Calcitriol, the active ingredient in Calcijex Injection, is a man-made form of vitamin D, which is needed in the body for building and maintaining strong bones. It is also used to treat problems that can be associated with long term kidney dialysis such as low calcium levels and high levels of parathyroid hormone. It is usually used alongside a certain diet, supplements and sometimes other medications. It works by changing parathyroid hormone levels and increasing calcium levels in the blood. Calcijex is injected into the vein as directed by your doctor and your dosage is dependent upon your condition and how much has been prescribed by your doctor.