New medicines (AQA GCSE Biology Combined Science): Revision Notes
New medicines
New medicines need to be carefully tested before doctors can use them. Scientists must check that new drugs are safe and work properly to treat diseases.
What are medical drugs?
A medical drug is a substance that treats the cause of a disease or helps reduce its symptoms. These medicines help our bodies fight illness and feel better.
In the past, people found drugs by extracting them from plants and microorganisms found in nature. However, most modern medicines are now synthesised, which means scientists create them using chemical reactions in laboratories. This allows pharmaceutical companies to make large amounts of medicine quickly and consistently.
The shift from natural extraction to synthetic production has revolutionised medicine manufacturing. While natural sources provided the foundation for many important drugs, synthetic production allows for precise control over quality, quantity, and consistency of medicines.
Traditional sources of drugs
Many important medicines originally came from natural sources. Here are some key examples you should know:
Digitalis comes from foxglove plants and helps treat irregular heartbeat problems. Aspirin was first made from willow bark and leaves - it helps reduce aches and pains. Penicillin comes from a special type of mould called Penicillium and fights bacterial diseases.
Penicillin is particularly important because Alexander Fleming discovered it in 1928. This discovery revolutionised medicine because it was one of the first effective treatments for serious bacterial infections.
Traditional Drug Sources:
- Digitalis → Foxglove plants → Treats irregular heartbeat
- Aspirin → Willow bark and leaves → Reduces pain and inflammation
- Penicillin → Penicillium mould → Fights bacterial infections
Each of these natural sources provided compounds that became the foundation for life-saving medicines.
Drug testing process
Before any new medicine can be given to patients, it must go through extensive testing. Scientists need to find out three crucial things about each drug:
- Toxicity - how poisonous or harmful the drug might be to the human body
- Efficacy - how well the drug actually works at treating the disease
- Dose - exactly how much of the drug patients need to take for it to be effective
All three factors - toxicity, efficacy, and dose - must be thoroughly understood before any drug can be approved for human use. Missing or inadequate testing in any of these areas can lead to serious health consequences for patients.
Preclinical testing
This is the first stage of testing new drugs. Scientists test promising new substances in laboratories using cultures of cells and tissues. If the drug shows good results, they then test it on live animals to check for safety.
Laboratory testing helps scientists understand how the drug works and whether it might be safe enough to try on humans later. This stage can take several years and involves extensive research to ensure the drug shows promise before moving to human trials.
Clinical trials
Once preclinical testing is complete, the drug moves to clinical trials where real people are involved. This happens in careful stages to keep everyone safe.
First, very small doses are given to healthy volunteers to check the drug doesn't cause harmful side effects in humans. If the drug proves safe, scientists then give different doses to patients who actually have the disease. This helps them find the optimum dose - the amount that works best to treat the condition.
Placebo effect and double-blind trials
Sometimes people feel better after taking medicine simply because they expect it to work, even if the medicine contains no active ingredients. This is called the placebo effect.
To make sure new drugs really work, scientists use double-blind trials. In these trials, some patients get the real drug while others get a placebo (a fake medicine that looks identical but contains no active ingredients). Importantly, neither the patients nor the doctors know who is getting which treatment until after the trial ends.
Double-blind trials are essential for accurate drug testing. Without this method, it would be impossible to determine whether a drug's effectiveness is real or simply due to patients' expectations. This could lead to ineffective drugs being approved for use.
This method helps scientists see the true difference between patients who received the real medicine and those who got the placebo. It ensures that any improvement is really due to the drug and not just people expecting to feel better.
Key Points to Remember:
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Medical drugs treat diseases or reduce symptoms - they can come from natural sources or be made synthetically in laboratories
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All new drugs must be tested for toxicity (harm), efficacy (effectiveness), and correct dose before being used on patients
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Drug testing has two main stages: preclinical testing (in labs with cells and animals) followed by clinical trials (with real people)
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Double-blind trials use placebos to make sure drugs really work and aren't just making people feel better because they expect to improve
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Important traditional drugs include penicillin (from mould), aspirin (from willow bark), and digitalis (from foxglove plants)