AUM 122Introduction to Action and Uses of Medicines
Sources of Medicines and Branches of Pharmacology
8 minute read
What you will learn
- List the sources of medicines with examples of each
- Distinguish natural, semi-synthetic and synthetic medicines
- Describe medicines made by biotechnology
- Name the branches of pharmacology
- Say what each branch studies
- Match medicines with their sources
Key points
- Medicines come from plants, animals, minerals, microorganisms, chemical synthesis and biotechnology.
- Plant sources: morphine from the opium poppy, quinine from cinchona bark, digoxin from foxglove, artemisinin from Artemisia annua.
- Animal sources: heparin from pigs, antivenoms and antisera from animal blood, cod liver oil and some hormones.
- Mineral sources: magnesium sulfate, kaolin, zinc oxide, iron salts, sodium chloride.
- Microbial sources: penicillin from a mould, streptomycin from soil bacteria.
- Semi-synthetic drugs are made by changing a natural substance. Synthetic drugs are made entirely in a laboratory.
- Branches include pharmacokinetics, pharmacodynamics, therapeutics, toxicology, pharmacognosy and clinical pharmacology.
Sources of medicines
| Source | Examples |
|---|---|
| Plants | Morphine and codeine (opium poppy), quinine (cinchona bark), digoxin (foxglove), atropine (belladonna), artemisinin (Artemisia annua, the source of artemether and artesunate) |
| Animals | Heparin (from pig intestine), insulin (originally from pig and cattle pancreas), antivenoms and antisera (from animal blood), cod liver oil, some hormones and enzymes |
| Minerals | Magnesium sulfate and magnesium trisilicate, kaolin, zinc oxide, iron salts, sodium chloride, calamine |
| Microorganisms | Penicillin (from a mould, Penicillium), streptomycin (from soil bacteria, Streptomyces), many other antibiotics |
| Chemical synthesis | Paracetamol, sulfonamides, ciprofloxacin, aspirin, many modern drugs made completely in the laboratory |
| Semi-synthesis | Amoxicillin and ampicillin (from penicillin), many steroids from plant or animal starting materials |
| Biotechnology (genetic engineering) | Human insulin made by bacteria or yeast, and many vaccines and biological medicines |
Natural, semi-synthetic and synthetic
- A natural medicine is taken from a plant, animal, mineral or microbe, and may be purified.
- A semi-synthetic medicine is made by changing a natural substance chemically, often to improve its action or stability.
- A synthetic medicine is made entirely from simple chemicals in the laboratory.
Crude drugs and pure drugs
- A crude drug is the plant or animal material itself, for example dried leaves or bark.
- A pure drug is the active substance isolated from it, for example morphine from opium.
- Pure drugs have a measurable, consistent dose, which is why most modern medicines are pure drugs.
Herbal and traditional medicines
Many people use herbal medicines. They may be useful, but the amount of active substance can vary, there may be side effects and interactions, and many have not been tested. A technician should record that a patient uses herbal products and tell the pharmacist.
Branches of pharmacology
| Branch | What it studies |
|---|---|
| Pharmacokinetics | What the body does to the drug: absorption, distribution, metabolism and excretion |
| Pharmacodynamics | What the drug does to the body: its effects and how it works |
| Pharmacotherapeutics (therapeutics) | The use of drugs to treat disease |
| Toxicology | The harmful effects of drugs and poisons, and how to treat poisoning |
| Pharmacognosy | Drugs from plant and animal sources |
| Clinical pharmacology | The study of drugs in people, including how to use them safely |
| Chemotherapy | The use of drugs to kill or stop germs, parasites or cancer cells, with little harm to the patient |
| Pharmacogenetics | How inherited differences affect a person's response to drugs |
| Pharmacovigilance | Monitoring and reporting the safety of medicines after they are on the market |
| Posology | The study of doses |
Memory aid. Pharmacokinetics is about the movement of the drug through the body (what the body does to the drug). Pharmacodynamics is about the drug's action (what the drug does to the body).
Why sources and branches matter
- The source affects purity, storage, allergies and religious or cultural concerns. For example, some products of animal origin may matter to some patients.
- The branches give you a map of the subject. You will meet each one in later lessons.
Exam focus
- List four sources of medicines with one example each.
- State what pharmacokinetics and pharmacodynamics mean, and how they differ.
- Give the source of quinine, penicillin, heparin and insulin.
- Common mistake: swapping pharmacokinetics (what the body does to the drug) and pharmacodynamics (what the drug does to the body).
Quick check
Test yourself before you move on. Pick an answer to see the explanation.
1.Quinine, used against malaria, comes from:
2.Penicillin is obtained from:
3.Pharmacodynamics is the study of:
4.Which of the following is a mineral source of medicine?
5.A medicine made by chemically changing a natural substance is called: