimulation under the muscarinic autoinhibition blocked-condition, in the superfusion experiments of the preparation which has been preloaded with labeled choline [2]. Cimetropium has a potent antimuscarinic effect in inhibition of contraction of longitudinal muscle preparations. Cimetropium Bromide behaves as a competitive antagonist of muscarinic-mediated contractions in isolated colonic preparations from both species, with affinity values (pA2) ranging between 7.41 and 7.82 [1].

Cimetropium Bromide (10-100 μg/kg) counteracts colonic motor response to neostigmine administration (ID50: 27.9 μg/kg); both tonic and phasic components of contractile response are affected. Cimetropium is a potent inhibitor of large bowel motility evoked by both exogenous and endogenous stimuli when administered intravenously to conscious dogs provided with a colonic Thiry fistula. In a comparable range of doses (3-100μg/kg), the drug inhibits motor activity elicited by intraluminal distension [1].