Calcium¿¡ ´ëÇÑ Mechanism_Of_Action Á¤º¸ Calcium plays a vital role in the anatomy, physiology and biochemistry of organisms and of the cell, particularly in signal transduction pathways. More than 500 human proteins are known to bind or transport calcium. The skeleton acts as a major mineral storage site for the element and releases Ca2+ ions into the bloodstream under controlled conditions. Circulating calcium is either in the free, ionized form or bound to blood proteins such as serum albumin. Parathyroid hormone (secreted from the parathyroid gland) regulates the resorption of Ca2+ from bone. Calcitonin stimulates incorporation of calcium in bone, although this process is largely independent of calcitonin. Although calcium flow to and from the bone is neutral, about 5 mmol is turned over a day. Bone serves as an important storage point for calcium, as it contains 99% of the total body calcium. Low calcium intake may also be a risk factor in the development of osteoporosis. The best-absorbed form of calcium from a pill is a calcium salt like carbonate or phosphate. Calcium gluconate and calcium lactate are absorbed well by pregnant women. Seniors absorb calcium lactate, gluconate and citrate better unless they take their calcium supplement with a full breakfast. The currently recommended calcium intake is 1,500 milligrams per day for women not taking estrogen and 800 milligrams per day for women on estrogen. There is close to 300 milligrams of calcium in one cup of fluid milk. Calcium carbonate is currently the best and least expensive form of calcium supplement available. Cyanocobalamin¿¡ ´ëÇÑ Mechanism_Of_Action Á¤º¸ Vitamin B12 is used in the body in two forms: Methylcobalamin and 5-deoxyadenosyl cobalamin. The enzyme methionine synthase needs methylcobalamin as a cofactor. This enzyme is involved in the conversion of the amino acid homocysteine into methionine. Methionine in turn is required for DNA methylation. 5-Deoxyadenosyl cobalamin is a cofactor needed by the enzyme that converts L-methylmalonyl-CoA to succinyl-CoA. This conversion is an important step in the extraction of energy from proteins and fats. Furthermore, succinyl CoA is necessary for the production of hemoglobin, the substances that carries oxygen in red blood cells. Pyridoxine¿¡ ´ëÇÑ Mechanism_Of_Action Á¤º¸ Vitamin B6 is the collective term for a group of three related compounds, pyridoxine (PN), pyridoxal (PL) and pyridoxamine (PM), and their phosphorylated derivatives, pyridoxine 5'-phosphate (PNP), pyridoxal 5'-phosphate (PLP) and pyridoxamine 5'-phosphate (PMP). Although all six of these compounds should technically be referred to as vitamin B6, the term vitamin B6 is commonly used interchangeably with just one of them, pyridoxine. Vitamin B6, principally in the form of the coenzyme pyridoxal 5'-phosphate, is involved in a wide range of biochemical reactions, including the metabolism of amino acids and glycogen, the synthesis of nucleic acids, hemogloblin, sphingomyelin and other sphingolipids, and the synthesis of the neurotransmitters serotonin, dopamine, norepinephrine and gamma-aminobutyric acid (GABA). Riboflavin¿¡ ´ëÇÑ Mechanism_Of_Action Á¤º¸ Binds to riboflavin hydrogenase, riboflavin kinase, and riboflavin synthase. Riboflavin is the precursor of flavin mononucleotide (FMN, riboflavin monophosphate) and flavin adenine dinucleotide (FAD). The antioxidant activity of riboflavin is principally derived from its role as a precursor of FAD and the role of this cofactor in the production of the antioxidant reduced glutathione. Reduced glutathione is the cofactor of the selenium-containing glutathione peroxidases among other things. The glutathione peroxidases are major antioxidant enzymes. Reduced glutathione is generated by the FAD-containing enzyme glutathione reductase.
Pharmacology
Cyanocobalamin¿¡ ´ëÇÑ Pharmacology Á¤º¸ Cyanocobalamin (Vitamin B12) is a water-soluble organometallic compound with a trivalent cobalt ion bound inside a corrin ring. It is needed for nerve cells and red blood cells, and to make DNA. Vitamin B12 deficiency is the cause of several forms of anemia. Pyridoxine¿¡ ´ëÇÑ Pharmacology Á¤º¸ Vitamin B6 (pyridoxine) is a water-soluble vitamin used in the prophylaxis and treatment of vitamin B6 deficiency and peripheral neuropathy in those receiving isoniazid (isonicotinic acid hydrazide, INH). Vitamin B6 has been found to lower systolic and diastolic blood pressure in a small group of subjects with essential hypertension. Hypertension is another risk factor for atherosclerosis and coronary heart disease. Another study showed pyridoxine hydrochloride to inhibit ADP- or epinephrine-induced platelet aggregation and to lower total cholesterol levels and increase HDL-cholesterol levels, again in a small group of subjects. Vitamin B6, in the form of pyridoxal 5'-phosphate, was found to protect vascular endothelial cells in culture from injury by activated platelets. Endothelial injury and dysfunction are critical initiating events in the pathogenesis of atherosclerosis. Human studies have demonstrated that vitamin B6 deficiency affects cellular and humoral responses of the immune system. Vitamin B6 deficiency results in altered lymphocyte differentiation and maturation, reduced delayed-type hypersensitivity (DTH) responses, impaired antibody production, decreased lymphocyte proliferation and decreased interleukin (IL)-2 production, among other immunologic activities. Riboflavin¿¡ ´ëÇÑ Pharmacology Á¤º¸ Riboflavin or vitamin B2 is an easily absorbed, water-soluble micronutrient with a key role in maintaining human health. Like the other B vitamins, it supports energy production by aiding in the metabolising of fats, carbohydrates, and proteins. Vitamin B2 is also required for red blood cell formation and respiration, antibody production, and for regulating human growth and reproduction. It is essential for healthy skin, nails, hair growth and general good health, including regulating thyroid activity. Riboflavin also helps in the prevention or treatment of many types of eye disorders, including some cases of cataracts.
Cyanocobalamin¿¡ ´ëÇÑ ´Ü¹é°áÇÕ Á¤º¸ Very high (to specific plasma proteins called transcobalamins); binding of hydroxocobalamin is slightly higher than cyanocobalamin. Pyridoxine¿¡ ´ëÇÑ ´Ü¹é°áÇÕ Á¤º¸ 22% Riboflavin¿¡ ´ëÇÑ ´Ü¹é°áÇÕ Á¤º¸ 60%
Half-life
Cyanocobalamin¿¡ ´ëÇÑ ¹Ý°¨±â Á¤º¸ Approximately 6 days (400 days in the liver). Pyridoxine¿¡ ´ëÇÑ ¹Ý°¨±â Á¤º¸ 15-20 days Riboflavin¿¡ ´ëÇÑ ¹Ý°¨±â Á¤º¸ 66-84 minutes
Absorption
Cyanocobalamin¿¡ ´ëÇÑ Absorption Á¤º¸ Readily absorbed in the lower half of the ileum. Pyridoxine¿¡ ´ëÇÑ Absorption Á¤º¸ The B vitamins are readily absorbed from the gastrointestinal tract, except in malabsorption syndromes. Pyridoxine is absorbed mainly in the jejunum. Riboflavin¿¡ ´ëÇÑ Absorption Á¤º¸ Vitamin B2 is readily absorbed from the upper gastrointestinal tract.
Cyanocobalamin¿¡ ´ëÇÑ Toxicity Á¤º¸ Anaphylactic reaction (skin rash, itching, wheezing)-after parenteral administration. ORL-MUS LD50 > 8000 mg/kg Pyridoxine¿¡ ´ëÇÑ Toxicity Á¤º¸ Oral Rat LD50 = 4 gm/kg. Toxic effects include convulsions, dyspnea, hypermotility, diarrhea, ataxia and muscle weakness. Riboflavin¿¡ ´ëÇÑ Toxicity Á¤º¸ Not Available
Drug Interactions
Calcium¿¡ ´ëÇÑ Drug_Interactions Á¤º¸ Alendronate Formation of non-absorbable complexesAmprenavir The antiacid decreases the absorption of amprenavirAtazanavir This gastric pH modifier decreases the levels/effects of atazanavirChloroquine The antiacid decreases the absorption of chloroquineCiprofloxacin Formation of non-absorbable complexesDapsone Formation of non-absorbable complexesDelavirdine The antiacid decreases the effect of delavirdineDemeclocycline Formation of non-absorbable complexesDoxycycline Formation of non-absorbable complexesEnoxacin Formation of non-absorbable complexesFosamprenavir The antiacid decreases the absorption of amprenavirGrepafloxacin Formation of non-absorbable complexesIbandronate Formation of non-absorbable complexesIndinavir The antiacid decreases the absorption of indinavirItraconazole The antacid decreases the effect of the imidazoleKetoconazole The antacid decreases the effect of the imidazoleLevofloxacin Formation of non-absorbable complexesLevothyroxine Calcium decreases absorption of levothyroxineLomefloxacin Formation of non-absorbable complexesMethacycline Formation of non-absorbable complexesMinocycline Formation of non-absorbable complexesMoxifloxacin Formation of non-absorbable complexesNorfloxacin Formation of non-absorbable complexesOfloxacin Formation of non-absorbable complexesOxytetracycline Formation of non-absorbable complexesPefloxacin Formation of non-absorbable complexesPolystyrene sulfonate Formation of non-absorbable complexesRisedronate Formation of non-absorbable complexesTetracycline Formation of non-absorbable complexesTrovafloxacin Formation of non-absorbable complexesClodronate Formation of non-absorbable complexesEtidronic acid Formation of non-absorbable complexesMycophenolate mofetil Formation of non-absorbable complexesTemafloxacin Formation of non-absorbable complexes Cyanocobalamin¿¡ ´ëÇÑ Drug_Interactions Á¤º¸ Not Available Pyridoxine¿¡ ´ëÇÑ Drug_Interactions Á¤º¸ Not Available Riboflavin¿¡ ´ëÇÑ Drug_Interactions Á¤º¸ Not Available
Calcium¿¡ ´ëÇÑ Description Á¤º¸ Calcium plays a vital role in the anatomy, physiology and biochemistry of organisms and of the cell, particularly in signal transduction pathways. The skeleton acts as a major mineral storage site for the element and releases Ca2+ ions into the bloodstream under controlled conditions. Circulating calcium is either in the free, ionized form or bound to blood proteins such as serum albumin. Although calcium flow to and from the bone is neutral, about 5 mmol is turned over a day. Bone serves as an important storage point for calcium, as it contains 99% of the total body calcium. Low calcium intake may also be a risk factor in the development of osteoporosis. The best-absorbed form of calcium from a pill is a calcium salt like carbonate or phosphate. Calcium gluconate and calcium lactate are absorbed well by pregnant women. Seniors absorb calcium lactate, gluconate and citrate better unless they take their calcium supplement with a full breakfast. Cyanocobalamin¿¡ ´ëÇÑ Description Á¤º¸ Cyanocobalamin (commonly known as Vitamin B12) is the most chemically complex of all the vitamins. Cyanocobalamin's structure is based on a corrin ring, which, although similar to the porphyrin ring found in heme, chlorophyll, and cytochrome, has two of the pyrrole rings directly bonded. The central metal ion is Co (cobalt). Cyanocobalamin cannot be made by plants or by animals, as the only type of organisms that have the enzymes required for the synthesis of cyanocobalamin are bacteria and archaea. Higher plants do not concentrate cyanocobalamin from the soil and so are a poor source of the substance as compared with animal tissues. Cyanocobalamin is naturally found in foods including meat (especially liver and shellfish), eggs, and milk products. [HMDB] Nicotinamide¿¡ ´ëÇÑ Description Á¤º¸ An important compound functioning as a component of the coenzyme NAD. Its primary significance is in the prevention and/or cure of blacktongue and pellagra. Most animals cannot manufacture this compound in amounts sufficient to prevent nutritional deficiency and it therefore must be supplemented through dietary intake. [PubChem] Pyridoxine¿¡ ´ëÇÑ Description Á¤º¸ The 4-methanol form of vitamin B 6 which is converted to pyridoxal phosphate which is a coenzyme for synthesis of amino acids, neurotransmitters (serotonin, norepinephrine), sphingolipids, aminolevulinic acid. Although pyridoxine and Vitamin B 6 are still frequently used as synonyms, especially by medical researchers, this practice is erroneous and sometimes misleading (EE Snell; Ann NY Acad Sci, vol 585 pg 1, 1990). [PubChem] Riboflavin¿¡ ´ëÇÑ Description Á¤º¸ Nutritional factor found in milk, eggs, malted barley, liver, kidney, heart, and leafy vegetables. The richest natural source is yeast. It occurs in the free form only in the retina of the eye, in whey, and in urine; its principal forms in tissues and cells are as flavin mononucleotide and flavin-adenine dinucleotide. [PubChem]