Alfacalcidol is a synthetic form of Vitamin D which is used to treat conditions related to calcium and phosphate metabolism. It helps in the absorption of calcium and phosphate from the digestive system and also regulates the production and activity of parathyroid hormone, which is important in maintaining calcium balance in the body. It is prescribed to treat conditions such as hypocalcemia (low blood calcium levels), osteoporosis (weak bones), and renal osteodystrophy (bone disease due to chronic kidney disease). Alfacalcidol may also be used to prevent or treat certain types of bone disorders in people with kidney disease. It is available in different forms such as capsules, drops, and injections. The dosage and duration of treatment may vary depending on the condition being treated and individual patient factors, and should be determined by a healthcare professional.