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ALIMENTARY TRACT AND METABOLISM › VITAMINS › VITAMIN A AND D, INCL. COMBINATIONS OF THE TWO › Vitamin D and analogues
alfacalcidol
A11CC03
Forms & Strengths
- Oral capsules: 0.25 mcg, 0.5 mcg, 1 mcg
- Oral drops: 2 mcg/mL
Adult Dosing
- Initial dose: 1 mcg daily
- Maintenance dose: 0.25 to 1 mcg daily adjusted according to biochemical response
- Renal bone disease: 0.5 to 1 mcg daily
- Hypoparathyroidism: 1 mcg daily
Pediatric Dosing
- Neonates and infants: 0.05 to 0.1 mcg/kg daily
- Children under 20 kg: 0.05 mcg/kg daily
- Children over 20 kg: 1 mcg daily
Indications
- Renal osteodystrophy
- Hypoparathyroidism and pseudohypoparathyroidism
- Neonatal hypocalcemia
- Vitamin D-dependent rickets
- Osteoporosis (management in specific regions)
Mechanism of Action
- Synthetic analogue of vitamin D3 (1alpha-hydroxycholecalciferol)
- Rapidly converted in the liver to calcitriol (1,25-dihydroxyvitamin D3)
- Stimulates intestinal calcium and phosphate absorption
- Promotes bone mineralization and suppresses parathyroid hormone secretion
Contraindications
- Hypercalcemia
- Hyperphosphatemia (unless secondary to hypoparathyroidism)
- Hypervitaminosis D
- Known hypersensitivity to alfacalcidol or excipients
Adverse Reactions
- Hypercalcemia
- Hypercalciuria
- Hyperphosphatemia
- Nausea, vomiting, and constipation
- Pruritus and rash
- Nephrocalcinosis and renal impairment with prolonged overdose
Drug Interactions
- Thiazide diuretics: increased risk of hypercalcemia
- Digitalis glycosides: increased risk of cardiac arrhythmias due to hypercalcemia
- Magnesium-containing antacids: risk of hypermagnesemia
- Enzyme-inducing anticonvulsants (e.g., phenytoin, phenobarbital): may reduce efficacy of alfacalcidol
- Other vitamin D analogues: additive toxic effects and hypercalcemia
Curated Content: Needs Vetting Before Put to Clinical Use