1. Clinical Overview
Disodium Hydrogen Citrate is an oral systemic alkalizer and urinary alkalinizing agent. It is a sodium salt of citric acid that, upon metabolism, increases the plasma bicarbonate concentration, buffers excess hydrogen ion concentration, raises blood pH, and reverses metabolic acidosis. It also alkalinizes urine, increasing the solubility of uric acid and cystine, thereby preventing crystal formation and aiding in the dissolution of existing stones. It is a cornerstone therapy for metabolic acidosis and urinary stone prophylaxis in the Indian clinical setting.
| Onset | Duration | Bioavailability |
|---|---|---|
| Within 30-60 minutes after oral administration. | Approximately 3-6 hours, depending on renal function and dose. | Not applicable in the conventional sense as it is an electrolyte/alkalizer. The citrate ion is readily absorbed from the gastrointestinal tract. |
2. Mechanism of Action
Disodium Hydrogen Citrate acts as a systemic and urinary alkalinizer. After oral administration, the citrate anion is absorbed and metabolized in the liver to bicarbonate (HCO3-). This generated bicarbonate enters the systemic circulation, where it acts as a buffer, neutralizing excess hydrogen ions (H+) and raising the blood pH, thereby correcting metabolic acidosis. In the kidneys, the increased bicarbonate load leads to enhanced urinary excretion of bicarbonate, raising the urinary pH. A higher urinary pH increases the ionization and solubility of uric acid and cystine, preventing their crystallization and promoting the dissolution of existing stones.
3. Indications & Uses
- Chronic Metabolic Acidosis (e.g., in Renal Tubular Acidosis)
- Prophylaxis and Treatment of Uric Acid and Cystine Renal Stones
- Urinary Alkalinization during therapy with sulfonamides or methotrexate to prevent crystalluria
4. Dosage & Administration
Adult Dosage: 10-20 ml (3.06 - 6.12 gm) diluted in a glass of water, 3-4 times daily. Dose must be individualized based on urinary pH (target 6.5-7.5) and clinical response.
Administration: Must be diluted in a full glass of water (at least 120-240 ml) before ingestion to minimize GI upset and ensure proper absorption. Administer after meals. Monitor urinary pH with pH strips to titrate dose to target range (6.5-7.5).
5. Side Effects
Common side effects may include:
- Nausea, abdominal discomfort
- Diarrhea or loose stools (osmotic effect)
- Alkaline taste
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Potassium-Sparing Diuretics (Amiloride, Spironolactone) | Increased risk of severe hyperkalemia due to combined effect of reduced potassium excretion and alkalinization. | Major |
| Lithium | Increased urinary pH can decrease renal lithium clearance, leading to increased lithium levels and toxicity. | Major |
| Methenamine (Hexamine) | Urinary alkalinization inactivates methenamine, which requires acidic urine for its antibacterial effect. | Major |
| Quinidine, Flecainide | Alkalinization of urine can decrease renal excretion of these drugs, potentially increasing their plasma levels and toxicity. | Moderate |
| Salicylates (Aspirin) | Alkalinization increases renal excretion of salicylates, reducing their plasma levels. Used therapeutically in overdose. | Moderate |
| Anticholinergics | May enhance GI absorption of citrate due to delayed gastric emptying. | Minor |
7. Patient Counselling
- DO dilute the syrup in a full glass of water before drinking.
- DO take after meals to reduce stomach upset.
- DO monitor your urinary pH with the test strips provided by your doctor, as instructed.
- DO inform all your doctors and your dentist that you are taking this medicine.
- DO maintain adequate fluid intake (2-3 liters per day unless contraindicated).
- DON'T take it undiluted.
- DON'T take antacids containing sodium bicarbonate or calcium carbonate concurrently without consulting your doctor.
- DON'T use salt substitutes (often high in potassium) without medical advice.
8. Toxicology & Storage
Overdose: Signs of severe metabolic alkalosis (tetany, neuromuscular excitability, confusion, seizures), hypernatremia (intense thirst, fever, tachycardia, hypertension, pulmonary edema), and hypokalemia (muscle weakness, paralysis, cardiac arrhythmias).
Storage: Store at room temperature (15-30°C), protected from light and moisture. Keep the bottle tightly closed. Keep out of reach of children. Do not freeze. Discard any unused medicine after the expiry date.