calcifediol + calcitriol

Calcifediol + calcitriol is a combination of two vitamin D analogs used to supplement or replace vitamin D activity in the body. Both are involved in the regulation of calcium and phosphate metabolism. **Calcifediol** (25-hydroxyvitamin D3) serves as a prohormone that is converted in the kidneys primarily to **calcitriol** (1,25-dihydroxyvitamin D3), the hormonally active form of vitamin D. **Calcitriol** directly activates the vitamin D receptor, leading to increased calcium and phosphate absorption from the intestine, reduced parathyroid hormone synthesis, and effects on bone and kidney. This combination could theoretically be used in specific, advanced cases of vitamin D deficiency or disorders of calcium metabolism, such as chronic kidney disease with secondary hyperparathyroidism, where endogenous conversion may be impaired. However, co-administration is not standard due to risk of additive toxicity and is not widely documented as a fixed-dose or approved pharmaceutical product[4][2].