CALCIUM GLUCONATE

Medical Diagnosis and Drugs, Medications

CALCIUM GLUCONATe

(gloo'koe-nate)

Classifications: fluid and electrolytic replacement solution;
Therapeutic: fluid and electrolyte replacement solution
Pregnancy Category: B

Availability

500 mg, 650 mg, 975 mg, 1 g tablets; 10% injection

Action

Calcium gluconate acts like digitalis on the heart, increasing cardiac muscle tone and force of systolic contractions (positive inotropic effect).

Therapeutic Effect

Rapidly and effectively restores serum calcium levels in acute hypocalcemia of various origins and effective as a cardiac stabilizer under conditions of hyperkalemia or resuscitation.

Uses

Negative calcium balance (as in neonatal tetany, hypoparathyroidism, vitamin D deficiency, alkalosis). Also to overcome cardiac toxicity of hyperkalemia, for cardiopulmonary resuscitation, to prevent hypocalcemia during transfusion of citrated blood. Also as antidote for magnesium sulfate, for acute symptoms of lead colic, to decrease capillary permeability in sensitivity reactions, and to relieve muscle cramps from insect bites or stings. Oral calcium may be used to maintain normal calcium balance during pregnancy, lactation, and childhood growth and to prevent primary osteoporosis. Also in osteoporosis, osteomalacia, chronic hypoparathyroidism, rickets, and as adjunct in treatment of myasthenia gravis and Eaton-Lambert syndrome.

Unlabeled Uses

To antagonize aminoglycoside-induced neuromuscular blockage, and as "calcium challenge" to diagnose Zollinger-Ellison syndrome and medullary thyroid carcinoma.

Contraindications

Ventricular fibrillation, metastatic bone disease, injection into myocardium; administration by SC or IM routes; renal calculi, hypercalcemia, predisposition to hypercalcemia (hyperparathyroidism, certain malignancies); digitalis toxicity.

Cautious Use

Digitalized patients, renal or cardiac insufficiency, arrhythmias; dehydration; diarrhea; hyperphosphatemia; sarcoidosis, history of lithiasis, immobilized patients; pregnancy (category B).

Route & Dosage

All doses are in terms of elemental calcium: 1 g calcium gluconate = 90 mg (4.5 mEq, 9.3%) elemental calcium

Supplement for Osteoporosis
Adult: PO 1–2 g b.i.d. to q.i.d. IV 7 mEq q1–3d
Child: PO 45–65 mg/kg/d in divided doses. IV 1–7 mEq q1–3d
Neonate: PO 50–130 mg/kg/d (max: 1 g)

Hypocalcemia
Adult: IV 2–15 g/d continuous or divided dose
Child: IV 200–500 mg/kg/d (max: 2–3 g/dose)
Neonate: IV Not more than 0.93 mEq

Hypocalcemic Tetany
Adult: IV 1–3 g prn
Child: IV 100–200 mg/kg/dose, may repeat q6–8h
Neonate: IV 200 mg followed by 500 mg/kg/d infusion

CPR
Adult: IV 2.3–3.7 mEq x 1

Hyperkalemia with Cardiac Toxicity
Adult: IV 500–800 mg (max dose: 3 g)

Exchange Transfusions with Citrated Blood
Adult: IV 500–1000 mg for each 500 mL of blood
Neonate: IV 98 mg for each 100 mL of blood

Administration

Oral

Ensure that chewable tablets are chewed or crushed before being swallowed with a liquid.
Give with meals to enhance absorption.

Intravenous

PREPARE: Direct: May be given undiluted. Intermittent/Continuous: May be diluted in 1000 mL of NS.

ADMINISTER: Direct: Give direct IV at a rate of 0.5 mL or a fraction thereof over 1 min. Do not exceed 2 mL/min. Intermittent/Continuous: Give slowly, not to exceed 200 mg/min for adults or 100 mg/min for children. Use a small-bore needle into a large vein to avoid possibility of extravasation and resultant necrosis. With children, scalp veins should be avoided. Avoid rapid infusion. High concentrations of calcium suddenly reaching the heart can cause fatal cardiac arrest.

INCOMPATIBILITIES Solution/additive: Amphotericin B, cefamandole, dobutamine, methylprednisolone, metoclopramide, concentration-dependent incompatibility with other electrolytes. Y-site: Amphotericin B cholesteryl complex, fluconazole, indomethacin, lansoprazole, meropenem.

Injection should be stopped if patient complains of any discomfort.
Patient should be advised to remain in bed for 15–30 min or more following injection, depending on response.

Adverse Effects (≥1%)

Body as a Whole: Tingling sensation. With rapid IV, sensations of heat waves (peripheral vasodilation), fainting. GI: PO preparation: Constipation, increased gastric acid secretion. CV: (With rapid infusion) hypotension, bradycardia, cardiac arrhythmias, cardiac arrest. Skin: Pain and burning at IV site, severe venous thrombosis, necrosis and sloughing (with extravasation).

Diagnostic Test Interference

IV calcium may cause false decreases in serum and urine magnesium (by Titan yellow method) and transient elevations of plasma 11-OHCS levels by Glenn-Nelson technique. Values usually return to control levels after 60 min; urinary steroid values (17-OHCS) may be decreased.

Interactions

Drug: May enhance inotropic and toxic effects of digoxin; magnesium may compete for GI absorption; decreases absorption of tetracyclines, quinolones (ciprofloxacin); antagonizes the effects of verapamil and possibly other calcium channel blockers (IV administration).

Pharmacokinetics

Absorption: 30% from small intestine. Onset: Immediately after IV. Distribution: Crosses placenta. Elimination: Primarily in feces; small amounts in urine, pancreatic juice, saliva, and breast milk.

Nursing Implications

Assessment & Drug Effects

Assess for cutaneous burning sensations and peripheral vasodilation, with moderate fall in BP, during direct IV injection.
Monitor ECG during IV administration to detect evidence of hypercalcemia: decreased QT interval associated with inverted T wave.
Observe IV site closely. Extravasation may result in tissue irritation and necrosis.
Monitor for hypocalcemia and hypercalcemia (see Signs & Symptoms, Appendix F).
Lab tests: Determine levels of calcium and phosphorus (tend to vary inversely) and magnesium frequently, during sustained therapy. Deficiencies in other ions, particularly magnesium, frequently coexist with calcium ion depletion.

Patient & Family Education

Report S&S of hypercalcemia (see Appendix F) promptly to your care provider.
Milk and milk products are the best sources of calcium (and phosphorus). Other good sources include dark green vegetables, soy beans, tofu, and canned fish with bones.
Calcium absorption can be inhibited by zinc-rich foods: nuts, seeds, sprouts, legumes, soy products (tofu).
Check with physician before self-medicating with a calcium supplement.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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