Pharmacokinetic Aspects of Drug Design

In the foregoing sections, pharmacon metabolism has been considered in relation to the pharmacodynamic, especially toxic aspects of action. Drug distribution also plays a role in the pharmacodynamic phase of drug action. Modulation of drug distribution, for instance, exclusion of penetration of particular barriers in the organism (e.g. the blood-brain barrier), or preferential bioactivation or bioinactivation in particular tissues, can modulate the spectrum of action of compounds and possibly exclude particular undesired effects. 

With regard to the pharmacokinetic phase of action, a distinction can be made between distribution over the various compartments or tissues, and the time-concentration relationship in particular compartments. Modulation of the pharmacokinetics by suitable molecular manipulation is important at an early stage in the design procedure. Here a distinction can be made between the modulation of the rate and possibly the site of bioinactivation or bioactivation, and modulation of the distribution, including the rate of absorption and rate of elimination. 

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