U.S. Department of Health & Human Services Divider Arrow National Institutes of Health Divider Arrow NCATS

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Showing 1391 - 1400 of 1871 results

Vitamin A is important for growth and development as well as maintenance of the immune system and good vision. Vitamin A is needed by the retina of the eye in the form of retinal, which combines with the protein opsin to form rhodopsin. Together Vitamin A and Rhodopsin form the light-absorbing molecule necessary for both low-light (scotopic vision) and color vision. Vitamin A also functions in a very different role as retinoic acid (an irreversibly oxidized form of retinol) which is an important hormone-like growth factor for epithelial and other cells. In foods of animal origin, the major form of vitamin A is an ester, primarily retinyl palmitate, which is converted to retinol (chemically an alcohol) in the small intestine. The retinol form functions as a storage form of the vitamin, and can be converted to and from its visually active aldehyde form, retinal. Vitamin A is effective for the treatment of Vitamin A deficiency. Vitamin A refers to a group of fat-soluble substances that are structurally related to and possess the biological activity of the parent substance of the group called all-trans retinol or retinol. Vitamin A plays vital roles in vision, epithelial differentiation, growth, reproduction, pattern formation during embryogenesis, bone development, hematopoiesis and brain development. It is also important for the maintenance of a proper functioning immune system. The precise mechanism of action of vitamin A differs based on the biological use case, and some mechanisms are better known than others. To facilitate vision Vitamin A (all-trans retinol) is converted in the retina to the 11-cis-isomer of retinaldehyde or 11-cis-retinal. 11-cis-retinal functions in the retina contributing to the transduction of light into the neural signals necessary for vision. While attached to opsin in rhodopsin 11-cis-retinal is isomerized to all-trans-retinal by light which triggers the nerve impulse to the brain allowing for the perception of light. All-trans-retinal is then released from opsin and reduced to all-trans-retinol. All-trans-retinol is isomerized to 11-cis-retinol in the absence of light and then oxidized to 11-cis-retinal. 11-cis-retinal recombines with opsin to re-form rhodopsin. Night blindness or defective vision at low illumination results from a failure to re-synthesize 11-cis retinal rapidly. During epithelial differentiation the role of Vitamin A (as in other physiological processes) involves the binding of Vitamin A to two families of nuclear retinoid receptors (retinoic acid receptors, RARs; and retinoid-X receptors, RXRs). These receptors function as ligand-activated transcription factors that modulate gene transcription. When there is not enough Vitamin A to bind these receptors, natural cell differentiation and growth are interrupted.
Phylloquinone is often called vitamin K1 or phytonadione. It is a fat-soluble vitamin that is stable to air and moisture but decomposes in sunlight. It is found naturally in a wide variety of green plants. Phylloquinone is also an antidote for coumatetralyl. Vitamin K is needed for the posttranslational modification of certain proteins, mostly required for blood coagulation. MEPHYTON (Phytonadione tablets) are indicated in the following coagulation disorders which are due to faulty formation of factors II, VII, IX and X when caused by vitamin K deficiency or interference with vitamin K activity: anticoagulant-induced prothrombin deficiency caused by coumarin or indanedione derivatives; hypoprothrombinemia secondary to antibacterial therapy; hypoprothrombinemia secondary to administration of salicylates; hypoprothrombinemia secondary to obstructive jaundice or biliary fistulas but only if bile salts are administered concurrently, since otherwise the oral vitamin K will not be absorbed. MEPHYTON tablets possess the same type and degree of activity as does naturally-occurring vitamin K, which is necessary for the production via the liver of active prothrombin (factor II), proconvertin (factor VII), plasma thromboplastin component (factor IX), and Stuart factor (factor X). The prothrombin test is sensitive to the levels of three of these four factors II, VII, and X. Vitamin K is an essential cofactor for the gamma-carboxylase enzymes, which catalyze the posttranslational gamma-carboxylation of glutamic acid residues in inactive hepatic precursors of coagulation factors II (prothrombin), VII, IX, and X. Gamma-carboxylation converts these inactive precursors into active coagulation factors, which are secreted by hepatocytes into the blood. Supplementing with Phylloquinone results in a relief of vitamin K deficiency symptoms, which include easy bruisability, epistaxis, gastrointestinal bleeding, menorrhagia and hematuria. Oral phytonadione is adequately absorbed from the gastrointestinal tract only if bile salts are present. After absorption, phytonadione is initially concentrated in the liver, but the concentration declines rapidly. Very little vitamin K accumulates in tissues. Little is known about the metabolic fate of vitamin K. Almost no free unmetabolized vitamin K appears in bile or urine. In normal animals and humans, phytonadione is virtually devoid of pharmacodynamic activity. However, in animals and humans deficient in vitamin K, the pharmacological action of vitamin K is related to its normal physiological function; that is, to promote the hepatic biosynthesis of vitamin K-dependent clotting factors. MEPHYTON tablets generally exert their effect within 6 to 10 hours.
mixture
Status:
First approved in 1940
Source:
Ephynal Acetate by Hoffmann-La Roche
Source URL:

Class:
MIXTURE



It is known that Vitamin E, traditionally known as α¬ tocopherol, is a mixture of eight different compounds, four tocopherols and four tocotrienols, each one being designated as α, β, γ and δ forms. The two groups differ in the hydrophobic tridecyl side chain which is saturated (phytyl) in tocopherols and unsaturated having three double bonds (geranyl) in tocotrienols. During the last few years, it has been found that all the eight forms are biologically active and perform specific functions. Clinical research has shown that mixture of tocotrienols and tocopherols offer synergistic protective action against heart ailments and cancer that is not exclusively offered by α¬tocopherol. The other advantage of mixed tocopherols and tocotrienols is their role in slowing down aging. Diseases like diabetes 1 and 2, autoimmune diseases, bacterial and viral infections, Alzheimer disease, fungal (Candida) infections are prevented by these compounds. It helps in the maintenance of bones, muscles, eyes (vision), memory, sleep, lungs, infertility, skin and wrinkles. Although all forms of Vitamin E exhibit antioxidant activity, it is known that the antioxidant activity of vitamin E is not sufficient to explain the vitamin's biological activity. Vitamin E's anti-atherogenic activity involves the inhibition of the oxidation of LDL and the accumulation of oxLDL in the arterial wall. Vitamin E's antithrombotic and anticoagulant activities involves the downregulation of the expression of intracellular cell adhesion molecule(ICAM)-1 and vascular cell adhesion molecule(VCAM)-1 that lowers the adhesion of blood components to the endothelium. Its antioxidant effects explain the neuroprotective effects of vitamin E. The immunomodulatory effects of Vitamin E have been demonstrated in vitro, where alpha-tocopherol increases mitogenic response of T lymphocytes from aged mice. The mechanism of this response by vitamin E is not well understood, however it has been suggested that vitamin E itself may have mitogenic activity independent of its antioxidant activity. The mechanism of action of vitamin E's antiviral effects (primarily against HIV-1) involves its antioxidant activity. Vitamin E reduces oxidative stress, which is thought to contribute to HIV-1 pathogenesis, as well as to the pathogenesis of other viral infections. Vitamin E also affects membrane integrity and fluidity and, since HIV-1 is a membraned virus, altering membrane fluidity of HIV-1 may interfere with its ability to bind to cell-receptor sites, thus decreasing its infectivity.
mixture
Status:
US Approved OTC
Source:
21 CFR 349.12(c) ophthalmic:demulcents gelatin
Source URL:
First approved in 2012
Source:
Sulfur Colloid by Anazao Health Corporation
Source URL:

Class:
MIXTURE

Showing 1391 - 1400 of 1871 results