Adult: Available preparations:
Ca carbonate 1,500 mg (equivalent to 600 mg elemental Ca) and vitamin D3 10 mcg (equivalent to 400 IU) conventional tab
Ca carbonate 1,500 mg (equivalent to 600 mg elemental Ca) and vitamin D3 10 mcg (equivalent to 400 IU) chewable tab
Ca carbonate 1,500 mg (equivalent to 600 mg elemental Ca) and vitamin D3 10 mcg (equivalent to 400 IU) effervescent tab
Ca carbonate 1,250 mg (equivalent to 500 mg elemental Ca) and vitamin D3 11 mcg (equivalent to 440 IU) effervescent granules for oral solution
Prophylaxis and treatment: Dosage must be individualised according to the patient’s deficit or daily maintenance requirements. As 1,500 mg/400 IU conventional and chewable tab: 1 tab bid, preferably 1 tab in the morning and 1 tab in the evening. As 1,500 mg/400 IU effervescent tab: 1 tab bid dissolved in approx 200 mL of water, preferably 1 tab in the morning and 1 tab in the evening. As 1,250 mg/440 IU effervescent granules: 1 or 2 sachets daily, dissolved in a glass of water. Dosage recommendations may vary among individual products and between countries (refer to detailed product guideline). Elderly: Same as adult dose.
Administration
Should be taken with food.
Contraindications
Nephrolithiasis, nephrocalcinosis, hypervitaminosis D, hypercalcaemia, hypercalciuria; diseases leading to hypercalcaemia or hypercalciuria (e.g. bone metastases or other malignant bone diseases, myeloma, primary hyperparathyroidism). Severe renal failure and impairment.
Special Precautions
Patient with achlorhydria, hypoparathyroidism; risk factor for hypercalcaemia (e.g. sarcoidosis), history of kidney stones, high tendency to calculus formation. Immobilised patients with osteoporosis. Mild to moderate renal impairment. Elderly. Pregnancy and lactation.
Monitor serum Ca levels and renal function (e.g. serum creatinine).
Overdosage
Symptoms: Hypercalcaemia characterised by anorexia, thirst, vomiting, nausea, abdominal pain, muscle weakness, fatigue, mental disturbances, polyuria, polydipsia, nephrocalcinosis, bone pain, renal calculi, and cardiac arrhythmia and coma in severe cases. High amounts of Ca ingestion may cause Milk-alkali syndrome, irreversible renal damage and soft calcification. Management: Discontinue use of Ca carbonate and vitamin D3 treatment. Empty contents of the stomach in patients with impaired consciousness, rehydrate, and based on the severity may consider combined or isolated treatment with bisphosphonates, loop diuretics, corticosteroids and calcitonin. Closely monitor serum electrolytes, renal function and diuresis.
Drug Interactions
May enhance the arrhythmogenic effects of cardiac glycosides.
Calcium carbonate: Increased risk of hypercalcaemia with thiazide diuretics. May decrease the gastrointestinal absorption of bisphosphonates, Na fluoride, quinolones, tetracyclines, levothyroxine, Fe, zinc and strontium. Ca absorption may be reduced by systemic corticosteroids.
Vitamin D3: Decreased effects with phenytoin, barbiturates, rifampicin, glucocorticosteroids. May reduce gastrointestinal absorption with colestyramine or paraffin oil.
Food Interaction
Food may increase Ca absorption. Bran, foods high in oxalates, or whole grain cereals may decrease Ca absorption.
Action
Description: Ca and vitamin D3 administration counteracts the rise of PTH that is caused by Ca deficiency and increased bone resorption.
Calcium carbonate is used as a supplementary source of Ca to help prevent or decrease the rate of bone loss in osteoporosis. It also acts as an antacid by neutralising gastric acidity resulting in increased gastric and duodenal pH.
Vitamin D3 is a fat-soluble sterol essential for the proper regulation of Ca and phosphate homeostasis, bone metabolism and mineralisation.
Synonym: vitamin D3: colecalciferol, cholecalciferol. Pharmacokinetics: Absorption: Calcium carbonate: Absorbed from the gastrointestinal tract, predominantly in the duodenum.
Vitamin D3: Well-absorbed from the gastrointestinal tract (in the presence of bile). Distribution: Enters breastmilk.
Calcium carbonate: Primarily in bones and teeth. Plasma protein binding: Approx 40%, to albumin. Metabolism: Calcium carbonate: Converted into Ca chloride by gastric acid.
Vitamin D3: Metabolised in the liver by vitamin D 25-hydroxylase via hydroxylation into active metabolite, 25-hydroxycolecalciferol; further converted in the kidneys by vitamin D 1-hydroxylase to form the active 1,25-dihydroxycolecalciferol (calcitriol). Excretion: Via faeces and urine.
Chemical Structure
Calcium carbonate Source: National Center for Biotechnology Information. PubChem Database. Calcium carbonate, CID=10112, https://pubchem.ncbi.nlm.nih.gov/compound/Calcium-carbonate (accessed on Jan. 21, 2020)
Vitamin D3 Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 5280795, Cholecalciferol. https://pubchem.ncbi.nlm.nih.gov/compound/Cholecalciferol. Accessed Feb. 22, 2021.
Storage
Store below 25°C. Protect from light and moisture.
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