Overview
This lecture introduces the fundamental concepts of pharmacology, covering drug definitions, classifications, pharmacokinetics, pharmacodynamics, routes of administration, drug absorption, metabolism, excretion, receptor types, and drug interactions.
Introduction to Pharmacology
- Pharmacology is the study of actions, mechanisms, uses, and adverse effects of drugs.
- A drug is a natural or synthetic substance that alters physiological states in living organisms.
- Drugs are categorized as medicinal (used for prevention, treatment, diagnosis) or non-medicinal (used recreationally).
Drug Naming and Classification
- Each drug has a generic name (active ingredient) and a brand name (given by the manufacturer).
- Drugs are classified by pharmacotherapeutic action, pharmacological action, molecular action, and chemical nature.
Routes of Drug Administration
- Main routes: oral, intravenous, subcutaneous, intramuscular, transdermal, rectal, inhalation, and sublingual.
- Each route has specific advantages, disadvantages, and suitability based on drug properties and therapeutic needs.
Pharmacokinetics (PK)
- Pharmacokinetics studies drug absorption, distribution, metabolism, and excretion (ADME).
- Absorption depends on lipid solubility, molecular size, pH, and bioavailability.
- Distribution is influenced by blood flow, tissue binding, and drug properties.
- Metabolism mainly occurs in the liver (phases 1 and 2), transforming drugs for elimination.
- Excretion is primarily via kidneys, but also through bile, lungs, sweat, and breast milk.
Pharmacodynamics (PD)
- Pharmacodynamics involves the effects of a drug on the body, including mechanism of action at molecular and organ levels.
- Drugs act via receptors, enzymes, or physical/chemical properties.
Drug-Receptor Interactions
- Drug targets include enzymes and receptors.
- Receptors: ion channel-linked, G protein-coupled, tyrosine kinase-linked, DNA-linked.
- Agonists activate receptors; antagonists block receptor activation (competitive or non-competitive).
Drug Interactions
- Pharmacodynamic interactions involve direct effects of drugs on each other.
- Pharmacokinetic interactions involve changes in absorption, distribution, metabolism, or excretion affecting other drugs.
Key Terms & Definitions
- Pharmacokinetics — study of how the body affects a drug (ADME).
- Pharmacodynamics — study of how a drug affects the body.
- Bioavailability — proportion of a drug that reaches systemic circulation.
- Agonist — a substance that activates a receptor.
- Antagonist — a substance that blocks receptor activation.
- First pass metabolism — drug metabolism in liver/intestine before reaching systemic circulation.
Action Items / Next Steps
- Review the main routes of drug administration and their pros and cons.
- Study the phases of drug metabolism (phases 1 and 2).
- Prepare for further exploration of drug-receptor interactions in future lectures.