Clinical pharmacology: the basics

Clinical pharmacology is the study of pharmacodynamics and pharmacokinetics in humans. The relationship between dose, concentration and pharmacodynamic response may be explored using biomarkers for both desired and undesired effects of drugs. The action of drugs is due to receptor affinity, efficacy and the concentration of drug at the site of action. Factors affecting the concentration of drug include bioavailability, determined by absorption and pre-systemic metabolism, distribution, clearance and elimination. Drug interactions may occur due to pharmacodynamic and pharmacokinetic factors, many of the latter being attributable to changes in drug metabolism. As well as contributing to our understanding of established treatments, clinical pharmacology plays a critical role in the development of new medicines.