Drugs - Fighting Disease

• Some drugs relieve symptoms - others cure the problem
• Painkillers (e.g. aspirin) are drugs that relieve pain. However, they don't actually tackle the cause of the disease of kill pathogens, they just help to reduce the symptoms
• Other drugs apart from pain killers do a similar thing - reduce the symptoms without tackling the underlying cause. E.g. lots of 'cold remedies' don'y actually cure colds
• Antibiotics (e.g. penicillin) work different to paint killers - they actually kill (or prevent the growth of) the bacteria causing the problem without killing your own body cells
• Different types of antibiotics kill different types of bacteria, so it's important to be treated with the right one
• Antibiotics don't destroy viruses (e.g. flu virus). Viruses reproduce using your body cells, which makes it very difficult to develop drugs that destroy just the virus without killing the body's cells
• The use of antibiotics has greately reduced the number of deaths from communicable diseases caused by bacteria
• Bacteria can become resistant to antibiotics
• Bacteria can mutate - sometimes the mutations cause them to be resistant to an antibiotic
• If you have an infection, some of the bacteria might be resistant to antibiotics. This means that when you treat the infection, only the non-resistant strains of bacteria will be killed
• If you take antibiotics and a strain of the bacteria is resistant to it, the individual resistant bacteria will survive and reproduce, and the population of the resistant strain will increase. This is an example of natural selection
• A resistant strain could cause a serious infection that can't be treated by antibiotics. E.g. MRSA causes serious wound infections and is resistant to the powerful antibiotic meticillin
• Many drugs originally came from plants
• Plants produce a variety of chemicals to defend themselves against pests and pathogens. Some of these chemicals can be used as drugs to treat human diseases or relieve symptoms
• A lot of our current medicines were discovered by studying plants used in traditional cures:

  • Aspirin is used as a painkiller and to lower fever. It was developed from a chemical found in willow
  • Digitalis is used to treat heart conditions. It was developed from a chemical found in foxgloves
• Some drugs were extracted from microorganisms:

  • Alexander Fleming was clearing out some Petri dishes containing bacteria. He noticed that one of the dishes of bacteria also had mould on it and the area around the mold was free of bacteria
  • He found that the mould (called penicillium notatum) on the Petri dish was producing a substance that killed the bacteria - this substance was penicillin
• These days, drugs are made on a large scale in the pharmaceutical industry - they're synthesised by chemicals in labs. However, the process still might start with a chemical extracted from a plant