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 (tə-kĭs′tə-rôl′, -rōl′)
An inactive compound, C28H44O, that is formed by irradiation of a precursor of vitamin D3 and can be converted back into that precursor.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
References in periodicals archive ?
Supplementation by active forms of vitamin D (1,25 (OH)2D3 (calcitriol) and 1a-calcidiol) is preferable because the other forms (cholecalciferol and tachysterol) require liver hydroxylation and have a small therapeutic range with a long half-life, increasing the risk of over and underdosage.
Moreover excess of UVB rays also transform previtamin [D.sub.3] into biologically inactive metabolites, tachysterol and lumisterol.
However, prolonged exposure to sunlight does not produce toxic amounts of vitamin [D.sub.3] because of the pre-[D.sub.3] conversion to the biologically inactive compounds called lumisterol and tachysterol [6].