Criteria of an ideal antacid preparation:

• The antacid should not be absorbable or cause systemic alkalosis
• The antacid should not be a laxative or causes constipation
• The antacid should exert its effect rapidly and over a long period of time
• The antacid should buffer in the pH 4-6 range
• The reaction of the antacid with gastric HCl acid should not cause a large evolution of gas
• The antacid should probably inhibit pepsin

Action mechanism

Antacids perform a neutralization reaction, i.e. they buffer gastric acid, raising the pH to reduce acidity in the stomach. When gastric hydrochloric acid reaches the nerves in the gastrointestinal mucosa, they signal pain to the central nervous system. This happens when these nerves are exposed, as in peptic ulcers. The gastric acid may also reach ulcers in the esophagus or the duodenum.

Other mechanisms may contribute, such as the effect of aluminum ions inhibiting smooth muscle cell contraction and delaying gastric emptying.

Antacid therapy

Antacids are alkaline bases used to neutralize the excess gastric HCl associated with gastritis and peptic ulcers. It acts by two ways (i) by neutralizing of already secreted HCl and (ii) by inactivating of proteolytic enzyme e.g. – pepsin, which acts at lower pH to be said 1-2. As the secretion of gastric HCl is continuous basis so it takes continuous administration of antacid preparations.