BMS 113 · Common Core (Tronc commun)Section 1.1 · Introduction to pharmacology
Section 1 of 31
What pharmacology studies
Explain what pharmacology is, how it differs from pharmacy, and name its main branches.
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Why this matters
If you do not know what pharmacology actually studies, you will confuse the science with the professional handling of medicines, and you will not know which question to ask about a drug. Every later unit of this course — how drugs move, how they act, how they are tested — builds on this distinction. Getting it clear now keeps the rest of the course organised in your head.
What you need to know first
No prior science is needed. You only need the everyday experience of taking or giving a medicine, and the willingness to keep the words “drug”, “medicine” and “pharmacology” apart. Unit 1.2 defines the word drug in detail.
Words to know (5)
Pharmacology
The science that studies how chemical substances interact with living organisms. Asking how paracetamol lowers fever is pharmacology.
Pharmacy
The profession that prepares, stores, dispenses and advises on medicines. Counting tablets and labelling a box is pharmacy work.
Pharmacognosy
The study of medicines that come from natural sources such as plants, animals and minerals. Finding artemisinin in Artemisia annua is pharmacognosy.
Pharmaceutics
The science of turning a pure drug into a stable, usable product such as a tablet or a syrup. Deciding that a drug should be a syrup for children is pharmaceutics.
Toxicology
The study of poisons and of the harmful effects of substances. Studying liver damage after a paracetamol overdose is toxicology.
One idea at a timeIdea 1 / 4
In one sentence Pharmacology is the science that asks what a chemical substance does to a living body, and what the body does to that substance.
Pharmacology is the study of drugs and living systems
Following a medicine from its source to its effects links several questions: where it comes from, the form it is given in, how it enters the body, what the body does to it, what it does to the body, and its useful and harmful effects. The word comes from the Greek pharmakon (drug) and logos (study). Because almost every treatment of disease uses a drug, pharmacology is the backbone of the medical profession.
For example
Paracetamol is a simple example: pharmacology asks how it is absorbed after swallowing, how the liver changes it, how it lowers fever, and why too much of it damages the liver.
Pause and check yourself
In one sentence, what two directions does pharmacology study?
Show the answer
It studies what the drug does to the body and what the body does to the drug, from the origin of the drug to its useful and harmful effects.
Read detailed explanations
Observation, experiment and evidence
Pharmacology is an experimental science: statements about drugs must be tested, not assumed. François Magendie (1783–1855) insisted that “facts and facts alone are the basis of science”, and used animal experiments to establish how drugs act. Claude Bernard (1813–1878) later showed in 1842 that curare — an arrow poison — acts at the neuromuscular junction, and proposed a site of action rather than a vague “power”. That shift matters to beginners because it explains why modern teaching keeps asking mechanism: once you know where a drug acts, you can predict its effects, its side effects and its antidotes. It also explains why the same drug can help one patient and harm another — the experiment defines the average, the patient supplies the variation. Throughout this course, separate what has been measured from what has been assumed, and note that many traditional preparations have not passed this test even when they are widely used.
Therapeutic index: the gap between help and harm
Every drug has a dose that helps and a higher dose that harms. The therapeutic index (also called the therapeutic window or margin) is the gap between the dose that produces the wanted effect and the dose that produces danger. A wide window means small mistakes are unlikely to hurt the patient; a narrow window means the same drug can be useful and lethal within a small dose range. This idea recurs throughout the course. It explains why some drugs are sold only on prescription, why some need blood-level monitoring, and why “if one tablet helps, two must help more” is dangerous reasoning. Digoxin, used in heart failure, is a classic narrow-window drug: the difference between a therapeutic and a toxic level is small, so dose and monitoring matter. Paracetamol is often described as safe, yet it too has a ceiling: exceeding it overloads the liver’s detoxifying pathway and causes liver injury.
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Four sciences, one medicine
A medicine reaches a patient only when pharmacognosy, pharmaceutical chemistry, pharmaceutics and pharmacology each answer their own question.
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01 / 5Pharmacognosy
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Pharmacognosy
The study of medicines from natural sources. It identifies the plant, animal or mineral, the part used, and the active ingredient it contains. Without it, a traditional remedy cannot be standardised or reproduced.
Schematic overview; not to scale. The four sciences overlap in practice — a formulation scientist and a pharmacologist often work on the same experiment.
Key points to remember
✓Pharmacology is the science of how chemical substances interact with living organisms.
✓Pharmacy is the profession that handles medicines; pharmacology is the science of how they work.
✓Pharmacology belongs to a family with pharmacognosy, pharmaceutical chemistry, pharmaceutics and toxicology.
✓Pharmacology is divided into branches, including clinical, molecular, systems, neuro-, cardiovascular and behavioural pharmacology.
Go deeper
Worked example
Placing a new medicine in the family of sciences. A research team reports a new molecule extracted from a local plant. It relieves fever in laboratory animals. You are asked which pharmaceutical sciences are involved and what questions each one must answer.
Pharmacognosy: confirm the plant species, the part used (leaf, bark, root) and how the active ingredient is identified and harvested.
Pharmaceutical chemistry: determine the chemical structure and decide whether it can be purified or synthesised in the laboratory.
Pharmaceutics: choose a dosage form — for example a syrup for children or a tablet for adults — and test that it stays stable.
Pharmacology: study absorption, distribution, metabolism and excretion, then the mechanism that lowers fever and the toxic dose.
The four sciences answer different questions about the same molecule. No single one can move a plant extract to a patient alone.
Common misconception
A common beginner error is to treat “drug”, “medicine” and “pharmacology” as synonyms. Pharmacology is the study, not the substance; and not every chemical that changes the body is used as a medicine.
Check your reasoning
In your own words, why can a pharmacist not work safely without pharmacology, even if the prescription is written correctly?
Reveal an answer
Because the prescription states what to give, not why or with what risk. Pharmacology supplies the reasons: whether the dose suits the patient, which interactions matter, what side effects to warn about, and when to send the patient back to the prescriber.
Where this comes from
BMS 113 General Pharmacology I lecture notes · Unit 1.1–1.2, pp. 5–6
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About this course and its sources
Bilingual lessons organised from the supplied BMS 113 General Pharmacology I lecture notes. Diagrams are original educational schematics; pharmacology, nursing and French-language review are pending.