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Specific absorbance: at nm using water as solvent.Cyanocobalamin is very hygroscopic in the anhydrous form.It is stable to autoclaving for short periods at C.The vitamin B coenzymes are very unstable in light.Purification is achieved by chromatography using aluminium silicate as the adsorbent.Sharply defined red bands are formed during the development of the chromatograms indicating the location of the vitamin.The red band is separated mechanically and eluted with water. The concentrated water solution on addition of acetone gives the crystalline vitamin which can be further purified by recrystallization from aqueous acetone. Cyanocobalamin may be in the form of powder, tablets or injections.Cyanocobalamin injection is a stable solution of cyanocobalamin in water for injections containing sufficient acetic acid or hydrochloric acid to adjust the PH of the solution to about. Hydroxocobalamin and cyanocobalamin are the principal vitamin B forms in clinical use.Mecobalamin, adenosylcobalamin and hydroxocobalamin are the most stable vitamin B derivatives which are both coenzymes nucleic acid synthesis.Hydroxocobalamin is generally preferred to cyanocobalamin for vitamin B injection because it binds firmly to plasma proteins and is retained longer in the body than cyanocobalamin.Cyanocobalamin and hydoxocobalamin are more stable outside the body, and are therefore administered by intramuscular route though cyanocobalamin can also be administered orally or intranasally.Hydroxocobalamin is formulated as injections whiles cyanocobalamin may be formulated as tablet or injections.A deep subcutaneous injection of hydroxocobalamin or cyanocobalamin is also possible.Cyanocobalamin powder can be formulated into different dosage forms.The major portion is excreted within the first eight hours.Intravenous administration results in even more rapid excretion with little opportunity for liver storage.Gastrointestinal absorption of vitamin B depends on the presence of sufficient intrinsic factor and calcium ions.Intrinsic factor deficiency causes pernicious anemia, which may be associated with subacute combined degeneration of the spinal cord.Prompt parenteral administration of vitamin B prevents progression   of neurologic damage.The average diet supplies about to ugday of vitamin B in a proteinbound form that is available for absorption after normal digestion.Vitamin B is not present in foods of plant origin, but is abundant in foods of animal origin.In people with normal absorption, deficiencies have been reported only in strict vegetarians who consume no products of animal origin. Vitamin B is bound to intrinsic factor during transit through the stomach; separation occurs in the terminal ileum in the presence of calcium, and vitamin B enters the mucosal cell for absorption.It is then transported by the transcobalamin binding proteins.A small amount is absorbed by simple diffusion, but this mechanism is adequate only with very large doses.Oral absorption is considered too undependable to rely on in patients with pernicious anemia or other conditions resulting in malabsorption of vitamin B.Cyanocobalamin is the most widely used form of vitamin B, and has hematopoietic activity apparently identical to that of the antianaemia factor in purified liver extract.Hydroxycobalamin is equally as effective as cyanocobalamin, and they share the cobalamin <a href="http://www.targetmol.com/compound/GS-7340">Targetmol's Tenofovir alafenamide</a> molecular structure.DRI is the general term for a set of reference values used for planning and assessing nutrient intakes of healthy people.For infants aged to months, the FNB established an AI for vitamin B that is equivalent to the mean intake of vitamin B in healthy, breastfed infants.

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