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Option 9.7 - Pharmaceuticals: 3. Pharmaceuticals can stop messages or stop the inflammation response

Syllabus reference (October 2002 version)
3. When some pharmaceuticals are introduced into the circulatory system they can stop messages moving across the synapse or stop the inflammation response continuing.	Students learn to: identify that inflammation can be caused by injury infection trauma environmental conditions explain that inflammation is a complex response by blood and blood vessels to injury is essential for life and preservation of function can cause tissue damage and loss of function explain the advantages and disadvantages of inflammation outline the role of prostaglandins in magnifying the inflammation response describe pain as a an interpretation by the brain of messages from nerves sent across synapses from the injury site to the brain identify that the principal ingredient in aspirin is acetyl salicylic acid, which belongs to a group of pharmaceuticals called analgesics, commonly called ‘pain killers’ explain the relationship between the relief of pain by aspirin and the inhibition of the production of several different chemical processes in the body including prostaglandins signal crossing the synapse	Students: gather, process, analyse and present diagrammatic information to relate the physiological responses to damage such as swelling, redness and fever due to: small blood vessels becoming enlarged and causing more blood to flow to the area fluids moving out of the small blood vessels into the damaged tissues white blood cells becoming attracted to the damaged tissues white blood cells releasing chemicals such as histamine and prostaglandins, which promote the process of inflammation increase in body temperature if a large or significant area is involved plan, choose equipment or resources and perform a first-hand investigation to use available evidence to determine the rate of solubility of a range of analgesics and to relate their solubility to dispensing form soluble enteric-coated capsule

Extract from Senior Science Stage 6 Syllabus (Amended October 2002) © Board of Studies, NSW.
[Edit: 16 Sep 08].

Prior Learning: Stages 4-5 Syllabus, Outcome 4.8 (content 4.8.5a) and Outcome 5.8 (content-5.8.4a).

Background: Pharmaceuticals have been used for thousands of years but how they worked wasn’t known. Modern research is now enabling us to know how the pharmaceuticals work. This has enabled pharmaceuticals to be developed that are more specific and have fewer side effects.

identify that inflammation can be caused by

• injury
• infection
• trauma
• environmental conditions

• Inflammation is a localised protective response by body cells produced as a result of physical injury (trauma), destruction of tissue, or infection by microorganisms.
  
  
• Inflammation can also be caused by environmental conditions such as extremes of heat and cold or exposure to harmful chemicals or allergens.

gather, process, analyse, and present diagrammatic information to relate the physiological responses to damage such as swelling, redness and fever due to:

• small blood vessels becoming enlarged and causing more blood to flow to the area
• fluids moving out of the small blood vessels into the damaged tissues
• white blood cells becoming attracted to the damaged tissues
• white blood cells releasing chemicals such as histamine and prostaglandins, which promote the process of inflammation
• increase in body temperature if a large or significant area is involved

• Gather information from health books and from the Internet. Either photocopy drawings or photographs or even better redraw diagrams or draw them from descriptions. Do the drawings in pencil and then colour them, put them on overhead projection sheets or do them on your computer. Make them quite large, for example an A4 sheet as a minimum size for each drawing. Each diagram should have a caption with it. You might choose to do cartoon diagrams.
  
  
• Process the information by organising the diagrams in a logical sequence. Make sure that the information is accurate by cross checking information from various sources.
  
  
• Analyse the information in the diagrams to make sure the information in all the dot points agrees with the rest and that it has been expressed in a succinct and clear manner to relate the physiological responses to damage listed.

Some useful information:
The classic signs of inflammation are redness, swelling, fever and pain.
Chemical messengers or mediators such as histamine initiate the above processes.
Prostaglandins are released by the action of histamine on damaged cells and certain white blood cells nearby. Their role is outlined below.
Histamine is a substance found in many body cells and is released from injured cells that contain it. White blood cells migrating to the injured site also release histamine.
Histamine causes the enlargement of capillaries and makes them more permeable (leaky).

• Present the above information as a flow chart showing the sequence of events.

explain that inflammation

• is a complex response by blood and blood vessels to injury
• is essential for life and preservation of function
• can cause tissue damage and loss of function

• The inflammatory response is a complex series of events that include vasodilation of blood vessels (redness), increase in capillary permeability (oedema) and an influx of white blood cells (phagocytes).
  
  
• Other symptoms of inflammation are pain, heat and loss of function.
  
  
• Intervention by the body’s repair processes then proceeds, to preserve tissue function.
  
  
• If necessary the repair process can be assisted by the administration of drugs and other therapeutic measures.
  
  
• Overreaction by the inflammatory response can damage normal tissue and lead to loss of function by enzymes destroying ( lysing) these tissues.

explain the advantages and disadvantages of inflammation

• Inflammation alerts the body to infection or injury. The swelling and stiffness produced can partly immobilise traumatised tissue to prevent further injury. Healing can then commence and tissue function can be restored.
  
  
• An unwanted consequence of inflammation is that healthy tissue can be damaged, particularly if the healing process fails and inflammation continues. The individual may then suffer continuing pain and ongoing tissue damage.

outline the role of prostaglandins in magnifying the inflammation response

• Prostaglandins are a class of chemical messengers released by cells stressed during the inflammatory process.
  
  
• They were named this way because they were thought to originate from the prostate gland, but have been found widely distributed.
  
  
• Prostaglandins initiate the following events that magnify the inflammatory response independently, and enhance the effects of histamines.
  • Capillaries near the damaged tissue dilate (widen) due to the influence of histamines. Blood supply to the damaged area therefore increases causing swelling and redness.
  • Prostaglandins promote the immigration of white blood cells, through the leaky capillary walls, to the injured tissue.
  • Certain prostaglandins activate and enhance the pain produced by inflammation.

More information is available at the Web site: Answers.com , a website with several definitions of prostaglandins from reputable dictionaries and encyclopedias.

describe pain as an interpretation by the brain of messages from nerves sent across synapses from the injury site to the brain

• Pain receptors consisting of free nerve endings are located almost everywhere in the body.
  
  
• Overstimulation of sensory receptors leads to the sensation of pain. This is relayed by nerve impulses to the peripheral nervous system and then to the central nervous system. The brain interprets the signal as pain.
  
  
• The impulses travel rapidly across synapses so that the pain sensation is felt almost immediately.

identify that the principal ingredient in aspirin is acetyl salicylic acid, which belongs to a group of pharmaceuticals called analgesics, commonly called ‘pain killers’

• The principal ingredient in aspirin is acetyl salicylic acid, which belongs to a group of pharmaceuticals called analgesics, commonly called ‘pain killers’.

explain the relationship between the relief of pain by aspirin and the inhibition of the production of several different chemical processes in the body including prostaglandins signal crossing the synapse

• Aspirin sticks to the enzyme that makes prostaglandins, cyclooxygenase 2, and thwarts the production of these prostaglandins.
  
  
• Aspirin also inhibits the “good” prostaglandins that maintain the thickness of the stomach lining. A side effect of this can be stomach bleeding, if high doses of aspirin are taken.
  
  
• The messenger histamine activates cells that produce building blocks of the prostaglandin - PE₂ that is involved in the pain process. Aspirin therefore reduces pain by blocking the production of this neurotransmitter, inhibiting the signal crossing the synapse.

plan, choose equipment or resources for, and perform a first hand investigation to use available evidence to determine the rate of solubility of a range of analgesics and to relate their solubility to dispensing form

• soluble
• enteric-coated
• capsule

• Investigate what analgesics are available to use and what forms they come in. You could go to a large chemist shop and check the shelves for analgesics or look on the Internet. Record each one, noting the brand name, the active ingredient in each one and the form/forms they are in.
  
  
• Find out the equipment that is available and plan a suitable investigation, for that equipment. Consider if you need to use a control and how you are going to compare the different dispensing forms.
  
  
• When you have decided how you are going to do the investigation choose the equipment you will need.
  
  
• Perform the investigation, recording your results in a table so they can be analysed. Repeat the investigation if you consider it necessary, to get reliable results.

Some useful information
Aspirin is supplied in various dispensing forms depending on its therapeutic application.
Enteric coated aspirin tablets have a coating which prevent them from dissolving in the stomach contents and causing irritation or bleeding. They instead pass into the small intestine where the aspirin is absorbed into the bloodstream.

• National drug regulatory authorities require tablet dissolution tests for quality control. These tests require special standardised apparatus, however, one simplified procedure that can be used by student investigations at school is reproduced below.

A possible procedure

1. Tablets are stirred in a solvent at a controlled rate and at body temperature. The solvent is 0.01M hydrochloric acid solution, chosen to simulate the acidity of stomach contents.
   
   
2. Samples of the solution are taken at regular intervals and analysed to determine the drug concentration. Students could use data logging devices to determine the drug concentration continuously and display the dissolution rates of different formulations graphically. A plot of drug concentration versus time is constructed and compared with the stated drug specification.