Post on 02-Jan-2016
DOSAGE CALCULATIONS
DesiredWhat is the desired
(ordered amount)?
DOSAGE CALCULATIONS
HaveWhat do you have
(amount on hand)?
DOSAGE CALCULATIONS
VehicleHow is the dosage measured
(quantity)?
DOSAGE CALCULATIONS
D
HV
Desired over Have times Vehicle
DOSAGE CALCULATIONS
Desired over Have times Vehicle
The order readsLasix 20 mg po
You haveLasix 20 mg tablets
How many tablets will you give?
DOSAGE CALCULATIONS
20 mg1 tablet
Desired over Have times Vehicle
20 mg
DOSAGE CALCULATIONS
20 mg1 tablet
The labels of Desired and Have MUST match
20 mg
DOSAGE CALCULATIONS
20 mg1 tablet
20 mg
If the labels match, then they cancel each other out
DOSAGE CALCULATIONS
201 tablet
20
Reduce the fraction if possible
DOSAGE CALCULATIONS
11 tablet
1
Do the multiplication
DOSAGE CALCULATIONS
1 1 tablet = 1 tablet
Calculate the Dosage
DOSAGE CALCULATIONS
Give 1 tablet
Amount to Give
DOSAGE CALCULATIONS
Desired over Have times Vehicle
The order readsLasix 30 mg po
You haveLasix 20 mg tablets
How many tablets will you give?
DOSAGE CALCULATIONS
30 mg1 tablet
Desired over Have times Vehicle
20 mg
DOSAGE CALCULATIONS
30 mg1 tablet
The labels of Desired and Have MUST match
20 mg
DOSAGE CALCULATIONS
30 mg1 tablet
If the labels match, then they cancel each other out
20 mg
DOSAGE CALCULATIONS
301 tablet
20
Reduce the fraction if possible
DOSAGE CALCULATIONS
31 tablet
2
Do the multiplication
DOSAGE CALCULATIONS
11 tablet
21
Calculate the Dosage
DOSAGE CALCULATIONS
Give 1
Amount to Give
1
2Tablets
DOSAGE CALCULATIONS
Desired over Have times Vehicle
The order readsDilantin Suspension 200 mg po
You haveDilantin Suspension 125 mg / 5 mL
How many mL will you give?
DOSAGE CALCULATIONS
200 mg5 mL
Desired over Have times Vehicle
125 mg
DOSAGE CALCULATIONS
200 mg
The labels of Desired and Have MUST match
125 mg5 mL
DOSAGE CALCULATIONS
If the labels match, then they cancel each other out
200 mg
125 mg5 mL
DOSAGE CALCULATIONS
200
1255 mL
Reduce the fraction if possible
DOSAGE CALCULATIONS
5 mL
Do the multiplication
8
5
DOSAGE CALCULATIONS
8
11 mL
Calculate the Dosage
DOSAGE CALCULATIONS
Give 8 mL
Amount to Give
DOSAGE CALCULATIONS
Does the dosage need to be converted?
The order readsMorphine Sulfate gr ¼ sc
You haveMorphine Sulfate 10 mg / 1 mL
How many mL will you give?
DOSAGE CALCULATIONS
Caution: The labels MUST match!
The order readsMorphine Sulfate gr ¼ sc
You haveMorphine Sulfate 10 mg / 1 mL
How many mL will you give?
CONVERSIONS
Converting Between the Systems
Weight
60 mg = gr i
The Metric System and the Apothecary System
CONVERSIONS
Setting Up the Proportion
Step 1: What DO you know?
60 mg = 1 gr
This is the first part of your proportion
60 mg : 1 gr :: 45 mg : x gr
CONVERSIONS
Setting Up the Proportion
Step 1: What DO you know?
60 mg = 1 gr
This is the first part of your proportion
60 mg : 1 gr :: 45 mg : x gr
CONVERSIONS
Setting Up the Proportion
Step 2: What do you WANT to know?
x mg = gr ¼
This is the second part of your proportion
60 mg : 1 gr :: x mg : ¼ gr
CONVERSIONS
Checking the Proportion
Step 3: Are the labels in the same order?
60 mg : 1 gr :: x mg : ¼ gr
mg : gr mg : gr
Caution: Changing the order of the labels
will yield the WRONG ANSWER
CONVERSIONS
Step 4: Solve the proportion
60 mg : 1 gr :: x mg : ¼ gr
x = 60 ¼
60 4
x =
x = 15 mg
Caution: Don’t forget to LABEL your answer
CONVERSIONS
Step 4: Solve the proportion
60 mg : 1 gr :: x mg : ¼ gr
x = 60 ¼
60 4
x =
x = 15 mg
Caution: Do you have the RIGHT label?
DOSAGE CALCULATIONS
Look back at the order
The order readsMorphine Sulfate gr ¼ sc
You now knowgr ¼ = 15 mg
You can convert this order toMorphine Sulfate 15 mg sc
DOSAGE CALCULATIONS
Now use Desired over Have times Vehicle
The order isMorphine Sulfate 15 mg sc
You haveMorphine Sulfate 10 mg / 1 mL
How many mL will you give?
DOSAGE CALCULATIONS
15 mg1 mL
Desired over Have times Vehicle
10 mg
DOSAGE CALCULATIONS
15 mg
The labels of Desired and Have MUST match
10 mg1 mL
DOSAGE CALCULATIONS
If the labels match, then they cancel each other out
15 mg
10 mg1 mL
DOSAGE CALCULATIONS
15
101 mL
Reduce the fraction if possible
DOSAGE CALCULATIONS
3= 1.5
2
Remember: The metric system uses decimals
DOSAGE CALCULATIONS
1.5 1 mL
Do the multiplication and calculate the dosage
DOSAGE CALCULATIONS
Give 1.5 mL
Amount to Give
DOSAGE CALCULATIONS
Look back to the original order
The order is
Morphine Sulfate 15 mg sc
You have
Morphine Sulfate 10 mg / 1 mL
You will give
1.5 mL Morphine Sulfate
DOSAGE CALCULATIONS
You can also use the Proportion Method
The order isMorphine Sulfate 15 mg sc
You haveMorphine Sulfate 10 mg / 1 mL
How many mL will you give?
Using the Proportion Method
Step 1: What do you Have (Label)?
Morphine Sulfate 10 mg / 1 mL
This is the first part of your proportion
10 mg : 1 mL :: 45 mg : x gr
DOSAGE CALCULATIONS
Using the Proportion Method
Step 2: What do you Desire (Order)?
Morphine Sulfate 15 mg
This is the second part of your proportion
10 mg : 1 mL :: 15 mg : x mL
DOSAGE CALCULATIONS
Using the Proportion Method
Step 3: Are the labels in the same order?
10 mg : 1 mL :: 15 mg : x mL
mg : gr mg : gr
Caution: Changing the order of the labels
will yield the WRONG ANSWER
DOSAGE CALCULATIONS
Step 4: Solve the proportion
10 mg : 1 mL :: 15 mg : x mL
15 = 10x
1510
= x
x =
Caution: Don’t forget to LABEL your answer
DOSAGE CALCULATIONS
1.5 mL
Step 4: Solve the proportion
10 mg : 1 mL :: 15 mg : x mL
15 = 10x
1510
= x
x =
Caution: Do you have the RIGHT label?
DOSAGE CALCULATIONS
1.5 mL
DOSAGE CALCULATIONS
Look back to the original order
The order is
Morphine Sulfate 15 mg sc
You have
Morphine Sulfate 10 mg / 1 mL
You will give
1.5 mL Morphine Sulfate
DOSAGE CALCULATIONS
Calculate this dose using the D/H * V Method
The order readsDilantin Suspension 400 mg po
You haveDilantin Suspension 125 mg / 5 mL
How many mL will you give?
DOSAGE CALCULATIONS
Calculate this dose using the Proportion Method
The order readsDilantin Suspension 400 mg po
You haveDilantin Suspension 125 mg / 5 mL
How many mL will you give?
Desired over Have times Vehicle
– or –
Set up a Proportion
DOSAGE CALCULATIONS
It’s really YOUR Choice