development and use of drugs

• sources of new antibodies

  new drugs are needed because :

  • new diseases are emerging
  • there are still many diseases for which there are no effective treatments
  • some antibiotic treatments are becoming less effective

  new medicine can be discovered in a number of ways
• Accidental discovery

  antibiotic penicillin was an accidental discovery by Alexander Fleming - well documented

  • the fungus Penicillin releases compounds that kill bacteria
  • classic example of how science works - a scientist makes an observation + sets out to explain what he or she had seen

  →it was the work of Florey and Chain, who purified penicillin, that really demonstrated the potential value of antibiotics

  →showing how important it is for scientist to work together
• Traditional remedies

  • morphine has its origins in the use of sap from unripe poppy seed-heads; opium from poppies was used as an anaesthetic + 19th century morphine + opium were being used

  → these opiate drugs reduce nervous action in the central nervous system; if the nerves can’t carry impulses, then no pain is felt

  • medicinal use of willow-bark extract to relieve pain + fever has a long history

  →after discovery of its active ingredient, a way was later found to reduce side effect of stomach bleeding, by adding an acetyl group, leading to the development of the drugs aspirin + ibuprofen
• Observation of wildlife

  many animals make use of plants with medicinal properties

  • e.g. monkeys, bears + other animals rub citrus oils on their coats as insecticides + antiseptics in order to prevent insect bites and infection
  • birds line their nests with medicinal leaves in order to protect chicks from blood-sucking mites
• Further plant research

  • scientists isolate the active ingredient found in plants for traditional remedies

  →can be then analysed + similar molecules can be manufactured

  • new chemical fingerprinting technology enables scientists to screen natural chemicals more effectively for their activity as potential medicines
• Research onto disease-causing mechanisms

  pharmaceutical companies conduct research on how microorganisms cause disease

  • many make use of plasma membranes e.g HIV virus binds to CD4 + CCR5 receptors on surface Th cells
  • if binding between pathogen + receptor site can be blocked, then disease-causing pathogen cannot gain access to the cell

  →the glycoprotein receptor molecules can be isolated + sequenced + once amino acid sequence is known, molecular modelling can be used to determine of receptor
• Research onto disease-causing mechanisms 2

  • next step is to find drug that mimics shape of receptor + could be used to find virus itself, which would block virus from entering T helper cells

  → in a similar way, drugs that inhibit action of certain enzymes can also be developed
• Personalised medicine

  sequencing technology + molecular modelling have huge potential for future medicine

  • it is possible to screen genomes of plants for microorganisms to identify potential medicinal compounds from DNA sequences

  →once technology is fully developed, maybe possible to sequence genes from individuals with a particular condition to develop specific drugs for the condition; known as personalised medicine
• Synthetic Biology

  • molecules mimicking biological systems is one form of synthetic biology
  • another way synthetic biology is used is to design to construct new devices + system that may be useful in research, healthcare or in manufacturing e.g. development of tomatoes which contain pigment anthocyanin

  →this pigment is found in fruit such as blueberries + specific health benefits; they are antioxidants + help protect against coronary heart disease
• Antibiotic use + abuse

  antibiotics prevent growth of fungi or bacteria

  • most antibiotic currently in use as derivation of a compound made by bacteria from genus Streptomyces
  • overuse + misuse of antibiotics have enabled microorganisms to develop resistance, and many current antibiotics have limited effectiveness as a result

  → some bacteria have become infamous for their multiple to a range of antibiotics including Clostridium difficile (C. diff) + methicillin-resistant Staphylococcus aureus