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Pharmacology: Pharmacodynamics: Sodium Alginate is used with an antacid or a H2 - receptor antagonist, in the management of gastro-oesophageal reflux. The alginate reacts with gastric acid to form a viscous gel (often termed a raft) which floats on top of the gastric contents. This raft then acts as a mechanical barrier to reduce reflux.
Aluminium Hydroxide is an antacid. It is given orally in doses up to 1g, between meals and at bedtime.
Calcium carbonate is used as an antacid, usually in oral doses of up to 1.5g. Calcium carbonate binds phosphate in the gastrointestinal tract to form insoluble complexes and reduce phosphate absorption.
Pharmacokinetics: Aluminium hydroxide slowly reacts with the hydrochloric acid in the stomach to form soluble aluminium chloride, some of which is absorbed.
The aluminium compounds remaining in the gastrointestinal tract, which account for most of a dose, form insoluble, poorly absorbed aluminium salts in the intestines including hydroxides, carbonates, phosphates and fatty acid derivatives, which are excreted in the faeces.
Calcium carbonate is converted to calcium chloride by gastric acid. Some of the calcium is absorbed from the intestines and the unabsorbed portion is excreted in the faeces.
