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CHAPTER 3 Life Span Considerations 5/23/2017 Winter 2013 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 1 Life Span Considerations Pregnancy Breast-feeding Neonatal and pediatric Older Adult 5/23/2017 Winter 2013 2 Pregnancy First trimester is the period of greatest danger for druginduced developmental defects Drugs cross the placenta by diffusion During the last trimester, the greatest percentage of maternally absorbed drug gets to the fetus FDA has implemented pregnancy safety categories 5/23/2017 Winter 2013 3 US Food and Drug Administration Drug Categories Regarding Pregnancy A - Adequate studies in pregnant women demonstrate no risk to the fetus B - Animal studies indicate no risk, but there are no adequate studies in pregnant women; or animal studies show adverse effects, but adequate studies in pregnant women have not demonstrated a risk C - A potential risk; these drugs may be used when potential benefits outweigh the potential risks D -There is evidence of human fetal risk, but potential benefits to mother may be acceptable despite risk X -Teratogenic or abortifacients; risk in pregnant woman clearly outweighs any possible benefit 5/23/2017 Winter 2013 4 Breast-feeding Breast-fed infants are at risk for exposure to drugs consumed by the mother Consider risk-to-benefit ratio 5/23/2017 Winter 2013 5 5/23/2017 Winter 2013 6 Neonatal and Pediatric Considerations: Pharmacokinetics Absorption ◦ Gastric pH less acidic ◦ Gastric emptying slowed ◦ Intramuscular absorption faster and irregular 5/23/2017 Winter 2013 7 Neonatal and Pediatric Considerations: Pharmacokinetics (cont’d) Distribution ◦ The younger the person, the greater the percentage of total body water ◦ Greater total body water means lower fat content ◦ Decreased level of protein binding ◦ Immature blood-brain barrier— more drugs enter the brain 5/23/2017 Winter 2013 8 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 5/23/2017 Winter 2013 9 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 5/23/2017 Winter 2013 10 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 5/23/2017 Winter 2013 11 Methods of Dosage Calculation for Pediatric Patients Body surface area method ◦ Using the West nomogram Always use weight in kilograms, not pounds Body weight dosage calculations ◦ Using mg/kg 5/23/2017 Winter 2013 12 The Older Adult Older Adult: older than age 65 Use of over-the-counter medications Increased incidence of chronic illnesses Sensory and motor deficits Polypharmacy 5/23/2017 Winter 2013 13 Young Adult 20 – 40 Middle Adult 40 – 65 Later Adult >65 Stages of Aging 5/23/2017 Winter 2013 14 Sources Adults of Difficulty for Older Use of OTC medications Increased incidence of chronic illnesses Polypharmacy 5/23/2017 Winter 2013 15 Physiologic Changes in the Older Adult Patient Cardiovascular Gastrointestinal Hepatic Renal 5/23/2017 Winter 2013 16 The Older Adult: 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 5/23/2017 Winter 2013 17 The Older Adult: 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) 5/23/2017 Winter 2013 18 The Older Adult: Pharmacokinetics (cont’d) Metabolism ◦ Aging liver produces fewer microsomal enzymes, affecting drug metabolism ◦ Reduced blood flow to the liver 5/23/2017 Winter 2013 19 The Older Adult: Pharmacokinetics (cont’d) Excretion ◦ Decreased glomerular filtration rate ◦ Decreased number of intact nephrons 5/23/2017 Winter 2013 20 The Older Adult: Problematic Medications Analgesics, including NSAIDs and opioids Anticoagulants Anticholinergics Antidepressants Antihypertensives Cardiac glycosides (digoxin) Sedatives and hypnotics, CNS depressants Thiazide diuretics 5/23/2017 Winter 2013 21