Methyl anisotropinium (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 Its use as treatment adjunct in peptic ulcer has been replaced by the use of more effective agents.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. Methyl anisotropinium inhibits 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. It is used in conjunction with antacids or histamine H2-receptor antagonists in the treatment of peptic ulcer, to reduce further gastric acid secretion and delay gastric emptying.