calcium gluconate

electrolyte· Brands: Calglucon, Gluconal, GenericIVPO

Mechanism of action

Calcium gluconate provides calcium ions that are essential for neuromuscular excitability, muscle contraction, blood coagulation, and bone formation. By increasing serum calcium levels, it reverses hypocalcemia and its associated symptoms. It stabilizes neuronal membranes and reduces permeability, thereby decreasing neuromuscular excitability and relieving manifestations such as tetany and seizures.

Pharmacokinetics

After intravenous administration, calcium is distributed throughout the body and about 40% is bound to plasma proteins. It is excreted primarily in urine, with less in feces. Oral absorption is variable and incomplete due to poor solubility and binding to intestinal anions; bioavailability is approximately 25-30%. Absorption is enhanced in an acid environment and by vitamin D. The onset of action is immediate after IV administration, and effects last several hours.

Indications & dosing

Hypocalcaemia (symptomatic)

Give 10% solution slowly over 5-10 min; monitor ECG.

adult · IV: 1–2 g may repeat · Give 10% solution slowly over 5-10 min; monitor ECG.

Hyperkalaemia with ECG changes

Use as adjunct; monitor ECG and potassium.

adult · IV: 1–2 g may repeat in 5 min · Use as adjunct; monitor ECG and potassium.

Hypermagnesaemia

Administer slowly; monitor serum magnesium.

adult · IV: 1–2 g may repeat · Administer slowly; monitor serum magnesium.

Calcium channel blocker overdose

Initial dose; consider infusion of 0.5 g/h after.

adult · IV: 1–2 g repeat as needed · Initial dose; consider infusion of 0.5 g/h after.

Hypocalcaemia (paediatric)

Use 10% solution; dilute for neonates.

pediatric · IV: 100–200 mg/kg may repeat · Use 10% solution; dilute for neonates.

Hypocalcaemia (neonatal)

Administer slowly with cardiac monitoring.

neonatal · IV: 100–200 mg/kg single dose · Administer slowly with cardiac monitoring.

Contraindications & precautions

Hypercalcemia · Calcium administration would worsen hypercalcemia.
Hypercalciuria or calcium-containing renal calculi · May increase urinary calcium and risk of stone formation.
Digitalis toxicity · Calcium enhances the cardiotoxic effects of digitalis.
Severe hyperphosphatemia · Risk of calcium phosphate precipitation in tissues.
Ensure correct concentration and rate for IV administration; avoid rapid infusion.
Monitor serum calcium and ECG during treatment, especially in patients on digoxin.
Avoid extravasation; use a large vein for IV administration.
Caution in patients with renal impairment due to altered calcium handling.
Do not mix with phosphate or bicarbonate solutions to avoid precipitation.

Adverse effects

Pain, burning, or irritation at injection site
Flushing and sensation of warmth
Nausea and vomiting
Cardiac arrhythmias (bradycardia, ectopy, ventricular fibrillation)serious
Extravasation causing tissue necrosisserious
Hypercalcemia (with rapid infusion or overdose)serious

Monitoring, pregnancy & toxicity

Serum calcium · before and during treatment
Serum potassium, magnesium and other electrolytes · at baseline and periodically
ECG · during IV administration, especially in hyperkalemia treatment
Injection site for extravasation · during IV infusion
Renal function · at baseline and periodically in prolonged therapy
Pregnancy: Calcium gluconate is safe in pregnancy when used for indicated conditions such as hypocalcemia, hyperkalemia, or magnesium toxicity. It is compatible with pregnancy; no dose adjustment is required. Use only if clearly needed.
Toxicity: Hypercalcemia: nausea, vomiting, weakness, polyuria, confusion, bradycardia or arrhythmias · Discontinue infusion; monitor cardiac rhythm; correct dehydration with IV fluids; consider loop diuretics, calcitonin, or bisphosphonates for severe hypercalcemia.
Toxicity: Extravasation causing tissue necrosis · Stop the infusion immediately; do not flush. Aspirate as much of the drug as possible; apply cold compresses and consider hyaluronidase, and consult a surgeon for severe injuries.
Toxicity: Rapid IV administration (especially in patients on digitalis) can cause hypotension, cardiac depression, or arrhythmias · Administer slowly and with continuous cardiac monitoring; reduce rate in patients receiving digoxin.

Clinical notes

Calcium gluconate is used for acute hypocalcemia, cardiac arrest with hyperkalemia, and as an antidote for magnesium sulfate toxicity or calcium channel blocker overdose. Intravenous administration must be slow to prevent cardiac arrhythmias; rapid infusion can cause bradycardia, hypotension, and arrhythmias. Extravasation can cause tissue necrosis; ensure proper catheter placement. Use caution in patients on digoxin, as hypercalcemia can precipitate digoxin toxicity. Oral calcium gluconate is used as a supplement when higher elemental calcium content is not required. Doses are adjusted based on serum calcium levels and clinical response.

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BNF; local formulary