Pharmacokinetic-pharmacodynamic modeling of midazolam effects on the human central nervous system

Clin Pharmacol Ther. 1988 Jul;44(1):14-22. doi: 10.1038/clpt.1988.106.


The effect of midazolam on alpha-activity of the EEG and latency of the P-100 of the visual evoked response (VER) was studied in six healthy subjects. Drug concentration was related to effect with the Emax model that was used with either a threshold drug concentration or a sigmoid exponent. An effect compartment was included in the pharmacokinetic-pharmacodynamic model. Four subjects showed hysteresis, and mean values of half-lives-k(eo) ranged from 0.26 to 0.60 hour. Mean values of EC50 ranged from 42.0 to 48.1 ng/ml. Goodness of fit did not differ significantly between the sigmoid Emax model and the threshold Emax model. The sigmoid exponent estimated was 3.7 +/- 1.8 (EEG, mean +/- SD) and 2.9 +/- 1.4 (VER); the threshold concentration was estimated at 15.7 +/- 11.1 ng/ml (EEG) and 11.3 +/- 7.0 ng/ml (VER). We conclude that the Emax model adequately describes the relationship between midazolam concentration and effect and that the sigmoid exponent can be substituted by a threshold drug concentration, with a comparable fit of the model to the data.

MeSH terms

  • Central Nervous System / drug effects*
  • Central Nervous System / physiology
  • Data Interpretation, Statistical
  • Electroencephalography
  • Evoked Potentials, Visual / drug effects
  • Humans
  • Midazolam / blood
  • Midazolam / pharmacokinetics*
  • Midazolam / pharmacology
  • Models, Biological


  • Midazolam