drugs

• 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
• Drugs from plants

  • The heart drug digitalis originates from foxgloves
  • The painkiller aspirin originates from willow
• Drugs from microorganisms

  • 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

  First discovered by Alexander Flemming in 1928
• Penicillin discovery

  1. Flemming left some Petri dishes contaminated with mould

  2. Found the bacteria would not grow near the mould

  3. Discovered 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

  • Toxicity - does it have harmful side effects?
  • Efficacy - does the drug work?
  • 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 - 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
• Stages of drug development

  • Preclinical Testing
  • Whole organism testing
  • Clinical trials
• 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
• Drug testing

  1. Computer models

  2. Skin cells grown using human stem cells

  3. Test for efficacy and possible side effects
• Many substances fail this first test of a preclinical drug trial because they damage cells or do not seem to work
• Preclinical drug trial - second part

  1. Test on animals

  2. Give known amount of substance

  3. Monitor for side-effects
• In the UK, new medicines have to undergo these tests
• It is illegal to test cosmetics and tobacco products on animals
• Human clinical trials

  1. Test on healthy volunteers to check safety

  2. Test on people with illness to ensure safety and efficacy

  3. Start with low doses, increase to optimum dosage