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Drugs Dictionary: Calcium Carbonate

Calcium Carbonate

Trade Name

Tums, Rolaids (OTC antacids); generic calcium carbonate. Also in supplements (e.g., Os-Cal)

Classification

Antacid; calcium supplement; electrolyte

Dosage/Route

  • * Dosage:
    •      – Chewable tablets: 500 mg, 750 mg, 1000 mg (elemental calcium varies; e.g., 500 mg tablet = 200 mg Ca)
    •      – Tablets: 600 mg, 1250 mg
    •      – Suspension: 1250 mg/5 mL
  • * Route: Oral (PO)

Usual Dosage

  • * Antacid (Adults): 500-1000 mg PO PRN (every 2-4 hours); max 6-8 g/day short-term
  • * Calcium Supplement: 500-1500 mg elemental calcium/day (1-3 g CaCO₃) divided BID-TID
  • * Children: 45-65 mg/kg/day elemental Ca, divided doses
  • * With meals (supplement) or PRN (antacid)

Mechanism of Action

  • * Antacid: Neutralizes gastric acid (HCl) in the stomach, raising pH to relieve heartburn/indigestion
  • * Supplement: Provides elemental calcium for absorption in the small intestine, supporting bone health and correcting hypocalcemia; binds phosphate in CKD (less effective than calcium acetate)

Side Effects & Adverse Effects

  • * Side Effects: Constipation, bloating, gas, chalky taste
  • * Adverse Effects:
    •      – Hypercalcemia (rare, chronic overuse; thirst, confusion, kidney stones)
    •      – Milk-alkali syndrome (high doses with milk; nausea, alkalosis)
    •      – Rebound acid hypersecretion (after antacid effect wears off)

Nursing Management (Implications & Teachings)

  • * Implications:
    •      – Monitor calcium levels (normal 8.5-10.2 mg/dL) if supplement; GI symptoms (constipation)
    •      – Assess for hypercalcemia (EKG changes, lethargy) with prolonged use
    •      – Avoid with iron, tetracyclines (binds, reduces absorption—space 2 hr)
    •      – Chew tablets fully; shake suspension
  • * Teachings:
    •      – Antacid: Take PRN after meals or at symptom onset
    •      – Supplement: Take with meals (enhances absorption)
    •      – Report severe constipation, confusion, or flank pain
    •      – Increase fluids/fiber; limit if on dialysis (per MD)

Indication for This Patient

  • * Antacid: Heartburn, indigestion, acid reflux (GERD)
  • * Calcium supplement: Hypocalcemia, osteoporosis prevention/treatment, CKD phosphate binding (less common)

Time

  • * Timing:
    •      – Antacid: PRN, every 2-4 hr.
    •      – Supplement: BID-TID with meals.
  • * Onset: Antacid: minutes; Supplement: days-weeks for bone effect.
  • * Duration: Antacid: 1-3 hr; Supplement: ongoing

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