CALCIUM AND VITAMIN D PREPARATIONS. Calcium and vitamin D are two essential nutrients long known for their role in bone health.

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1 CALCIUM AND VITAMIN D PREPARATIONS. Calcium and vitamin D are two essential nutrients long known for their role in bone health. Estimated Average Requirement (EAR): Reflects the estimated median requirement and is particularly appropriate for applications related to planning and assessing intakes for groups of persons. Recommended Dietary Allowance (RDA): Derived from the EAR and meets or exceeds the requirement for 97.5 percent of the population. Tolerable Upper Intake Level (UL): As intake increases above the UL, the potential risk of adverse effects may increase. The UL is the highest average daily intake that is likely to pose no risk of adverse effects to almost all individuals in the general population. Adequate Intake (AI): Used when an EAR/RDA cannot be developed; average intake level based on observed or experimental intakes. Calcium is required for: Muscle and nerve functional integrity. Cardiac function. Coagulation of blood. Cementing substance of the bones. Daily requirements: g/day. It increases during pregnancy and lactation. Normal serum calcium: 9-11mg% mg% exists in ionized form, which is the active form. Uses: As a supplement during pregnancy and lactation or when dietary calcium is

2 low. Osteomalacia and osteoporosis. Hypoparathyroidism. Acute tetany: 10 ml calcium gluconate 10% i.v in emergency. Control of Calcium Metabolism Parathyroid hormone. Calcitonin. Vitamin D Types of Preparation There are various types of calcium. Some are made of derivatives of oyster shell or bone. Also, calcium antacid formulations can be used as supplements. Calcium carbonate and phosphate preparations have the highest concentration of elemental calcium - about 40%. The elemental calcium content of calcium citrate is 21%, of calcium lactate 13%, and of calcium gluconate, 9%. CALCIUM PREPRATION Absorption Calcium absorption is inefficient, averaging only about 30% and decreases with age. Taking calcium with food increases its absorption, particularly so with calcium carbonate Potential Indicators of Adverse Outcomes for Excess Intake of Calcium Hypercalcemia Hypercalciuria Vascular and soft tissue calcification Nephrolithiasis (kidney stones) Prostate cancer Interactions with iron and zinc Constipation Vitamin D It is a fat-soluble vitamin. Normally, adults do not require vitamin D. Children and female during pregnancy and lactation require units/day.

3 Forms of vitamin D: Vit.D2 (ergocalciferol): it is of plant origin & formed by ultraviolet irradiation of ergosterol in plants. Vit.D3 (cholecalciferol): it is made by ultraviolet irradiation of 7- dehydrocholesterol. It is the form presents in natural foods and is formed in the skin. Vitamin D Supplements Normally, the body makes its own supply of vitamin D. A precursor molecule is produced by skin cells, converted to an intermediate form by exposure to sunlight, and processed into its final state by the liver and kidneys. Vitamin D is added to dairy products and offered in supplements primarily to sustain people in areas are the sunlight is too weak to initiate vitamin D production. But when too much is taken, it causes excessive amounts of calcium excreted from the urine that in turns causes release of calcium from the bones that results in bone loss. It is recommended that to take no more than 50 grams (2,000 IU) daily. VITAMIN D Activation of vitamin D: D2 & D3 are made active by two hydroxylation reactions: 25-hydroxylation in the liver to 25-OH-cholecalciferol (calcifediol). 1α-hydroxylation in the kidney under the influence of parathyroid hormone to 1α- 25(OH)2 cholecalciferol (calcitriol). Absence or deficiency of hydroxylase enzyme in the kidney causes renal rickets. Renal rickets is treated with (1α-hydroxycholecalciferol) = alfacalcidol (one alpha). Functions of vitamin D: Increases absorption of calcium & phosphate from intestine. Increases reabsorption of calcium & phosphate from renal tubules. It deposits calcium into bone. It raises plasma calcium and phosphate. Increases excretion of magnesium in the urine.

4 Uses: Rickets and osteomalacia. In renal failure & renal rickets use 1α-OHcholecalciferol (alfacalcidol or one-alpha) that needs only hepatic hydroxylation to be more active (1α- 25(OH)2 cholecalciferol) Pregnancy and lactation Hypoparathyroidism. Hypophosphatemia. Osteoporosis. Psoriasis: local vitamin D (creams or ointments) preparation is available. : Adverse reactions Hypervitaminosis-D: Hypercalcemia, hypercalciuria and soft tissue calcification especially in the kidney & blood vessels (calcinosis) Potential Indicators of Adverse Outcomes for Excess Intake of Vitamin D Intoxication and related hypercalcemia and hypercalciuria Serum calcium Measures in infants: retarded growth, hypercalcemia Emerging evidence for all-cause mortality, cancer, cardiovascular risk, falls and fractures Forms available for clinical uses include 1. Natural forms: D2 = ergocalciferol. It is of plant origin. D3 = cholecalciferol. It is of an animal origin and formed by sunrays in the skin. 2. Active metabolites: Calcitriol. Alfacalcidol or one-alpha (1α- OH- cholecalciferol) 3. Vit. D analogue Dihydrotachysterol. REFRENCES Katzung Lippincots pharmacology xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

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