Transcript Chapter 10 Pediatric and Geriatric Considerations

Math for the Pharmacy Technician:
Concepts and Calculations
Egler • Booth
Chapter 10: Pediatric and
Geriatric Considerations
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Pediatric and Geriatric
Considerations
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Learning Objectives
When you have successfully completed Chapter 10, you
will have mastered skills to be able to:
 Explain why dosages calculations for
specific populations must be based on the
individual patient.
 Identify factors that affect the absorption,
distribution, biotransformation, and
elimination of drugs in special
populations.
 Determine safe doses for special
population patients.
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Learning Objectives
(con’t)
 Determine safe doses for special
populations.
 Calculate patient dosages based on
body weight.
 Calculate pediatric dosages using
Clark’s Rule.
 Calculate pediatric dosages using
Young’s Rule.
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Learning Objectives
(con’t)
 Find a patient’s body surface area
(BSA).
 Calculate patient dosages based on a
patient’s BSA.
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Introduction
 Two special populations require extra
consideration when calculating
medication dosages
 Pediatric (children under age 18)
 Geriatric (mature adults over age 65)
 Risk of harm is far greater due to
way they break down and absorb
medications
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Introduction




(con’t)
Clarify all confusing drug orders
Calculate with absolute accuracy
Verify that dose is safe
Seek assistance from your
supervisor
Do not take short cuts with
medication calculations
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Factors that Impact Dosing
 Normal dose of medication makes
assumptions
 About the patient’s body and age
 That body systems are fully developed
and functioning
 Special populations may need
dosages adjusted due to this
assumption not being true
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Pharmacokinetics
 Study of how drugs are used by the
body




Absorption
Distribution
Biotransformation
Elimination
Understanding these processes allows
for adjustments for special
populations
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Absorption
 Process that moves a drug from the
site where it is given into the
bloodstream
 IV medications bypass the absorption
process by going directly into the
bloodstream
 Oral medications absorbed in digestive
system
 Topical absorbed through the skin
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Distribution
 Process that moves the drug from
the bloodstream to other body
tissues and fluids
 Target site is where the drug
product produces its desired effect
 Each drug affects drug target sites
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Biotransformation
 Process that chemically changes the
drug in the body
 Occurs primarily in the liver
 Helps to protect the body from
foreign chemicals including drugs
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Elimination
 Process where the drug leaves the
body
 Main way of eliminating is in the
urine
 Other ways





Air that we exhale
Sweat
Feces
Breast milk
Other body secretions
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Drug Adjustment
 Adjustment is needed if one of these four
processes are not functioning within
certain limits.
 Dose adjustment is made according to
nature and severity of patient’s condition.
 You are not expected to make these
adjustments, but be aware that they may
have to be done.
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Conditions That Impact
Dosing
Functions of body systems change over
the life of a person
Newborns – systems not developed yet
 pH of stomach is lower
 Thinner skin
 Liver still developing
 Less circulation to muscles
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Conditions That Impact Dosing
(con’t)
Geriatrics – systems begin to
deteriorate




Skin and veins become fragile
Decreased liver function
Decreased kidney function
Poor circulation
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Working with Special
Populations
 Other Considerations
 Parent or caretaker may be
administering or assisting them
with medications
 These individuals will need
education regarding any regular
or special requirements
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Teaching Patients or
Caretaker About Medications
1.
2.
3.
4.
5.
6.
Name of the medication
Purpose
How to store it
How long patient needs to take the
medication
How and when to take it
How to know if it is effective
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Teaching Patients or Caretaker
About Medications (con’t)
7.
8.
9.
10.
11.
12.
Required follow-up tests, doctor
appointments
Possible side effects and what to do
Interactions with other drugs and
foods
Symptoms to report to the doctor
What to do if a dose is missed
Keeping a list of all medications
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Ensuring Safe Dosages
 When you are working with special
populations, always check the package
insert, drug label, or product literature to
ensure the safety of the dose to be
administered.
 Drug orders may be written in several
ways. If you measure the medication, you
have the responsibility to check whether
the dose is the standard recommended
dose.
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Ensuring Safe Dosages (cont.)
 The recommended dose is sometimes
written as a range, with a minimum
and a maximum recommended dose.
In this case, you will need to
determine if the dose ordered is not
less than the minimum or greater
than the maximum recommended
dose.
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Review and Practice
Ensuring Safe Dosages
(con’t)
Determine whether the following order is
safe. If safe, calculate the amount to
administer.
Patient: Child who weighs 14.5 kg
Ordered: Amoxil 75 mg PO q8h
On hand: Usual child dose 20-40 mg/kg
day q8h
Answer: Dosage doesn’t fall within recommended
dosage range; contact the physician.
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CAUTION !
Convert ounces carefully.
 The weight of babies is often measured in
pounds and ounces.
 Because 16 oz = 1 lb, an ounce is not a
tenth of a pound.
 A baby who weighs 8 lb 6 oz does not
weigh 8.6 lb.
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CAUTION! (con’t)
Convert 6 ounces
to pounds using
1 lb
16 oz as the
conversion
6 oz  1lb  0.375 lb
16 oz
Thus, 8 lb 6 oz = 8.375 lb
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Dosages Based on Body
Weight
Calculating dosage based on body weight:
1. Convert the patient’s weight to kilograms
2. Calculate the desired dose, D, by
multiplying dose ordered by the weight in
kilograms such as
mg
m cg
x kg  desired dose or
x kg  desired dose
kg
kg
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Dosages Based on Body
Weight (con’t)
3. Confirm whether or not the desired
dose is safe by checking the label,
package insert, or product
literature. If unsafe, consult the
physician who wrote the order
4. Calculate the amount to
administer, using fraction
proportion, ratio proportion,
dimensional analysis, or the
formula method
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Review and Practice
Dosages Based on Body Weight
(con’t)
Calculate the amount to administer to a threeyear-old who weighs 34 lb.
Ordered: hysocyamine sulfate 5 mcg/kg subq
1 h pre-anesthesia
On hand: hysocyamine sulfate 0.5 mg/mL
Answer: 0.15 mL
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Pediatric Specific Dosage
Calculations
 There are two other forms of
calculations used to calculate
pediatric doses, Clark’s Rule and
Young’s Rule.
 Clark’s Rule uses the weight of the child
to determine the desired dose and
 Young’s Rule uses the age of the child
to determine the desired dose.
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Pediatric Specific Dosage
Calculations (con’t)
 Memory Tip
Young = age; the word “young”
refers to the age of an individual, and
Young’s Rule uses the age of the child
to determine the desired dose.
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Pediatric Specific Dosage
Calculations (con’t)
 Clark’s Rule for children’s dosage
calculations uses the following
formula:
Child's weight in pounds
× average adult dose = pediatric patient's dose
150 pounds
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Review and Practice
Pediatric Specific Dosage
Calculations (con’t)
Using Clark’s Rule, find the amount to
be dispensed. The patient is a 6-yearold child who weighs 50 lb; the
average adult dose is 250 mg.
50 lb
 250 mg  83.3 mg
150 lb
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10-32
Pediatric Specific Dosage
Calculations (con’t)
 Young’s Rule for children’s dosage
calculations uses the following
formula. (this formula can be used
only if the child is a least 1 year of
age):
child' s age in years
child' s age in years  12 years
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 average adult dose  pediatric patient' s dose
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Review and Practice
Pediatric Specific Dosage
Calculations (con’t)
Using Young’s Rule, find the amount to
be dispensed. The patient is a 6-yearold child who weighs 50 lb; the
average adult dose is 250 mg.
6 years
 250mg  83.3 mg
6 years  12 years
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10-34
Dosages Based on Body
Surface Area (BSA)
 BSA calculations are used to provide
more accurate dosage calculations
specific to the patient’s size and
severity of his/her illness.
 Some medications are based on
patient’s body weight only.
 Both weight and height are used to
determine a patient’s body surface.
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Calculating BSA Using a
Formula
 A patient’s BSA is stated in square
meters or m2
 To calculate the BSA you must know
the height and weight
 Use a formula or a special chart
called a nomogram
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Calculating BSA Using a
Formula
To determine a patient’s Body Surface
Area (BSA):
1. If you know the height in cm and
weight in kg, calculate
height
(cm)

weight
(kg)
BSA 
m2
3600
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Calculating BSA Using a
Formula (con’t)
2. If you know the height in
inches and weight in pounds,
calculate
height
(in)

weight
(lb)
BSA 
m2
3131
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Review and Practice
Calculating BSA Using a Formula
(con’t)
Find the body surface area for an adult who
is 5’6” tall and who weighs 168 lb.
BSA = 1.9 m2
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Calculating the Body Surface
Area (BSA) using a Nomogram
 Using a straight edge, align the
straight edge so it intersects at the
height and weight
 Doing so will create an intersection
in the BSA scale
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Review and Practice
Calculating the BSA using
a Nomogram (con’t)
Find the body surface for a
baby who is 24 in and
weighs 14 lb and 8 oz
Use the “Child’s
Nomogram”
BSA = 0.21 m2
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Calculating Dosage Based
on BSA
Calculating dosage based on BSA:
1. Calculate the patient’s BSA.
2. Calculate the desired dose:
dosage ordered x BSA = desired dose
3. Confirm whether or not the desired dose is
safe. If unsafe, consult the physician who
wrote the order.
4. Calculate the amount to administer,
using fraction proportions, ratio
proportions, or the formula method.
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Review and Practice
Calculating Dosage Based on BSA
(con’t)
Ordered: Ceenu (1st dose) 140 mg now
for a child whose height is 38 in and
weight is 47 lb
According to the package the first dose
is a single oral dose providing 130
mg/m2
The dose ordered 140 mg is above the first
recommended dose. Contact the physician.
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Review and Practice
True or False
A baby who weighs 6 lb 8 oz
weighs 6.8 lb.
Answer: False
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Review and Practice
True or False
A baby who weighs 9.5 lb
weighs 9 lb 8 oz.
Answer: True
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Review and Practice
What two things are pediatric dosages
often based on?
Answer: Weight and BSA
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Pediatric and Geriatric
Calculations
No matter how rushed you may feel,
you cannot take shortcuts with any
medication calculations, especially
patients from special populations.
THE END
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