New Medicines (WJEC GCSE Biology: Combined Science)

• 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

Risks

• Risks of developing new drugs include side effects that present themselves in patients even after extensive testing has been carried out 
  • Often new side effects and harmful effects do not show up until lots of people are taking the new drug

Benefits

• Drug testing allows large-scale data collection to further develop new and improved drugs whilst minimising the risks
• Overall, the benefits of developing new drugs often outweigh the risks

Ethical issues

• Testing drugs on live animals raises some ethical issues
• It can be considered cruel to test drugs on animals as it can cause pain and distress to the animals
  • Animals are often kept in small unnatural laboratory cages 
  • The drugs may cause harmful effects to the animals being tested
• Some people think it is necessary to test on live animals to ensure the safety of humans
• Some people think it is ok to test on animals as laboratories adhere to strict protocols ensuring animals' basic needs are met and looked after
• New technologies have been and continue to be developed that give alternatives to testing on animals
  • Using computer models is one example of how a drug can be tested without the need for animal testing
  • It is thought that new technologies could supersede the need for animal testing; this would be beneficial as testing on an animal is not a foolproof way to ensure the safety of a new drug on humans, as animals will metabolise medications differently to humans