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Indications and Dosage
Oral
Supplementation of calcium and vitamin D3 Adult: Calcium (expressed in terms of elemental calcium): 19-50 yr: 1000 mg/day and >50 yr: 1200 mg/day. Vitamin D3: 10 mcg daily. 20 mcg daily for patients with limited sunlight exposure, low vitamin D diet or bedridden elderly patients.
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Renal Impairment
Use with caution in renal failure. Frequent monitoring of serum calcium and phosphorus needed.
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Contraindications
Patients with hypercalcaemia, hypercalciuria or hypophosphatemia. Nephrolithiasis, hypervitaminosis D.
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Special Precautions
Impaired calcium absorption in achlorhydria which is common in elderly. Increased risk of hypercalcaemia and hypercalciuria in hypoparathyroid patients on high doses of vitamin D. History of kidney stones. Renal impairment.
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Adverse Reactions
Constipation, nausea, abdominal pain, hypercalcaemia, hypercalciuria, headache, muscle weakness.
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Overdosage
Overdose can lead to hypercalcaemia. Symptoms: Anorexia, thirst, nausea, vomiting, abdominal pain, muscle weakness, mental disturbances, polydipsia, polyuria and cardiac arrhythmias. Treatment of hypercalcaemia: Rehydrate and discontinue calcium supplement and any treatment with thiazide diuretics or vitamin D. Corticosteriods may be given to reduce the GI absorption of calcium. Biphosphonates may also be used for life-threatening hypercalcaemia.
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Drug Interactions
Reduced absorption of tetracyclines, quinolones and oral biphosphates with concurrent calcium use. Calcium absorption may be reduced by corticosteriods. Increased risk of hypercalcemia and metabolic alkalosis with thiazide diuretics. High blood calcium level may increase the effect of caridac glycosides. Reduced erlotinib efficacy with calcium. Increased risk of hypercalaemia with paricalcitol. Enzyme-inducing antiepileptics increases the metabolism of Vit D.
Potentially Fatal: Fatal encephalopathy can occur in patients with renal failure when given calcium citrate and aluminium products concurrently due to marked rise in aluminium levels. |
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Food Interaction
Foods that are rich in oxalic acid (e.g. spinach and rhubarb) and phytic acid (e.g. whole cereals) may reduce calcium absorption by formation of insoluble calcium salts.
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Action
Description:
Mechanism of Action: Calcium salt can be used in the prevention and treatment of calcium deficiency states. It is also used as an adjunct in the prevention and treatment of osteoporosis. Vitamin D3 is a fat-soluble sterol. It is necessary for the regulation and regulation of calcium and phosphate homoeostasis and bone mineralisation. Pharmacokinetics: Absorption: Calcium: Approx 33% of oral calcium absorbed via active transport and passive diffusive in small intestine. Vitamin D3: Well-absorbed from GI tract in the presence of bile. Distribution: Calcium: Skeletal tissue, breast milk. Crosses placenta. Vitamin D: Vitamin D and metabolites binds to vitamin D -binding protein and are circulated in the blood. May be stored in adipose and muscle tissue for prolonged periods. Metabolism: Vitamin D3: Hydroxylated in liver to form 25-hydroxycholecalciferol, then hydroxylated in kidney to form active metabolite 1,25-dihydroxycholecalciferol. Excretion: Calcium salt: Unabsorbed calcium mainly excreted via faeces. Excess absorbed calcium excreted via urine. Vitamin D: Vitamin D and metabolites are mainly excreted in the bile and faeces. |
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MIMS Class
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