indication

For the treatment of disorders of the upper gastro-intestinal region that are due to an excess of hydrochloric acid in the gastric juice, i.e. duodenal ulcers, benign gastric ulcers. Also for prophylaxis of recurrent gastric and duodenal ulcers

pharmacology

Roxatidine acetate suppresses the effect of histamine on the parietal cells of the stomach (H2-receptor antagonist). This suppressive action is dose-dependent. As a result, the production and secretion, particularly of gastric acid, are reduced. Roxatidine acetate has no antiandrogenic effects and does not influence drug-metabolizing enzymes in the liver.

mechanism of action

The H2 antagonists are competitive inhibitors of histamine at the parietal cell H2 receptor. They suppress the normal secretion of acid by parietal cells and the meal-stimulated secretion of acid. They accomplish this by two mechanisms: histamine released by ECL cells in the stomach is blocked from binding on parietal cell H2 receptors which stimulate acid secretion, and other substances that promote acid secretion (such as gastrin and acetylcholine) have a reduced effect on parietal cells when the H2 receptors are blocked.

toxicity

Oral, mouse LD50: 1000 mg/kg

biotransformation

Roxatidine acetate is rapidly metabolised to the primary, active desacetyl metabolite.

absorption

Well absorbed orally (80–90% bioavailability).

half life

5-6 hours