1: Introduction to pharmacology

Section 1: Introduction to Pharmacology

Pharmacology is the foundational science exploring the interactions between chemical substances (drugs) and living systems. It encompasses understanding how drugs produce their effects (both therapeutic and adverse), how the body handles drugs, and how these principles are applied to treat disease. Its scope extends from molecular interactions to whole-body responses, forming the bedrock of rational, evidence-based therapeutics.

The discipline branches into two core areas:
Pharmacokinetics (PK) – "what the body does to the drug" – covering Absorption, Distribution, Metabolism, and Excretion (ADME).
Pharmacodynamics (PD) – "what the drug does to the body" – focuses on mechanisms of drug action, primarily via interactions with receptors, enzymes, ion channels, or other molecular targets. Other vital branches include Pharmacotherapeutics (using drugs to treat disease), Toxicology (study of harmful effects), Pharmacogenomics (how genes influence drug response), and Pharmacoepidemiology (drug effects in large populations).

Essential terminology includes:

• Drug: Any chemical substance (excluding essential nutrients) that alters biological function when administered.
• Medicine: A drug formulated for safe administration to prevent, diagnose, or treat disease.
• Therapeutic Effect: The desired, beneficial action of a drug.
• Adverse Drug Reaction (ADR): Any unintended, harmful response to a drug.
• Receptor: A specific protein (often on cell membranes) where a drug binds to initiate its effect.
• Agonist: A drug that binds to a receptor and activates it.
• Antagonist: A drug that binds to a receptor and blocks its activation by agonists.

Pharmacology is intrinsically interdisciplinary. It integrates principles from Physiology (understanding normal body function), Biochemistry (molecular pathways), Pathology (disease processes), Microbiology (for anti-infectives), and Genetics (variations in drug response). Understanding these connections is crucial for predicting drug actions and interactions within complex biological systems.

The ultimate goals of pharmacology are to optimize efficacy (achieving the desired therapeutic effect) while maximizing safety (minimizing harm and adverse reactions). This drives the development of new drugs and guides clinical decision-making to ensure rational prescribing – selecting the right drug, dose, and duration for the right patient based on scientific evidence.