Calcium Carbonate

Indications

Oral
Hyperacidity
Adult: Per tablet contains 500 mg calcium carbonate: Take 1-2 tablets as needed, up to a max of 16 tablets/day. May suck or chew tablets. Pregnant women: 1-2 tablets as needed, up to a max of 7 tablets in 24 hr.

CrCl (ml/min)	Dosage Recommendation
<25	Dosage adjustments may be needed depending on serum calcium levels.

Oral
Hyperphosphataemia in patients with chronic renal failure
Adult: Initially, 2.5 g daily, given in divided doses, may increase up to 17 g daily in divided doses if needed.

CrCl (ml/min)	Dosage Recommendation
<25	Dosage adjustments may be needed depending on serum calcium levels.

Contraindications

Patients with Ca renal calculi or history of renal calculi; hypercalcaemia; hypophosphataemia. Patients with suspected digoxin toxicity.

Warnings / Precautions

Renal impairment, hypoparathyroid disease, hypercalcaemia-associated diseases. Calcium absorption is impaired in achlorhydria; use an alternate salt and take with food. Caution when used in patients with a history of kidney stones.

Adverse Reactions

Constipation, flatulence; hypercalcaemia; metabolic alkalosis; milk-alkali syndrome, tissue-calcification. Gastric hypersecretion and acid rebound (with prolonged use).

Drug Interactions

Co-administration with thiazide diuretics or vit D may lead to milk-alkali syndrome and hypercalcaemia. Decreased absorption with corticosteroids. Decreases absorption of tetracyclines, atenolol, iron, quinolones, alendronate, Na fluoride, Zn and calcium-channel blockers. Enhances cardiac effects of digitalis glycosides and may precipitate digitalis intoxication.
See Below for More calcium carbonate Drug Interactions

Food Interactions

Absorption may be increased with food. Decreased absorption with bran, foods high in oxalates and whole grain cereals. Calcium may reduce iron absorption.

Mechanism of Actions

Calcium carbonate can neutralise gastric acid rapidly and effectively. However, it may adversely activate Ca dependent processes, leading to secretion of gastric and hydrochloric acid. It can induce rebound acid secretion and, prolonged high doses may cause hypercalcemia, alkalosis and milk-alkali syndrome.
Absorption: Converted to calcium chloride by gastric acid. Some of the calcium is absorbed in the intestines. Calcium is absorbed in soluble, ionized form; solubility of calcium is increased in an acidic environment.
Distribution: Crosses placenta, enters breast milk.
Excretion: Mainly in the faeces as unabsorbed calcium; urine (20%).

Administration

May be taken with or without food. (Take w/ meals for better absorption. Avoid taking w/ large amt of fibre-rich food.)

ATC Classification

A12AA04 - calcium carbonate ; Belongs to the class of calcium-containing preparations. Used as dietary supplements.
A02AC01 - calcium carbonate ; Belongs to the class of calcium-containing antacids.