Pharmacology: Sodium bicarbonate acts as urinary alkaliser by increasing the excretion of free bicarbonate ions in the urine, thus effectively raising the urinary pH. By maintaining an alkaline urine, the actual dissolution of uric acid stones may be accomplished. It also acts as an antacid by chemically neutralizing or buffering existing quantities of stomach acid but has no direct effect in its output. This action results in increased pH value of stomach contents, thus providing relief of hyperacidity symptoms.
Sodium Citrate and Citric Acid: Sodium citrate is metabolized to bicarbonates which increases urinary pH by increasing the excretion of free bicarbonate ions without producing systemic alkalosis when administered in recommended doses. A rise in urinary pH increases the solubility of cystine in the urine and the ionization of uric acid to more soluble urate ion. By maintaining an alkaline urine, the actual dissolution of uric acid stones may be accomplished. It also reacts chemically to neutralize or buffer existing quantities of gastric hydrochloric acid but has no direct effects in its output. Sodium bicarbonate is excreted through renal and also via lungs by forming CO2. Sodium citrate, citric acid and absorbed tartaric acid are excreted through the urine.