title: S-mephenytoin 4-hydroxylation in older Americans.
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.
authors.affiliation: Department of Psychiatry, University of Pittsburgh, Pennsylvania.
authors.forename: B G
authors.initials: BG
authors.lastname: Pollock
authors.forename: J M
authors.initials: JM
authors.lastname: Perel
authors.forename: M
authors.initials: M
authors.lastname: Kirshner
authors.forename: L P
authors.initials: LP
authors.lastname: Altieri
authors.forename: A L
authors.initials: AL
authors.lastname: Yeager
authors.forename: C F
authors.initials: CF
authors.lastname: Reynolds
mesh_terms: D000368:Aged; D000375:Aging / Q000378:metabolism*; D001189:Aryl Hydrocarbon Hydroxylases; D044383:Black People; D002851:Chromatography, High Pressure Liquid; D003404:Creatinine / Q000097:blood; D065731:Cytochrome P-450 CYP2C19; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D006801:Humans; D006900:Hydroxylation; D008617:Mephenytoin / Q000378:metabolism*; D006899:Mixed Function Oxygenases / Q000378:metabolism; D010672:Phenytoin / Q000031:analogs & derivatives* / Q000032:analysis / Q000097:blood; D014481:United States; D044465:White People; D001741:Black or African American
chemical_list: C001419:hydroxyphenytoin; D010672:Phenytoin; D003577:Cytochrome P-450 Enzyme System; D003404:Creatinine; D006899:Mixed Function Oxygenases; D001189:Aryl Hydrocarbon Hydroxylases; C045793:CYP2C19 protein, human; D065731:Cytochrome P-450 CYP2C19; D008617:Mephenytoin