Used primarily in the management of secondary hyperparathyroidism in patients with chronic kidney disease (CKD), especially those on dialysis. It helps regulate calcium and phosphorus metabolism by suppressing parathyroid hormone (PTH) levels. As a vitamin D analog, it activates the vitamin D receptor in the parathyroid glands, reducing PTH overproduction. This action helps prevent bone disorders and mineral imbalances commonly seen in CKD patients. It is administered orally or intravenously, depending on the formulation and clinical setting.