Cytoprotective and antiulcer activities of the antacid magaldrate in the rat.

The cytoprotective and antiulcer activities of the antacid magaldrate (ES Riopan) as well as its effects on gastric mucosal blood flow and mucus secretions, were determined in the rat. Magaldrate afforded protection against gastric necrotic lesions induced by absolute ethanol (ED50, as magaldrate, 419 mg/kg); gastric ulcers induced by acidified acetylsalicylic acid (ED50 540 mg/kg), stress (cold restraint, ED50 388 mg/kg), indometacin (ED50 281 mg/kg), and pylorus ligation; and intestinal ulcers induced by cysteamine (ED50 243 mg/kg) and indometacin (ED50 184 mg/kg). At a dose of 8 ml/kg (1728 mg/kg magaldrate), the cytoprotective effect of magaldrate against ethanol was evident 1 min after oral administration and lasted more than 8 h. The cytoprotection induced by magaldrate was decreased by pretreatments with the depletor of endogenous thiols, n-ethylmaleimide, or with the cyclooxygenase inhibitor, indometacin. Magaldrate did not affect gastric mucosal blood flow, but it increased gastric mucus secretion. This later effect may be a factor responsible for the cytoprotective activity of the agent. The efficacy of magaldrate may be due not only to its antacid, bile sequestering, and antipeptic activities, but also to its cytoprotective activity. The present results suggest that magaldrate could be effective in preventing gastric damage caused by alcohol and antiinflammatory drugs.