The principles of pharmacology (2).

This is the second part of a paper which examines the principles of pharmacology. This article reviews the fundamental principals of drug action and effect: pharmacodynamics. An understanding of pharmacodynamics is important to enable the perioperative practitioner to practise safely. The reader is encouraged to consider the activity questions that appear throughout the article and expand his/her knowledge by further reading. A brief review of the historical background of the development of pharmacology will help put present day understanding into perspective.