Discovering & Developing New Medicines
- Traditionally, drugs were extracted from plants and microorganisms
- New drugs are being developed all the time by scientists at universities and drug companies around the world
- All new drugs need to be tested and trialled before they can be used in patients. They are tested for:
- Toxicity – does it have harmful side effects?
- Efficacy – does the drug work?
- Dose – what dose is the lowest that can be used and still have an effect?
The three stages of drug development
- Preclinical testing
- The drug is tested on cells and tissues in the lab
- Computer models may also be used to simulate the metabolic pathways that may be taken by the drug
- Efficacy and toxicity are tested at this stage
- Whole organism testing
- The drug is tested on animals to see the effect in a whole organism – all new medicines in the UK have to have tests on two different animals by law
- Efficacy, toxicity and dosage are tested at this stage
- Clinical trials
- The drug is tested on human volunteers first, generally with a very low dose then increased. This is to make sure it is safe in a body that is working normally
- The next stage is to test on patients with the condition
- The patients are often split into two groups; one given the drug the other given a placebo. This is called a double-blind study – neither the doctor nor the patient knows if the patient is getting the placebo or the active drug
- Once the drug is found to be safe then the lowest effective dose is tested at this stage
Drug testing phases diagram
Examiner Tip
Be sure you know the definitions of keywords associated with the development of new drugs:
- Blind trial - the patient does not know whether they are taking the drug being tested or a placebo
- Double-blind trial - both the doctors and the patients do not know whether they are taking the drug being tested or a placebo (only the drug company will know)
- Blind and double-blind trials prevent bias in any results obtained
- Placebo - a substance administered like the drug but does not have any effects on the body
- Placebo effect - the patient/volunteer expects treatment to work and so 'feels better', even though they have not been given the drug (they have been given the placebo)