COMPOSITION Ultra-D 40000 Capsule: Each capsule contains Cholecalciferol USP (Vitamin D3) 40000 IU. Ultra-D 20000 Capsule: Each capsule contains Cholecalciferol USP (Vitamin D3) 20000 IU. Ultra-D 1000 Tablet: Each film coated tablet contains Cholecalciferol USP (Vitamin D3) 1000 IU. PHARMACOLOGY The active form of Vitamin D3, Calcitriol, exerts its effect by binding to the Vitamin D receptors (VDRs) which are widely distributed through many body tissues. Vitamin D3 has a half life of about 50 days as it is fat soluble. Vitamin D3 is absorbed in the small intestine and bound to specific -globulins and transported to the liver where it is metabolised to 25-hydroxy Vitamin D3 (Calcidiol). A second hydroxylation to 1,25-dihydroxy Vitamin D3 (Calcitriol) occurs in the kidney. This metabolite is responsible for the vitamin's ability to increase the absorption of calcium. Non-metabolised Vitamin D3 is stored in tissues such as fat and muscle. Vitamin D3 is eliminated via faeces and urine. INDICATIONS Vitamin D3 deficiency can occur in people whose exposure to sunlight is limited and in those whose diet is deficient in vitamin D3. Vitamin D3 is essential for the effective calcium and phosphate absorption required for healthy bones and teeth, preventing rickets, osteomalacia and osteoporosis. Vitamin D3 is also essential to prevent pre-eclampsia during pregnancy and breast feeding as it is an essential nutrient for a growing infant. Vitamin D3 has vital role on immunity boost up.