Calcium-A & D

Uses

• • Treatment of osteoporosis, rickets, osteomalacia, tetany and hypoparathyroidism
• • In pregnancy & lactation due to increase demand
• • In kidney disease and pancreatitis
• • During therapy with antiseizure medications
• • The prevention and treatment of calcium deficiency/vitamin D deficiency especially in the housebound and institutionalized elderly subjects.

Calcium-A & D is also used to associated treatment for these conditions: Deficiency, Vitamin D

How Calcium-A & D works

Most individuals naturally generate adequate amounts of vitamin D through ordinary dietary intake of vitamin D (in some foods like eggs, fish, and cheese) and natural photochemical conversion of the vitamin D3 precursor 7-dehydrocholesterol in the skin via exposure to sunlight.

Conversely, vitamin D deficiency can often occur from a combination of insufficient exposure to sunlight, inadequate dietary intake of vitamin D, genetic defects with endogenous vitamin D receptor, or even severe liver or kidney disease . Such deficiency is known for resulting in conditions like rickets or osteomalacia, all of which reflect inadequate mineralization of bone, enhanced compensatory skeletal demineralization, resultant decreased calcium ion blood concentrations, and increases in the production and secretion of parathyroid hormone . Increases in parathyroid hormone stimulates the mobilization of skeletal calcium and the renal excretion of phosphorus . This enhanced mobilization of skeletal calcium leads towards porotic bone conditions .

Ordinarily, while vitamin D3 is made naturally via photochemical processes in the skin, both itself and vitamin D2 can be found in various food and pharmaceutical sources as dietary supplements. The principal biological function of vitamin D is the maintenance of normal levels of serum calcium and phosphorus in the bloodstream by enhancing the efficacy of the small intestine to absorb these minerals from the diet . At the liver, vitamin D3 or D2 is hydroxylated to 25-hydroxyvitamin D and then finally to the primary active metabolite 1,25-dihydroxyvitamin D in the kidney via further hydroxylation . This final metabolite binds to endogenous vitamin d receptors, which results in a variety of regulatory roles - including maintaining calcium balance, the regulation of parathyroid hormone, the promotion of the renal reabsorption of calcium, increased intestinal absorption of calcium and phosphorus, and increased calcium and phosphorus mobilization of calcium and phosphorus from bone to plasma to maintain balanced levels of each in bone and the plasma .

Dosage

Calcium-A & D dosage

Adults and Elderly and children above 12 years of age: 2 tablets per day, preferably one tablet each morning and evening.Children: Not recommended for children under 12 years.

Side Effects

The use of calcium supplements has, rarely, given rise to mild gastro-intestinal disturbances, such as constipation, flatulence, nausea, gastric pain, diarrhoea. Following administration of vitamin D supplements occasional skin rash has been reported. Hypercalciuria, and in rare cases hypercalcaemia have been seen with long term treatment at high dosages.

Toxicity

The use of pharmacological or nutraceutical vitamin d and/or even excessive dietary intake of vitamin d is contraindicated in patients with hypercalcemia, malabsorption syndrome, abnormal sensitivity to the toxic effects of vitamin d, and hypervitaminosis D .

Hypersensitivity to vitamin d is one plausible etiologic factor in infants with idiopathic hypercalcemia - a case in which vitamin d use must be strictly restricted .

As vitamin d intake is available via fortified foods, dietary supplements, and clinical drug sources, serum concentrations and therapeutic dosages should be reviewed regularly and readjusted as soon as there is clinical improvement . Dosage levels are required to be individualized on an individual patient by patient basis as caution must be exercised to prevent the presence of too much vitamin d in the body and the various potentially serious toxic effects associated with such circumstances .

In particular, the range between therapeutic and toxic doses is quite narrow in vitamin d resistant rickets . When high therapeutic doses are used, progress should be followed with frequent blood calcium determinations .

When treating hypoparathyroidism, intravenous calcium, parathyroid hormone, and/or dihydrotachysterol may be required .

Maintenance of normal serum phosphorus levels by dietary phosphate restriction and/or administration of aluminum gels as intestinal phosphate binders in those patients with hyperphosphatemia as frequently seen in renal osteodystrophy is essential to prevent metastatic calcification .

Mineral oil interferes with the absorption of lipid-soluble vitamins, including vitamin d preparations .

The administration of thiazide diuretics to hypoparathyroid patients who are concurrently being treated with vitamin d can result in hypercalcemia .

At this time, no long term animal studies have been performed to evaluate vitamin potential for carcinogens, mutagenesis, or fertility .

As various animal reproduction studies have demonstrated fetal abnormalities in several species associated with hypervitaminosis D, the use of vitamin d in excess of the recommended dietary allowance during normal pregnancy should be avoided . The safety in excess of 400 USP units of vitamin d daily during pregnancy has not been established . The abnormalities observed are similar to the supravalvular aortic stenosis syndrome described in infants that is characterized by supravalvular aortic stenosis, elfin facies, and mental retardation .

In a nursing mother given large doses of vitamin D, 25-hydroxycholecalciferol appeared in the milk and caused hypercalcemia in her child. Caution is subsequently required when contemplating the use of vitamin d in a nursing woman, and the necessity of monitoring infants' serum calcium concentration if vitamin d is administered to a breastfeeding woman .

Adverse reactions associated with the use of vitamin d are primarily linked to having hypervitaminosis D occurring [FDA Lanel]. In particular, hypervitaminosis D is characterized by effects specific effects on specific organ systems. At the renal system, hypervitaminosis D can cause impairment of renal function with polyuria, nocturne, polydipsia, hypercalciuria, reversible asotemia, hypertension, nephrocalcinosis, generalized vascular calcification, or even irreversible renal insufficiency which may result in death . Elsewhere, hypervitaminosis D can also cause CNS mental retardation . At the level of soft tissues, it can widespread calcification of the soft tissues, including the heart, blood vessels, renal tubules, and lungs . In the skeletal system, bone demineralization (osteoporosis) in adults can occur while a decline in the average rate of linear growth and increased mineralization of bones, dwarfism, vague aches, stiffness, and weakness can occur in infants and children . Finally, hypervitaminosis D can also lead to nausea, anorexia, and constipation at the gastrointestinal level as well as mild acidosis, anemia, or weight loss via metabolic processes .

The LD(50) in animals is unknown .

Precaution

Patients with mild to moderate renal failure or mild hypercalciuria should be supervised carefully. Periodic checks of plasma calcium levels and urinary calcium excretion should be made in patients with mild to moderate renal failure or mild hypercalciuria. Urinary calcium excretion should also be measured. In patients with a history of renal stones urinary calcium excretion should be measured to exclude hypercalciuria. With long-term treatment it is advisable to monitor serum and urinary calcium levels and kidney function, and reduce or stop treatment temporarily if urinary calcium exceeds 7.5mmol/24 hours. Allowances should be made for calcium and vitamin D supplements from other sources.

Interaction

Concurrent administration of Thiazide diuretics may increase the risk of hypercalcemia. Calcium salts reduce the absorption of a number of other drugs such as Biphosphonates, Fluoride, some Fluoroquinolones and Tetracyclines.

Elimination Route

Vitamin D3 and D2 are readily absorbed from the small intestine (proximal or distal) .

Half Life

Although certain studies suggest the half-life of 1,25-hydroxyvitamin D3 may be approximately 15 hours, the half-life of 25-hydroxyvitamin D3 appears to have a half-life of about 15 days . Intriguingly however, the half-lives of any particular administration of vitamin d can vary and in general the half-lives of vitamin D2 metabolites have been demonstrated to be shorter overall than vitamin D3 half-lives with this being affected by vitamin d binding protein concentrations and genotype in particular individuals .

Clearance

Some studies propose an estimated clearance rate for 1,25-dihydroxyvitamin D as 31 +/- 4 ml/min in healthy adults .

Elimination Route

The primary excretion route of vitamin D is via the bile into the feces .

Pregnancy & Breastfeeding use

During pregnancy and lactation treatment should always be under the direction of a physician. During pregnancy and lactation, requirements for calcium and vitamin D are increased but in deciding on the required supplementation allowances should be made for availability of these agents from other sources. If calcium iron supplements are both required to be administered to the patient, they should be taken at different times.

Overdoses of vitamin D have shown teratogenic effects in pregnant animals. In humans, long term hypercalcaemia can lead to physical and mental retardation, aortic stenosis and retinopathy in a new born child. Vitamin D and its metabolites pass into the breast milk.

Contraindication

Hypersensitivity to any component of the product. Hypercalcaemia for example, as a result of hyperparathyroidism, vitamin D overdose, decalcifying tumours scuh as myeloma, bone metastases or sarcoidosis. Severe hypercalciuria, renal stones. Osteoporosis due to immobilization.

Acute Overdose

The most serious consequence of acute or chronic overdose is hypercalcaemia due to vitamin D toxicity. Symptoms include nausea, vomiting, polyuria, and constipation. Chronic overdoses can lead to vascular and organ calcification as a result of hypercalcaemia. Treatment should consist of stopping all intake of calcium and vitamin D and rehydration.

Storage Condition

Store in a cool and dry place. Keep out of the reach of children. Protect from light.

Innovators Monograph

You find simplified version here Calcium-A & D