Download presentation
Presentation is loading. Please wait.
1
CHAPTER 3 Life Span Considerations
4/16/2017 Winter 2013
2
Life Span Considerations
Pregnancy Breast-feeding Neonatal and pediatric Older Adult 4/16/2017 Winter 2013
3
Pregnancy First trimester is the period of greatest danger for drug-induced 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 4/16/2017 Winter 2013
4
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 4/16/2017 Winter 2013
5
Breast-feeding Breast-fed infants are at risk for exposure to drugs consumed by the mother Consider risk-to-benefit ratio 4/16/2017 Winter 2013
6
4/16/2017 Winter 2013
7
Neonatal and Pediatric Considerations: Pharmacokinetics
Absorption Gastric pH less acidic Gastric emptying slowed Intramuscular absorption faster and irregular 4/16/2017 Winter 2013
8
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 4/16/2017 Winter 2013
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 4/16/2017 Winter 2013
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 4/16/2017 Winter 2013
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 4/16/2017 Winter 2013
12
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 4/16/2017 Winter 2013
13
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 4/16/2017 Winter 2013
14
Young Adult 20 – 40 Middle Adult 40 – 65 Later Adult >65
Stages of Aging 4/16/2017 Winter 2013
15
Sources of Difficulty for Older Adults
Use of OTC medications Increased incidence of chronic illnesses Polypharmacy 4/16/2017 NRS 112/328 Summer 2011 15 4/16/2017 Winter 2013
16
Physiologic Changes in the Older Adult Patient
Cardiovascular Gastrointestinal Hepatic Renal 4/16/2017 Winter 2013
17
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 4/16/2017 Winter 2013
18
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) 4/16/2017 Winter 2013
19
The Older Adult: Pharmacokinetics (cont’d)
Metabolism Aging liver produces fewer microsomal enzymes, affecting drug metabolism Reduced blood flow to the liver 4/16/2017 Winter 2013
20
The Older Adult: Pharmacokinetics (cont’d)
Excretion Decreased glomerular filtration rate Decreased number of intact nephrons 4/16/2017 Winter 2013
21
The Older Adult: Problematic Medications
Analgesics, including NSAIDs and opioids Anticoagulants Anticholinergics Antidepressants Antihypertensives Cardiac glycosides (digoxin) Sedatives and hypnotics, CNS depressants Thiazide diuretics 4/16/2017 Winter 2013
Similar presentations
