From the Guidelines
Alfacalcidol is a form of active vitamin D.
Key Characteristics
- It is used to counter calcitriol deficiency, prevent secondary hyperparathyroidism, and increase phosphate absorption from the gut 1.
- The optimal dose varies from patient to patient, with requirements generally higher during early childhood and puberty (growth phases) 1.
- Alfacalcidol should be given once per day owing to its longer half-life, with an equivalent dosage 1.5–2.0 times that of calcitriol 1.
- In adults, calcitriol or alfacalcidol doses usually prescribed range from 0.50 to 0.75 μg daily for calcitriol and 0.75–1.5 μg daily for alfacalcidol 1.
Clinical Use
- Alfacalcidol is recommended for treating children with overt X-linked hypophosphataemia (XlH) phenotype, in combination with oral phosphorus (phosphate salts) 1.
- In adults, alfacalcidol is recommended for symptomatic patients with X-linked hypophosphataemia (XLH) to reduce osteomalacia and its consequences, and to improve oral health 1.
- The major side effects of alfacalcidol are increases in serum levels of calcium and phosphorus, leading to hypercalcemia and worsening of hyperphosphatemia 1.
Important Considerations
- Careful monitoring of serum levels of calcium, phosphorus, and intact PTH is essential when using alfacalcidol 1.
- Treatment with alfacalcidol should not be undertaken or continued if serum phosphorus levels exceed 6.5 mg/dL, due to the risk of further elevating serum phosphorus levels 1.
From the FDA Drug Label
DESCRIPTION Calcitriol is a synthetic vitamin D analog which is active in the regulation of the absorption of calcium from the gastrointestinal tract and its utilization in the body.
- Alfacalcidol is another term for Calcitriol, a synthetic vitamin D analog.
- It is used to regulate calcium absorption in the body. 2
From the Research
Definition and Mechanism of Action
- Alfacalcidol is a non-endogenous analog of vitamin D, also known as 1-alpha-hydroxyvitamin D3 3.
- It can bypass the renal and intestinal regulatory mechanisms that control the production of calcitriol (1,25-hydroxyvitamin D3), the active form of vitamin D 3.
- Alfacalcidol may be metabolized into calcitriol with a limited risk of hypercalcemia 3.
Therapeutic Applications
- Alfacalcidol has been evaluated in animal and human studies for its effects on bone mineral density and fracture rates 3.
- It has been shown to produce beneficial effects in muscle, immune system, and autoimmune diseases, including rheumatoid arthritis 3.
- Alfacalcidol is used in the treatment of osteoporosis, particularly in post-menopausal women and patients with glucocorticoid-induced osteoporosis 4, 5.
- It has been compared to plain vitamin D in several studies, with results indicating that alfacalcidol is superior in increasing bone mineral density and reducing fracture risk 4, 5.
Comparison to Other Vitamin D Analogues
- Alfacalcidol requires 25-hydroxylation to become the active hormonal form of vitamin D3, whereas calcitriol is the active form of vitamin D 6.
- Doxercalciferol, another vitamin D analogue, is transformed into the active hormonal form of vitamin D2 following 25-hydroxylation 6.
- Paricalcitol, a vitamin D2 analogue, has been specifically developed to suppress parathyroid hormone (PTH) in renal patients with a limited calcemic effect 6.
Clinical Efficacy
- Studies have shown that alfacalcidol is effective in increasing bone mineral density and reducing fracture risk in patients with osteoporosis 4, 5, 7.
- Alfacalcidol has been shown to be superior to plain vitamin D in the treatment of glucocorticoid-induced osteoporosis 5.
- The combination of alfacalcidol with bisphosphonates, such as alendronate, has been shown to be effective in improving the therapeutic outcome of osteoporosis treatment 7.