Gastric antisecretory activity of lansoprazole in different experimental models: comparison with omeprazole

• 1.1. The activity of the novel proton pump inhibitor lansoprazole was examined in different gastric secretion models in vitro and in vivo, in comparison with omeprazole.
• 2.2. In the conscious cat with gastric fistula lansoprazole (0.25-2 μmol/kg i.v.) caused a dose-dependent reduction of the acid secretion induced by dimaprit, pentagastrin, 2-deoxy-d-glucose and bombesin, being approximately as potent as omeprazole (0.25–1.5 μmol/kg i.v.). Similar to omeprazole, lansoprazole was also more effective when administered in hyperacidic states.
• 3.3. In the anaesthetized rat with lumen perfused stomach lansoprazole (0.03–1 μmol/kg i.v.) was approximately 3 times more potent than omeprazole (0.1–3 μmol/kg i.v.) in inhibiting the acid secretion induced by histamine, 2-deoxy-d-glucose and forskolin.
• 4.4. In the isolated gastric fundus from the immature rat lansoprazole (1–30 μM) reduced basal acid secretion and the acid response to histamine and forskolin, with a potency not significantly different from that of omeprazole.
• 5.5. No significant differences were found in the different species between lansoprazole and omeprazole as for the duration of action.
• 6.6. In conclusion, lansoprazole exerts a marked antisecretory effect in a variety of gastric secretion models from different species. However, it did not significantly differ from omeprazole when considering either the potency or the duration of action.