Drug Action Across the Life Span

CHAPTER
3
Drug Action Across the Life Span
CHAPTER FOCUS
This chapter details the effects of drugs on patients
across the life span from newborn babies to the
older adults. Drugs are metabolized differently
depending on age and gender. Nursing implications
for monitoring drug therapy are also reviewed in
this chapter.
KEY TERMS
gender-specific medicine
pharmacogenetics
polymorphisms
passive diffusion
hydrolysis
intestinal transit
protein binding
drug metabolism
metabolites
polypharmacy
therapeutic drug monitoring
LEARNING OBJECTIVES
1. Discuss the effects of patient age on drug action.
2. Cite major factors associated with drug absorption,
distribution, metabolism, and excretion in
the pediatric and geriatric populations.
3. Cite major factors associated with drug absorption,
distribution, metabolism, and excretion in
men and women.
CHAPTER
OUTLINE
Drug
Absorption
Drug
Distribution
TEACHING
STRATEGIES
Review what are considered agerelated
issues for drug absorption:
drug routes, gastric pH, presence of
enzymes, and intestinal transit times.
Discuss how gender affects drug
absorption, such as slower transit
time and gastric pH differences in
women compared with men.
Identify the ways that drugs are transported
by the circulating body fluids
to the sites of action, and how they
depend on blood volume, body mass,
tissue fat, and blood flow to various
organs.
Discuss the aging process and the
resulting decrease in total body water
and lean body mass while total fat
increases, thus affecting drug distribution.
COLLABORATIVE
LEARNING ACTIVITIES
Make a table on the board with the routes
of administration (oral, IM, IV, and subcutaneous)
as columns, and gender and
ages as rows. Have students compare men
and women using each drug route. Indicate
which drug route is more effective depending
on age.
Make cards with the words passive diffusion,
hydrolysis, and intestinal transit. Have
pairs of students review the definitions
before explaining each word to the class.
Copyright © 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
15

16 Chapter 3 Drug Action Across the Life Span
Drug
Metabolism
Drug Excretion
Nursing
Implications
when
Monitoring
Drug Therapy
Review the hepatic system and its
role in inactivating medications; thus,
drug metabolism occurs via enzyme
action in the liver.
Identify those factors that affect
liver function, including the presence
of liver disease and heart failure.
Review the renal system and how the
renal tubules eventually excrete drugs
from the body.
Discuss the alternative routes of
excretion, including the GI system.
Review how monitoring of drug
concentrations is done by drawing
blood levels 30 minutes before the
next dose of medication to see the
lowest blood level (called a trough),
and then 20 minutes after the next
dose is given to get the highest blood
level (called a peak).
Discuss the different ways to administer
drugs to children.
Review growth and development
to assist in understanding the
difference between use of liquids for
infants and how older children can
take chewable drugs.
Identify the need to do a thorough
drug history for older adult patients
and review multidrug regimens.
Divide the class in half, with one side
representing the renal system and the other
representing the hepatic system. Give each
group cards with drug names. By exchanging
cards, have students determine which
drugs are metabolized primarily by their
organ system. After the exchange, review
the results of the exercise with the class.
Assign one student to be a patient and
another to be the nurse. Role play what a
nurse would explain to the patient about a
peak and trough drug level needing to be
drawn for gentamicin. Have the class assist
with the explanation if needed.
List on the board the following: infants,
toddlers, preschool children. Have Post-Its
available with names of drugs that are liquid,
chewable, powders, and tablets. Have
students come up and place the Post-Its
under the appropriate headings for each
drug. Review the exercise with the class.
WEB RESEARCH ACTIVITY
Have students search for information online about
drugs and breastfeeding. Compare this information
with what is covered in the text, and have them write
down their observations, with citations of the web
pages that were visited.
CASE STUDIES
1. Several patients are assigned to one nurse. Their
ages are 46 years, 75 years, and 92 years. Which
patient is the most likely to respond readily to
drug administration? Which patient is the most
likely to have a drug interaction? Explain why
this occurs.
2. A newborn baby, 7 days old, is admitted to the
hospital with refractory vomiting and a diagnosis
of pyloric stenosis. The physician has ordered
IV fluids to keep the baby hydrated. What nursing
considerations are important to remember
when dealing with newborn babies? Discuss
your findings in class.
Copyright © 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

CHAPTER
3
Student Name ________________________________________________________
Date ___________________________ ID # ______________________________
Drug Action Across the Life Span
Quiz
MULTIPLE CHOICE
_____ 1.
_____ 2.
_____ 3.
_____ 4.
Gender-specific medicine studies the differences
in the normal function of men
and women and how each sex differs in
their experience of ____________.
1. life
2. disease
3. symptoms
4. healthcare
What factors influence drug absorption
from the gastrointestinal tract?
1. pH and renal function
2. passive diffusion, renal function, and
muscle mass
3. gastric transit time, pH, and passive
diffusion
4. renal function, pH, and gastric transit
time
In infants, which of the following factors
influence the ability of a drug to be
absorbed and distributed in the body?
(Select all that apply.)
1. presence of necessary enzymes
2. thickness of the dermal layer of the
skin
3. percent of total body fluid present
and adipose tissue
4. total amount of muscle mass and
fluid ingested daily
In older adults, the best indicator of renal
function is:
1. urine output.
2. BUN (blood urea nitrogen) test.
3. creatinine clearance test.
4. urinalysis.
_____ 5.
_____ 6.
_____ 7.
_____ 8.
When an older adult patient is taking
multiple drugs at the same time, it increases
the chance of drug:
1. absorption.
2. excretion.
3. interaction.
4. distribution.
“Peak” and “trough” levels are drawn:
1. to identify the development of drug
tolerance.
2. to determine the degree of therapeutic
response to prescribed medication.
3. 20 minutes after the drug administration
and 30 minutes before next
dose.
4. 30 minutes after drug administration
and 20 minutes before next dose.
Pediatric drug dosages may be based on
estimated body surface area (BSA) because:
1. infants’ percentage of body fluids is
less than that of adults.
2. therapeutic drug monitoring is based
on BSA.
3. BSA is a substitute for therapeutic
monitoring.
4. weight changes and growth of the
individual are accurately reflected in
BSA.
The least accurate measuring device for
oral forms of liquid medication is a(n):
1. oral syringe.
2. dropper.
3. medicine cup.
4. household teaspoon.
Copyright © 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
17

Student Name ________________________________________________________
Date ___________________________ ID # ______________________________
_____ 9.
When “off-label use” of medications is
prescribed, the nurse should:
1. refuse to administer the medication.
2. cross-check dosage in references or
with the pharmacist.
3. administer the prescribed medication.
4. consult the prescribing physician before
administering the medication.
_____ 10. During initiation of a newly prescribed
medication for a geriatric patient, it is
recommended that:
1. normal adult doses be used.
2. 1/3 to 1/2 of the normal adult dose
be administered.
3. multiple new medications be initiated
simultaneously.
4. new medications have therapeutic
drug levels performed.
_____ 11. Drugs in which classification are known
to be potentially teratogenic?
1. anti-inflammatory medications (e.g.,
aspirin, ibuprofen)
2. HMG-CoA reductase inhibitors and
angiotensin-converting enzyme inhibitors
3. antibiotics
4. xanthine derivatives and anticholinergic
bronchodilating agents
COMPLETION
Complete the following statements.
12. CYP3S4 is the component of the cytochrome
P-450 system of enzymes necessary for the
_____________________ of drugs.
13. The placement of a transdermal drug system on
the lower extremities of an older patient may result
in _____________________ drug absorption.
14. In passive diffusion, the drug moves from an
area of _____________________ concentration
to an area of _____________________ concentration.
15. With active transport, the movement is from an
area of _____________________ concentration
to an area of _____________________ concentration.
18
Copyright © 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.