Comparative metabolism of lorazepam in man and four animal species

J Clin Psychiatry. 1978 Oct;39(10 Pt 2):11-5.


The metabolic disposition of lorazepam (Wy-4036) in man, dog, cat, rat and miniature swine is compared. Except in the cat, absorption of lorazepam is rapid in these species. Absorption in humans is nearly complete. Lorazepam glucuronide is the major metabolite in all species except the rat in which a dihydrodiol derivative is the main product of lorazepam biotransformation. Lorazepam glucuronide, which has no demonstrable CNS activity, is also present in the plasma of all species investigated. The concentrations of lorazepam in rat brain correlate well with those in plasma but are about three times higher. The urinary route of excretion predominates in man, dog and miniature swine while in the rat the bulk of the drug-related material is eliminated with the feces as a consequence of biliary excretion.

Publication types

  • Comparative Study

MeSH terms

  • Absorption
  • Animals
  • Anti-Anxiety Agents / metabolism*
  • Biotransformation
  • Brain Chemistry
  • Cats
  • Dogs
  • Feces / analysis
  • Glucuronates / blood
  • Glucuronates / metabolism
  • Humans
  • Lorazepam / analysis
  • Lorazepam / blood
  • Lorazepam / metabolism*
  • Lorazepam / urine
  • Oxidation-Reduction
  • Rats
  • Species Specificity*
  • Swine
  • Tissue Distribution


  • Anti-Anxiety Agents
  • Glucuronates
  • Lorazepam