Anisotropine methylbromide is a quaternary ammonium compound. Its use as treatment adjunct in peptic ulcer has been replaced by the use of more effective agents. Depending on the dose, anisotropine methylbromide may reduce the motility and secretory activity of the gastrointestinal system, and the tone of the ureter and urinary bladder and may have a slight relaxant action on the bile ducts and gallbladder. In general, smaller doses of anisotropine methylbromide inhibit salivary and bronchial secretions, sweating, and accommodation; cause dilatation of the pupil; and increase the heart rate. Larger doses are required to decrease motility of the gastrointestinal and urinary tracts and to inhibit gastric acid secretion. Quaternary ammonium compounds such as anisotropine methylbromide inhibit the muscarinic actions of acetylcholine on structures innervated by postganglionic cholinergic nerves as well as on smooth muscles that respond to acetylcholine but lack cholinergic innervation. These postganglionic receptor sites are present in the autonomic effector cells of the smooth muscle, cardiac muscle, sinoatrial and atrioventricular nodes, and exocrine glands. By being an antagonist of the M2 receptor on the smooth muscle of the GI tract, this drug inhibits the Gi signalling pathway leading to decreased intracellular calcium levels and muscle relaxation, therefore decreasing the motility of the GI tract. Possible side effects of using anisotropine methylbromide may include constipation, dry mouth, urinary retention, and headache.

Anisotropine Methylbromide M2 GI Tract Relaxation Pathway References