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Drug Reference

sodium bicarbonate

Alkalinising agent· Brands: Sodibicarb, BrioschiIVPO

Mechanism of action
Sodium bicarbonate is a weak base that dissociates into sodium and bicarbonate ions. The bicarbonate ion buffers hydrogen ions to form carbonic acid, which then dissociates into water and carbon dioxide. This raises blood pH and shifts the oxyhaemoglobin dissociation curve. In the urine, increased filtered bicarbonate alkalinises the urine, which can trap weak acids and reduce their reabsorption. In hyperkalaemia, alkalinisation drives potassium into cells. In poisoning with weak acids such as salicylates or tricyclic antidepressants, serum alkalinisation reduces tissue penetration of the toxin.
Pharmacokinetics
After intravenous administration, bicarbonate acts within seconds to minutes. Oral doses neutralise gastric acid and are absorbed from the gastrointestinal tract; unabsorbed bicarbonate is excreted in faeces. Bicarbonate distributes throughout the extracellular fluid. It is not metabolised in the liver. The kidneys regulate bicarbonate balance, filtering bicarbonate and reabsorbing most of it in the proximal tubule. When plasma bicarbonate exceeds the renal threshold, excess is excreted in urine. The apparent half-life is not well defined because bicarbonate is integral to normal acid-base homeostasis. Duration of effect depends on the underlying acid-base disorder, renal function, and ongoing acid production.
Indications & dosing

Severe metabolic acidosis (adult)

Dose guided by base deficit and arterial blood gases. Avoid routine use in lactic acidosis or ketoacidosis unless pH is severely reduced, as overcorrection can cause alkalosis, hypokalaemia and hypernatraemia.

  • adult · IV: 1–2 mEq/kg once, then titrate · Dose guided by base deficit and arterial blood gases. Avoid routine use in lactic acidosis or ketoacidosis unless pH is severely reduced, as overcorrection can cause alkalosis, hypokalaemia and hypernatraemia.

Cardiac arrest with documented severe metabolic acidosisoff-label

Not recommended routinely during cardiac arrest. Use only when severe metabolic acidosis is confirmed, with close monitoring of pH, sodium and potassium.

  • adult · IV: 1 mEq/kg single dose · Not recommended routinely during cardiac arrest. Use only when severe metabolic acidosis is confirmed, with close monitoring of pH, sodium and potassium.

Hyperkalaemia with metabolic acidosisoff-label

Give over 5 to 10 minutes with cardiac monitoring. Onset is slow and effect is transient; do not use as sole treatment for life-threatening hyperkalaemia.

  • adult · IV: 50 mEq single dose · Give over 5 to 10 minutes with cardiac monitoring. Onset is slow and effect is transient; do not use as sole treatment for life-threatening hyperkalaemia.

Tricyclic antidepressant toxicity with sodium channel blockadeoff-label

Target serum pH 7.45 to 7.55. Monitor for alkalosis, hypokalaemia and hypernatraemia. Ensure adequate ventilation before giving bicarbonate.

  • adult · IV: 1–2 mEq/kg bolus, repeat PRN · Target serum pH 7.45 to 7.55. Monitor for alkalosis, hypokalaemia and hypernatraemia. Ensure adequate ventilation before giving bicarbonate.

Urinary alkalinisation (e.g. salicylate poisoning, cystine stones)off-label

Dose adjusted to maintain urine pH above 7.0. Monitor serum pH, potassium and sodium. Correct hypokalaemia before alkalinisation to avoid paradoxical aciduria.

  • adult · PO: 650–1300 mg q4-6h · Dose adjusted to maintain urine pH above 7.0. Monitor serum pH, potassium and sodium. Correct hypokalaemia before alkalinisation to avoid paradoxical aciduria.

Chronic metabolic acidosis in chronic kidney disease

Titrate to normalise serum bicarbonate. Monitor for sodium overload, hypertension and oedema. Avoid in patients with volume overload or severe heart failure.

  • adult · PO: 650–1300 mg 1-2 times daily · Titrate to normalise serum bicarbonate. Monitor for sodium overload, hypertension and oedema. Avoid in patients with volume overload or severe heart failure.

Salicylate toxicity (adjunct to urinary alkalinisation)off-label

Used to alkalinise serum and urine. Ensure adequate potassium before and during therapy. Monitor serum pH, potassium and sodium closely.

  • adult · IV: 1–2 mEq/kg bolus then infusion · Used to alkalinise serum and urine. Ensure adequate potassium before and during therapy. Monitor serum pH, potassium and sodium closely.
Contraindications & precautions
  • Metabolic or respiratory alkalosis · Giving bicarbonate in an already alkalotic patient worsens alkalosis and can precipitate arrhythmias, seizures and reduced tissue oxygen delivery.
  • Hypocalcaemia · Alkalinisation lowers ionised calcium and may precipitate tetany, carpopedal spasm or seizures. Correct calcium first or use with close monitoring.
  • Hypernatraemia or sodium-retaining states such as heart failure, oedema and severe hypertension · Each dose delivers a substantial sodium load, which can worsen fluid overload and blood pressure control. Consider alternative alkalinising strategies.
  • Hypokalaemia · Alkalinisation shifts potassium into cells and can worsen hypokalaemia, predisposing to arrhythmias. Correct potassium before or during use.
  • Severe renal impairment with oliguria or anuria · Reduced ability to excrete the bicarbonate and sodium load increases the risk of alkalosis, hypernatraemia and volume overload.
  • Respiratory acidosis with inadequate ventilation · Bicarbonate generates carbon dioxide; without adequate alveolar ventilation this worsens hypercapnia. Ensure ventilation is supported first.
  • Do not mix or infuse through the same line as calcium-containing solutions, as calcium carbonate precipitate can form and occlude the line or embolise.
  • Monitor blood gases, sodium, potassium, calcium and renal function during therapy; adjust or stop treatment if alkalosis, hypernatraemia or hypokalaemia develops.
  • Use with caution in heart failure, renal impairment, hypertension and any sodium-restricted diet because the sodium load can worsen oedema and fluid overload.
  • In respiratory acidosis, ensure adequate ventilation is established before giving bicarbonate, as carbon dioxide generated may worsen hypercapnia.
  • Give intravenous doses into a large, patent vein and check for extravasation regularly; stop immediately if infiltration occurs to limit tissue necrosis.
  • Avoid routine use in cardiac arrest and in neonates except on specialist advice; follow current resuscitation and local formulary guidance.
Adverse effects
  • Metabolic alkalosisserious
  • Hypernatraemiaserious
  • Hypokalaemiaserious
  • Hypocalcaemia with tetany or carpopedal spasmserious
  • Hypercapnia and hypoventilation, particularly in respiratory failureserious
  • Fluid overload and pulmonary oedema from the sodium loadserious
  • Extravasation injury with tissue necrosis after intravenous administrationserious
  • Intracranial haemorrhage in neonates after rapid hypertonic intravenous infusionserious
  • Nausea, vomiting, bloating and belching after oral doses
  • Gastric distension and flatulence from carbon dioxide release in the stomach
Renal & hepatic adjustment
  • eGFR 0+: No specific eGFR-based dose reduction; titrate to serum bicarbonate and arterial pH. Use with caution in renal impairment because the sodium load may cause volume overload, hypertension, or metabolic alkalosis. Avoid in severe renal failure with oliguria or heart failure unless clearly indicated.
Monitoring, pregnancy & toxicity
  • Serum bicarbonate · Baseline and 30 to 60 minutes after IV dose, then at least daily during continuous therapy.
  • Arterial blood gases (pH, pCO2) · Baseline and after each dose or as clinically indicated; more frequently in critical illness.
  • Serum electrolytes (sodium, potassium, calcium, magnesium) · Baseline and at least daily; more often with IV therapy or renal impairment.
  • Fluid balance and weight · Daily during therapy to detect sodium and water retention.
  • Blood pressure · Monitor regularly, especially in patients with hypertension or heart failure.
  • Urine pH · If used for urinary alkalinisation, check each void or as per protocol; target pH 7.0 to 8.0 depending on indication.
  • Pregnancy: Use only when clearly indicated for severe metabolic acidosis, hyperkalaemia, or specific poisonings. No evidence of teratogenicity, but sodium load may exacerbate fluid retention and hypertension. Monitor maternal acid-base status and electrolytes closely.
  • Toxicity: Metabolic alkalosis: nausea, vomiting, confusion, tetany, seizures. · Stop sodium bicarbonate, correct underlying cause, and consider acetazolamide or dialysis if severe.
  • Toxicity: Hypernatraemia and volume overload: hypertension, oedema, pulmonary oedema. · Stop bicarbonate, restrict sodium, and use diuretics if appropriate.
  • Toxicity: Hypokalaemia: muscle weakness, arrhythmias. · Monitor serum potassium and replace as needed.
  • Toxicity: Hypocalcaemia: tetany, paraesthesia, seizures. · Monitor calcium and replace if symptomatic.
Clinical notes
Sodium bicarbonate is used for severe metabolic acidosis, such as that caused by shock, renal failure, diabetic ketoacidosis, or poisoning with tricyclic antidepressants or salicylates. It is also used for hyperkalaemia and for urinary alkalinisation. It is not indicated for respiratory acidosis unless there is a concurrent metabolic acidosis. Risks include metabolic alkalosis, hypernatraemia, hypokalaemia, hypocalcaemia, and paradoxical intracellular acidosis. It can generate carbon dioxide, which may worsen respiratory acidosis if ventilation is inadequate. Avoid in chloride-responsive metabolic alkalosis, hypocalcaemia, and severe sodium overload. It should be used with caution in heart failure, renal impairment, and hypertension because of the sodium load. Doses vary widely by indication; for teaching, IV 50 to 100 mmol of an 8.4% solution may be given slowly in cardiac arrest, and oral 1 to 2 g every 4 to 6 hours may be used for urinary alkalinisation, but these examples must be checked against local protocols and formularies. Monitor blood gases, electrolytes, and fluid balance.

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BNF; local formulary; UK Renal Association guidelines; product SPC; advanced life support guidelines