Lecture Math for the pharmacy technician Concepts and calculations Chapter 10 – Lynn M. Egler, Kathryn A. Booth

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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10-3

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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10-4

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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10-5

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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10-6

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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10-7

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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10-8

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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10-9

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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10-10

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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10-11

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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10-12

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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10-13

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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10-14

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

10-15

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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10-16

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


10-17

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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10-18

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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10-19

Teaching Patients or Caretaker
About Medications (con’t)
Required follow-up tests, doctor
appointments
8. Possible side effects and what to do
9. Interactions with other drugs and
foods
10. Symptoms to report to the doctor
11. What to do if a dose is missed
12. Keeping a list of all medications
7.

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10-20

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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10-21

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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10-22

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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10-23

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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10-24

CAUTION! (con’t)
Convert 6 ounces
to pounds using
1 lb
16 oz as the
conversion

6 oz × 1 lb = 0.375 lb
16 oz

Thus, 8 lb 6 oz = 8.375 lb
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Dosages Based on Body

Weight

10-25

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
mcg
x kg = desired dose or
x kg = desired dose
kg
kg
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