Download Pediatric Dosage Calculation

Pediatric Dosage Calculation
Professor Shaffer 2012-2013
How is Pediatric Dosage
Calculation Different than Adults?
• There is no standard dose
• All doses are based on a recommended
dosage based on:
Body weight in kilograms (for this dosage test)
Body Surface Area
Begin by Converting to Kilograms
• All MD orders will be ordered as a dose
per kg
• Convert the patient’s weight in lbs to kg by
dividing the weight in lbs by 2.2
• Example:
50 lbs divide by 2.2 = 22.7272727272727
Round to tenths place = 22.7 kg
Now you try!
1. Patients weight 48 lbs
How many kg does the patient weigh?
Patient weight 13.9 lbs
How many kg does the patient weigh?
The MD order
The MD order can be written in several
ways:
•
•
In a daily total (dose not specified) after
further calculation to be divided in equal
doses
Ex: 30mg/kg/day administer orally equally
divided in three doses
or
Per dose
Ex: 15mg/kg administer orally twice daily
Lets Try it!
Patients weight: 45 lbs
2. Give 30mg/kg/day administer orally equally
divided into three doses
How many mg per dose? How much is the
24 hr drug total?
3. Give 30mg/kg administer orally in three
divided doses
How many mg per dose? How much is the
24 hr drug total?
Is the dose safe?
• All pediatric dosages have a
recommended range in the drug guide
• These ranges are typically based on a 24
hour total amount of a dosage in mg, mcg,
gm, etc.
• Remember how to convert mcg to mg,
gram to mg etc.
Is the order safe?
• A statement from the drug guide will be
provided on the dosage assessment test
Ex: The drug guide states the recommended
safe dosage is 3-5 mg/kg/day to be
administered orally in 2 divided doses
Lets try it!
4. MD order Sporanox (itraconazole) 40 mg
administer orally twice daily
Patients weight 47 lbs
Drug guide recommends 3-5mg/kg/day
administer orally in 2 divided doses.
Is the dose safe?
Supply
• Pediatric medication is typically supplied in
liquid form
• Some children can swallow pills or the
medication may only come in tablet form
• Most of the dosage assessment questions
will consist of medication in liquid form,
few questions will be in tablet form
Remember….
• Supply is expressed as a dosage amount per a
commonly used quantity
• Example
250mg/5mL
100mg/mL
50mcg/mL
• This is different from the total amount of drug
dosage in the bottle
Calculate Liquid Medication
Dose desired
Dose on hand
X
quantity in mL
= volume to be administered
Lets try it!
5. MD order is to give 75 mg
Supply is 250mg/5mL
Calculate the amount to administer
Read a label
• Some dosage
questions will require
you to read a drug
label
Mixing
directions:
Add 30 mL
of water
Mix
Vigorously
Discard
after 5
days
Zantac
(ranitidine)
Oral
suspension
25mg/5mL
Lets try it!
6. Using the medication label supplied
above, how many milliliters should be
administered per dose if the MD order is
100 mg administer orally once daily?
Ok, so how do you round?
Look at it this way…
– If the calculated answer is <1 mL then round
to the hundredths place as this amount could
be easily administered in a 1 mL syringe
Example: If the answer was 0.75 mL, where
would you draw the solution to in this syringe?
What if the Answer is > 1 ml?
• If the calculated dose is greater than 1 ml
then you round to the tenths place
• Example- if the dose was 2.75 ml, using a
3 ml syringe you would need to round to
2.8ml, as 2.75ml can not be precisely
administered
For Example
• If the answer is 0.3762901
• Round to 0.38mL…..don’t forget the zero
in the ones place!
• If the answer is 1.3762901
• Round to 1.4 mL
NEVER…….
• Round to a whole number!!!!!
• If the answer is 1.89361
• Round to 1.9 mL NOT 2 mL
So Remember:
• < 1 mL rounds to 2 places to the right of
the decimal place
• >1 mL, kg, mg, mcg, anything else rounds
to only 1 place to the right of the decimal
place
Practice Rounding
• If you calculated the answer to be:
a. 2.76001 mg, round to:__________
b. 0.609113 mL , round to:_________
c. 8.92778 mL, round to:__________
d. 0.78912, round to:__________
e. 13.119542 kg, round to:_______
Intravenous
• Nothing new here….
Volume in mL x drop factor = gtt/min
Time in min
You are Ready!!! Lets put it all
together
8. The physician orders Kantrex
(kanamycin) oral suspension 150
mg/kg/day administer orally in 2 divided
doses.
Supply Kantrex 500mg/5mL.
Patients weight: 28 lbs
How many milliliters should be
administered per dose?
9. The physician orders Prostigmin
(neostigmine bromide) 8 mg administer
orally every 4 hrs
The drug guide recommended dosage is
2-4 mg/kg/day to be administered in
divided doses
Patients weight: 21 lbs
Is the physicians order safe?
Careful…some may have patients
weight in kg already!
10. The physician orders Primacor
(milrinone lactate) 50 mcg administer IM
stat.
Supply: 0.2mg/mL
Patients weight: 12 kg.
How many milliliters should be administered
per dose?
11. The physician orders Sustiva (efavirenz)
20mg/kg administer orally twice daily
Supply: Sustiva 50 mg tablets
Patients weight: 11 lbs
How many tablets are to be administered per
dose?
12. The physician orders IV fluids as follows:
Infuse 1000mL of 0. 45% normal saline
solution in 10 hours IV.
• Calculate the flow rate when the drop
factor is 10 drops per milliliters
You are ready to take the practice
test! Time yourself…you need to be
able to complete in 30 minutes