Episode One Debriefing: Teacher Guide

Transcription

1 AN IRRITATING PROBLEM The student will examine how the same medication (aspirin) has been developed in different ways in order to counter its most common side effect stomach irritation. Background Willow bark extract, used at least since the time of Hippocrates, relieves pain because it contains the chemical salicin. Salicin and other salicylates are useful as mild pain medications but produce stomach upset as a side effect. The need for a new drug prompted Felix Hoffman of Friedrich Bayer and Company to develop acetylsalicylic acid, an analgesic with the pain relieving ability of salicin but with less stomach irritation. Bayer marketed its new discovery in 1899 under the brand name Aspirin. Aspirin proved to be a success with the public, but it too can upset the stomach of some people. Since 1899, new types of aspirin have been developed which attempt to solve this problem by altering the interaction of the drug with stomach acid. Buffered aspirin contains an antacid to reduce stomach acid and lessen irritation. However, claims about the effectiveness of this drug are disputed. The Reconstructors 15 Plaguing Problem

2 Regular aspirin will dissolve in water, which has a ph of approximately 7.0. This ph is found in the mouth. Regular aspirin or buffered aspirin will dissolve in acid. An acidic ph is found in the stomach (ph < 4.0). Enteric aspirin will dissolve in a base. A basic ph is found in the intestines (ph > 8.0). Enteric aspirin is covered by a special coating which allows it to resist stomach acid and and allows it to dissolve in the small intestine, which has the ph level of a base. Enteric aspirin doesn t cause stomach irritation, but the coating slows down the absorption of the drug. The Reconstructors 16 Plaguing Problem

3 Learning Objectives The student will: Discuss the parts of the human digestive tract and their functions. Conduct an experiment to determine the solubility of different types of aspirins. Materials Human Digestive Tract Transparency Per each group of students: An Irritating Problem Student Activity Sheets safety goggles rubber gloves aprons one enteric (coated) aspirin (use a coated aspirin that is colored such as Ecotrin to help distinguish it from the other aspirins) one twist tie (used to seal plastic bags) one regular aspirin (try to differ the shapes of the regular and buffered or label with markers) one buffered aspirin three plastic cups one marker one piece of cheesecloth two graduated cylinders 150 ml water 100 ml vinegar 50 ml bleach one watch or timer Procedure 1. Prior to class, make a transparency of the Human Digestive Tract diagram. 2. State that there is a problem with willow bark extract (salicin). Using the digestive tract transparency, trace the route of willow bark extract from the mouth to the stomach. Discuss with students the function of the mouth, saliva, esophagus, peristalsis, stomach, and gastric juice. Describe how willow bark extract can interact with stomach acid to produce irritation. Continue the discussion with information on the small and large intestines and anus. 3. Tell students that aspirin was developed for the people to use instead of willow bark, but research indicates that it too can irritate the stomach. Discuss the development of aspirin and the different uses of aspirin. The Reconstructors 17 Plaguing Problem

4 4. Hand out the student activity sheet, An Irritating Problem, and the diagram of the human digestive tract. Present Beta's challenge: test the three new types of aspirin and determine which aspirins dissolve in an acidic environment and determine which could potentially irritate the stomach. 5. Explain that they will take all three aspirins and dip them into three different solutions that mimic the environment of the digestive tract. The water will represent the mouth, the acidic solution will represent the stomach, and the basic solution will represent the small intestine. 6. Divide the class into groups of two or three students to perform the experiment described in the student activity sheet, An Irritating Problem. Give each group of students three aspirins to test (aspirins A, B, and C). Each group should get one enteric (coated) aspirin, one buffered aspirin, and one regular aspirin. This activity is an adaptation of the Simulated Stomach by David Robson of The American Chemical Society. Extension Activities Science: Examine the digestive tract of the earthworm. History: Research the life of Felix Hoffman, the developer of aspirin. Language Arts: Replace the lyrics of a popular rap, country, jazz, or rock song with a poem about the parts of the human digestive tract and how they work. Mathematics: Analyze statistics on the use of aspirin compared to other nonsteroidal anti-inflammatory drugs for a period of time. Create a graph presenting this information. Mathematics: Research the development of a new drug and create a pie chart showing the cost of each phase. Visual Arts: Create a model of the human digestive tract from common household items. Standards National Science Education Standards, Grades 5-8 Science Content Standard A: All students should develop abilities necessary to do science. Science Content Standard C: All students should develop understanding of the structure and function of living systems. Science Content Standard F: All students should develop understanding of science and technology in society. The Reconstructors 18 Plaguing Problem

5 Books Graedon, J., Graedon, T., and Ferguson, T The Aspirin Handbook: A User's Guide to the Breakthrough Drug of the '90s. New York: Bantam Books. Gordon, M.A Drug Interactions: Protecting Yourself from Dangerous Drug, Medication, and Food Combinations. New York: Rosen Pub. Group. Hardman, J. G., et al., (Eds.) Goodman and Gilman's: The Pharmacological Basis of Therapeutics. (9th ed.). New York: McGraw-Hill. National Research Council National Science Education Standards. Washington, DC: National Academy Press. Web Sites How Stuff Works: Aspirin Milestones in Neuroscience Research American Chemical Society (Search for the Simulated Stomach Activity) Useless Information: Aspirin What is the Buffer System in Buffered Aspirin? The Reconstructors 19 Plaguing Problem

6 mouth esophagus stomach sm. intestine lg. intestine The Reconstructors 20 Plaguing Problem

7 Episode One Debriefing: Student Activity Sheet AN IRRITATING PROBLEM The student will examine how the same medication (aspirin) has been developed in different ways in order to counter its most common side effect stomach irritation. Materials two graduated cylinders rubber gloves safety goggles aprons one twist tie cheesecloth three plastic cups 100 ml vinegar 100 ml water 100 ml of a bleach solution (50ml bleach and 50ml water) Aspirin A Aspirin B Aspirin C one marker watch or timer Procedure 1. Before starting, put on safety goggles, rubber gloves, and an apron. 2. Pick one Aspirin A, one Aspirin B, one Aspirin C, and one piece of cheesecloth. 3. Pick 3 cups and label one cup Neutral, one cup Acid, and one cup Base. 4. Using a graduated cylinder, measure 100 ml tap water and pour it into the cup labeled Neutral. 5. Using a graduate cylinder, measure 100 ml vinegar and pour it into to the cup labeled Acid. 6. Get a new graduated cylinder or clean out the one that was used before. Add to it 50 ml water and 50 ml bleach. Pour this solution into the cup labeled Base. 7. Line up the cups (in order from left to right): Neutral, Acid, Base. 8. Place Aspirin A, Aspirin B, and Aspirin C in a small square of cheesecloth and twist closed. Use twist ties to make sure the cheesecloth stays closed. Make sure you are able to tell the difference between each aspirin. You may want to use a permanent marker to label each aspirin A, B, and C. The Reconstructors 21 Plaguing Problem

8 Episode One Debriefing: Student Activity Sheet 9. Dip the cheesecloth containing the three aspirins into the cup labeled Neutral Swirl the cheesecloth around for 10 minutes. 10. At the end of 10 minutes, record any changes to the aspirins on the An Irritating Problem data sheet. 11. Repeat steps 9 and 10, this time dipping the cheesecloth containing the three aspirin into the Acid cup. 12. Repeat steps 9 and 10, and this time dipping the cheesecloth containing the three aspirin into the Base cup. 13. Answer the questions on the data sheet. The Reconstructors 22 Plaguing Problem

9 Episode One Debriefing: Student Activity Sheet Name Class Date An Irritating Problem Data Sheet Observations In Solutions Solution in which it dissolved (water, acid or base) Time it took to dissolve Other observations Aspirin A Aspirin B Aspirin C Draw Conclusions 1. Which aspirin is most likely to dissolve in the mouth or stomach? Why? 2. Which aspirin is most likely to dissolve in the small intestine? Why? 3. Which type of aspirin is least likely to irritate the stomach? Why? The Reconstructors 23 Plaguing Problem