Abstract
To examine whether a drug-metabolizing enzyme changes with normal aging, the S:R index of S-mephenytoin 4-hydroxylation was determined in 150, unmedicated elderly Americans (mean age 75.4). Ten (6.7%) were identified as categorically slow metabolizers (S:R ratios greater than or equal to .95). This increased incidence of slow metabolizers was accounted for by a significant and previously unreported, increased proportion of slow metabolizers among the black (18.5%) as compared to the white subjects (4.1%) (P = .017). There was no relationship found between S:R ratios and age or creatinine clearance.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Aged
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Aging / metabolism*
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Aryl Hydrocarbon Hydroxylases*
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Black People
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Chromatography, High Pressure Liquid
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Creatinine / blood
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Cytochrome P-450 CYP2C19
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Cytochrome P-450 Enzyme System / metabolism
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Humans
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Hydroxylation
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Mephenytoin / metabolism*
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Mixed Function Oxygenases / metabolism
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Phenytoin / analogs & derivatives*
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Phenytoin / analysis
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Phenytoin / blood
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United States
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White People
Substances
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hydroxyphenytoin
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Phenytoin
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Cytochrome P-450 Enzyme System
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Creatinine
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Mixed Function Oxygenases
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Aryl Hydrocarbon Hydroxylases
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CYP2C19 protein, human
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Cytochrome P-450 CYP2C19
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Mephenytoin