Pharmacology · Electrolytes and rehydration solutions

Sodium hydrogen carbonate !

Sodium bicarbonate: an alkali given IV to correct severe metabolic acidosis and to make the urine alkaline in some poisonings.

Updated 2026-11-01

Class: Electrolytes and rehydration solutions
Target: Hydrogen ions: bicarbonate buffer of blood and urine (no receptor)
ATC code: B05XA02
WHO Model List of Essential Medicines

Also called: Sodium bicarbonate

Mechanism of action

Bicarbonate combines with hydrogen ions to form carbonic acid, which breaks down into water and carbon dioxide that the lungs exhale. Blood pH rises. In the urine, bicarbonate makes the pH alkaline, which traps weak acids such as salicylates and some barbiturates in the urine (ion trapping) and speeds their elimination.

Bicarbonate binds hydrogen ions in the blood
Carbonic acid splits into water and CO₂, which is exhaled
Blood pH rises
Alkaline urine traps weak acids such as salicylates

Pharmacokinetics

Distribution: Spreads through the extracellular fluid
Elimination: The CO₂ formed is exhaled; extra bicarbonate is excreted by the kidneys
Onset and duration: Acts quickly when given IV

Indications

Severe metabolic acidosis, for example from kidney disease, shock or uncontrolled diabetes Chronic kidney disease →
Acidosis in circulatory shock or severe dehydration Hypovolaemic shock →
Poisoning by salicylates, methanol or barbiturates (urine alkalinisation)
Severe diarrhoea with bicarbonate loss

Adverse effects

Common

Metabolic alkalosis with muscle twitching and irritability
Fluid and sodium load (oedema)
Low potassium
Burning at the infusion site

Contraindications

Chloride loss from vomiting or continuous gastric suction
Diuretics that cause hypochloraemic alkalosis

Key interactions

Calcium-containing solutions: Precipitate or haze in the same line
Norepinephrine and dobutamine: Physically incompatible in the same solution
Salicylates: Alkaline urine increases their excretion (used in poisoning)

What is monitored

Arterial blood gases and pH
Sodium, potassium and calcium
Fluid balance and signs of overload
Infusion site

Administration and safety

Given IV; hypertonic solution is irritating: use a large, well-running vein and avoid extravasation, which causes necrosis.
Incompatible with calcium solutions, norepinephrine and dobutamine: flush the line before and after.
Correct low potassium and low calcium first or alongside, because rising pH lowers both.
In newborns and children under two, rapid injection of hypertonic bicarbonate can cause hypernatraemia and possible intracranial haemorrhage; follow the paediatric protocol.

Nursing care

Check blood gases before and after doses; report a rising pH or bicarbonate.
Watch for signs of alkalosis: twitching, tingling, cramps, slow breathing.
Monitor potassium, which falls as pH rises.
Check the IV site often; stop and report at the first sign of leakage.
Watch for oedema and breathlessness in heart or kidney failure.

Pregnancy and breastfeeding

Used when clearly needed; the sodium load and alkalosis are the concerns.

Test yourself

Think of the answer, then tap the question to see it.

How does sodium bicarbonate help in salicylate poisoning?

It makes the urine alkaline; salicylate, a weak acid, ionises in the urine and is trapped there, so the kidney excretes more of it.

Which IV drugs and solutions are incompatible with sodium bicarbonate?

Calcium-containing solutions (precipitate), and norepinephrine and dobutamine in the same solution.

Why is sodium bicarbonate contraindicated with vomiting or gastric suction?

These cause chloride loss and metabolic alkalosis; adding bicarbonate worsens the alkalosis.

Which electrolyte falls when bicarbonate raises the blood pH?

Potassium, which shifts into cells; ionised calcium also falls.

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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: DailyMed - SODIUM BICARBONATE- sodium bicarbonate injection, solution (DailyMed (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); eEML - Electronic Essential Medicines List (World Health Organization, 2025).

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