Šalis: Jungtinės Valstijos
kalba: anglų
Šaltinis: NLM (National Library of Medicine)
phytonadione (UNII: A034SE7857) (phytonadione - UNII:A034SE7857)
KAISER FOUNDATION HOSPITALS
phytonadione
phytonadione 5 mg
PRESCRIPTION DRUG
New Drug Application
MEPHYTON- PHYTONADIONE TABLET KAISER FOUNDATION HOSPITALS ---------- TABLETS MEPHYTON (PHYTONADIONE) VITAMIN K DESCRIPTION Phytonadione is a vitamin which is a clear, yellow to amber, viscous, and nearly odorless liquid. It is insoluble in water, soluble in chloroform and slightly soluble in ethanol. It has a molecular weight of 450.70. Phytonadione is 2-methyl-3-phytyl-1, 4-naphthoquinone. Its empirical formula is C H O and its structural formula is: MEPHYTON (Phytonadione) tablets containing 5 mg of phytonadione are yellow, compressed tablets, scored on one side. Inactive ingredients are acacia, calcium phosphate, colloidal silicon dioxide, lactose, magnesium stearate, starch, and talc. 1 CLINICAL PHARMACOLOGY 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 a microsomal enzyme that catalyzes the posttranslational carboxylation of multiple, specific, peptidebound glutamic acid residues in inactive hepatic precursors of factors II, VII, IX, and X. The resulting gammacarboxyglutamic acid residues convert the precursors into active coagulation factors that are subsequently secreted by liver cells into the blood. 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 pharmac Perskaitykite visą dokumentą