Calcium gluconate is a pharmaceutical agent used to restore and maintain the body’s calcium balance. It is a common form of calcium supplementation, available in both injectable and oral forms for various medical needs. It provides a reliable source of calcium, an element necessary for numerous physiological functions. Calcium gluconate is recognized on the World Health Organization’s List of Essential Medicines.
Chemical Structure and Role
Calcium gluconate is chemically defined as the calcium salt of gluconic acid, which is an oxidized product of glucose. The structure involves a calcium atom bound to two gluconate molecules, allowing the gluconate to act as a carrier molecule that delivers the calcium into the body.
When used as a 10% solution, calcium gluconate contains approximately 93 milligrams of elemental calcium per 10 milliliters. This relatively lower concentration, compared to other salts like calcium chloride, makes it less irritating to blood vessels. The lower irritation risk is why calcium gluconate is often the preferred choice for intravenous administration, especially through peripheral veins.
Acute and Critical Medical Uses
The most critical applications of calcium gluconate involve stabilizing patients in emergency situations where electrolyte imbalances pose a serious threat to heart function. Intravenous calcium gluconate is the standard treatment for severe, symptomatic hypocalcemia, a condition characterized by dangerously low blood calcium levels. This intervention quickly replenishes the calcium ions needed for normal nerve and muscle function, preventing symptoms like muscle spasms and seizures.
Calcium gluconate also serves as an antidote for specific types of toxicity. It counteracts hypermagnesemia, where calcium ions competitively inhibit excessive magnesium at neuromuscular junctions. It also treats hydrofluoric acid (HF) burns, where a topical gel binds to toxic fluoride ions, preventing deep tissue damage. Furthermore, it stabilizes the heart’s electrical activity in cases of hyperkalemia (dangerously high potassium levels) by reducing the excitability of cardiac cells.
Oral Supplementation and Deficiency Treatment
Beyond emergency care, calcium gluconate is prescribed in oral forms, such as tablets or liquids, for the long-term management of calcium deficiencies. This includes treating chronic conditions like mild hypocalcemia resulting from vitamin D deficiency or parathyroid disorders. The oral route is suitable for maintenance therapy and general dietary supplementation when the diet is insufficient.
The supplemental use of calcium gluconate supports bone health, helping to prevent or manage osteoporosis and rickets, and maintains proper nervous system function. The oral form is absorbed more slowly than the intravenous solution, making it ideal for sustained, non-urgent calcium repletion.
Administration Methods and Safety Profile
Calcium gluconate is administered either intravenously (IV) or by mouth, depending on the patient’s condition and the urgency of the need for calcium. The IV route is reserved for acute, severe conditions and is typically given as a slow infusion into a vein. Careful monitoring of the patient’s heart rate and electrocardiogram (ECG) is necessary during IV administration because rapid injection can lead to a dangerously slow heart rate or cardiac arrhythmia.
If the IV solution leaks out of the vein into the surrounding tissue (extravasation), it can cause local irritation and tissue damage, although the risk is lower than with calcium chloride. Oral calcium gluconate is taken with water and may cause mild digestive side effects like upset stomach, nausea, or constipation. A serious contraindication is in patients simultaneously taking the heart medication digoxin, as the combination increases the risk of severe cardiac arrhythmias.