Abstract: A controlled-release pharmaceutical formulation including cholecalciferol and/or ergocalciferol, a method of making the formulation, and a method of administering the formulation to treat 25-hydroxyvitamin D insufficiency or deficiency, are disclosed. The composition and method of administration preferably result in delayed release of the vitamin(s) in the ileum of the small intestine and sustained, substantially constant, release of the vitamin(s) over an extended period, e.g., at least 4 hours or more. Individual and combined dosages of 500 IU to 50,000 IU per dosage form, preferably daily, are disclosed.

Abstract: The present invention provides a method of increasing or maintaining blood concentrations of 1,25-dihydroxyvitamin D in a patient by administering an amount of 1?-hydroxyvitamin D2. The invention also provides a method of concurrently lowering or maintaining plasma intact parathyroid hormone levels, increasing or maintaining serum calcium levels, maintaining serum phosphorous levels, or increasing or maintaining serum 1,25-dihydroxyvitamin D levels in a human patient by administering to the patient an amount of 1?-hydroxyvitamin D2. The invention also provides a method of reducing the risk of over suppression of plasma intact parathyroid hormone levels in a patient undergoing treatment for elevated levels of plasma intact parathyroid hormone, by administering 1?-hydroxyvitamin D2 in an amount sufficient to decrease elevated intact parathyroid hormone levels while avoiding an abnormally low bone turnover rate.