• Question: How comes that some drugs are good for you and some are bad?What chemical does a drug have that makes it bad?

    Asked by glama786 to Alastair, Hywel, Keith on 25 Jun 2010 in Categories: .
    • Photo: Keith Brain

      Keith Brain answered on 24 Jun 2010:


      I’m assuming that by drugs you mean any chemical you might take that affects the body but isn’t food, so this includes medicines. Most drugs are just fairly simple molecules. No one chemical makes all drugs bad, otherwise we’d just leave it out!

      Often, what makes a drug good also makes it bad! Drugs act at specific sites in the body called receptors. Different drugs bind to different receptors and so they can have different effects. Whether it’s a good or bad effect really depends on what is happening in the body at that time and where the drug gets to.

      For example, a drug called lignocaine is used to stop pain locally (you will have had it injected just under your skin in you have ever had stitches), which is good. If you have an irregular heart beat it might be injected into your vein, travel to your heart, and make it regular – which would be good. However, the same injection into a normal person would be bad, because it would slow and could even stop the heart.

      Also, the dose of drugs is very important. There is an important drug called warfarin, which was developed as a very effective rat poison. It stops blood clotting and will kill people if too much is given. However, in small doses it is one of the most effective ways we know for altering blood clotting and stopping heart attacks; a work colleague of mine is taking it regularly.

      So, drugs are not good or bad, but their effects will vary according to how much is given, how it is given, and the state of the body at the time.

      One final example – diamorphine is very effective, fast acting pain killer still used by some doctors in the UK. However, taking it can lead to addiction and too much causes death – its other name is heroin!

    • Photo: Hywel Vaughan

      Hywel Vaughan answered on 25 Jun 2010:


      I think that Keith has pretty much covered all bases here Glama!
      There is no one thing that makes drugs good or bad, like most things too much of a good thing can be quite bad for you!
      The effect of drugs relies on how your body reacts and how much of the drug is given. 🙂
      Nicely said Keith! Clearly your expertise here. 🙂

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