title: The effects of encainide versus diltiazem on the oxidative metabolic pathways of antipyrine.
abstract: The effects of diltiazem and encainide on the pharmacokinetics and metabolism of antipyrine were compared in nine healthy male volunteers. Diltiazem 90 mg every 8 hours for 5 days decreased the oral clearance of antipyrine from 2.34 to 1.86 L/hour (p less than 0.05) and increased half-life from 12.7 to 15.9 hours (p less than 0.05). Diltiazem reduced the formation rate constants for 3-hydroxymethylantipyrine by 27% (p less than 0.05) and 4-hydroxyantipyrine by 37% (p less than 0.05). There was also a 21% reduction in the formation rate constant for norantipyrine (0.05 less than p less than 0.10). Encainide 25 mg every 8 hours for 5 days had no apparent effect on the oral clearance or half-life of antipyrine, or on the formation rate constants for metabolites of antipyrine. In contrast to a previously published report in rats, encainide, unlike diltiazem, does not inhibit the oxidative metabolism of antipyrine in humans.
authors.affiliation: Division of Clinical and Hospital Pharmacy, University of Cincinnati, Ohio 45267.
authors.forename: M B
authors.initials: MB
authors.lastname: Bottorff
authors.forename: R L
authors.initials: RL
authors.lastname: Lalonde
authors.forename: D J
authors.initials: DJ
authors.lastname: Kazierad
authors.forename: T J
authors.initials: TJ
authors.lastname: Hoon
authors.forename: S J
authors.initials: SJ
authors.lastname: Tsiu
authors.forename: D M
authors.initials: DM
authors.lastname: Mirvis
mesh_terms: D000328:Adult; D000813:Anilides / Q000494:pharmacology*; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology*; D000983:Antipyrine / Q000378:metabolism* / Q000493:pharmacokinetics; D004110:Diltiazem / Q000494:pharmacology*; D004347:Drug Interactions; D016700:Encainide; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate / Q000187:drug effects; D010084:Oxidation-Reduction / Q000187:drug effects; D011897:Random Allocation
chemical_list: D000813:Anilides; D000889:Anti-Arrhythmia Agents; D004110:Diltiazem; D016700:Encainide; D000983:Antipyrine