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# Calcium Gluconate ## Overview Calcium gluconate is an inorganic salt of calcium used to treat or prevent calcium deficiencies. It is available in oral and intravenous (IV) formulations. ## Primary Indications * Treatment and prevention of hypocalcemia. * Adjunctive treatment in acute hyperkalemia to stabilize cardiac membranes. * Management of acute hypomagnesemia. * Treatment of fluoride poisoning. * As an antidote for magnesium sulfate overdose. ## Adult Dosing * **Hypocalcemia:** * **Oral:** 1 to 2 grams of elemental calcium (corresponding to approximately 980 mg to 1960 mg of calcium gluconate; 10% elemental calcium by weight) every 6 hours. Maximum dose not established, but typically guided by serum calcium levels. * **IV:** 2 to 3 grams of calcium gluconate (200-300 mg elemental calcium) administered slowly over 10-20 minutes. May be repeated every 6 hours as needed. Higher doses may be required in severe cases, administered via continuous infusion at a rate of 1-2 grams per hour, but this requires close cardiovascular monitoring. * **Hyperkalemia (cardiac membrane stabilization):** 1 to 3 grams of calcium gluconate (100-300 mg elemental calcium) IV over 5-10 minutes. *Note: This does not lower potassium levels but prevents cardiac arrhythmias.* * **Hypomagnesemia:** 1 to 2 grams of calcium gluconate (100-200 mg elemental calcium) IV administered slowly or as an infusion. * **Fluoride Poisoning:** 1 to 2 grams of calcium gluconate PO every 4-6 hours, or 1 gram IV every 4-6 hours. ## Pediatric Dosing * **Hypocalcemia:** * **Oral:** 45-65 mg/kg/day of elemental calcium (corresponding to 450-650 mg/kg/day of calcium gluconate) in divided doses every 6 hours. * **IV:** 100-200 mg/kg/day of elemental calcium (corresponding to 1000-2000 mg/kg/day of calcium gluconate) divided into 4-6 doses, administered slowly. Maximum infusion rate for newborns is 50 mg/kg/hour (2.5 mL/kg/hour of a 10% solution). In older children, a rate of 10-20 mg/kg/minute is generally safe. Maximum daily dose not established. * **Hyperkalemia (cardiac membrane stabilization):** 50-100 mg/kg (0.5-1 mL/kg of a 10% solution) IV over 5-10 minutes. Maximum dose 3 grams. ## Dose Adjustments No dose adjustments are generally recommended based on renal or hepatic impairment, however, caution is advised in moderate to severe renal impairment due to potential for hypercalcemia. ## Contraindications * Hypercalcemia. * History of calcium nephrolithiasis or renal osteodystrophy. * Ventricular fibrillation. * Use of cardiac glycosides (e.g., digoxin) in patients with hypercalcemia. ## Adverse Effects * **IV:** Hypotension, bradycardia, arrhythmias, peripheral vasodilation, tissue calcification and necrosis (if extravasation occurs), burning sensation, warmth. * **Oral:** Constipation, nausea, vomiting, abdominal pain. * Hypercalcemia can lead to confusion, lethargy, anorexia, polyuria, polydipsia, and cardiac abnormalities. ## Key Drug Interactions * **Tetracyclines and Fluoroquinolones:** Calcium gluconate can reduce the absorption of these antibiotics. Separate administration by at least 2 hours before or 4-6 hours after calcium. * **Bisphosphonates:** Reduced absorption of bisphosphonates. Separate administration by at least 2 hours before or after calcium. * **Thyroid Hormones (Levothyroxine):** Reduced absorption of levothyroxine. Separate administration by at least 4 hours. * **Cardiac Glycosides (Digoxin):** Increased risk of cardiotoxicity, especially in the presence of hypercalcemia. * **Thiazide Diuretics:** Increased risk of hypercalcemia. * **Calcium Channel Blockers:** May potentially antagonize the effects of calcium channel blockers. ## Monitoring * Serum calcium levels (total and ionized). * Electrolytes (potassium, magnesium, phosphate). * Renal function (BUN, creatinine). * Cardiac rhythm (especially with IV administration or in patients with cardiac disease). * Signs and symptoms of hypercalcemia. ## Clinical Pearls * IV calcium gluconate should be administered slowly to avoid hypotension and cardiac arrhythmias. Rates exceeding 10-20 mg/kg/minute in children and 100 mg/minute in adults can cause syncope and cardiac arrest. * IV calcium gluconate is pH neutral and can be infused peripherally; however, it is less potent than calcium chloride. Calcium chloride is preferred for emergent hypocalcemia and larger calcium replacement due to higher elemental calcium content and potency. * Extravasation of IV calcium gluconate can cause tissue irritation and necrosis; infiltrate the area with normal saline and consider hyaluronidase if extravasation occurs. * Oral calcium supplements should be taken with meals to enhance absorption. *** *Disclaimer: This information is for educational purposes only and does not substitute for professional medical advice. Always consult the most current prescribing information and guidelines from a healthcare professional before making any decisions related to patient care.*