Gastroprotective activity of the novel proton pump inhibitor lansoprazole in the rat.

1. The protective activity of lansoprazole was evaluated on gastric mucosal lesions induced by intragastric 25% NaCl (1 ml/rat for 1 hr) and by indomethacin (20 mg/kg for 6 hr) in the rat and compared with that of omeprazole. 2. Lansoprazole (3, 10 and 10 mumol/kg i.g.) dose-dependently prevented the formation of indomethacin-induced lesions, the inhibition being 99% at the highest dose. Omeprazole, 10 mumol/kg i.g., enhanced the damage by indomethacin while higher doses caused a reduction, lesion index being reduced by 98% at 100 mumol/kg. 3. Histologically in lansoprazole- as well as in omeprazole-pretreated rats, indomethacin-induced necrosis of the mucosa was absent, luminal epithelium being intact. 4. Lansoprazole (30, 100 and 300 mumol/kg) and omeprazole (30, 100 and 300 mumol/kg) dose-dependently reduced the formation of lesions by hypertonic saline. 5. Present results indicated that lansoprazole and omeprazole protect the gastric mucosa in different experimental models of gastric ulceration.