ATC Group: A02A Antacids

The World Health Organization's ATC classification organizes medical drugs based on therapeutic properties, chemical composition, and anatomy. It helps make essential medicines readily available globally and is widely used in the pharmaceutical industry.

Position of A02A in the ATC hierarchy

Level Code Title
1 A Alimentary tract and metabolism
2 A02 Drugs for acid related disorders
3 A02A Antacids

Group A02A contents

Code Title
A02AA Magnesium compounds
A02AB Aluminium compounds
A02AC Calcium compounds
A02AD Combinations and complexes of aluminium, calcium and magnesium compounds
A02AF Antacids with antiflatulents
A02AG Antacids with antispasmodics
A02AH Antacids with sodium bicarbonate
A02AX Antacids, other combinations

Active ingredients in A02A

Active Ingredient Description

Almagate is an aluminium- and magnesium-containing antacid.


Almasilate is an antacid compound, consisting of a crystalline aluminum/magnesium silicate polymer. It guffers gastric acid by binding hydrogen ions within the polymer.

Aluminium glycinate
Aluminium hydroxide

Aluminium hydroxide is a slow-acting antacid. It is used to provide symptomatic relief in gastric hyperacidity. In addition, the antipeptic and demulcent activity of aluminium hydroxide helps to protect inflamed gastric mucosa against further irritation by gastric secretions.

Aluminium phosphate
Calcium carbonate

Calcium carbonate releases, in a pH-dependent manner, calcium ions in the stomach. Calcium carbonate is widely used as antacid and extensively used as a dietary supplement.


Hydrotalcite is a layered double hydroxide of general formula Mg6Al2CO3(OH)16·4(H2O), whose name is derived from its resemblance with talc and its high water content. The carbonate anions that lie between the structural layers are weakly bound, so hydrotalcite has anion exchange capabilities. Hydrotalcite is also used as an antacid.


Magaldrate is a common antacid drug that is used for the treatment of duodenal and gastric ulcers, esophagitis from gastroesophageal reflux.

Magnesium carbonate

Magnesium carbonate, MgCO3 (archaic name magnesia alba), is an inorganic salt. The most common magnesium carbonate forms are the anhydrous salt called magnesite (MgCO3) and the di, tri, and pentahydrates known as barringtonite (MgCO3·2 H2O), nesquehonite (MgCO3·3 H2O), and lansfordite (MgCO3·5 H2O), respectively. The primary use of magnesium carbonate is the production of magnesium oxide by calcining.

Magnesium hydroxide

Magnesium hydroxide is practically insoluble in water and solution is not effected until the hydroxide reacts with hydrochloric acid in the stomach to form magnesium chloride. Its neutralising action is almost equal to that of sodium bicarbonate. When the dose is in excess of that required to neutralise the acid the intragastric pH may reach pH 8 or 9. Acid rebound following magnesium hydroxide is clinically insignificant. Magnesium hydroxide has an indirect cathartic effect resulting from water retention in the intestinal lumen.

Magnesium oxide

Magnesium oxide (MgO), or magnesia, is an empirical formula of MgO and consists of a lattice of Mg2+ ions and O2− ions held together by ionic bonding.

Magnesium peroxide
Magnesium silicate

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