Mechanism of action
Magaldrate reacts with gastric acid in stages. The hydroxymagnesium is relatively rapidly converted to magnesium ion and the aluminate to hydrated aluminium hydroxide; the magnesium ion rapidly neutralises or buffers existing acid while the aluminium hydroxide reacts more slowly to give a sustained antacid effect.A small amount of aluminium from aluminium hydroxide is absorbed from the intestine. Approximately 10% of the magnesium in magnesium hydroxide is absorbed from the intestine.