Transcript Pharmacology and the Nursing Process, 4th ed. Lilley/Harrington

Chapter 3
Lifespan Considerations
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Drug Therapy During Pregnancy
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Drugs cross the placenta by diffusion
Factors affecting safety:
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Drug properties
Fetal gestational age
Maternal factors
FDA has implemented pregnancy safety
categories
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Classroom Response Question
When teaching a pregnant woman about the use of drugs
during pregnancy, which statement will the nurse include?
A. Exposure of the fetus to drugs is most detrimental
during the second trimester of pregnancy.
B. Pregnant women must never take drugs to control high
blood pressure.
C. Drug transfer to the fetus is most likely to occur during
the last trimester of pregnancy.
D. The fetus is at greatest risk for drug-induced
developmental defects during the second trimester of
pregnancy.
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Drug Therapy During
Breastfeeding
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Breastfed infants are at risk for exposure to
drugs consumed by the mother
Consider risk-to-benefit ratio
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Neonatal and Pediatric
Considerations: Pharmacokinetics
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Absorption
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Gastric pH less acidic
Gastric emptying slowed
Intramuscular absorption faster and irregular
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Neonatal and Pediatric Considerations:
Pharmacokinetics (cont’d)
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Distribution
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Greater total body water means lower fat content
Decreased level of protein binding
Immature blood-brain barrier—more drugs enter the brain
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Neonatal and Pediatric Considerations:
Pharmacokinetics (cont’d)
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Metabolism
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Liver immature, does not produce enough microsomal enzymes
Older children may have increased metabolism, requiring higher
doses than infants
Other factors
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Neonatal and Pediatric Considerations:
Pharmacokinetics (cont’d)
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Excretion
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Kidney immaturity affects glomerular filtration rate and tubular
secretion
Decreased perfusion rate of the kidneys may reduce excretion of
drugs
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Factors Affecting Pediatric
Drug Dosages
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Skin is thin and permeable
Stomach lacks acid to kill bacteria
Lungs have weaker mucus barriers
Body temperatures less well regulated, and dehydration
occurs easily
Liver and kidneys are immature, impairing drug
metabolism and excretion
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Methods of Dosage Calculation for
Pediatric Patients
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Body surface area method
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Uses the West nomogram
Always use weight in kilograms, not pounds
Body weight dosage calculations
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Uses mg/kg
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Classroom Response Question
When administering medications to pediatric patients, the
nurse understands that the dosage calculations for
pediatric patients are different than for adults because
pediatric patients
A.
B.
C.
D.
are more likely to develop edema.
have more stomach acid.
have skin that is less permeable.
have immature liver and kidney function, resulting in
impaired drug metabolism and excretion.
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Considerations for Elderly Patients
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Elderly: older than age 65
High use of medications
Polypharmacy
Noncompliance, nonadherence
Increased incidence of chronic illnesses
Sensory and motor deficits
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The Elderly: Pharmacokinetics
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Absorption
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Gastric pH less acidic
Gastric emptying slowed
Movement through GI tract slowed
Blood flow to GI tract reduced
Use of laxatives may accelerate GI motility
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The Elderly: Pharmacokinetics
(cont’d)
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Distribution
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Lower total body water percentages
Increased fat content
Decreased production of proteins by the liver, resulting in
decreased protein binding of drugs (and increased circulation of
free drugs)
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The Elderly: Pharmacokinetics
(cont’d)
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Metabolism
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Aging liver produces fewer microsomal enzymes, affecting drug
metabolism
Reduced blood flow to the liver
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The Elderly: Pharmacokinetics
(cont’d)
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Excretion
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Decreased glomerular filtration rate
Decreased number of intact nephrons
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The Elderly:Problematic
Medications
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Analgesics, including NSAIDs and opioids
Anticoagulants
Anticholinergics
Antidepressants
Antihypertensives
Cardiac glycosides (digoxin)
Sedatives and hypnotics, CNS depressants
Thiazide diuretics
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Classroom Response Question
Which does the nurse identify as a pharmacokinetic
change that occurs in the elderly?
A. Gastric pH is more acidic
B. Fat content is decreased because of increased lean
body mass
C. Increased production of proteins by the liver
D. The number of intact nephrons is decreased
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