Correlation between in vitro and in vivo drug metabolism rate: oxidation of ethoxybenzamide in rat

J Pharmacokinet Biopharm. 1978 Aug;6(4):327-37. doi: 10.1007/BF01060096.


In vitro and in vivo correlations of the microsomal oxidation of drugs were examined, using ethoxybenzamide as a model drug. Ethoxybenzamide disappearance time course from rat plasma in vivo was analyzed by a two-compartment model assuming a Michaelis-Menten type elimination process. Ethoxybenazmide oxidation in vitro was measured by the appearance rate of salicylamide in rat liver microsomal suspension. Parameters obtained were Vmax = 3.46 and 3.77 mumoles/min/kg body weight and Km = 0.378 and 0.192 mM, in vitro and in vivo, respectively.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Benzamides / metabolism*
  • Blood Proteins / metabolism
  • Ethyl Ethers / metabolism*
  • In Vitro Techniques
  • Kidney / metabolism
  • Kinetics
  • Liver / metabolism
  • Lung / metabolism
  • Male
  • Microsomes / metabolism
  • Rats
  • Tissue Distribution


  • Benzamides
  • Blood Proteins
  • Ethyl Ethers