alfacalcidol + calcitriol

Alfacalcidol + calcitriol is a combination of two active vitamin D analogues, both used to manage disorders related to calcium and phosphate metabolism. Alfacalcidol (1α-hydroxycholecalciferol) is a prodrug that requires 25-hydroxylation in the liver to become calcitriol, the hormonally active form of vitamin D3. Calcitriol (1,25-dihydroxycholecalciferol) acts directly as the active metabolite and does not require further activation. Both compounds bind to the vitamin D receptor (VDR), promoting intestinal absorption of calcium and phosphate, suppressing parathyroid hormone secretion, and supporting bone mineralization. They are primarily indicated for conditions such as hypoparathyroidism, chronic kidney disease with secondary hyperparathyroidism or renal osteodystrophy, rickets/osteomalacia resistant to standard vitamin D therapy, and certain forms of osteoporosis[2][4][7]. The combination may be considered in rare clinical scenarios where both rapid onset (from calcitriol) and sustained effect (from alfacalcidol’s conversion) are desired; however, they are more commonly used interchangeably rather than together[2][7].