Cholecalciferol

Synonym :

Vitamin D Inactive

Mechanism :

It is a vitamin D derivative.
Natural supply of vitamin D depends mainly on exposure to the ultraviolet rays of the sun for conversion of 7-dehydrocholesterol in the skin to vitamin D3 (cholecalciferol). Vitamin D3 is then activated in the liver and the kidney before it is fully active at target tissues.

Indication :

Nutritional Rickets
Hypoparathyroidism
Osteomalacia
Vitamin D-dependent rickets
Familial Hypophosphatemia
Treatment of Vitamin D Deficiency

Contraindications :

Should not be given to patients with hypercalcemia or evidence of vitamin D toxicity. Also avoid in patients with hypersensitivity to propylene glycol and in premature infants.

Dosing :

Prevention of Vitamin D Deficiency:

Upto 1 year:

400 IU/day.

>1 year:

600 IU/day.

Hypoparathyroidism:

50,000 to 200,000 units orally or IM once a day given with calcium supplementation.

Osteomalacia:

1000 to 5000 units orally once a day (In patients with malabsorption of vitamin D, the dose is 10,000 units IM once a day or 10,000 to 25,000 units orally once a day)

Vitamin D-dependent rickets:

Less than 1 month:

1,000 IU/day for 2 to 3 months; once radiologic evidence of healing is observed, dose should be decreased to 400 IU/day.

1 to 12 months:

1,000 to 5,000 IU/day for 2 to 3 months; once radiologic evidence of healing is observed, dose should be decreased 400 IU/day.

Greater than 12 months:

5,000 to 10,000 IU/day for 2 to 3 months; once radiologic evidence of healing is observed, dose should be decreased to 400 IU/day.

Nutritional rickets:

Children (with normal absorption):

1,000 to 5,000 IU/day for 6 to 12 weeks.

Children with malabsorption:

10,000 to 25,000 IU/day.

Familial Hypophosphatemia:

Oral or IM:

Initial 40,000 to 80,000 IU/day with phosphate supplements. Daily dosage is increased at 3 to 4 month intervals by 10,000 to 20,000 IU increments.

Treatment of Vitamin D Deficiency:

Serum 25(OH)D level 5 to 15 ng/mL:

4000 IU/day for 12 weeks or 60,000 IU every other week for 10 weeks.

Serum 25(OH)D level less than 5 ng/mL:

8000 IU/day for 4 weeks then 4000 IU/day for 2 months for total therapy of 3 months or 60,000 IU/week for 4 weeks followed by 60,000 IU 2 times/month for a total therapy of 2 months.

Adverse Effect :

Hypercalcemia can lead to weakness, headache, somnolence, nausea, vomiting, dry mouth, constipation, muscle pain, bone pain, abdominal pain, polyuria, polydipsia, anorexia, weight loss, nocturia, conjunctivitis (calcific), pancreatitis, photophobia, rhinorrhoea, pruritus, hyperthermia, elevated BUN, albuminuria, hypercholesterolemia, elevated SGOT (AST) and SGPT (ALT), ectopic calcification, nephrocalcinosis, hypertension, cardiac arrhythmias.

Interaction :

Cholestyramine: Reduces intestinal absorption of alfacalcidol.
Phenytoin/Phenobarbital: May reduce endogenous plasma levels of 25(OH)D3 by accelerating metabolism.
Thiazides: Concomitant administration of thiazides causes hypercalcemia.
Digitalis: Hypercalcemia in such patients may precipitate cardiac arrhythmias.
Ketoconazole: Ketoconazole may inhibit both synthetic and catabolic enzymes of calcitriol.

Hepatic Dose :

No dosage adjustments are recommended. Higher doses may be needed due to reduced intestinal absorption.