people and medicine
page A 1.1
1. Molecule to medicine 2. Infections 3. Asthma
Early stages
Developing new pharmaceutical products is an ongoing quest. It can take up to twelve years and £350 m once a suitable method of treatment has been found.

People involved Number of compounds
Picture 3. A research scientist.
Picture 2. Roll your cursor over each stage in the process to see a summary about it. Click to go to more information.
Early research
Research Understanding a disease and determining a way to treat it can take up to twenty years. This research is going on all the time. Scientists will come up with a theory about what causes a disease. For example, the narrowing of airways that occurs during an asthma attack.

Target They will then target a part of the biological process that causes the problem. This might be a missing protein, a lack of a hormone or a defective gene. In the case of asthma, scientists knew that adrenalin acted as a bronchodilator and, although not suitable itself, they reasoned that a similar substance might work.

Discovery They will then look for or design suitable compounds which might prevent, treat or cure the disease. Sometimes these compounds are based on substances already produced in the body, or are developed from plant sources. Computers are very important in medical research because they are used to help design new compounds and to select those which look most promising.

It can take several years to get a group of likely compounds, and up to 10 000 possible new chemicals might be investigated.


A potential drug will only be selected for further research if it meets certain requirements:

  • it isn't poisonous
  • it will be effective against the disease
  • it won't break down too quickly in the body
  • no major problems can be foreseen for making it on a large scale.
Scientists will analyse compounds using computer models and laboratory tests to see if they match their theories for how to treat the disease.

Testing on animals. Click here to find out more about why this controversial stage is vitally necessary, and how scientists are trying to find alternative ways of testing new medicines.
Possible compounds which are selected must be tested thoroughly, to make sure they are both safe and effective. There are three stages of testing:
  • ‘in vitro’ tests
    This stage uses techniques such as cell culture to look at biological activity and to eliminate all but a few of the original possible compounds. Compounds that have obvious toxic effects can be eliminated at this stage. In vitro means "in glass" because the tests used to be done in glass test tubes or petri dishes. Now they are usually done in plastic blocks that have 96 wells in them.
  • ‘in vivo’ tests
    These are tests using laboratory animals, and they are a vital safety check. Because the bodies of other mammals work in similar ways to the human body, tests on animals show how the selected compounds are likely to react in the human body. The use of animals also gives important information about the dose level and how often to take a medicine.
Only once the compund has gone through these tests can it be given to humans in clinical trials.
As soon as a likely compound is found, the company applies for a patent. This is because it costs so much money to develop promising compounds. The patent protects the company against other companies marketing the same compound. The patent lasts for 20 years. However, because of the time taken to develop the product, it will only be protected for about ten years after it is launched.
Clinical trials
The chosen compound is tested on humans to check that there are no adverse side effects and to ensure that it does treat the disease. The clinical trials are in three phases:
Phase I Small numbers (20 to 80) of healthy volunteers take a short course of the new medicine. This is to look for factors such as:
  • lowest and highest dose
  • how long each dose works
  • side effects.

After Phase I trials, the company will ask the Medicines Control Agency for permission to run trials on patients with the target disease.

Phase II Longer term studies in healthy volunteers. Also, there are short term studies in several hundred patients (who have the target disease) to see how well the compound works on the disease.
Phase III Large scale studies in several thousand patients to look for statistical evidence that the compound is effective, what dosages will be required and potential side effects.
The company submits the results of these trials to the Medicines Control Agency when it applies for a licence to market the medicine.
Test yourself. Question A 1.1
How are potential medicines tested to make sure they are as safe as possible?

Text ©  GlaxoSmithKline