Exen-d

Uses

Adult: One Calcium Carbonate 500 tablet or as directed by the physician. For the prevention of osteoporosis, 1-3 Calcium Carbonate 500 tablet is recommended generally as a dietary supplement . Doses for children is half of those for adults. A large dose should not be taken without physician\'s advice.

Adolescent: One to two Calcium Carbonate tablet daily.

Children: One Calcium Carbonate tablet daily.

Vitamin D is used to treat and prevent bone disorders (such as rickets, osteomalacia). Vitamin D is made by the body when skin is exposed to sunlight. Sunscreen, protective clothing, limited exposure to sunlight, dark skin, and age may prevent getting enough vitamin D from the sun.

Vitamin D with calcium is used to treat or prevent bone loss (osteoporosis). Vitamin D is also used with other medications to treat low levels of calcium or phosphate caused by certain disorders (such as hypoparathyroidism, pseudohypoparathyroidism, familial hypophosphatemia). It may be used in kidney disease to keep calcium levels normal and allow normal bone growth.

Exen-d is also used to associated treatment for these conditions: Acid Reflux, Acid indigestion, Bloating, Calcium Deficiency, Calcium Metabolism Disorders, Calcium and Vitamin D Deficiencies, Colic, Dyspepsia, Gastric Ulcer, Gastroesophageal Reflux, Heartburn, Hemorrhoids, Hot Flushes, Hyperacidity, Hyperphosphataemia, Hypovitaminosis D, Low Bone Density, Osteodystrophy, Osteomalacia, Osteoporosis, Postmenopausal Osteoporosis, Postoperative Gas, Proctitis, Vertebral Fractures, Calcium loss, Gastrointestinal ulceration, Dietary supplementationCalcium and Vitamin D Deficiencies, Deficiency of Vitamin D3, Deficiency, Vitamin A, Deficiency, Vitamin D, Fracture Bone, Hip Fracture, Hypoparathyroidism, Hypophosphatemia, Familial, Menopause, Osteomalacia, Osteoporosis, Postmenopausal Osteoporosis, Vertebral Fractures, Vitamin D Resistant Rickets, Vitamin Deficiency, Severe Bone Resorption, Spine fracture, Calcium supplementation, Nutritional supplementation, Vitamin D Supplementation, Vitamin supplementation

How Exen-d works

Calcium carbonate is a basic inorganic salt that acts by neutralizing hydrochloric acid in gastric secretions. It also inhibits the action of pepsin by increasing the pH and via adsorption. Cytoprotective effects may occur through increases in bicarbonate ion (HCO₃^-) and prostaglandins. Neutralization of hydrochloric acid results in the formation of calcium chloride, carbon dioxide and water. Approximately 90% of calcium chloride is converted to insoluble calcium salts (e.g. calcium carbonate and calcium phosphate).

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 stimulate 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 .

In particular, calcitriol interacts with vitamin D receptors in the small intestine to enhance the efficiency of intestinal calcium and phosphorous absorption from about 10-15% to 30-40% and 60% increased to 80%, respectively . Furthermore, calcitriol binds with vitamin D receptors in osteoblasts to stimulate a receptor activator of nuclear factor kB ligand (or RANKL) which subsequently interacts with receptor activator of nuclear factor kB (NFkB) on immature preosteoclasts, causing them to become mature bone-resorbing osteoclasts . Such mature osteoclasts ultimately function in removing calcium and phosphorus from bone to maintain blood calcium and phosphorus levels . Moreover, calcitriol also stimulates calcium reabsorption from the glomerular filtrate in the kidneys .

Additionally, it is believed that when calcitriol binds with nuclear vitamin D receptors, that this bound complex itself binds to retinoic acid X receptor (RXR) to generate a heterodimeric complex that consequently binds to specific nucleotide sequences in the DNA called vitamin D response elements . When bound, various transcription factors attach to this complex, resulting in either up or down-regulation of the associated gene's activity. It is thought that there may be as much as 200 to 2000 genes that possess vitamin D response elements or that are influenced indirectly to control a multitude of genes across the genome . It is in this way that cholecalciferol is believed to function in regulating gene transcription associated with cancer risk, autoimmune disorders, and cardiovascular disease linked to vitamin D deficiency . In fact, there has been some research to suggest calcitriol may also be able to prevent malignancies by inducing cellular maturation and inducing apoptosis and inhibiting angiogenesis, exhibit anti-inflammatory effects by inhibiting foam cell formation and promoting angiogenesis in endothelial colony-forming cells in vitro, inhibit immune reactions by enhancing the transcription of endogenous antibiotics like cathelicidin and regulate the activity and differentiation of CD4+ T cells, amongst a variety of other proposed actions .

Dosage

Exen-d dosage

Calcium Carbonate is always used orally and when used as an antacid the recommended doses for adults are equivalent to 540-2000 mg Calcium Carbonate per day, doses for children being half of those for adults. As a dietary supplement, such as for the prevention of osteoporosis, 1250-3750 mg Calcium Carbonate (500-1500 mg calcium) daily is recommended in general, but again this will need to be tailored to the individual patient depending on any specific disease such as Calcium deficiency, malabsorption or parathyroid function. In pregnancy and lactation therecommended daily dose of calcium is 1200-1500 mg. In chronic renal failure the doses used vary from 2.5 - 9.0 gm Calcium Carbonate per day and need to be adjusted according to the individual patient. To maximize effective phosphate binding in this context the Calcium Carbonate should be given with meals.

Oral solution: Colecalciferol (Vitamin D3) is recommended 5-10 mcg or 1-2ml (200-400 IU)/day or as directed by the physician.

Chewable tablet: Cholecalciferol (Vitamin D3) is recommended 100 IU (1 tablet) daily, or as directed by physician. Take the medicine with food or within 1 hour after a meal. Place the tablet in mouth swallow after chewing.

Injection:

• Treatment of Cholecalciferol deficiency: 40,000 lU/week for 7 weeks, followed by maintenance therapy (1400-2000 lU/day). Follow-up 25 (OH) D measurements should be made approximately 3 to 4 months after initiating maintenance therapy to confirm that the target level has been achieved.
• Prevention of Vitamin D deficiency: 20,000 lU/Month.
• Treatment of Vitamin D deficiency:12-18 years: 20,000 IU, once every 2 weeks for 6 weeks. Prevention of Vitamin D deficiency, 12-18 years: 20,000 IU, once every 6 weeks.

Side Effects

In rare cases, flatulence, diarrhoea or constipation.

Generally all nutritional supplements are considered to be safe and well tolerable. However, few side-effects can generally occur including hypercalcaemia syndrome or Calcium intoxication (depending on the severity and duration of hypercalcaemia), occasional acute symptoms include anorexia, headache, nausea, vomiting, abdominal pain or stomach ache and constipation with the administration of Colecaciferol.

Toxicity

Chronic or acute administration of excessive doses of cholecalciferol may lead to hypervitaminosis D, manifested by hypercalcemia and its sequelae . Early symptoms of hypercalcemia may include weakness, fatigue, somnolence, headache, anorexia, dry mouth, metallic taste, nausea, vomiting, vertigo, tinnitus, ataxia, and hypotonia . Later and possibly more serious manifestation include nephrocalcinosis, renal dysfunction, osteoporosis in adults, impaired growth in children, anemia, metastatic calcification, pancreatitis, generalized vascular calcification, and seizures .

Safety of doses in excess of 400 IU (10mcg) of vitamin D3 daily during pregnancy has not been established . Maternal hypercalcemia, possibly caused by excessive vitamin D intake during pregnancy, has been associated with hypercalcemia in neonates, which may lead to supravalvular aortic stenosis syndrome, the features of which may include retinopathy, mental or growth retardation, strabismus, and other effects . Hypercalcemia during pregnancy may also lead to suppression of parathyroid hormone release in the neonate, resulting in hypocalcemia, tetany, and seizures .

Vitamin D is deficient in maternal milk; therefore, breastfed infants may require supplementation. Use of excessive amounts of Vitamin D in nursing mothers may result in hypercalcemia in infants. Doses of Vitamin D3 in excess of 10 µg daily should not be administered daily to nursing women.

Precaution

In the presence of mild hypercalciuria, excretion levels must be carefully monitored and where necessary the dose of calcium carbonate should be reduced or treatment should be stopped. Patients with a history of stone formation should also be recommended to increase their fluid intake. High dosage of vitamin D should be avoided during Calcium therapy unless specifically indicated.

People with the following conditions should exercise caution when considering taking vitamin D supplements: High blood Calcium or Phosphorus level, Heart problems, Kidney disease.

Vitamin D must be taken with adequate amounts of both Calcium and Magnesium supplementation. When Calcium level is low (due to insufficient vitamin D and calcium intake), the body activates the parathyroid gland, which produces PTH (parathyroid hormone). This hormone kick starts vitamin D hormone production and assists removal of Calcium from the bones to be used in more important functions such as neutralizing body acidity.

Interaction

Oral calcium can reduce internal absorption of tetracycline and fluoride prepa-rations and an interval of at least 3 hours should therefore be allowed between ingestion of these medications. Vitamin D increases internal absorption of calcium. The intestinal uptake of calcium may be reduced by concomitant ingestion of certain foods (e.g. spinach, milk and milk products).

Cholecalciferol is known to interact with Carbamazepine, Dactinomycin, Diuretics, Fosphenytoin, Miconazole, Phenobarbital, Phenytoin, Primidone

Volume of Distribution

Calcium is rapidly distributed taken up by skeletal tissues following absorption and distribution into extracellular fluids. Bone contains 99% of the body's calcium and the remaining 1% is approximately equally distributed between intracellular and extracellular fluids.

Studies have determined that the mean central volume of distribution of administered cholecalciferol supplementation in a group of 49 kidney transplant patients was approximately 237 L .

Elimination Route

Maximal absorption occurs at doses of 500 mg or less taken with food. Oral bioavailability depends on intestinal pH, the presence of food and dosage.

Cholecalciferol is readily absorbed from the small intestine if fat absorption is normal . Moreover, bile is necessary for absorption as well .

In particular, recent studies have determined aspects about the absorption of vitamin D, like the fact that a) the 25-hydroxyvitamin D metabolite of cholecalciferol is absorbed to a greater extent than the nonhydroxy form of cholecalciferol, b) the quantity of fat with which cholecalciferol is ingested does not appear to largely affect its bioavailability, and c) age does not apparently effect vitamin D cholecalciferol .

Half Life

At this time, there have been resources that document the half-life of cholecalciferol as being about 50 days while other sources have noted that the half-life of calcitriol (1,25-dihydroxyvitamin D3) is approximately 15 hours while that of calcidiol (25-hydroxyvitamin D3) is about 15 days .

Moreover, it appears that the half-lives of any particular administration of vitamin d can vary due to variations in vitamin d binding protein concentrations and genotype in particular individuals .

Clearance

Studies have determined that the mean clearance value of administered cholecalciferol supplementation in a group of 49 kidney transplant patients was approximately 2.5 L/day .

Elimination Route

Excreted mainly in the feces. The majority of renally filtered calcium is reabsorbed in the ascending limb of the loop of Henle and the proximal and distal convoluted tubules. Also secreted by sweat glands.

It has been observed that administered cholecalciferol and its metabolites are excreted primarily in the bile and feces .

Pregnancy & Breastfeeding use

Pregnant women : Calcium containing drugs are used widely in pregnancy by way of calcium supplement or antacid therapy. No relationship between malformation in general and calcium exposure has been noted.

Lactating mother : There is no contraindication to the use of calcium carbonate in lactating mother.

There is no evidence to suggest that vitamin D is teratogenic in humans even at very high doses. Colecalciferol should be used during pregnancy only if the benefits outweigh the potential risk to the fetus.

It should be assumed that exogenous Colecalciferol passes into the breast milk. In view of the potential for hypercalcaemia in the mother and for adverse reactions from Colecalciferol in nursing infants, mothers may breastfeed while taking Colecalciferol, provided that the serum Calcium levels of the mother and infant are monitored.

Contraindication

Hypersensitivity to the Calcium Carbonate or any inactive ingredient of the medication. Hypercalcemia (e.g. in hyperparathyroidism, overdosage of vitamin D, demineralizing tumours such as plasmacytomas and bone metastases), severe hypercalcuria, several renal insufficiency.

Colecalciferol is contraindicated in all diseases associated with hypercalcaemia. It is also contraindicated in patients with known hypersensitivity to Colecalciferol (or medicines of the same class) and any of the constituent excipients. Colecalciferol is contraindicated if there is evidence of vitamin D toxicity.

Special Warning

USE IN CHILDREN: Calcium carbonate has been extensively studied in children and infants with chronic renal failure and is both safe and effective.

USE IN ELDERLY: In case of elderly patients with renal failure when calcium carbonate is taken constipation may be troublesome one for this group. For this reason, monitoring of serum calcium and phosphate is of course indicated for elderly patients.

Acute Overdose

Symptoms: anorexia, headache, vomiting, constipation, dystrophy (weakness, loss of weight), sensory disturbances, possibly fever with thirst, polyuria, dehydration, apathy, arrested growth and urinary tract infections. Hypercalcaemia ensues, with metastatic calcification of the renal cortex, myocardium, lungs and pancreas.

Treatment: Immediate gastric lavage or induction of vomiting to prevent further absorption. Liquid paraffin should be administered to promote faecal excretion. Repeated serum calcium determinations are advisable. If elevated calcium levels persist in the serum, phosphates and corticosteroids may be administered and measures instituted to bring about adequate diuresis.

Storage Condition

Store in a cool, dry place in controlled room temperature.

Innovators Monograph

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