Discovery and development of drugs

• Drugs were traditionally extracted by plants and microorganisms:

  • The painkiller aspirin originates from willow
  • The heart drug digitalis orginates from foxgloves
  • Pencillin was discovered by Alexander Fleming from the Penicillium mould - area around mould was free from bacteria
• • Most new drugs are synthesise by chemists in the pharmaceutical industry
  • The process may still start with a chemical extracted from a plant
• • New drugs have to be tested and trailled before being used to check they are safe and effective
  • New drugs are tested for toxicity, efficacy and dose
• Drug Testing:

  The three main stages are:

  1. Preclinical testing
  2. Testing on live animals
  3. Clinical trial
• Preclinical testing:

  • Testing drugs on cells and tissues
  • Human cells and tissues cannot test for drugs that affect whole or multiple organ systems
• Testing on live animals:

  • Tests for efficacy - whether drug works and produces desired effects
  • Tests for toxicity - how harmful drug is
  • Tests for best dosage - concentratiin and how often to be given
• • Testing on live animals can be seen as cruel
  • Some think animals are too different from humans to produce any beneficial research
  • Some think testing on animals is safest way to make sure drug isn't dangerous before given to humans
• • clinical trials are blind - sometimes double blind, so doctors are not subconsciously influenced by own knowledge
  • Results aren‘t published until after peer review - helps to prevent false claims
• clinical trial:

  • given first to healthy volunteers to test for side effects
  • healthy volunteers given low dose at first
  • then given to people suffering from illness in double blind trial
  • to test for optimum dose and for efficacy
  • neither doctor or patient knows who has placebo
  • large trial to confirm efficacy of drug