Detailed and comprehensive notes on clinical trails and drug testing (Edexcel biology A). [“A-Level Biology: Edexcel A Year 1 & 2 Complete Revision & Practice” (CGP, ISBN: 2986), “Salters-Nuffield AS/A level Biology Student Book 1” (Pearson, ISBN: 1007) and “Salters-Nuffield A level Biolo...
Clinical Trials and Drug Testing
Historic Drug Testing
• William Withering was a scientist in the 1700s.
• He discovered that an extract of foxgloves could be used to treat dropsy (swelling brought about by heart
failure). This extract contained the drug digitalis.
• Withering made a chance observation – a patient suffering from dropsy made a good recovery after being
treated with a traditional remedy containing foxgloves.
• Withering knew foxgloves were poisonous, so he started testing different versions of the remedy with
different concentrations of digitalis – this became known as his digitalis soup.
• Too much digitalis poisoned his patients, while too little had no effect.
• It was through this crude method of trial and error that he discovered the optimum dosage to give to a patient.
Modern Drug Testing
Pre-Clinical Testing
• Consists of laboratory studies on isolated cells and tissue cultures.
• Assesses the safety and determines whether the compound is effective against the disease.
• Can take several years to complete.
Clinical Trials – Phase 1
• Involves testing a new drug on a small group of healthy individuals (can be tested on patients in some cases).
• Confirms how the compound interacts with the human body, including side effects, and the effects of different
doses are monitored.
• Typically takes several months to a year.
Clinical Trials – Phase 2
• Involves testing the drug on patients and on a larger scale – around 100-300 people.
• Tests how effective the drug is and assesses appropriate dosing levels.
• Typically takes around 2 years.
Clinical Trials – Phase 3
• Involves testing the drug on a very large group of patients – around 1000-3000 people, and comparing the
drug to existing treatments.
• Demonstrates the safety and effectiveness of the drug, confirms effective dosing levels, identifies side effects
and builds knowledge on the benefits and risks of the treatment.
• Involves the use of a placebo in a double-blind trial.
• Typically takes several years.
Placebo:
• In phase 2 and 3 clinical trials, the patients are split into two groups: one group is given the drug and the other
is given an inactive substance that looks like the drug – a placebo.
• Patients often show a placebo effect – they show some improvements because they believe they are receiving
treatment.
• Placebos allow researchers to determine whether the drug is actually having an effect.
• It can be considered unethical to give a patient a placebo, when they could be given something that is likely to
improve their condition, however there is no guarantee that the drug is as effective as current treatments.
Double Blind Tests
• Phase 2 and 3 clinical trials are usually double blind – neither the patients nor the doctors know who’s been
given the drug and who’s been given the placebo (or old drug).
• This reduces bias in the results because the attitudes of the patients and doctors can’t affect the results.
How is Modern Drug Testing Safer than Historical Methods?
• Modern drug testing involves preliminary tests on isolated cells and tissue culture.
• Modern drug testing involves testing on healthy individuals before patients to reduce the risk to patients.
17
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller JunaidAli025. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for £0.00. You're not tied to anything after your purchase.
