Yuji Iwanaga (1), Naoshi Miyashita (1), Takaharu Saito (1), Koji Morikawa (1) and Zen Itoh (2)
(1) Research and Development Division, Hokuriku Seiyaku, Co., Ltd., Inokuchi 37-1-1, Katsuyama, Fukui 911, Japan (2) GI Laboratories, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371, Japan
Abstract: The novel benzamide derivative itopride was assayed for its effect on gastrointestinal motility in conscious dogs when it was administered intraduodenally (i.d.). Gastrointestinal motility was measured by means of chronically implanted force transducers, and itopride at a dose of 10 mg/kg, i.d. or more increased the gastric contractile force during the digestive state. Intraduodenal cisapride, domperidone and metoclopramide also stimulated gastric motility, and their threshold doses were 1, 3 and 1 mg/kg, respectively. Dopamine infusion (1 mg/kg/hr, i.v.) caused the postprandial gastric motility to disappear, but it was immediately restored by itopride at a dose of 3 mg/kg, i.d. With itopride at 1 and 3 mg/kg, i.d., acetylcholine (0.05 mg/kg/min)-induced contractions were greatly enhanced. In addition to its gastric stimulation, itopride at doses of 10 - 1OO mg/kg, p.o. inhibited apomorphine (0.1 mg/kg, s.c.)-induced vomiting in dogs. In conclusion, intraduodenal itopride stimulates gastric motility through both anti-dopaminergic and anti-acetylcholinesterase actions. Its gastroprokinetic threshold dose was as large as 3 - 10 times those of cisapride, domperidone and metoclopramide. These findings suggest that itopride is an orally active gastroprokinetic with a moderate anti-emetic action.
Keywords:
Conscious dog, Gastroprokinetic, Itopride, Gastric motility, Anti-emetic action