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Transcript
Drug Therapy in
Pediatric
Patients
NURS 310 Winter 2016
1
MPinson_wi_16
Drug Therapy in Pediatric Patients
• Purpose of this lecture is to introduce basic concepts,
principles of drug therapy, and to promote critical
thinking among students
• Disclaimer: This lecture is introductory in nature and
does not attempt to comprehensively address all
clinically relevant and important considerations.
• Review of Burchum, J.R., & Rosenthal, L.D. (2016).
Drug Therapy in Pediatric Patients In Lehne’s
Pharmacology for Nursing Care, 9th edition (pp. 8891). St. Louis, Missouri: Elsevier Saunders.
• Lecture adapted by M Pinson, Winter 2016 from
powerpoint supplied by Elsevier Saunders.
• Sources of supplemental material are noted when
relevant.
2
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3
Drug Therapy in Pediatric Patients:
Learning Objectives
1. Purpose: to introduce basic concepts r/t drug therapy in the care of
neonates, infants and children, and promote critical thinking among
nursing students.
2. Describe the limitations of research, and consequent challenges of,
and requirements in, safely administering drug therapy to pediatric
patients.
3. Describe how immature organ systems during the first year of life
impact pharmacokinetics in neonates and infants. How do these
organ immaturities affect dosing of medications in this age group?
Describe several nursing implications r/t drug therapy in this age
group.
4. Describe how growth and development (particularly of the liver)
impact pharmacokinetics in children from age 1 year through age 16.
How do these changes affect dosing of medications in this age group?
Describe several nursing implications r/t drug therapy in this
age 4
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group.
Drug Therapy in Pediatric Patients:
Learning Objectives
5. Describe relative risk and give examples of adverse effects that
pediatric patients might experience.
6. Optional: Using the formula provided, practice calculating
“approximate initial doses” for a child. Use a reliable drug reference
to see how your approximation and the drug reference compare.
7. Identify several nursing implications associated with each pediatric
developmental age group.
8. Introduction to IV Therapy, and hydration rates
9. Describe several reasons why effective two-way communication is
important when a nurse provides education to a child’s caregiver.
10. Optional: role play with another person. Practice giving patient
education for a straightforward medication. Pick an easy drug that
you have administered in clinical, and a straightforward medication
order.
5
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Drug Therapy in Pediatric Patients
• Inadequate research data currently exists for prescribers
to ensure safe dosing for infants/children.
Two thirds of drugs used in pediatrics have never been
tested in pediatric patients
• Best Pharmaceuticals for Children Act (2002)
• Pediatric Research Equity Act of 2003
• 20 % of drugs were ineffective for children (even though
they were effective for adults)
• 30 % of drugs caused unanticipated side effects, some of
which were potentially lethal
• 20 % of drugs required dosages different from those that
had been extrapolated from dosages used in adults
• These laws were permanently reauthorized as part of the
6
FDA Safety and Innovation Act (FDASIA) of 2012
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Drug Therapy in Pediatric Patients
Pharmacokinetics: Comparison between Infants and Adults
Figure 10-1: Drug doses adjusted to body weight were administered to infants and
adults, via IV injection (left) or subcut (right). Duration/time above MEC, and peak
drug levels, differed significantly between infants and adults. Therefore, adjusting
dose
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amounts based on body size alone is inadequate to safely medicate neonates and infants.
Drug Therapy in Pediatric Patients:
Clearly, children are not little adults
• In what specific physiologic ways are neonates/infants
and children different from adults?
• How do these differences influence pharmacokinetics
and drug therapy in pediatric age groups?
• When do the differences in neonates/infants and
children become physiologically comparable to the
adult?
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8
Drug Therapy in Pediatric Patients
•
Neonates/infants are more sensitive to drugs than
adults
— due mainly to organ system immaturity
•
Neonates/infants are at increased risk for adverse
drug reactions
•
Young patients show greater individual variation
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9
Drug Therapy in Pediatric Patients: Stages & Definitions
“Pediatrics” broadly encompasses all patients younger than age 16
years. Many organs and functions are immature at birth. Different age
groups have unique therapeutic challenges and considerations.
Premature infants • Less than 36 weeks’ gestational age
10
Full-term infants
• 36 to 40 weeks’ gestational age
Neonates
• First 4 postnatal weeks
Infants
• Weeks 5 to 52 postnatal
Children
• 1 to 12 years old
Adolescents
• 12 to 16 years old
Drug Therapy in Pediatric Patients:
Pharmacokinetics in Neonates and Infants
• Neonates and infants have immature organs,
regulatory systems and other differences from mature
adults.
– affect pharmacokinetic processes
– neonates/infants are more sensitive to medications
than adults
11
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Drug Therapy in Pediatric Patients:
Pharmacokinetics in Neonates and Infants
• Absorption
– Oral administration
– Intramuscular administration
– Percutaneous (Transdermal) absorption
• Distribution
– Protein binding
– Blood-brain barrier
• Hepatic metabolism
• Renal excretion
12
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Pharmacokinetics in Neonates and Infants: ABSORPTION
● Absorption
– Oral administration
• Gastric emptying time
– Prolonged and irregular
– Adult function at 6 to 8 months
• Gastric acidity
– Very low 24 hours after birth
– Does not reach adult values until age 2 years
– Low acidity: Absorption of acid-labile drugs is increased
– Intramuscular administration
• During the first few days of life: Slow, Erratic, Delayed absorption as a
result of low blood flow
• During early infancy, absorption of intramuscular drugs more rapid than
in neonates and adults
– Transdermal absorption
•
•
•
•
Stratum corneum of infant’s skin is very thin
Blood flow to skin greater in infants than in older patients
More rapid and complete for infants than for older children and adults
Infants at increased risk of toxicity from topical drugs
13
Pharmacokinetics in Neonates and Infants: DISTRIBUTION
● Distribution
– Protein binding
• Binding of drugs to albumin and other plasma proteins is limited
in the infant
• Amount of serum albumin is relatively low
• Consequence? _______________
– Blood-brain barrier
• Not fully developed at birth
• Drugs and other chemicals have relatively easy access to the CNS
• Infants especially sensitive to drugs that affect CNS function
• Dosage should also be reduced for drugs used for actions outside
the CNS if those drugs are capable of producing CNS toxicity as a
side effect
– Endogenous compounds compete with drugs for available binding sites
• Limited drug/protein binding in infants
• Reduced dosage needed
• Adult protein binding capacity by 10 to 12 months of age
14
Pharmacokinetics in Neonates and Infants: METABOLISM
• Hepatic metabolism
– The drug-metabolizing capacity of newborns is low
– Neonates are especially sensitive to drugs that are
eliminated primarily by hepatic metabolism
– The liver’s capacity to metabolize many drugs increases
rapidly about 1 month after birth
– The ability to metabolize drugs at the adult level is
reached a few months later
– Complete liver maturation occurs by 1 year of age
15
Pharmacokinetics in Neonates and Infants: EXCRETION
• Renal excretion
– Significantly reduced at birth
– Low renal blood flow, low glomerular filtration, and
low active tubular secretion
– Drugs eliminated primarily by renal excretion must be
given in reduced dosage and/or at longer dosing intervals
– Adult levels of renal function achieved by 1 year
16
Drug Therapy in Pediatric Patients:
Pharmacokinetics in Neonates and Infants
• Did anyone notice a pattern about when
plasma-protein binding, kidney and liver
function mature to ~adult levels?
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17
Drug Therapy in Pediatric Patients:
Pharmacokinetics in Neonates and Infants
• As a consequence of organ immaturity, newborns and
babies in the first year of life have very different
pharmacokinetics from adults
–
–
–
–
–
Fewer albumin proteins  greater concentrations of free drug
Elevated free drug levels  more intense response
Decreased hepatic metabolism  prolonged response
Decreased renal elimination  prolonged response
Blood-brain-barrier not well-formed  CNS effects
18
Drug Therapy in Pediatric Patients:
Pharmacokinetics in Neonates and Infants
• Babies under the age of one year are “more
sensitive” to drugs
• Immaturity of organs puts neonates & infants at risk for:
– more intense, more prolonged responses
– increased risk of adverse effects due to kinetics
– Age-related unique adverse effects
• Example: kernicterus
• At the age of 1 year, most pharmacokinetic
parameters in children are similar to those of
adults
19
Drug Therapy in Pediatrics:
Case Study: Body Composition
A nurse is preparing to orient new nurses to the
pediatric unit. When discussing the pharmacokinetic
differences in the distribution of medication for
infants as compared with adults, the nurse will inform
the orientees that the amount of water in a young
infant’s body differs from that found in the body of an
adult.
How does it differ?
What are the clinical implications?
20
Drug Therapy in Pediatrics:
Case Study: Body Composition
What should the nurse teach the orientees about
young infants’ medication requirements related to
the administration of fat-soluble medications and
medications that bind to plasma proteins?
21
Drug Therapy in Pediatrics:
Case Study: Body Composition
Is there any information that the nurse should teach
the new orientees about the administration of
medications to young infants with regard to the
blood-brain barrier?
22
Questions?
23
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Drug Therapy in Pediatric Patients:
Pharmacokinetics in children aged one year and older
• Children aged one year and older have
pharmacokinetic parameters similar to adults,
except one important difference:
rate of hepatic metabolism varies
• In children age 1 year and older,
drug “sensitivity” is more like adults
24
Drug Therapy in Pediatric Patients
Pharmacokinetics in children aged one year and older
• From the age of 1 year until puberty, the rate of
hepatic metabolism varies
– Beginning ~ age 1 year, and until the baby reaches
age 2 years, metabolism is markedly faster than
adults
• Then a gradual decline begins in the rate of
hepatic metabolism
• Then a sharp decline in the rate of hepatic
metabolism occurs at puberty
• May need to increase dosage or decrease interval
between doses accordingly
25
Drug Therapy in Pediatric Patients
Pharmacokinetics in children aged one year and older
• Various stages of ongoing growth and development also
put children at risk for unique or age-related adverse
effects
• Examples :
• Growth suppression (caused by glucocorticoids)
• Discoloration of developing teeth (tetracyclines)
• Kernicterus (sulfonamides)
26
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Questions?
27
Drug Therapy in Pediatric Patients:
Dose Approximation based on Body Surface Area
Safe dose approximation and
the importance of careful monitoring
28
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Drug Therapy in Pediatric Patients:
Dose Approximation based on Body Surface Area
• Pediatric doses have been established for a few drugs,
but not most drugs
• Initial pediatric dosing is, at best, an approximation
• Nurses must be able to determine if a prescribed pediatric
dose is within a safe range
– Compare the patient’s prescribed dose to the
recommended safe dose as found in a reputable drug
reference
– Use a formula to determine if dose is safe
• Monitor carefully for therapeutic and adverse effects
29
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Drug Therapy in Pediatric Patients:
Dose Approximation based on Body Surface Area
• After an initial dose, pt must be monitored carefully
• Subsequent doses must be adjusted on the basis of:
– clinical response/outcome
– presence of adverse effects
– plasma drug concentrations
• Caution is warranted through at least the period of time
until steady-state drug levels are reached
– Half-lives in neonates and infants will be prolonged!
• Dose adjustments are especially important in younger
infants and neonates
30
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Drug Therapy in Pediatric Patients:
Dose Approximation based on Body Surface Area
Pediatric dosing is commonly based on body
surface area (BSA)
Approximate dosage for a child =
Body surface area of the child × adult dose
1.73 m²
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31
Example of a NOMOGRAM.
Historically, nomograms were used to determine Body Surface Area.
Calculations using a formula are more precise.
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32
Drug Therapy in Pediatric Patients:
Dosage Determination and Body Surface Area
• A number of different formulas have been developed over
the years to calculate BSA
• They give slightly different results.
• It is best to learn the policy of your employer/ clinical site
and follow that.
• The most commonly used formula may be that of
Mosteller, published in 1987 in The New England Journal of
Medicine. http://www.medicinenet.com/
• Years ago, a nomogram was used to determine BSA.
• Nowadays, online calculators are available.
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33
Drug Therapy in Pediatric Patients:
IV hydration rates
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34
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35
Drug Therapy in Pediatric Patients:
Promoting Adherence to a Medication Regimen
What is meant by “adherence”?
36
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Drug Therapy in Pediatric Patients:
Promoting Adherence to a Medication Regimen
• Effective two-way communication
• Individualized patient education
• Provide patient education in several ways
– always in writing in addition to verbal, infomercial, class,
etc
• Demonstration techniques should be included
when/if appropriate
• “Teach Back”
37
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Drug Therapy in Pediatric Patients:
Promoting Adherence to a Medication Regimen
Patient/ caregiver/ family need to know:
• Name of medication
• Purpose of medication
• Dosage size and timing (r/t meals, other meds,
time of day, symptom onset, and so forth)
• Administration route and technique
• Special considerations
• Treatment duration
• Drug storage- safety for children in household
• Nature and time course of desired responses
• Nature and time course of adverse effects:
teach possible adverse effects, how to respond,
when and how to follow-up with provider,
and when to call 911
38
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Question 1
The nurse provides teaching for the caregiver of a 2-monthold infant and a 3-year-old child. Both children will be taking
oral ampicillin (an acid-labile drug) to treat a bacterial
infection. The nurse determines that teaching is successful if
the caregiver makes which of the following statements?
A. “The dose will not be different, but the baby will take the
drug for 7 days instead of 10 days.”
B. “The dose will be higher for the baby, because the
infection is more serious.”
C. “The dose will be the same, because my children have the
same infection.”
D. “The dose will be smaller for the baby, because the drug
will be absorbed better in the stomach.”
39
Question 2
A 2-year-old child is prescribed an oral drug that is eliminated
by metabolism in the liver. Based on the child’s age, the nurse
would expect to make which adjustment?
A.
B.
C.
D.
The drug may need to be administered more frequently.
The dosage of the drug may need to be decreased.
The route should be changed from oral to intramuscular.
The drug should be administered on an empty stomach.
40
Question 3
A 15-month-old patient develops chemotherapyinduced nausea and vomiting. Which medication, if
ordered by the healthcare provider, should the nurse
question?
A. Ondansetron [Zofran]
B. Dexamethasone [Decadron]
C. Promethazine [Phenergan]
D. Metoclopramide [Reglan]
41
Question 4
A toddler has been prescribed a medication that does not
have an established pediatric dose. To calculate the
appropriate dose for the child, the nurse should consider
what information?
A.
B.
C.
D.
The child’s weight is 26 pounds.
The child’s height is 32 inches.
The child’s body surface area is 0.52 kg/m2.
The child’s age is 24 months.
42