List of products in the National Drug Code with proprietary name . This medication is used to treat people with serious kidney disease whose bodies make too much of a certain natural substance (parathyroid hormone-PTH). High amounts of PTH can affect other minerals in the body (such as calcium, phosphorus) that are needed for strong bones. Calcifediol belongs to a class of drugs known as vitamin D analogs. It works by decreasing PTH and increasing calcium and phosphorus in the body.