calcium carbonate

Essential for nervous, muscular, and skeletal systems.
Maintain cell membrane and capillary permeability.
Act as an activator in the transmission of nerve impulses and contraction of cardiac, skeletal, and smooth muscle.
Essential for bone formation and blood coagulation.

Therapeutic effects:

Replacement of calcium in deficiency states. Control of hyperphosphatemia in end-stage renal disease without promoting aluminum absorption.

Pharmacokinetics ⬆ ⬇

Absorption: Absorption from the GI tract requires vitamin D.

Distribution: Readily enters extracellular fluid.

Metabolism/Excretion: Excreted mostly in the feces; 20% eliminated by the kidneys.

Half-Life: Unknown.

Time/Action Profile ⬆ ⬇

(effects on serum calcium)

ROUTE	ONSET	PEAK	DURATION
PO	unknown	unknown	unknown
IV	immediate	immediate	0.5–2 hr

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Hypercalcemia;
Renal calculi;
Ventricular fibrillation.

Use Cautiously in:

Severe respiratory disease;
Renal impairment;
Cardiac disease.

Adv. Reactions/Side Effects ⬆ ⬇

CV: arrhythmias, bradycardia

GI: constipation, nausea, vomiting

GU: calculi, hypercalciuria

Neuro: headache

Interactions ⬆ ⬇

Drug-drug:

Hypercalcemia ↑ risk of digoxin toxicity.
Chronic use with antacids in renal impairment may lead to milk-alkali syndrome.
Ingestion by mouth ↓ absorption of orally administered tetracyclines, fluoroquinolones, phenytoin, and iron salts.
Excessive amounts may ↓ effects of calcium channel blockers.
May ↓ absorption of risedronate; do not take within 2 hr of calcium supplements.
May ↓ effectiveness of atenolol.
Thiazide diuretics may ↑ risk of hypercalcemia.
May ↓ effectiveness of sodium polystyrene sulfonate.

Drug-Food:

Cereals, spinach, or rhubarb may ↓ absorption of calcium supplements.

Route/Dosage ⬆ ⬇

1 g of calcium carbonate contains 400 mg of elemental calcium (20 mEq of calcium).
PO (Adults ): Prevention of hypocalcemia, treatment of depletion, osteoporosis: 500–4,000 mg/day (as calcium carbonate) in 1–3 divided doses. Antacid: 500–1,250 mg (as calcium carbonate) as needed. Hyperphosphatemia in end-stage renal disease : 500 mg (as calcium carbonate) with each meal; adjust dose every 2–3 wk, as needed, based on serum phosphorus concentrations.
PO (Children ): Supplementation: 30–75 mg/kg/day (as elemental calcium) in 4 divided doses.

Availability ⬆ ⬇

Capsules: 1.25 g (500 mg Ca)^OTC
Chewable tablets: 350 mg (300 mg Ca)^OTC; 420 mg (168 mg Ca)^OTC; 450 mg ^OTC; 500 mg (200 mg Ca)^OTC; 750 mg (300 mg Ca)^OTC; 1 g (400 mg Ca)^OTC; 1.25 g (500 mg Ca)^OTC
Gum tablets: 300 mg ^OTC; 450 mg ^OTC; 500 mg (200 mg Ca)^OTC
Lozenges: 600 mg (240 mg Ca)^OTC
Oral suspension: 1.25 g (500 mg Ca)/5 mL^OTC
Powder: 6.5 g (2400 mg Ca)/packet^OTC
Tablets: 500 mg (200 mg Ca)^OTC; 600 mg (240 mg Ca)^OTC; 650 mg (260 mg Ca)^OTC; 667 mg (266.8 mg Ca)^OTC; 1 g (400 mg Ca)^OTC; 1.25 g (500 mg Ca)^OTC; 1.5 g (600 mg Ca)^OTC

Assessment ⬆ ⬇

Calcium Supplement/Replacement: Observe closely for signs/symptoms of hypocalcemia (paresthesia, muscle twitching, laryngospasm, colic, cardiac arrhythmias, Chvostek’s or Trousseau’s sign). Implement a safe environment including fall and seizure precautions.
- Monitor patients receiving digoxin for signs/symptoms of toxicity.
Antacid: Assess for heartburn, indigestion, and abdominal pain. Inspect abdomen; auscultate bowel sounds.

Lab Test Considerations:

Monitor serum calcium or ionized calcium, chloride, sodium, potassium, magnesium, albumin, and intact parathyroid hormone (iPTH) concentrations before and periodically during therapy for treatment of hypocalcemia.
- May ↓ serum phosphate concentrations with excessive and prolonged use. When used to treat hyperphosphatemia in patients with chronic kidney disease, monitor phosphate levels.

Toxicity and Overdose:

Assess for nausea, vomiting, anorexia, thirst, severe constipation, paralytic ileus, and bradycardia. Contact health care professional immediately if these signs/symptoms of hypercalcemia occur.

Implementation ⬆ ⬇

PO: Administer 60–90 min after meals and at bedtime. Chewable tablets should be well chewed before swallowing. Dissolve effervescent tablets in 8 ounces of water. Follow PO doses with 8 ounces of water, except when using calcium carbonate as a phosphate binder in renal dialysis. Administer as a phosphate binder on an empty stomach before meals to optimize effectiveness in patients with hyperphosphatemia.

Patient/Family Teaching ⬆ ⬇

Explain purpose and side effects of medication to patient. Advise patient to read Patient Information before starting therapy. Advise not to take enteric-coated tablets within 1 hr of calcium carbonate; this will result in premature dissolution of the tablets. Advise patient on a regular schedule to take missed doses as soon as possible, then go back to regular schedule.
Advise patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to consult with health care professional before taking other medications.
Advise patient not to administer concurrently with foods containing large amounts of oxalic acid (spinach, rhubarb), phytic acid (brans, cereals), or phosphorus (milk or dairy products). Administration with milk products may lead to milk-alkali syndrome (nausea, vomiting, confusion, headache). Do not take within 1–2 hr of other medications if possible.
Advise patient that constipation may occur. Review methods of preventing constipation (↑ fiber, fluid intake, mobility) and use of laxatives. Severe constipation may indicate toxicity.
Calcium Supplement: Encourage patient to maintain a diet adequate in vitamin D (see Food Sources for Specific Nutrients).
Osteoporosis: Advise patient that exercise has been found to arrest and reverse bone loss. Patient should discuss any exercise limitations with health care professional before beginning program.
Rep: Advise women of reproductive potential to notify health care professional if pregnancy is planned or suspected or if breastfeeding.

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Pronunciation ⬇

Classifications ⬆ ⬇

Indications ⬆ ⬇

Action ⬆ ⬇