Testing New Drugs

Section 1 of 7What testing must show

Toxicity

• Toxicity Is the drug harmful, and what side effects does it cause?
• A drug is only useful if its benefits clearly outweigh any harm it does.

Efficacy

• Efficacy Does the drug actually work against the condition?
• It must produce a bigger improvement than no treatment or a placebo.

Dose

• Dose What is the lowest dose that still gives a benefit?
• Too low a dose does nothing, while too high a dose raises the risk of side effects.

Review

• Review Results are checked by other scientists (peer review) and then published in journals.
• Other laboratories can then repeat the work to confirm the findings.

Section 2 of 7Stages of development

1Preclinical

• Preclinical Tested on cells and tissues in a laboratory, and by computer models, for toxicity and efficacy.

2Animal testing

• Animal testing Tested on live animals, in the UK on two different species by law, to see effects on a whole organism,
  • including how the drug is absorbed and removed.

3Clinical trials

• Clinical trials First healthy volunteers receive a very low dose to check safety, then the dose is raised gradually.

4Patient trials

• Patient trials Patients with the condition then test doses to find the best one and to confirm that the drug works.

Section 3 of 7Running a fair clinical trial

1

Recruit a large group of patients with the condition, chosen to have similar age, sex and severity of illness.

2

Split them at random into two groups, one given the drug and the other a placebo that looks, tastes and is taken in exactly the same way.

3

Make it a double-blind study: neither the patients nor the doctors know who has which until the end.

4

Measure the same outcome in every patient over the same period, for example blood pressure or number of symptoms.

5

Compare the improvement in each group and look for a real difference that is larger than chance would explain.

6

Have the results checked by independent scientists before the drug is approved for general use.

Section 4 of 7Why each feature is used

Feature	Purpose
Placebo	Shows whether improvement is caused by the drug and not by belief in treatment
Double-blind	Stops bias in how patients report effects or how doctors judge them
Large sample	Makes the results more reliable and less affected by chance
Random allocation	Spreads differences between people evenly across both groups
Starting with a low dose	Protects volunteers from harm if the drug is more toxic than expected
Peer review	Independent experts check the methods and conclusions before publication

Section 5 of 7Worked example: interpreting a trial

Trial of a new blood pressure drug

Set-up

• Set-up 200 patients are split randomly into 100 on the drug and 100 on a placebo for 12 weeks.

Result

• Result Average blood pressure falls by 15 mmHg in the drug group and by 3 mmHg in the placebo group.

Conclusion

• Conclusion Subtracting the placebo effect, the drug appears to cause a fall of about 12 mmHg, which suggests it is effective.

Next steps

• Next steps Side effects are compared, and other scientists review the data before the drug is approved.

Section 6 of 7Key terms

Term	Meaning
Toxicity	How harmful a substance is to the body.
Efficacy	How well a drug produces its intended effect.
Placebo	A dummy treatment that contains no active drug.
Double-blind trial	A trial in which neither patients nor doctors know who gets the real drug.
Peer review	Evaluation of scientific work by independent experts before it is published.
Clinical trial	A test of a new drug on human volunteers or patients.

Section 7 of 7Exam technique

1

Saying a placebo is a weaker version of the drug. It contains no active ingredient at all.

2

Describing a single-blind trial as double-blind. Both patients and doctors must be unaware.

3

Giving the first human dose as a high one. Early doses are very low.

4

Forgetting that animal and cell tests come before any human trial.

5

Judging a drug from a small trial. Large samples are needed for reliable conclusions.