<p>Sodium chloride is the major extracellular cation. It is important in electrolyte and fluid balance, osmotic pressure control and water distribution as it restores sodium ions. It is used as a source of electrolytes and water for hydration, treatment of metabolic acidosis, priming solution in haemodialysis and treatment of hyperosmolar diabetes. It is also used as diluents for infusion of compatible drug additives. Sodium bicarbonate raises blood and urinary pH by dissociation to provide bicarbonate ions, which neutralises the hydrogen ion concentration. It also neutralises gastric acid via production of carbon dioxide.</p>