Drugs in Medicine (Cambridge (CIE) IGCSE Biology): Revision Note

What is a drug?

Drug definition

• A drug is any substance taken into the body that modifies or affects chemical reactions in the body

• Some drugs are medicinal drugs that are used to treat the symptoms or causes of a disease - for example, antibiotics

  • The liver is the primary site for drug metabolism

Antibiotics

What are antibiotics?

• Antibiotics are chemical substances made by certain fungi or bacteria that affect the working of bacterial cells, either by disrupting their structure or function or by preventing them from reproducing

• Antibiotics are effective against bacteria but not against viruses

• Antibiotics target processes and structures that are specific to bacterial (prokaryotic) cells; as such they do not generally harm animal cells

Antibiotic resistance & use: extended

• Commonly prescribed antibiotics are becoming less effective due to a number of reasons:

  • overuse and being prescribed when not really necessary

  • patients failing to complete the fully prescribed course by a doctor

  • large scale use of antibiotics in farming to prevent disease when livestock are kept in close quarters, even when animals are not actually sick

• This has led to the effectiveness of antibiotics being reduced, and the incidence of antibiotic resistance increasing

• These bacteria are commonly known as 'superbugs' and the most common is MRSA

How to prevent antibiotic resistance

• Ways individuals can help prevent the incidence of antibiotic resistance increasing include:

  • only taking antibiotics when absolutely essential

  • ensuring that the entire course of antibiotics prescribed is completed even if they feel better after a few days