Testing new medicines: from laboratory to clinic: Understand the rigorous process of drug development including preclinical testing using cells, tissues and…
Testing new medicines: from laboratory to clinic is part of Communicable diseases in GCSE AQA Higher Biology.
4 min
Reading time
17
Lessons in this topic
GCSE AQA Higher
Pathway
Reviewed by Revise Right
Content review
Testing new medicines: from laboratory to clinic: Understand the rigorous process of drug development including preclinical testing using cells, tissues and…
Use this lesson to stay inside Communicable diseases while connecting the detail back to the wider Infection and response topic.
Read the core explanations from Testing new medicines: from laboratory to clinic before testing yourself from memory.
Every medicine in your local pharmacy has survived a brutal 10-15 year testing process. Why so long? Because one mistake could harm millions of people. The thalidomide disaster of the 1960s - where a 'safe' morning sickness drug caused severe birth defects - changed everything. Now every potential medicine must prove it's both safe and effective before reaching patients.
Think of drug development like building a bridge. You wouldn't let cars cross without testing the materials, checking the design, and gradually increasing the load. The same logic applies to medicines - we start small and work up to human trials only when we're confident it won't cause harm.
Before any human volunteers get involved, scientists test potential medicines in the laboratory. This preclinical testing happens in three stages, each more complex than the last.
Stage 1: Cell cultures - Scientists grow human cells in petri dishes and test whether the drug kills the target disease cells without harming healthy ones. This is quick and cheap, but cells in a dish behave differently from cells in a living body.
Stage 2: Tissue samples - Next, they test on small pieces of human tissue (like skin or liver samples). This gives a better idea of how the drug affects groups of cells working together, but still doesn't show the full body response.
Stage 3: Live animals - Finally, they test on animals (usually mice, then larger mammals). This reveals how the whole body processes the drug - does it reach the right organs? Does it cause unexpected side effects? How quickly is it broken down?
Every stage of testing focuses on three crucial questions. Get any of these wrong, and the drug fails.
Toxicity - Is it poisonous? Even water can kill you if you drink too much, so scientists need to find the dose where the medicine helps without causing harm. They test increasing doses until they find the level that causes problems - this sets the safety limit.
Efficacy - Does it actually work? A medicine might be perfectly safe but completely useless. Scientists compare treated groups with untreated controls to see if the drug makes a real difference to the disease.
Dose - How much should patients take? Too little and it won't work. Too much and it becomes toxic. Scientists test different amounts to find the 'Goldilocks zone' - just right for maximum benefit with minimum side effects.
Once preclinical tests show promise, the drug moves to clinical trials. This is where things get serious - real people are involved, so the safety protocols become even stricter.
Worked example: The Three Phases of Clinical Trials
A new painkiller has passed all preclinical tests. Describe how it would progress through clinical trials.
Answer: The drug progresses from small safety trials to large effectiveness studies before regulatory approval.
Why start with healthy volunteers? This might seem backwards - why not test directly on patients who need the medicine? The answer is ethics. Healthy volunteers can give proper informed consent without the desperation of illness clouding their judgment. Plus, if something goes wrong, their bodies are better equipped to cope.
Drug development questions often ask you to sequence the stages or explain why each stage is necessary. Here's how to tackle them like a pro.
Common exam mistake: Students often say animal testing is 'cruel' or 'unnecessary' in exam answers. While these are valid ethical concerns, exam questions want scientific explanations. Focus on why each stage provides essential safety data that can't be obtained any other way.
6-mark question structure: If asked to evaluate the drug testing process, mention both benefits (prevents harmful drugs reaching market, ensures effectiveness) and limitations (time-consuming, expensive, animal welfare concerns). Always conclude with a judgment about whether the benefits outweigh the costs.
Published by Revise Right. Use the official specification reference to check the requirements for your course. Content updated: 2026-03-20.
Move to the related lessons or back to the topic page when you need the wider sequence before exam-style practice.
Stage 1: Cell cultures - Scientists grow human cells in petri dishes and test whether the drug kills the target disease cells without harming healthy ones. This is quick and cheap, but cells in a dish behave differently from cells in a living body.
By the end of this lesson, you should be able to Describe the stages of drug development from laboratory to clinic; Explain why preclinical testing uses cells, tissues and animals; Compare the purposes of different phases of clinical trials; Evaluate the importance of testing for toxicity, efficacy and dose.
Read each section, then close the notes and explain the idea from memory. Check your explanation against the page and finish with an exam question from Infection and response.