Transcript Math for Medications - EdTech-at

Math for Medications
Some terms you’ll see:
Desired Dose
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Available Dose
Ratio & Proportion
Cross Product
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Math for Medications
0011 0010 1010 1101 0001 0100 1011
• The purpose of this class is for the
learner to be able to calculate drug
dosages of tablets and liquids.
• You will calculate the drug
dosages using the formula or ratio
& proportion method.
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Math for Medications- the
Formula Method for Tablets
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Desired dose X
Available dose
•
dd
ad
Vehicle = ATA
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x
v = ATA
(amount to administer)
Problem
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• The doctor ordered Benadryl 75 mg. The
drug label reads Benadryl 0.025 grams.
How many tablets are needed?
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• Read the problem and identify what you’ve
been given.
Problem
0011 0010 1010 1101 0001 0100 1011
•
•
•
•
dd = 75 mg
ad = 0.025 grams
v = 1 tab
Have both dd & ad in the same unit of
measure
0.025 g = 25 mg.
• ad = 25 mg
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Problem
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• Put the numbers into the formula:
75 mg
25 mg
x
1 tab =
3 tabs
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Math for Medications- The Ratio
& Proportion Method for Tablets
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• We will use the same problem but will cross
multiply.
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Problem
0011 0010 1010 1101 0001 0100 1011
• The doctor ordered Benadryl 75 mg. The
drug label reads Benadryl 0.025 grams.
How many tablets are needed?
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• Read the problem and identify what you’ve
been given.
Problem
0011 0010 1010 1101 0001 0100 1011
• The known ratio:
25 mg
1 tablet
• The unknown ratio:
75 mg
N tablets
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Problem
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• Write the proportion :
25 mg
1 tablet
x
75 mg
N tablets
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Problem
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• Cross Multiply:
25 mg
1 tablet
x
75 mg
N tablets
25mg X N tab = 1 X 75 mg
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Problem
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• Solve for N by dividing both sides of the
equation by 25:
• 25 N
=
75
25
25
or N = 3
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Problem
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• Substitute 3 for N in the original proportion
and your answer is : You would administer
3 tablets to give a dosage of 75 mg.
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Math for Medications for Liquids
0011 0010 1010 1101 0001 0100 1011
• Calculate drug dosages using the formula
method or ratio & proportion method for
liquids.
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Problem
0011 0010 1010 1101 0001 0100 1011
• The doctor has ordered Gentamycin
Sulphate 25 mg.
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• The label reads Gentamycin Sulphate 40
mg/mL. How much Gentamycin will you
administer?
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Problem - Using the Formula
Method
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• Identify:
dd =
25 mg
ad =
40 mg
v =
1 mL
• Put the numbers in the formula:
25 x 1 mL
= 0.625 mL
40
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Problem
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• Round off to the nearest decimal place:
• 25 x 1 mL= 0.625 mL or 0.6 mL
40
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Problem- Using the Ratio &
Proportion method
0011 0010 1010 1101 0001 0100 1011
• Cross product ( Cross Multiply) :
• The know ratio:
40 mg
1 mL
• The unknown ratio:
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25 mg
N mL
Problem
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• Proportion:
40 mg = 25mg
1 mL
N mL
• Cross Multiply:
40 x N = 1 x 25
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Problem
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• Solve for N:
40N
=
25
40
40
N=
0.625
N = 0.625
Round off:
N = 0.6 mL
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0011 0010 1010 1101 0001 0100 1011
• Substitute for N in the original proportion:
• Proportion:
40 mg = 25mg
1 mL
0.6 mL
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Math for Medications
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Another way to calculate
Math for Medications
The “Math Chart”
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• Lets look at another way to calculate
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Math for Medications
The “Math Chart”
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• When we are calculating drug dosages of
tablets and liquids we always have 2 pieces
of information.
• 1) What the label reads
• 2) What has the doctor ordered
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Math for Medications
The “Math Chart”
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• The first step that we do when we use the
Math Chart is to draw the chart which
simply looks like this:
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Math for Medications
The “Math Chart”
0011 0010 1010 1101 0001 0100 1011
• The second step in using the Math Chart is
to label the chart.
• An important thing to remember when
labelling the chart is to make sure that the
top sections are the same and the bottom
sections are the same.
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Mg
Mg
Tablets
Tablets
Math for Medications
The “Math Chart”
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• Once we have our chart filled in, all we do
is
MULTIPLY ON THE DIAGONAL AND
DIVIDE BY WHAT’S LEFT
Ex:
Mg
30
45 Mg
1
Tablets
1
Lets do our calculations:
45 X 1 ÷ 30 = 1.5 tablets
Tablets
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Math for Medications
The “Math Chart”
0011 0010 1010 1101 0001 0100 1011
• Lets look at the first example
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Math for Medications
The “Math Chart”
0011 0010 1010 1101 0001 0100 1011
• The doctor ordered Benadryl 75 mg. The
drug label reads Benadryl 0.025 grams.
How many tablets are needed?
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**The first thing we have to do is to look at
what information we have.
1) What the label reads – 0.025g for 1 tablet
2) What the doctor ordered – 75mg
Math for Medications
The “Math Chart”
0011 0010 1010 1101 0001 0100 1011
***Before me make our chart we have to
make sure both units are the same.
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• In this question, we have 0.025 g & 75 mg
• Lets change 0.025g to mg by multiplying by
1000
• Now both units are the same 25mg and
75mg and we can make our chart
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Math for Medications
The “Math Chart”
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• Step 1 - Make the chart and label it
• Step 2 – Fill in the information that we have
Mg
Mg
25
75
1
Tablets
•
Tablets
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Step 3 – Do the calculations MULTIPLY ON THE DIAGONAL AND
DIVIDE BY WHAT’S LEFT
75 X 1 ÷ 25 = 3 tablets
Math for Medications
The “Math Chart”
0011 0010 1010 1101 0001 0100 1011
• Lets try the next example:
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• The doctor has ordered Gentamycin
Sulphate 25 mg.
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• The label reads Gentamycin Sulphate 40
mg/mL. How much Gentamycin will you
administer?
Math for Medications
The “Math Chart”
0011 0010 1010 1101 0001 0100 1011
**The first thing we have to do is to look at
what information we have.
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1) What the label reads – 40mg for 1 mL
2) What the doctor ordered 25mg
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Math for Medications
The “Math Chart”
0011 0010 1010 1101 0001 0100 1011
• Step 1 - Make the chart and label it
• Step 2 - Fill in the information we have
Mg
Mg
40
25
1
mL
mL
• Step 3 – Do our calculations
• 25 x 1 ÷ 40 = 0.625 mL
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Rules to Remember
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• Example: 0.66mg = 0.7 mg
1. Put 0 to the left of the decimal if there is
no whole number.
2. Adults: round of drug doses to the nearest
1/10 or 0.1.
3. Pediatrics: Round off drug doses to the
nearest 1/100 or 0.01
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Rules to Remember
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• Do not round off until your final answer:
For example: 100 mg x 15 mL
80 mg
10=1.25 x 15 mL = 18.75 mL
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Not 1.3 x 15 mL which would =19.5mL
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References
0011 0010 1010 1101 0001 0100 1011
• AOM coursepack
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