Medical Dosage CalculationMedical Dosage Calculation
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Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
CHAPTER
Tenth EditionA Dimensional Analysis ApproachA Dimensional Analysis Approach
Preparation of Solutions
8
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
Directory
• Classroom Response System Questions• Lecture Note Presentation
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
Classroom Response System Questions
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Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
Question #1
If a 25% solution is diluted, what might be the strength of the resulting solution?
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Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
Question #1 Choices
1. 50%
2. 25%
3. 10%
4. 75%
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
Question #1 Response
1. 50%
2. 25%
3. 10%
4. 75%
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
Question #2
If a 1:69 solution is diluted, what might be the strength of the resulting solution?
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
Question #2 Choices
1. 1:30
2. 1:90
3. 2:120
4. 3:12
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
Question #2 Response
1. 1:30
2. 1:90
3. 2:120
4. 3:12
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
Question #3
If 1 liter of a solution contains 100 grams of pure drug, what is the strength of this solution as a fraction, ratio, and as a percentage?
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
Question #3 Choices
1. 1/100 strength, 1:100, 1%
2. 1/1000 strength, 1:1000, 0.1%
3. ½ strength, 1:2, 50%
4. 1/10 strength, 1:10, 10%
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
Question #3 Response
1. 1/100 strength, 1:100, 1%
2. 1/1000 strength, 1:1000, 0.1%
3. ½ strength, 1:2, 50%
4. 1/10 strength, 1:10, 10%
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
Question #4
The strength stated on a drug label is 100 mg/mL. Write this strength in the form of a percentage.
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
Question #4 Choices
1. 500%
2. 50%
3. 5%
4. 10%
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
Question #4 Response
1. 500%
2. 50%
3. 5%
4. 10%
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
Question #5
The physician orders minoxidil (Rogaine) 2%; apply 2 mL to scalp b.i.d. How many milligrams of minoxidil will be applied to the scalp with each dose?
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
Question #5 Choices
1. 40 mg
2. 4 mg
3. 5 mg
4. 2 mg
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
Question #5 Response
1. 40 mg
2. 4 mg
3. 5 mg
4. 2 mg
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
Lecture Note Presentation
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Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
Learning Outcomes
1. Describe the strength of a solution as a ratio, fraction and as a percent.
2. Determine the amount of solute (drug) in a given amount of solution.
3. Determine the amount of solution that would contain a given amount of solute (drug).
4. Do the calculations necessary to prepare a solution from a solute.
5. Do the calculations necessary to prepare solutions for irrigations, soaks, and nutritional feedings.
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
Strength of a Solution
Examples of strength using stated units of measurement:
Strength =
Amount of Drug (Solute)
Amount of Solution
5 mg
mL,
25 mcg
5 mL, and
8 g
L
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Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
• Solution strength can also be stated without explicit units of measurement. For example, a solution which is 1 part iodine in 2 parts of solution has strength of:
Ratio
Fraction
Percent
Strength of a Solution
1:2
50%
1
2strength
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
• Measure the Amount of Drug (Solute) in either g or mL
• Measure the Amount of the Solution in mL
Strength of a Solution
1:100 NaCl solution has 1 g NaCl in 100 mL of the solution
1/3 strength solution of Iodine has 1 mL of Iodine in 3 mL of solution.
7% magnesium sulfate solution has7 g magnesium sulfate in 100 mL of solution
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Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
• What is the strength of a 500 milliliter solution that contains 50 mL of iodine?
strength =
amount of drugamount of solution
The strength is 1:10, 1/10 strength, or 10%
= 50 mL
500 mL
1
10
Find the Strength
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
• What is the strength of a 200 milliliter solution that contains 50 g of NaCl?
strength =
50g200mL
=14=25%
The strength is 1:4, ¼ strength, or 25%
=
50 g -------------200 mL
4
1
Find the Strength
strength =
amount of drugamount of solution
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
• How many grams of dextrose would you need to prepare 1000 milliliters of a 5% solution?
Amount of solution is 1,000 milliliters.
Strength is 5%
Find the amount of solute in a given amount of solution of known strength
5
100
⎛
⎝⎜⎞
⎠⎟
5 g
100 mLThis means
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
So, you need 50 grams of dextrose to prepare 1,000 milliliters of a 5% solution.
50 g
Convert 1,000 mL of solution to g of dextrose
1,000 mL ×
5 g100 mL
=? g
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
• How would you prepare 250 milliliters of a 1/2% creosol solution? Creosol comes in liquid form.
Amount of solution is 250 milliliters.
Finding the Amount of Solute
This means
Strength is ½% or 0.5%
0.5 g Creosol
100 mL Solution
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
0.5 g Creosol
100 mL Solution
So, 1.25 milliliters of creosol is diluted with water to 250 milliliters of solution.
=1.25 mL Creosol
Convert 250 mL solution to ? mL of Creosol
0.5 g Creosol
100 mL Solution=? mL of Creosol
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
You want to convert the 40 grams of pure drug to milliliters of solution.
40 g = ? mL
Find the amount of solution of known strength containing a given amount of solute
• How many milliliters of a 20% magnesium sulfate solution will contain 40 grams of the solute magnesium sulfate?
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
In a 20% solution, there are 20 grams of solute per 100 mL of solution. So, the strength is
1
2
200 mL
So, 200 mL of a 20% magnesium sulfate solution contains 40 g of magnesium sulfate.
20 g
100 mL
40 g
1×100 mL20 g
=? g
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
• How many ounces of full-strength Sustacal are needed to make 16 ounces of ¼ strength Sustacal?
Finding the Amount of Solute
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Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
= 4 oz
So, 4 oz of full-strength Sustical are needed to make 16 ounces of ¼ strength Sustical.
16 oz Solution = ? oz Sustical
= ? oz Sustical
1
4strength means
1 oz (Sustical)
4 oz (Solution)
16 oz Solution
1×1 oz (Sustical)4 oz (Solution)
16 oz Solution
1×1 oz (Sustical)4 oz (Solution)
1
4
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
Chapter Summary
• The strength of a solution is the ratio of the amount of solute dissolved in the solution to the total volume of the solution.
• The strength of a solution may be expressed in the form of a ratio,fraction,or percentage.
• A 1/2 strength solution is a 1:2 or a 50% solution, and should not be confused with a 1/2 % solution.
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
Chapter Summary
• The amount of solute dissolved in the solution should be expressed in milliliters if the solute is a liquid.
• The amount of solute dissolved in the solution should be expressed in grams if the solute is a solid or powder.
• The volume of a solution should be expressed in milliliters.
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
Chapter Summary
• To determine the amount of solute contained in a given amount of a solution of known strength, use the strength as the known equivalence.
• To determine amount of a solution of known strength containing a given amount of solute, use the strength as the known equivalence.
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
• The strength of a particular solution may be written in many different forms. The following strengths are all equivalent:
• With stated Units of Measurement
Rates500 mg/mL
500 mg per mL
500 mg
1 mL
Equivalence 500 mg = 1 mL
Chapter Summary
{
Copyright ©2012, ©2008 by Pearson Education, Inc.All rights reserved.
Medical Dosage Calculations: A Dimensional Analysis Approach, Tenth EditionJune L. Olsen • Anthony P. Giangrasso • Dolores Shrimpton
• Without stated Units of Measurement
Fraction 1/2 strength
Ratio 1:2
Percentage 50%
Chapter Summary