A family of lipo-soluble steroids important to the absorption, metabolism, and function of calcium and phosphorus and the growth and development of bone and tooth enamel.
Found naturally in animal tissues, cholecalciferol (vitamin D3) is formed in the skin when ultraviolet light activates cholesterol conversion into vitamin D3. Ultraviolet irradiation of ergosterol (plant vitamin D) forms ergocalciferol (vitamin D2).
PO
Vitamin D resistant rickets: 12,000 to 500,000 USP u daily.
Hypoparathyroidism: 50,000 to 200,000 USP u daily concomitantly with calcium lactate 4 g, 6 times per day.
Dosage must be individualized under close medical supervision.
Calcium intake should be adequate. Blood calcium and phosphorus determinations must be made every 2 weeks, or more frequently if necessary.