Electronic Journal of Science Education Vol. 5 No. 2 - December 2000 - Laipply Editor's Note: Many thanks to the author for demonstrating that learning cycles can be planned for and taught to any educational level.

Basic College-Level Pharmacology: Therapeutic Drug Range Lesson Plan

by

Richelle S. Laipply
University of Akron

Introduction

In order to boost achievement, especially when learning complex material, college-level students should not always be sitting passively in lecture. One way to get students actively involved is to structure inquiry-based instruction and cooperative learning into college science classes. The National Science Foundation's goal for undergraduate education in science, mathematics, engineering, and technology is that students have direct experience with the methods and processes of inquiry (NSF, 1996). This position is supported by the Society for College Science Teachers, which recommends teaching practices that promote critical thinking and problem solving through collaborative student work (Halyard, 1993).

Investigations of scientific concepts using inquiry are highly adaptable to college laboratory settings. However, inquiry as a part of college-level science teaching should not be limited to the laboratory. It can and should be included in the traditional college lecture, as well. Working cooperatively through small group discussion following the presentation of new concepts, students can help each other delve below the superficial level of understanding. This is achieved by explaining what the key content means to them and by seeking clarification by questioning one another and the instructor. Small-group learning has been found to increase self-esteem, improve the ability to work in teams (Johnson, Johnson, & Smith, 1998), and has been linked to a number of cognitive gains. One cooperative learning cycle approach implemented in college biology was associated with higher scores on process questions involving conceptual understanding and interpreting and explaining results (Ebert-May, Brewer, & Allred, 1997). This lesson utilizes the Learning Cycle to structure inquiry; the teacher provides the problem to investigate, but does not inform the students of expected outcomes (BSCS, 1993).

The purpose of this lesson is to demonstrate therapeutic drug range, a basic concept in pharmaceutical science. Since this principle is considered in every patient receiving medication, the topic is of interest to students in the health care professions as well as to anyone who has ever taken medicine. This is accomplished through the use of graphing to discover patterns as a part of data analysis, and interpretation of provided investigation data.


Grade Level: Freshman or Sophomore College Level.

Time: One 50 minute session.

Objective: Students will demonstrate an understanding of the classic pattern effect of drug concentration over time and therapeutic drug range by creating and interpreting a graph of drug concentration in human blood over an eight hour period.

Background Knowledge:

(Teacher) The teacher needs to have knowledge of pharmacokinetics. This information describes what happens to a drug following administration and includes absorption, distribution, metabolism, and excretion of the drug. This lesson leads smoothly into the pharmacokinetics unit. The teacher must know the components of the therapeutic drug range graph that the students will create. Definitions of the following vocabulary will also be provided during the lesson by the teacher: therapeutic range, minimal effective concentration, maximal effective concentration, toxic level, onset of action, duration of action, termination of action, loading dose, and maintenance dose.

The relationship of the drug response and time is the time-response relationship. Duration of action is the length of time that a drug produces an effect. Most drugs produce effects over a constant period of time. The time from drug administration to the first observable effect is called the onset of action. The drug response will continue as long as there is enough concentration at the site of action. As the drug is metabolized and excreted, the response decreases because the level of drug is decreasing. Termination of action occurs when the response is no longer observed. Duration of action refers to the period from the onset of action to the time when the response is no longer perceptible. Time-response graphs are used to determine the frequency with which a drug is administered in order to maintain an effective response (Hitner, H. & Nagle, B., 1999, p. 3-9).

Since this lesson is designed as a small group activity, knowledge of cooperative learning roles and experience in facilitating groups is also helpful.

(Students) Students should be familiar with drawing graphs, metric units of measurement (for drug concentrations), and dosing schedules. If students have not participated in cooperative learning before, some time should be taken before the lesson to describe the group process.

Materials List:

Each student will be given graph paper and an individual evaluation sheet.

Each group of 4-5 students will be given one group evaluation sheet.

Safety: There are no safety precautions in this lesson.


Engagement

Pre-assessment: Ask the students to hypothesize how dosages of drugs might be determined by pharmaceutical companies. Is there a possibility that a patient could be given too much of a "good thing?" Too little? Ask them for personal examples of this phenomenon.

Problem: A patient is receiving oral medication. Over the course of six hours, blood levels of the drug are measured before administration and each half hour thereafter. The results are listed below.

Hour Drug Concentration (mg/ml)
0 0
0.5 25
1 100
1.5 180
2 200
2.5 170
3 125
3.5 85
4 50
4.5 40
5 25
6 0

In small groups of 4-5 students, students will discuss and answer the evaluation questions. Evaluation question(s) are included for each part of the Learning Cycle. One group member will record the answers on the back of one sheet of graph paper, to be turned in at the completion of the lesson.


Evaluation Questions (Engagement):

1. From the charted data, what is the general trend in concentration over the time frame?

2. What do you suppose occurred between hour "0" and hour "1"?

3. What do you suppose occurred between hour "5" and hour "6"?



Exploration

Processing of data: In groups of 4 or 5 students (4 being preferable), students will plot hours of time on the x-axis and the corresponding drug concentrations on the y-axis on furnished graph paper. Each group member will create their own graph, collaborate to make sure each is correct and select one graph to turn in at the end of the lesson. Instructions will be given for students to include up to eight hours of time and up to 300 mg/ml on their graphs. Answers to the eight evaluation questions must also be written on the back of the graph paper and the graph must include the correct labels.



Evaluation Questions (Exploration):
Students will analyze their graphs and answer the following questions:

4. The minimal effective concentration for this drug is 100 mg/ml. Draw and label a continuous dotted line parallel to the x-axis to demonstrate when the patient's blood level was below this concentration.

5. The maximal effective concentration is 250 mg/ml. Draw and label a continuous dotted line parallel to the x-axis to demonstrate if the patient's blood level reaches this concentration.



Explanation

One student from each group will form a team to draw and label one graph on the board. The "class graph" will be used by the teacher to describe components of the graph.

Vocabulary: The teacher will define and describe the following terms as the students label the graph using these terms: minimal effective concentration, maximal effective concentration, onset of action, duration of action, termination of action, loading dose, maintenance dose, and toxic level. (See Teacher Background Knowledge)


Evaluation Question (Explanation):

From the charted data, how long is the duration of action, the onset of action, and at what hour is the peak level achieved?



Elaboration

Introduce therapeutic range and the rationale used for dosage schedules. Therapeutic range is the drug concentration between the minimal effective concentration and the maximal effective concentration. Drug levels below the therapeutic range will not produce the desired effect while levels above this range may cause more side effects or toxic effects in the body. Dosing schedules are established to maintain a constant level of the drug within the therapeutic range for the length of the therapy.

Problem: Using the graph of therapeutic drug range, when will the patient receive the next dosage?



Evaluation Questions (Elaboration):

7. Determine the probable dosing schedule for this drug.

8. Justify your answer to the above question.



Closure:

Close this lesson by reviewing the pattern of the graph along with some speculation about what is occurring in the patient's body at different time periods. As an assignment for the next class meeting, ask the students to obtain the dosing schedules for three over-the-counter medications. This information can be obtained from the drugstore shelf or from a home medicine cabinet.


References

Biological Sciences Curriculum Study (BSCS) (1993). Developing biological literacy. Colorado Springs, CO: BSCS P

ress.

Ebert-May, D., Brewer, C., & Allred, S. (1997). Innovation in large lectures: Teaching for active learning. Bioscience, 47(9), 601-607.

Halyard, R.A. (1993). Introductory science courses: The SCST position statement. Journal of College Science Teaching, September/October, 29-31.

Hinter, H., & Nagle, B. (1999). Basic pharmacology (4th Ed.).New York: Glencoe/ McGraw-Hill.

Johnson, D.W., Johnson, R.T., & Smith, K.A. (1998). Active learning: Cooperation in the college classroom (2nd Ed.). Edina, Minn.: Interaction Books, 1998.

National Science Foundation (1996). Shaping the future: New expectations for undergraduate education in science, mathematics, engineering, and technology. Report by Advisory Committee to NSF, Directorate for Education and Human Resources.

About the author...

Richelle Laipply serves as assistant professor at The University of Akron in the Allied Health Division of the Community & Technical College. Laipply teaches anatomy and physiology, pharmacology, and disease pathology to students enrolled in associate degree health care programs. She is a registered medical technologist and holds a master's degrees in Biology and Technical Education. She is engaged in implementing inquiry-based teaching into large science lecture classses.


Student Activity Sheet

Problem:

A patient is receiving an oral medication. Over the course of six hours, blood levels of the drug are measured before administration and each half hour thereafter. The results are listed below.

Hour Drug Concentration (mg/ml)
0 0
0.5 25
1 100
1.5 180
2 200
2.5 170
3 125
3.5 85
4 50
4.5 40
5 25
6 0


Instructions:
Work in groups of four to complete this lesson. On the graph paper, each student is to create a graph of the time vs. drug concentration values, including eight hours of time on the x-axis and 300 mg/ml on the y-axis. After plotting the points, draw a line to connect them. Make sure your graphs are labeled completely. Select one graph from each group to turn in at the end of class. After assuring that all group members have collaborated to answer the Evaluation

Questions, turn in one set of answers to the questions with your group graph.



Evaluation Questions

Engagement

1. Explain the pattern of the graph. What is the general trend in concentration over the time frame?

2. What do you suppose occurred between hour "0" and hour "1"?

3. What do you suppose occurred between hour "5" and hour "6"?


Exploration

4. The minimal effective concentration for this drug is 100 mg/ml. Draw and label a continuous dotted line parallel to the x-axis to demonstrate this. At what hour(s) is the patient's blood level below this concentration?

5. The maximal effective concentration is 250 mg/ml. Draw and label a continuous dotted line parallel to the x-axis to demonstrate this. Does the patient ever reach this concentration?


Explanation

6. From the charted data, how long is the duration of action, the onset of action, and at what hour is the peak level achieved?


Elaboration

7. Determine the probable dosing schedule for this drug.

8. How have you arrived at this schedule? Be able to justify your dosing schedule to the rest of the class.

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