2.18 Developing New Medicines

Question 1

What are most medicines made from?

Answer 1

Plants

Question 2

Aspirin is a common painkiller than is used for lowering fevers. What was it originally developed from?

Answer 2

A chemical found in the bark of willow trees

Question 3

In order to develop a new drug, what needs to be identified first?

Answer 3

A target that the drug will act upon

Question 4

What would the target of a medicine be?

Answer 4

The target is likely to be a gene or protein that is linked to the development or progression of the disease

Question 5

Once a target has been identified, what will scientists then have to do in the process of making medicines?

Answer 5

Scientists then have to find a chemical substance that will have the effect they want on the target (e.g. stop an enzyme from working). To do this, large libraries of chemical substances have to be screened (using very high-tech processes) to assess their likely effectiveness. The result of the screening is unlikely to find a chemical substance that will work exactly in the way the scientists want. Instead the most promising chemicals are selected and modified, and then undergo further tests.

Question 6

What are the three main things to keep in mind when testing drugs?

Answer 6

• Efficacy: how well the drug works (effect you’re looking for)
• Toxicity: how harmful the drug is (any side effects/damage to cells)
• Dosage: how much of the drug (concentration)

Question 7

Describe what happens in the preclinical stage of testing drugs (2)

Answer 7

• In preclinical testing, drugs are first tested on cultured human cells (cultured means that they’ve been grown in a lab). However, you can’t use human cells to test drugs that affect whole or multiple body systems, e.g. a drug for blood pressure must be tested on a whole animal.
• The next step is to test the drug on live animals. Both of these steps are used to test that the drug is effective and to find out how safe it is.

Question 8

Describe what happens in the clinical testing stage of testing new drugs (2)

Answer 8

• First, the drug is tested on healthy volunteers to make sure that it is safe i.e. that it doesn’t have any harmful side effects when the body is working normally. Then, successful drugs can be tested on people that have the disease, to test its effectiveness and safety.
• For many clinical tests, patients are randomly put into 2 groups. One is given the new drug, one is given a placebo. This is to allow for the placebo effect. Clinical trials may be blind - the patient in the study doesn’t know whether they’re getting the drug or the placebo. In fact, they’re often double-blind - neither the patient nor the doctor knows until all the results have been gathered. This is so the doctors monitoring the patients and analysing the results aren’t subconsciously influenced by their knowledge. Trials can also be open-label - the doctor and the patient are aware of who is receiving the drug. These might be used when comparing the effectiveness of two very similar drugs.

Question 9

What problem is there with using placebos in clinical tests?

Answer 9

There are ethical issues around giving a placebo to people with the disease instead of a potential treatment, especially if the disease has severe symptoms.

Question 10

Why are clinical tests sometimes double-blind?

Answer 10

It helps to avoid any bias by the patients or doctors. If patients know they received the drug, then they may be more likely to report side effects. If doctors know who has been given the real drug, then they may pay closer attention to those patients, and document their symptoms more carefully.

Question 11

What are scientists looking for when working with healthy volunteers during the clinical testing stage of testing medicines?

Answer 11

The maximum dosage they can give without any side effects

Question 12

What are scientists looking for when working with the diseased volunteers in the clinical testing stage of testing medicines?

Answer 12

The optimum dosage where the efficacy is maximised while the toxicity is minimised

Question 13

What happens to the results of testing new medicines once they are written up?

Answer 13

They are peer-reviewed by other scientists

Question 14

What does the term ‘efficacy’ mean?

Answer 14

How well a drug produces the desired effect

Question 15

What does the term ‘toxicity’ mean?

Answer 15

How harmful a drug is e.g. how many side effects

Question 16

What does the term ‘dosage’ mean?

Answer 16

How much of the drug is required to give the desired effect

Question 17

Describe the stages of testing new medicines in brief terms (4)

Answer 17

1) Stage 1 - Test the drug on human cells and tissues
2) Stage 2 - Test the drugs on live animals
3) Stage 3a - Test the drug on healthy volunteers to find the maximum dosage before side effects occur
4) Stage 3b - Test the drug on patients that suffer from the relevant disease, to find the optimum dosage

Question 18

Why is it important that new medicinal drugs undergo testing before they are used? (3)

Answer 18

• To determine the optimum dose
• To make sure they are safe to use
• To make sure they are an effective treatment

Question 19

In a double blind trial, who knows who is given the trial drug, and who is given the placebo?

Answer 19

Only the researcher

Question 20

What is a placebo?

Answer 20

A substance or treatment that contains no active drug