Introduction to General Pharmacology
Pharmacology is the branch of science that deals with the study of drugs and their actions on living organisms.
The word “Pharmacology” comes from Greek origins:
- Pharmacon – meaning drug
- Logos – meaning study or science
Hence, General Pharmacology means the scientific study of drugs — their sources, properties, effects, and therapeutic uses.
Pharmacology helps us understand how drugs work inside the body and how the body affects the drugs.
These actions can be beneficial, such as curing a disease, or harmful, such as causing side effects.
According to the World Health Organization (WHO),
“A drug is any substance used to diagnose, prevent, or treat diseases in humans or animals.”
ORIGINAL NOTES:
Main Divisions of Pharmacology
Pharmacology is broadly divided into two main branches:
1. Pharmacokinetics
It deals with what the body does to the drug — including its absorption, distribution, metabolism, and excretion.
Pharmacokinetics helps in deciding how much drug to give and how often.
2. Pharmacodynamics
It deals with what the drug does to the body, including mechanism of action, site of action, dose-response relationship, and drug-receptor interactions.
Together, these two areas explain how a drug produces its effects safely and effectively.
Scope of Pharmacology
The scope of pharmacology is very broad and connects with several other disciplines in medicine and pharmacy.
Below are the key areas under pharmacology:
1. Chemotherapy
Study of drugs used to destroy or inhibit harmful organisms like bacteria, viruses, or cancer cells while sparing normal body cells.
2. Toxicology
Study of poisons, harmful effects of chemicals, and how to manage or prevent toxicity.
3. Pharmacotherapeutics
Application of drugs in treating diseases. It focuses on selecting the right drug, right dose, and right duration for effective treatment.
4. Clinical Pharmacology
Deals with testing new drugs in humans (clinical trials) and studying the safety, efficacy, and side effects of drugs in real-life use.
5. Iatrogenic Diseases
Diseases unintentionally caused by medical treatment or drug use. Proper drug knowledge helps reduce such complications.
6. Therapeutic Index
The Therapeutic Index (TI) shows how safe a drug is.
- LD₅₀: Dose that causes death in 50% of subjects.
- ED₅₀: Dose that produces desired effect in 50% of subjects.
Drugs with a high TI (e.g., Penicillin) are safer, while those with a low TI (e.g., Digoxin, Warfarin) require careful monitoring.
7. Biological Half-Life
The time required for the drug concentration in the body to fall by half — important for determining dosing intervals.
8. Pharmacogenetics & Pharmacoepidemiology
- Pharmacogenetics studies how a person’s genes influence their response to drugs.
- Pharmacoepidemiology studies the effects and safety of drugs in large populations.
Importance of Studying General Pharmacology
Understanding General Pharmacology helps pharmacy and medical students to:
- Learn how drugs work in the human body
- Prescribe medicines safely and effectively
- Avoid drug interactions and adverse effects
- Develop new and improved medicines
In D.Pharmacy, general pharmacology forms the foundation for all advanced pharmacology topics and clinical applications.
