Neutralization reaction is between acid and base results in the formation of salt and water. Antacids are used to decrease the acidity of stomach. Antacids not only decrease HCL concentration but also cause inactivation of pepsin which is proteolytic enzyme and require pH of 4 for the conversion but when there is decrease hydrochloric acid secretion there will be less of the pepsin present. Efficiency of an antacid is determined by its capacity to neutralize HCL and whether the stomach is full or not. Commonly used antacid are combination of magnesium hydroxide and aluminum hydroxide, aluminum cause constipation whereas magnesium causes the diarrhea by relaxing smooth muscles of GI tract and induction of smooth muscles plus increase secretion of water respectively, so nullify each other's effect when used in combination. Calcium carbonate is also used it cause the production of carbon dioxide. Sodium bicarbonate cause Transient metabolic alkalosis because of increase HCO-3 ions. Magnesium, calcium and aluminum can cause toxicity in renal impaired patients. Antacids are use in symptomatic relief of GERD and peptic ulcer, also help in the healing of duodenal ulcer.
