General Pharmacology Overview

Study Notes

Pharmacology is the science of drugs.
Derived from the Greek word "pharmacon."
Studies drug actions (beneficial and harmful) on tissues, organs, and organisms.
A "drug" is any substance used for diagnosis, prevention, or cure of disease in humans or animals (derived from the French word "drogue," meaning dry herb).

Pharmacodynamics (PD): Study of drug actions and mechanisms on living organisms.
Pharmacokinetics (PK): Study of drug absorption, distribution, biotransformation, and excretion. (Often abbreviated to ADME)
Pharmacognosy: Study of identifying drugs, including their sources, physical, and chemical characteristics.
Pharmacy: Study concerning drug selection, standardization, compounding, dispensing, identification, and preservation of medical substances.

Pharmacogenomics (PG): Use of drugs in gene therapy.
Clinical Pharmacology: Study of drug effects in clinical settings, including drug kinetics.
Pharmacotherapeutics (Chemotherapy): Deals with the therapeutic uses and effects of drugs.
Toxicology: The branch of pharmacology dealing with adverse effects of drugs and poisonous substances, including sources, diagnosis, and treatment of xenobiotics.
Immunopharmacology: Examines the effect of drugs on the immune system.

Standard books provide information on drugs, including a list of official drugs.
An "official drug" is any drug listed in one of the official pharmacopoeias.

Selected list of widely used drugs.
Physical and chemical properties of drugs.
Tests for drug identity, purity, potency, and medicinal preparations.
List of added drugs (newly available) and deleted drugs (due to toxicity).
Examples: British Pharmacopeia (B.P), United States Pharmacopeia (U.S.P), Egyptian Pharmacopeia (E.P), and International Pharmacopeia (published by WHO).

Published by the American Pharmaceutical Association (APA).
Selection of drugs based on therapeutic effect rather than use.
Contains formulas for common pharmacy preparations (e.g., pills, powders, solutions).

Annual publication of the council of pharmacy and chemistry of the American Medical Association.
Contains descriptions of drugs marketed in an acceptable manner.
Contains monographs for all new and individually available drugs.

Organic Sources:
- Plants: Active principles extracted from leaves, seeds, or roots (e.g., atropine, morphine, strychnine). Used in pure form or in preparations.
- Animals: Hormones (e.g., insulin, heparin, thyroid extract, gonadotrophins), anti-sera (e.g., anti-tetanic sera). Animal tissues/organs for replacement therapy.
- Synthetics: Hormones, aspirin, procaine, cortisone, adrenaline, and sulfonamides.
- Microorganisms: Bacteria and fungi; Important source of antibacterial substances (e.g., penicillin, vaccines, toxoids, bacitracin).
Inorganic Sources: MgSO4 (for constipation), NaHCO3 (for gastric acidity), ZnSO4 (for zinc deficiency), and liquid paraffin.

Enteral Routes:
- Oral (swallowed): Safe and economic, but can be slow, irregular, or unsuitable for various situations, and certain drugs are destroyed by gastric acid or enzymes.
- Sublingual: Rapid absorption, used in emergencies like heart attacks.
- Rectal: Suitable for vomiting, certain strong odors/tastes, and hepatic/inactivation.
Parenteral Routes:
- Inhalation: Quick absorption and onset, rapid effective concentration; potential for local irritation or cardiac toxicity.
- Injection:
  - Intravenous (IV): Very rapid action, useful for large volumes, emergencies; local irritation potentially causing thrombosis, and rapid dosage may cause cardiac arrest.
  - Intraperitoneal: Useful for lab animals, rapid absorption.
  - Intramuscular (IM): Rapid action, suitable for suspension/colloids; may cause pain or abscesses.
  - Subcutaneous (SC): Slow, prolonged action, suitable for non-irritant drugs; absorption can be enhanced or slowed.
  - Intradermal: Small doses between skin layers, vaccination/sensitivity tests.
  - Intra-articular: For joints (osteoarthritis, rheumatic arthritis).
  - Intracardiac: Cardiac resuscitation.
  - Intraspinal/subarachnoid: Spinal anesthesia.
Local Application (Topical):
- Applied directly to skin or mucous membranes (e.g., ointments, lotions, tinctures, eye drops).
- Implantation: Small pellets for slow absorption, used in hormonal therapy and estrus synchronization.