biology B1 (1)

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  • Created by: haidee
  • Created on: 01-04-12 16:29


  • a drug is a substance that alters the way in which our body works
  • it could affect your mind, body or both
  • some drugs are used for pleasure or recreation and others are used as medicines
  • some such as painkillers and antibiotics are mostly beneficial to humans but can cause harm if not used properly
  • others such as tobacco and cannabis which some people use to relax, increase the rick of ill health considerably
  • people have been using drugs for thousands of years
  • people made beer in Babylon 8000 years ago
  • Egyptian hieroglyphics picture writing about alcohol and it affects 4000 years ago
  • indigenous people found ways of using natural substances found in local plants
  • 500 years ago the Incas in the Andes, South America chewed coca leaves as it stopped them feeling hungry and helped them to work hard in difficult places
  • today we get anaesthetics and cocaine form the coca plant
  • south American Indians used the bark of the cinchona tree to treat Malaria as this contains quinine which can be used to treat a wide range of conditions including malaria

Developing new medicines

  • every new medicinal treatment has to be tested and trailed
  • a good medicine is: effective- must prevent or cure the disease it is aimed at, safe- the drug must not be toxic and have no unacceptable side effects, stable- you must be able to use the drug under normal conditions and store it for some time, excreted from the body- the drug must be able to reach the target area of the body and then be broken down safely and excreted (removed from the body)
  • it can take up to 12 years to bring a new medicine into the doctor's surgery and cost up to £350 million

1. researchers target a particular disease

2. researchers may screen hundreds of thousands of chemicals

3. possible drugs are made from the most successful chemical compounds

4. the potential medicines are tested on isolated cells and tissues cultures in the lab, this is called in Vitro testing

5. a small number of chemicals which make it this far are then tested on animals, this finds out how they work on whole organisms and tells us what dose could be used and any possible side effects

route 1: animals testing long term to see the long term effects of the medicine

route 2: phase 1- clinical trials on a small number of healthy volunteers used to look at the safety of the medicine in humans, phase 2- a small number of patients suffering from the disease are used to see of the drugs is safe and effective, phase 3- a larger number of patients are used and their progress is monitored

  • a medicine is granted a licence and doctors can now use it to treat patients
  • the medicine is still monitored to make sure that it is safe

Double blind trial

  • in human clinical trials scientists use a double blind trial to see *** effective the new treatment…


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