Discovery and development of drugs

• Traditionally, drugs were extracted from plants and microorganisms.

  • 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 made by chemists in the pharmaceutical industry. However, the starting point may still be a chemical extracted from a plant
• New medical drugs need to be tested and trialled to:

  • make sure they’re safe for people to use
  • make sure they’re effective
• A drug’s toxicity is a measure of how harmful the drug is to the person taking it
• A drug’s efficacy is a measure of how well the drug works
• A drug’s dosage is how much of, and how often, the drug should be taken.
• During preclinical testing of a new drug, cells, tissues and live animals are used to test the drug’s toxicity, efficacy and dosage.
• During clinical trials of a new drug, healthy volunteers and patients test the drug.

  Trials start with a very low dose - if the drug’s safe, more trials find the optimum dosage.

  double blind trials then test the drug’s efficacy against a placebo
• A new drug is tested against a placebo to check that the drug actually works and it’s not the placebo effect
• In a double blind trial of a new drug, the testers are randomly split into two groups - one group gets a placebo and the other gets the new drug. Nobody knows who got what, not even the scientists running the trial, until the trial ends
• Benefits of a double blind trial of a new drug

  • It minimises the placebo effect
  • it reduces the chance of a scientist influencing the results - either subconsciously or on purpose
• The results of a new drug’s test and trials are only published after peer review to prevent false claims about the drug being made