Lesson Plan Industry Sector
Health Science and Medical Technology

## Dosage Calculations

### Lesson Plan Overview / Details

The purpose of this lesson is to instruct students in using the D/H x Q formula to calculate medication dosages.

### Lesson Includes Review Time

Length
3 - 4 Class Periods

### Activities in this Lesson

• Allow students 4-6 minutes to read the attached article. Then ask:

1. Do you think that such mistakes rarely happen or do the happen all of the time and the public just doesn’t hear about it?
2. Whom do you think should be held responsible for a mistake such as this?
3. What if this happened in the hospital or doctor’s office, who would be responsible?
4. Is there a way for a nurse to avoid making such a mistake?

#### Resources and Materials

• Day 1 Lecture

Lecture

Explain that mistakes such as that in the article can be avoided. Dosages and physician’s orders must be checked and rechecked and verified with the ordering physician if any question arises. This is especially true when calculating medication dosages for children and the elderly.

One way that nurses can avoid such mistakes is to calculate dosages using a standardized formula. The formula most commonly used is D/H x Q. We are going to be practicing using D/H x Q to calculate medication dosages from physician’s orders.

We will begin by first having a review of basic math. This is so that you can be refreshed on using decimals since dosages are calculated and rounded to the nearest 10 th of a number. This makes it easier to prepare medications for administration particularly liquids that must be poured or drawn up in a syringe since medication cups and syringes are calibrated in 10ths of a cc/ml.

Though we are focusing specifically on the calculations of medications today, in other class sessions we will learn about drug classifications, parts of a medication prescription, and routes of administration of drugs.

• Day 1 Demo / Modeling

On the attachment below is an example of each type of math problem on the Basic Math Review Sheet. You may write the examples on the board, use the LCD projector or overhead projector for students to reference as they work. You could have a student come up to the board to solve the problem and you confirm the correct answer. This would get the students involved in the process.

#### Resources and Materials

• Print a copy of the Math Conversions Worksheet for each student. Allow them to work on the sheet. Grade the work of students as they turn it in using the key provided. Those that score 90% or better, assign them to work with a student that is having difficulty with the work. Explain to the Peer Tutor that they are to show their “student” the steps to the answer not give them the answer because the goal is to have every student be able to work problems independently in preparation for the quiz at the end of the unit. Allow the students 15-20 minutes to work. Poll the room for those that need assistance. Have a few students come to the board and answer the first few problems. Correct as needed. Instruct students that those not done are to complete the sheet for homework and turn it in at the beginning of class tomorrow.

#### Resources and Materials

• If needed, give additional support to those students still having difficulty with decimals. You can do this by working one-on-one with students or you can assign peers to assist individual students as they sometimes work besy with "one of their own."

• Day 1 Closure

Poll the class getting a feel for how prepared students feel. Remind them that today's lesson was preparation so they should not worried about the grade received in terms of Pass or Fail, but rather as a part of training for industry-related math. Assure them that you are there to help them get it. Remind those that have to complete today's worksheet for homework that you will be collecting those sheets at the start of class tomorrow.

• Day 2 Lecture

Collect any homework from yesterday.

Inform students that today we will be going a step further by looking at common metric and household measures that are used in medication orders.

You will print the conversions sheet below. The sheet contains two charts on each page so only print half the number of students in the class then cut he sheets in half. For those students that wish to make flashcards to aid them in memorizing the conversions, provide cards to students if you have them available.

#### Resources and Materials

• Day 2 Demo / Modeling

Collect any homework from yesterday.

Inform students that today we will be going a step further by looking at common metric and household measures that are used in medication orders.

Print the attachment below then write the examples  on the board for students to use as reference as they work on the sheet. Advise them to set the problems up as in the example to decrease the risk of errors.

#### Resources and Materials

• Print a copy of the worksheet attached in this section for each students.

Do the first couple of problems with the students (set them up as they were on the Day 2 Demonstration sheet).

Allow them 20 minutes to work as you poll the room. Grade the work of students as they turn it in using the key provided. Those that score 90% or better, assign them to work with the same student as yesterday. Explain to the Peer Tutor that they are to show their “student” the steps to the answer not give them the answer because the goal is to have every student be able to work problems independently in preparation for the quiz at the end of the unit. Poll the room and assist as needed.

While the students are working, finish grading yesterday’s work and return it to the students.

#### Resources and Materials

• Day 2 Assessment

*Have students take turns coming up to the board and work each problem.

*Correct as needed.

*If you have any students that need more practice, make up 5-10 problems similar to those on the worksheet and send them home with the students for homework.

• Day 2 Closure

Wrap up by letting students know that they did a good job today. Tomorrow they will be calculating dosages.

*If you have any students that need more practice, make up 5-10 problems similar to those on the worksheet and send them home with the students for homework.

• Day 3 Hooks / Set

Write the following calculation on the board. ask the students to verify the correctness or error of the answer.

Streptomycin 500mg Elixir The medication is available at 250mg/2ml.

500/250 x 1 ml = 2 ml

Correct: 500/250 x 2ml = 4ml

Give them the correct answer. Poll the room for which students got it correct. Remid them that verifyng teh accuracy of dosage calculations is a part of their job and they are to call the physician should they encounter an error at the clinical setting.

• Day 3 Lecture

You will now introduce D/H x Q. Explain that this formula is the most common method used in nursing schools and in hospitals to calculate medication dosages. The formula simplifies the process and decreases the risk of error because it allows for a standard way to arrive at a dosage each time. This means that there is less guessing involved.

D = Dose order (how much the physician has ordered the patient to take)

H = Dose on Hand (how the medication is prepared by the manufacturer for example 10mg or 50 units)

Q = Quantity (form of drug for example, ml, tabs, packet, etc.)

• Day 3 Demo / Modeling

Here you will print the document below. It contains 3 examples that you can write on the board for students. inform them that should take notes for later reference.