Microorganisms and plants have been evolving for millions of years and along the way they've evolved to produce a range of substances that are able to do all sorts of things including killing pathogens
Instead of having to develop all of our drugs from scratch we've been able to take these substances from them and either use them directly as medicines or sometimes modify them in a lab of it first and then use them as medicines
Substances taken from nature and used as medicines
Aspirin (from willow tree bark)
Digitalis (from foxglove plants)
Penicillin (from Penicillium fungus)
Efficacy
How well the drug works, e.g. how good is an antibiotic at killing bacteria or how well does a pain relief medication reduce your pain
Toxicity
How harmful the drug is, e.g. does it damage our cells or have any side effects
Dosage
How much of the drug or what concentration of the drug should be given
Drug testing stages
1. Testing on human cells and tissues (pre-clinical)
2. Testing on live animals (pre-clinical)
3. Clinical testing on healthy volunteers
4. Clinical testing on patients
Clinical trials
Blind (volunteers don't know if they have real drug or placebo)
Double-blind (neither volunteers nor doctors know who has real drug)
The purpose of blind and double-blind trials is to avoid any unconscious bias
Once drug testing is complete, the results are peer-reviewed by other scientists to check the tests were fair
