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

• 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 work

• 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 resistance