Route- and dose-dependent pharmacokinetics of hexobarbitone in the rat: a re-evaluation of the use of sleeping times in metabolic studies

M Van der Graaff, N P Vermeulen, D D Breimer

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

The metabolic clearance (CL) and half-life of racemic hexobarbitone and sleeping time were studied in rats following intra-arterial (i.a.), intraperitoneal (i.p.) and oral (p.o.) administration, at dose levels of 25 and 100 mg kg-1 of its sodium salt. CLp.o. was higher than CLi.a. at both 25 and 100 mg kg-1. CLi.a. and CLi.p. values were much lower, but CLi.p. was higher than CLi.a. at 25 mg kg-1 and lower than CLi.a. at 100 mg kg-1. There was no distinct dependency of the half-lives on route of administration, but a slight increase upon increasing the dose was observed. Hexobarbitone blood concentrations at which the rats awoke were significantly higher after 100 mg kg-1 i.p. than after 100 mg kg-1 i.a., although there was only a small difference in sleeping time. It is postulated that the rate of uptake of the barbiturates into the portal system after i.p. administration is so high that transient saturation of hepatic first-pass metabolism occurs. Therefore neither CLi.p. nor sleeping times can be used as an accurate reflection of drug-metabolizing enzyme activity in the rat; instead CLp.o. should be used.

Original languageEnglish
Pages (from-to)550-4
Number of pages5
JournalJournal of Pharmacy and Pharmacology
Volume37
Issue number8
DOIs
Publication statusPublished - Aug 1985

Keywords

  • Animals
  • Dose-Response Relationship, Drug
  • Half-Life
  • Hexobarbital
  • Kinetics
  • Male
  • Rats
  • Rats, Inbred Strains
  • Sleep
  • Time Factors
  • Journal Article

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