Alfacalcidol

25-hydroxycholecalciferol, 25-hydroxyvitamin D3, Calcidiol, Calcifediol

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 :

• Treatment and prophylaxis of renal osteodystrophy & cholestatic liver disease
• Vitamin D deficiency in liver patients
• Hypophosphatemic rickets
• Neonatal hypocalcemia

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 :

0.25 mcg or 0.50 mcg capsules.

Prophylaxis against early neonatal hypocalcaemia in premature babies: Oral

0.1 mcg/kg/day.

Neonatal hypocalcemia: Oral

Initially 0.05-0.1 mcg/kg OD then modify according to response. (Max: 2 mcg/day).

Hypophosphatemic rickets: Oral

Neonates and premature infants: 0.05-0.1 mcg/kg/day.

<20 kg: 0.05 mcg/kg/day.

>20 kg: 1 mcg/day.

Vitamin D deficiency in liver patients: Oral

0.05-0.1 mcg/kg/dose OD (Max starting dose 1 mcg). Then adjust dose according to levels.

Treatment and prophylaxis of renal osteodystrophy & cholestatic liver disease: Oral

<20 kg: 0.015-0.03 mcg/kg OD. Max: 0.5 mcg.

>20 kg: 0.25-0.5 mcg OD.

Adjust dose according to response.

Adverse Effect :

Hypercalcemia syndrome, weakness, headache, somnolence, nausea, vomiting, dry mouth, constipation, muscle pain, bone pain, abdominal pain, polyuria, polydipsia, anorexia, weight loss, nocturia, conjunctivitis (calcific), pancreatitis, photophobia, rhinorrhea, pruritus, hyperthermia, decreased libido, elevated BUN, albuminuria, hypercholesterolemia, elevated AST/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: May inhibit both synthetic and catabolic enzymes of calcitriol.

Renal Dose :

Hepatic Dose :