Calcimega

Uses

This preparation is used for Pernicious anemia,Vitamin B12 deficiency due to low intake from food,Thyrotoxicosis, Hemorrhage, Malignancy, Liver or kidney disease,Gastric bypass surgery, Total or partial gastrectomy, Gluten enteropathy or sprue, Folic acid deficiency, Macrocytic anaemia

Nicotinamide is an ingredient found in a variety of cosmetic products.

Vitamin D is an ingredient found in a variety of supplements and vitamins.

Vitamin D is indicated for use in the treatment of hypoparathyroidism, refractory rickets (also known as vitamin D resistant rickets), and familial hypophosphatemia .

Calcimega is also used to associated treatment for these conditions: Anemia, Anemia, Pernicious, Combined Vitamin B1 and B12 deficiency, Convalescence, Diabetic Neuropathies, Folate deficiency, Iron Deficiency Anemia (IDA), Neuritis, Vitamin B1 deficiency, Vitamin B12 Deficiency, Vitamin B12 concentration, Vitamin B6 Deficiency, Vitamin Deficiency, Nutritional supplementation, Vitamin supplementationGastrointestinal insufficiency, Hepatic Insufficiency, Macrocytic anemia, Secondary anemia, Vitamin Deficiency, Severe debilitation, Dietary and Nutritional Therapies, Nutritional supplementation, Dietary supplementationDeficiency, Vitamin D

How Calcimega works

Vitamin B12 serves as a cofactor for methionine synthase and L-methylmalonyl-CoA mutase enzymes. Methionine synthase is essential for the synthesis of purines and pyrimidines that form DNA. L-methylmalonyl-CoA mutase converts L-methylmalonyl-CoA to succinyl-CoA in the degradation of propionate , an important reaction required for both fat and protein metabolism. It is a lack of vitamin B12 cofactor in the above reaction and the resulting accumulation of methylmalonyl CoA that is believed to be responsible for the neurological manifestations of B12 deficiency . Succinyl-CoA is also necessary for the synthesis of hemoglobin .

In tissues, vitamin B12 is required for the synthesis of methionine from homocysteine. Methionine is required for the formation of S-adenosylmethionine, a methyl donor for nearly 100 substrates, comprised of DNA, RNA, hormones, proteins, as well as lipids . Without vitamin B12, tetrahydrofolate cannot be regenerated from 5-methyltetrahydrofolate, and this can lead to functional folate deficiency , . This reaction is dependent on methylcobalamin (vitamin B12) as a co-factor and is also dependent on folate, in which the methyl group of methyltetrahydrofolate is transferred to homocysteine to form methionine and tetrahydrofolate. Vitamin B12 incorporates into circulating folic acid into growing red blood cells; retaining the folate in these cells . A deficiency of vitamin B12 and the interruption of this reaction leads to the development of megaloblastic anemia.

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

Calcimega dosage

Usual Adult Dose for Pernicious Anemia

Initial dose: 1000 mcg intramuscularly or deep subcutaneous once a day for 6 to 7 daysIf clinical improvement and reticulocyte response is seen from the above dosing:

• 100 mcg every other day for 7 doses, then
• 100 mcg every 3 to 4 days for 2 to 3 weeks, then
• Maintenance dose: 100 to 1000 mcg monthly

Administer concomitant folic acid if needed. Chronic treatment should be done with an oral preparation in patients with normal intestinal absorption.

Usual Adult Dose for B12 Nutritional Deficiency: 25 to 2000 mcg orally daily

Usual Adult Dose for Schilling Test: 1000 mcg intramuscularly is the flushing dose

Usual Pediatric Dose for B12 Nutritional Deficiency: 0.5 to 3 mcg daily

Side Effects

Arthralgia (12%), Dizziness (12%), Headache (12%), Nasopharyngitis (12%), Anaphylaxis, Angioedema, Congestive heart failure, Peripheral vascular disease,Pulmonary edema, Diarrhea, Dyspepsia, Polycythemia vera, Sore throat, Nervousness, Rhinitis, Glossitis, Hypoesthesia

Toxicity

LD50 Oral (mouse): > 5,000 mg/kg .

General toxicity

Vitamin B12 is generally non-toxic, even at higher doses. Mild, transient diarrhea, polycythemia vera, peripheral vascular thrombosis, itching, transitory exanthema, a feeling of swelling of entire body, pulmonary edema and congestive heart failure in early treatment stages, anaphylactic shock and death have been observed after vitamin B12 administration .

Carcinogenesis and mutagenesis

Long term studies in animals examining the carcinogenic potential of any of the vitamin B12 formulations have not completed to date. There is no evidence from long-term use in patients with pernicious anemia that vitamin B12 has carcinogenic potential. Pernicious anemia is known to be associated with an increased incidence of stomach carcinoma, however, this malignancy has been attributed to the underlying cause of pernicious anemia and has not been found to be related to treatment with vitamin B12 .

Use in pregnancy

No adverse effects have been reported with ingestion of normal daily requirements during pregnancy .

A note on the use of the nasal spray in pregnancy

Although vitamin B12 is an essential vitamin and requirements are increased during pregnancy, it is currently unknown whether the nasal spray form can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. The nasal spray form should be given to a pregnant woman only if clearly needed, as it is considered a pregnancy category C drug in this form. Sufficient well-controlled studies have not been done to this date in pregnant women .

Use in lactation

Vitamin B12 has been found distributed into the milk of nursing women in concentrations similar to the maternal blood vitamin B12 concentrations. No adverse effects have been reported to date with intake of normal required doses during lactation .

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

Intensive treatment of B12-deficient megaloblastic anemia may cause hypokalemia and sudden death. Use with caution in patients with Leber optic nerve atrophy. Thrombocytosis may occur with treatment of severe vitamin B12 megaloblastic anemia

Interaction

Absorption reduced by antibiotics, aminosalicylic acid, anticonvulsants, biguanides, cholestyramine, cimetidine, colchicine, K salts, methyldopa.

Volume of Distribution

Cobalamin is distributed to tissues and stored mainly in the liver and bone marrow .

Elimination Route

Vitamin B12 is quickly absorbed from intramuscular (IM) and subcutaneous (SC) sites of injection; with peak plasma concentrations achieved about 1 hour after IM injection .

Orally administered vitamin B12 binds to intrinsic factor (IF) during its transport through the stomach. The separation of Vitamin B12 and IF occurs in the terminal ileum when calcium is present, and vitamin B12 is then absorbed into the gastrointestinal mucosal cells. It is then transported by transcobalamin binding proteins . Passive diffusion through the intestinal wall can occur, however, high doses of vitamin B12 are required in this case (i.e. >1 mg). After the administration of oral doses less than 3 mcg, peak plasma concentrations are not reached for 8 to 12 hours, because the vitamin is temporarily retained in the wall of the lower ileum .

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

Half Life

Approximately 6 days (400 days in the liver) .

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

During vitamin loading, the kidney accumulates large amounts of unbound vitamin B12. This drug is cleared partially by the kidney, however, multiligand receptor megalin promotes the reuptake and reabsorption of vitamin B12 into the body , .

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

Elimination Route

This drug is partially excreted in the urine . According to a clinical study, approximately 3-8 mcg of vitamin B12 is secreted into the gastrointestinal tract daily via the bile. In patients with adequate levels of intrinsic factor, all except approximately 1 mcg is reabsorbed. When vitamin B12 is administered in higher doses that saturate the binding capacity of plasma proteins and the liver, the unbound vitamin B12 is eliminated rapidly in the urine. The body storage of vitamin B12 is dose-dependent .

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

Pregnancy & Breastfeeding use

Pregnancy Category A. Adequate and well-controlled human studies have failed to demonstrate a risk to the fetus in the first trimester of pregnancy (and there is no evidence of risk in later trimesters).

Lactation: Drug distributed in milk.

Contraindication

Leber's disease, tobacco amblyopia.

Innovators Monograph

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