1. Lifespan Considerations
Chapter 3
Lifespan Considerations
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

2. Drug Therapy During Pregnancy
Drugs cross the placenta by diffusion
Factors affecting safety:
Drug properties
Fetal gestational age
Maternal factors
FDA has implemented pregnancy safety categories
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

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4. Classroom Response Question
When teaching a pregnant woman about the use of drugs during pregnancy, which statement will the nurse include?
Exposure of the fetus to drugs is most detrimental during the second trimester of pregnancy.
Pregnant women must never take drugs to control high blood pressure.
Drug transfer to the fetus is most likely to occur during the last trimester of pregnancy.
The fetus is at greatest risk for drug-induced developmental defects during the second trimester of pregnancy.
Correct answer: C
Rationale: Drug transfer to the fetus is most likely to occur during the last trimester of pregnancy. Exposure of the fetus to drugs is most detrimental during the first trimester of pregnancy and the fetus is at greatest risk for drug-induced developmental defects during the first trimester of pregnancy. Pregnant women need to take medications to control situations such as high blood pressure.
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.

5. Drug Therapy During Breastfeeding
Breastfed infants are at risk for exposure to drugs consumed by the mother
Consider risk-to-benefit ratio
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

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7. Neonatal and Pediatric Considerations: Pharmacokinetics
Absorption
Gastric pH less acidic
Gastric emptying slowed
Intramuscular absorption faster and irregular
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

8. Neonatal and Pediatric Considerations: Pharmacokinetics (cont’d)
Distribution
Greater total body water means lower fat content
Decreased level of protein binding
Immature blood-brain barrier—more drugs enter the brain
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

9. Neonatal and Pediatric Considerations: Pharmacokinetics (cont’d)
Metabolism
Liver immature, does not produce enough microsomal enzymes
Older children may have increased metabolism, requiring higher doses than infants
Other factors
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

10. Neonatal and Pediatric Considerations: Pharmacokinetics (cont’d)
Excretion
Kidney immaturity affects glomerular filtration rate and tubular secretion
Decreased perfusion rate of the kidneys may reduce excretion of drugs
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

11. Factors Affecting Pediatric Drug Dosages
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

12. Methods of Dosage Calculation for Pediatric Patients
Body surface area method
Uses the West nomogram
Always use weight in kilograms, not pounds
Body weight dosage calculations
Uses mg/kg
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14. 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
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.
Correct answer: D
Rationale: In pediatric patients, body temperature is less well-regulated and dehydration occurs easily; pediatric patients lack stomach acid to kill bacteria, and have skin that is thinner and more permeable. It is true that pediatric patients have immature liver and kidney function, resulting in impaired drug metabolism and excretion.
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.

15. Considerations for Elderly Patients
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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17. The Elderly: Pharmacokinetics
Absorption
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

18. The Elderly: Pharmacokinetics (cont’d)
Distribution
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)
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

19. The Elderly: Pharmacokinetics (cont’d)
Metabolism
Aging liver produces fewer microsomal enzymes, affecting drug metabolism
Reduced blood flow to the liver
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

20. The Elderly: Pharmacokinetics (cont’d)
Excretion
Decreased glomerular filtration rate
Decreased number of intact nephrons
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

21. The Elderly:Problematic Medications
Analgesics, including NSAIDs and opioids
Anticoagulants
Anticholinergics
Antidepressants
Antihypertensives
Cardiac glycosides (digoxin)
Sedatives and hypnotics, CNS depressants
Thiazide diuretics
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

22. Classroom Response Question
Which does the nurse identify as a pharmacokinetic change that occurs in the elderly?
Gastric pH is more acidic
Fat content is decreased because of increased lean body mass
Increased production of proteins by the liver
The number of intact nephrons is decreased
Correct answer: D
Rationale: In elderly patients, the gastric pH is less acidic because of a gradual reduction in the production of hydrochloric acid in the stomach, fat content is increased because of decreased lean body mass, and there is decreased production of proteins by the aging liver and reduced protein intake. It is correct that the number of intact nephrons decrease in the elderly.
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.