Transl Clin Pharmacol.  2017 Dec;25(4):157-161. 10.12793/tcp.2017.25.4.157.

Pharmacodynamic principles and the time course of immediate drug effects

Affiliations
  • 1Department of Pharmacology & Clinical Pharmacology, University of Auckland, Auckland, New Zealand. n.holford@auckland.ac.nz

Abstract

This tutorial defines the principles of the concentration - effect relationship which are the basis of pharmacodynamics. The two key parameters of pharmacodynamics are the maximum response (Emax) and the concentration producing 50% of Emax (Câ‚…â‚€). The time course of effect is illustrated under the assumption that drug effects are immediately related to concentration in the central compartment e.g. plasma. The related idea of duration of drug action and its relationship to dose is shown to have a simple relationship with drug half-life.

Keyword

emax model; Emax; Câ‚…â‚€; time course of drug effect; duration of drug action

MeSH Terms

Half-Life
Plasma

Figure

  • Figure 1 Clinical pharmacology is defined by the relaionship between dose, concentration and effect.

  • Figure 2 Concentration, effect and the Emax model.

  • Figure 3 Log Concentration and Effect.

  • Figure 4 Sigmoid Emax model curves with different values of the Hill exponent.

  • Figure 5 Time course of effect when initial concentration is 10 times the C50.

  • Figure 6 Time course of effect when initial concentration is equal to the C50.

  • Figure 7 Time course of effect when initial concentration is 100 times the C50.

  • Figure 8 Schematic diagram of the 3 regions of the time course of effect.

  • Figure 9 Duration of response and half-life.


Cited by  2 articles

Pharmacodynamic principles and target concentration intervention
Nick Holford
Transl Clin Pharmacol. 2018;26(4):150-154.    doi: 10.12793/tcp.2018.26.4.150.

Treatment response and disease progression
Nick Holford
Transl Clin Pharmacol. 2019;27(4):123-126.    doi: 10.12793/tcp.2019.27.4.123.


Reference

1. Hill AV. The possible effects of the aggregation of the molecules of hemoglobin on its dissociation curves. J Physiol (Lond). 1910; 40:iv–vii.
2. Perutz MF. Nobel Lecture: X-ray Analysis of Haemoglobin. Nobelprize.org. Nobel Media AB;2014. Accessed 30 Oct. 2017. http://www.nobelprize.org/nobel_prizes/chemistry/laureates/1962/perutz-lecture.html.
3. Goutelle S, Maurin M, Rougier F, Barbaut X, Bourguignon L, Ducher M, et al. The Hill equation: a review of its capabilities in pharmacological modelling. Fundam Clin Pharmacol. 2008; 22:633–648. DOI: 10.1111/j.1472-8206.2008.00633.x. PMID: 19049668.
Article
Full Text Links
  • TCP
Actions
Cited
CITED
export Copy
Close
Share
  • Twitter
  • Facebook
Similar articles
Copyright © 2024 by Korean Association of Medical Journal Editors. All rights reserved.     E-mail: koreamed@kamje.or.kr