Harrison's Internal Medicine Chapter 5. Principles of Clinical Pharmacology Principles of Clinical Pharmacology: Introduction Drugs are the cornerstone of modern therapeutics. Nevertheless, it is well recognized among physicians and among the lay community that the outcome of drug therapy varies widely among individuals. While this variability has been perceived as an unpredictable, and therefore inevitable, accompaniment of drug therapy, this is not the case. The goal of this chapter is to describe the principles of clinical pharmacology that can be used for the safe and optimal use of available and new drugs. Drugs interact with specific target molecules to produce their. | Chapter 005. Principles of Clinical Pharmacology Part 1 Harrison s Internal Medicine Chapter 5. Principles of Clinical Pharmacology Principles of Clinical Pharmacology Introduction Drugs are the cornerstone of modern therapeutics. Nevertheless it is well recognized among physicians and among the lay community that the outcome of drug therapy varies widely among individuals. While this variability has been perceived as an unpredictable and therefore inevitable accompaniment of drug therapy this is not the case. The goal of this chapter is to describe the principles of clinical pharmacology that can be used for the safe and optimal use of available and new drugs. Drugs interact with specific target molecules to produce their beneficial and adverse effects. The chain of events between administration of a drug and production of these effects in the body can be divided into two components both of which contribute to variability in drug actions. The first component comprises the processes that determine drug delivery to and removal from molecular targets. The resultant description of the relationship between drug concentration and time is termed pharmacokinetics. The second component of variability in drug action comprises the processes that determine variability in drug actions despite equivalent drug delivery to effector drug sites. This description of the relationship between drug concentration and effect is termed pharmacodynamics. As discussed further below pharmacodynamic variability can arise as a result of variability in function of the target molecule itself or of variability in the broad biologic context in which the drug-target interaction occurs to achieve drug effects. Two important goals of the discipline of clinical pharmacology are 1 to provide a description of conditions under which drug actions vary among human subjects and 2 to determine mechanisms underlying this variability with the goal of improving therapy with available drugs as well as pointing .
