CIE IGCSE Biology: 复习笔记:15.1.1 Drugs for Medicine

CIE IGCSE Biology: 复习笔记:15.1.1 Drugs for Medicine

What is a Drug?

  • 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 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.


How-antibiotics-workHow antibiotics work

Antibiotic Resistance & Use: Extended



  • Since the first antibiotic was discovered in 1928, many more have been discovered and developed and antibiotics were and are widely overused
  • 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
  • Ways individuals can help prevent the incidence of antibiotic resistance increasing include:
    • only taking antibiotics when absolutely essential
    • when prescribed a course of antibiotics, ensure that the entire course is completed even if you feel better after a few days



Antibiotic_resistanceAntibiotic resistance