Before a promising compound can be safely tested on people, a great deal more detailed research must be done to answer vital questions about its chemical properties and ability to treat a particular disease or symptom.
This is known as pre-clinical research. It’s carried out in the laboratory in test tubes, known as in vitro research, and in living organisms, known as in vivo research. Computer technology is also used.
Pre-clinical research involves a wide range of complex technical tests to find out much more about what chemical groups the compound contains, how these behave in water and fat, for example, and how they react with other chemicals and in different cells and tissues.
Similar versions (analogues) are made in a bid to uncover side effects and hone the effective (active) ingredients.
What the research can tell us
All this research shows whether the compound has the potential to act like a medicine by answering the following questions:
- how much of the compound is likely to be absorbed
- where is it likely to work
- is it likely to reach the target cells/tissues
- how much is it likely to be changed by organs, such as the liver, kidneys, skin or lungs
- what harmful chemicals and break-down products is it likely to produce
- will it do more harm than good - could it potentially cause cancer or harm an unborn child, for example
- how quickly will it be cleared from the body
- will it stay in the body long enough to do its job, but without causing other problems in the process?
If it becomes clear that the compound is potentially unsafe or unlikely to work, no further tests will be done and it will not be developed further.
For compounds with real potential to become medicines, pre-clinical research results decide the starter range of doses to be tested in people, as well as the format to be used—syrup, capsule, pill or injection, for example.
Why are animals still used?
The international Helsinki declaration and a European Directive require every new potential prescription medicine to be first tested in animals before it can be tested and used in people.
This is because test tube results may not always be the same when tested in living tissues, and no matter how sophisticated the technology, it is still very difficult to predict how a compound will work in the complex environment of the human body.
To find out more, download our animal work in the licensing of medicines fact sheet (57Kb)
Before a licence can be granted, researchers have to prove that the use of animals is justified, and stick to clearly defined and strict regulations, designed specifically for this purpose.
The regulations set out the circumstances under which animal experiments can take place, as well as standards relating to welfare, humane treatment, staff qualifications, and facilities.
Find out more...
The Medical Research Council (MRC) (external link)
Coalition for Medical Progress (external link)
The Association of the British Pharmaceutical Industry (external link)
Home Office statistics (external link)