Biology

• Traditionally drugs were extracted from plants and microorganisms
• New drugs are being developed all the time by scientists at universities and drug companies around the world
• Lots of the medications that we use today are based on chemicals extracted from plants
• Medications based on chemicals extracted from plants


  • The heart drug digitalis originates from foxgloves
  • The painkiller aspirin originates from willow
• Penicillin was discovered by Alexander Fleming from the Penicillium mould
• Most new drugs are synthesised by chemists in the pharmaceutical industry. However, the starting point may still be a chemical extracted from a plant
• Penicillin was first discovered by Alexander Flemming in 1928. He left some Petri dishes that had been contaminated with mould and found the bacteria would not grow near the mould
• He discovered that the mould (Penicillium notatum) was releasing a chemical (penicillin) that killed the bacteria surrounding it
• New drugs are now developed by the pharmaceutical industry. Many of these still have plants as their source
• Testing New Drugs


  1. Toxicity - does it have harmful side effects?

  2. Efficacy - does the drug work?

  3. Dose - what dose is the lowest that can be used and still have an effect?
• The results of any testing are then peer-reviewed to make sure that the results are described accurately. The results would then be published in journals
• Developing New Drugs


  1. Preclinical testing is done in a laboratory using cells, tissues and live animals

  2. Clinical trials use healthy volunteers and patients

  3. Very low doses of the drug are given at the start of the clinical trial

  4. If the drug is found to be safe, further clinical trials are carried out to find the optimum dose for the drug

  5. In double-blind trials, some patients are given a placebo
• All new medicines in the UK have to have tests on 2 different animals by law
• Pharmaceutical companies are always looking to find new medications these include: Vaccinations to different diseases, Antibiotics that have a different action on the bacteria, so that bacteria are not resistant to them, Painkillers with fewer side effects, Antiviral drugs that don't damage the body's tissues
• Sources of these medications may be plants or microorganisms
• You should be able to describe the process of discovery and development of potential new medicines, including preclinical and clinical testing in the exam