Apo-Cal , BioCal, Calcite-500, Calsan , Cal-Sup, Caltrate , Chooz, Dicarbosil, Equilet, Mallamint, Mega-Cal, Nu-Cal, Os-Cal, Oystercal, Titralac, Tums
Classifications: fluid and electrolytic replacement solution; antacid;
Therapeutic: fluid and electrolytic replacement solution
; antacid
Prototype: Calcium gluconate
Pregnancy Category: B for calcium acetate; other salts not rated


Calcium carbonate: 125 mg, 250 mg, 650 mg, 750 mg, 1.25 g, 1.5 g tablets;

Calcium acetate: 667 mg tablets;

Calcium citrate: 950 mg, 2376 mg tablets;

Calcium phosphate tribasic: 1565.2 mg tablets


Calcium carbonate is a rapid-acting antacid with high neutralizing capacity and relatively prolonged duration of action. Decreases gastric acidity, thereby inhibiting proteolytic action of pepsin on gastric mucosa. All forms of calcium salts are used for calcium replacement therapy.

Therapeutic Effect

Effectively relieves symptoms of acid indigestion and useful as a calcium supplement.


Relief of transient symptoms of hyperacidity as in acid indigestion, heartburn, peptic esophagitis, and hiatal hernia. Also used as calcium supplement when calcium intake may be inadequate and in treatment of mild calcium deficiency states. Control of hyperphosphatemia in chronic renal failure (calcium acetate).

Unlabeled Uses

For treatment of hyperphosphatemia in patients with chronic renal failure and to lower BP in selected patients with hypertension.


Hypercalcemia and hypercalciuria (e.g., hyperparathyroidism, vitamin D overdosage, decalcifying tumors, bone metastases), calcium loss due to immobilization, severe renal failure, renal calculi, GI hemorrhage or obstruction, dehydration, digitalis toxicity; hypochloremic alkalosis, ventricular fibrillation, cardiac disease, pregnancy (category B).

Cautious Use

Decreased bowel motility (e.g., with anticholinergics, antidiarrheals, antispasmodics), the older adult.

Route & Dosage

All doses are in terms of elemental calcium: 1 g calcium carbonate = 400 mg (20 mEq, 40%) elemental calcium; 1 g calcium acetate = 250 mg (12.6 mEq, 25%) elemental calcium; 1 g calcium citrate = 210 mg (12 mEq, 21%) elemental calcium; 1 g tricalcium phosphate = 390 mg (19.3 mEq, 39%) elemental calcium ; calcium lactate = 130 mg (6.5 mEq, 13%) elemental calcium

Supplement for Osteoporosis
Adult: PO 1–2 g b.i.d. or t.i.d.

Adult: PO 0.5–2 g 4–6 times/d

Adult: PO Calcium acetate 2–4 tablets with each meal

Supplement for Mild Hypercalcemia
Child: PO 500 mg/kg/d in divided doses (lactate)


  • When used as antacid, give 1 h after meals and at bedtime. When used as calcium supplement, give 1–1 ? h after meals, unless otherwise directed by physician.
  • Chewable tablet should be chewed well before swallowing or allowed to dissolve completely in mouth, followed with water. Powder form may be mixed with water.
  • Ensure that sustained-release form of drug is not chewed or crushed. It must be swallowed whole.

Adverse Effects (≥1%)

GI: Constipation or laxative effect, acid rebound, nausea, eructation, flatulence, vomiting, fecal concretions. Metabolic: Hypercalcemia with alkalosis, metastatic calcinosis, hypercalciuria, hypomagnesemia, hypophosphatemia (when phosphate intake is low). CNS: Mood and mental changes. Urogenital: Polyuria, renal calculi.


Drug: May enhance inotropic and toxic effects of digoxin; magnesium may compete for GI absorption; decreases absorption of tetracyclines, quinolones (ciprofloxacin).


Absorption: Approximately 1/3 of dose absorbed from small intestine. Distribution: Crosses placenta. Elimination: Primarily in feces; small amounts in urine, pancreatic juice, saliva, breast milk.

Nursing Implications

Assessment & Drug Effects

  • Note number and consistency of stools. If constipation is a problem, physician may prescribe alternate or combination therapy with a magnesium antacid or advise patient to take a laxative or stool softener as necessary.
  • Lab tests: Determine serum and urine calcium weekly in patients receiving prolonged therapy and in patients with renal dysfunction.
  • Record amelioration of symptoms of hypocalcemia (see Signs & Symptoms, Appendix F).
  • Observe for S&S of hypercalcemia in patients receiving frequent or high doses, or who have impaired renal function (see Appendix F).

Patient & Family Education

  • Do not continue this medication beyond 1–2 wk, since it may cause acid rebound, which generally occurs after repeated use for 1 or 2 wk and leads to chronic use. It is potentially dangerous to self-medicate. Do not take antacids longer than 2 wk without medical supervision.
  • Avoid taking calcium carbonate with cereals or other foods high in oxalates. Oxalates combine with calcium carbonate to form insoluble, nonabsorbable compounds.
  • Do not use calcium carbonate repeatedly with foods high in vitamin D (such as milk) or sodium bicarbonate, as it may cause milk-alkali syndrome: hypercalcemia, distaste for food, headache, confusion, nausea, vomiting, abdominal pain, metabolic alkalosis, hypercalciuria, polyuria, soft tissue calcification (calcinosis), hyperphosphatemia and renal insufficiency. Predisposing factors include renal dysfunction, dehydration, electrolyte imbalance, and hypertension.

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

© 2006-2023 Last Updated On: 02/01/2023 (0)
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