Development of Drugs & Drug Testing (Edexcel International A Level Biology): Revision Note

Development of Drugs & Drug Testing

• Whenever new drugs are developed, they first need to be tested for effectiveness and side-effects, before they can be sold to the general public

• These are known as clinical trials and are crucial to avoid exposing the public to drugs that may pose a risk to their health

• Drug testing has not always been this scientific or regulated in the past

Digitalis soup

• William Withering was an English scientist from the 1700s

• He is best known for his work on using digitalis as a treatment for swelling caused by heart failure (known as dropsy)

• Withering treated his patients with an extract made from foxgloves, which contains the drug digitalis

• Foxglove is poisonous to humans, so he made different versions of his remedy containing different concentrations of digitalis

• These versions were called his digitalis soup

• He experimented on his patients to find the most effective concentration of digitalis that would treat dropsy without poisoning the patient

Modern methods of drug testing

• Modern drug testing protocols are much more rigorous than those of the past

• The first step is modelling the potential effects of the drug, using computers

• Next, the drug will be tested on human tissues in a laboratory, before being tested on animals

• Should the drug pass these steps without causing any major problems, then it will continue to the clinical trial stage where human test subjects will take it

• There are three phases of testing during clinical trials:

  • Phase 1 involves a small group of healthy individuals to determine how the body will react to the drug, the side effects of the drug and the correct dosage that should be taken

  • Phase 2 will be done on a larger group of patients (non-healthy individuals who require the drug) to determine the effectiveness of the drug

  • Phase 3 involves comparing the drug to existing drugs to see if it works any better. A large number of patients are split into two groups, each of which receives either the new drug or the existing one

Placebos

• Placebos are typically done during phase 2 of a clinical trial

• Patients are split into two groups - one will receive the drug and the other group will be given a placebo, which looks exactly like the drug but contains no active ingredients

  • The patients are not told which group they are in

• This provides a way for scientists to determine whether the drug actually works

• Certain patients display what is known as the placebo effect 

  • This is where a patient will show improvements in their health due to the belief that they are receiving the drug

Double blind studies

• These happen during phase 2 and 3 of clinical trials

• Double blind means that neither the patient nor the doctor knows which patient is receiving the drug or the placebo

• This reduces the effect that the attitude of either doctor or patient may have on the results

  • For example, in some cases, a doctor may believe a patient is improving more if they know the patient is receiving the drug