Medicines and drugs antacids

Acid indigestion/heartburn Acid indigestion (discomfort in stomach) and heartburn (acid rising into oesaphagus) are conditions which arise when excess hydrochloric acid is produced by the gastric glands in the walls of the stomach. The acid, which creates an acidic environment of pH 0.3 to 1.2 is needed to kill any bacteria in the food ingested provide the optimum pH environment for the digestive enzymes which act in the stomach.

Action of antacids Antacids are substances which are used to neutralize excess hydrochloric acid in the stomach so the pH level returns to the desired level. aluminium hydroxide, magnesium hydroxide, magnesium carbonate and sodium hydrogen carbonate are commonly used as active ingredients in such antacids as they are weak bases – write equations!! sodium hydroxide or potassium hydroxide are not used as antacids because they are strong alkalis and are too corrosive to the body tissue.

equations Al(OH)3 (s) + 3HCl (aq)  AlCl3 (aq) + 3H2O (l)   MgCO3 (s) + 2HCl (aq)  MgCl2 (aq) + H2O (l) + CO2(g) NaHCO3(s) + HCl (aq)  NaCl (aq) + H2O (l) + CO2(g)

Alginates Some antacids also contain compounds called ‘alginates’ which produce a neutralizing layer on top of stomach contents and prevent acid in the stomach from rising into the oesophagus and causing heartburn.

Anti-foaming agents Antacids which use carbonates will also contain anti- foaming agents such as dimethicone. These reduce the bloating of the stomach as a result of the carbon dioxide production.