Pharmacodynamic principles and target concentration intervention

Abstract

This tutorial reviews the principles of dose individualisation with an emphasis on target concentration intervention (TCI). Once a target effect is chosen then pharmacodynamics can predict the target concentration and pharmacokinetics can predict the target dose to achieve the required response. Dose individualisation can be considered at three levels: population, group and individual. Population dosing, also known as fixed dosing or "one size fits all" is often used but is poor clinical pharmacology; group dosing uses patient features such as weight, organ function and co-medication to adjust the dose for a typical patient; individual dosing uses observations of patient response to inform about pharmacokinetic and pharmacodynamics in the individual and use these individual differences to individualise dose.

Keywords: Target concentration; Target concentration intervention; Target dose; Target effect; Therapeutic drug monitoring.

Figure 1. Predictable Sources of Variability in the Clearance of Propofol (data from Peeters, Allegaert et al. 2010).[10]

Figure 2. The Properties of the Drug and Treatment That Point to the Need for TCI.

Figure 3. The target concentration strategy.

Figure 4. Sampling strategy for most drugs.

Figure 5. Sampling strategy for gentamicin.

Figure 6. TDM and TCI.