FreeScienceLessons · AQA BiologyDrug Testing and Development
Key facts
Drug development and testing
New drugs must be tested for safety (toxicity, side effects), efficacy (does it work?), and dosage.
Preclinical testing — tested on cells, tissues and live animals before human trials.
Clinical trials: Phase 1 = small group of healthy volunteers (safety). Phase 2 = small group of patients (efficacy + dosage). Phase 3 = large group of patients (compared to existing treatment or placebo).
Double-blind trial — neither the patient nor the doctor knows who receives the drug or placebo. Eliminates bias.
Placebo — an inactive treatment. Patients taking it may still improve (placebo effect) — the trial must account for this.
Thalidomide — prescribed as a sleeping pill in the 1950s. Found to cause birth defects when taken in pregnancy. Now used to treat leprosy and some cancers. Led to much stricter drug testing.
Monoclonal antibodies — production
Lymphocyte (produces a specific antibody) + tumour cell → hybridoma cell.
Hybridoma cells divide rapidly and produce many identical antibodies (monoclonal).
All antibodies are specific to the same antigen.
Uses: pregnancy tests, cancer diagnosis, cancer treatment (attached to radioactive substance or drug to target tumour cells), research.
Exam questions — 3 questions · 11 marks
⚡ Extended questions included. Read the hint. Write in full sentences. AI marks against the AQA mark scheme.
1 markDouble-blind trialAQA 8461 P1 style
Why is a double-blind trial used when testing a new drug?
A So the drug company does not know the results until the trial is finished
B To ensure neither the patient nor the doctor knows who is receiving the drug or placebo, eliminating bias from both sides
C So the drug can be tested on twice as many patients
D To test two different drugs against each other simultaneously