Introduction to Pharmacology

Introduction to Pharmacology

• Pharmacology is the study of substances that interact with a specific molecule in the biologic system called a receptor, activating or inhibiting normal body processes.
• Medical pharmacology is the science of substances used to prevent, diagnose, and treat disease.
• Toxicology is the branch of pharmacology that deals with the undesirable effects of chemicals on living systems.

Definition of a Drug

• A drug is a chemical substance of known structure, other than a nutrient or an essential dietary ingredient, which, when administered to a living organism, produces a biological effect.
• Drugs may be synthetic chemicals, chemicals obtained from plants or animals, or products of genetic engineering.

Branches of Pharmacology

• Pharmacogenetics: the study of genetic influences on responses to drugs.
• Pharmacogenomics: the use of genetic information to guide the choice of drug therapy on an individual basis.
• Pharmacoepidemiology: the study of drug effects at the population level.
• Pharmacoeconomics: the branch of health economics that aims to quantify in economic terms the cost and benefit of drugs used therapeutically.

Factors to Know for Each Drug

• Classification (drug class)
• Pharmacodynamics (mechanism of action, pharmacological effects)
• Pharmacokinetics (administration, absorption, distribution, metabolism, excretion)
• Clinical use (indications)
• Adverse effects and toxicity
• Contraindications and precautions
• Drug interactions
• Any specific information related to drug use

The Cell as a Target for Drug Action

• Drug molecules must exert some chemical influence on one or more cell constituents to produce a pharmacological response.
• Drug molecules must bind to particular constituents of cells and tissues to produce an effect.
• The critical binding sites are called 'drug targets'.
• Most drug targets are protein molecules.

Drug Specificity

• For a drug to be useful, it must act selectively on particular cells and tissues.
• Drug targets generally show a high degree of ligand specificity; they bind only molecules of a certain precise type.
• The principles of binding site and ligand specificity can be recognized in the actions of mediators such as angiotensin.

Drug Action

• A drug is a chemical applied to a physiological system that affects its function in a specific way.
• With few exceptions, drugs act on target proteins, namely: receptors, enzymes, carriers, and ion channels.
• Specificity is reciprocal: individual classes of drug bind only to certain targets, and individual targets recognize only certain classes of drug.