Itopride, a gastroprokinetic benzamide derivative was launched in
Japan for the relief of gastrointestinal symptoms in patients with chronic gastritis.
ltopride is a dopamine D2-receptor antagonist that stimulates acetylcholine (Ach)
release on the postganglionic cholinergic neurons to cause Ach accumulation at
muscarinic receptors and, therefore, enhances Ach-induced gastric contractions. In
animal models, itopride was reported to increase GI transit and gastric emptying.
Dopamine D2 receptor blockade,acetylcholinesterase inhibitor
Dopamine D2-receptor antagonist with anticholinesterase activity. Gastroprokinetic
Itopride hydrochloride is a new prokinetic drug.
Itopride hydrochloride enhances the gastrointestinal motility by blocking the activity of dopamine on the D2 receptors, on the post-synaptic cholinergic nerves and by inducing the liberation of acetylcholine in the myenteric plexus. It also inhibits the hydrolysis of the released acetylcholine with the help of acetylcholinesterase.
itopride was found to inhibit both ache and horse serum butyrylcholinesterase (buche). the itopride ic50 against ache was, however, 100-fold less than that against buche. the recovery of ache activity inhibited by low dose of neostigmine was partial, but that inhibited by itopride was complete. double reciprocal plots showed that both vmax and km were affected by itopride, indicating a "mixed" type inhibition, although primarily being an uncompetitive one. in addition, the inhibitory effect of itopride on cholinesterase (che) activity in guinea pig gastrointestine was much weaker than that on pure ache [1].
previoius animal study showed that in conscious dogs with implanted strain gauge force transducers, itopride could stimulate contractile activity in the gastrointestinal tract from stomach to colon. whereas, mosapride was able to stimulate contractile activity only in the gastric antrum and ileum. moreover, in rats s andguinea pig, itopride could accelerate colonic luminal transit, however, both mosapride and cisapride failed to enhance colonic transit. such findings suggested that itopride had a stimulatory action on propelling colonic luminal contents, colonic peristalsis, which was quite different from mosapride and cisapride [2].
[1] iwanaga y,kimura t,miyashita n,morikawa k,nagata o,itoh z,kondo y. characterization of acetylcholinesterase-inhibition by itopride. jpn j pharmacol.1994 nov;66(3):317-22.
[2] tsubouchi t,saito t,mizutani f,yamauchi t,iwanaga y. stimulatory action of itopride hydrochloride on colonic motor activity in vitro and in vivo. j pharmacol exp ther.2003 aug;306(2):787-93.
