Otilonium bromide: a selective spasmolytic for the gastrointestinal tract.

Experimental studies have shown that otilonium bromide (OB) inhibits both baseline and chemically or physically stimulated gastrointestinal motility. The spasmolytic activity of OB in the gastrointestinal tract occurs at doses that do not affect gastric secretion or produce typical atropine-like side-effects. The mechanism of action is composite: interference with calcium ion movement from intra- and extracellular sites; blockade of calcium channels; and binding to muscarinic receptors and tachykinin neurokinin-2 receptors. Pharmacokinetic studies have shown that OB accumulates in the lower intestine and has poor systemic absorption. Clinical studies have confirmed OB as a potent spasmolytic drug with a good tolerability profile. Studies in patients with irritable bowel syndrome demonstrated OB to be superior to placebo and reference drugs in parameters such as pain, abdominal distension and motility. The composite and local mechanism of OB action reduces hypermotility and modulates visceral sensation: factors thought to be responsible for pain improvement recorded in clinical trials. The compound is marketed worldwide and no serious adverse events have been reported as yet, confirming its excellent tolerability.