General principles of pharmacology.

Historically, the clinician was responsible for information about the sources, physical and chemical properties, compounding, and dispensing of drugs. These activities are now delegated to pharmacologists and pharmacists. Today the practitioner's responsibility requires the rational clinical use of therapeutic agents for the prevention, diagnosis, and treatment of disease. Understanding how chemicals act on body homeostasis at the molecular level is the foundation for developing new drugs. Understanding drug actions at the molecular level is also the basis for rational pharmacotherapy. In addition, it has been emphasized repeatedly that drugs seldom exert their beneficial effects without also causing adverse side effects. The inevitability of this therapeutic dilemma lends credence to the statement that there are no safe biologically active agents. In dealing with this certainty, once again, the clinician trained in molecular mechanisms of drug action, principles of disposition, pharmacotherapeutics, and toxicology has the advantage.