The antiulcer effects of OPC-12759, a novel antiulcer agent were compared with those of cetraxate in various experimental ulcer models and on gastric secretion in rats. OPC-12759 (0.3-30 mg/kg, b.i.d., p.o.) significantly accelerated the healing rate of acetic acid-induced gastric ulcer in a dose-dependent manner, while cetraxate did not. When administered orally at 0.3-30 mg/kg, b.i.d., for 7 days, pretreatment with OPC-12759 (0.3-30 mg/kg, b.i.d., p.o.) prevented the formation of acute gastric ulcers, induced by: restraint water immersion stress, aspirin, indomethacin, histamine, serotonin, platelet activating factor (PAF) and DDC. Cetraxate showed antiulcer activity against a part of the OPC-12759-positive gastric ulcer models. Given intraperitoneally at the single dosing range of 10-100 mg/kg, OPC-12759 inhibited the formation of these acute gastric ulcer models. OPC-12759 administered orally at 0.3-30 mg/kg, b.i.d., for 7 days did not inhibit basal gastric secretion in pylorus ligated rats. The results indicated that OPC-12759 possesses wide spectrum antiulcer activity as compared with cetraxate.