Special Populations Flashcards
Pediatric aging
Premature: 36 weeks gestational age Full term infant: 36-40 Neonates: first 4 postnatal weeks Infants 5-52 weeks postnatal Children: 1-12 years Adolescents 12-18 years
Pregnancy
1st Trimester: greatest danger for drug-induced developmental defects (teratogenic effects)
3rd Trimester: drugs diffuse across the placenta
- increased blood flow to fetus
enlarged fetus
more free drug in mothers blood
FDA Pregnancy Safety Categories
Category A: remote risk fo fetal harm
Category B: Animal studies show safety - use with caution
Category C: only given if the potential benefit justifies potential risk for the fetus
Category D: positive evidence of human fetal risk, but used for life threatening situations
Category X: never to be given
Breastfeeding
Infants are at risk for exposure to drugs consumed by mother - milk is not a usual excretion route
Pediatric - Absorption
- Less acidic
- Slower peristalsis
- Immature liver = less first pass effect
- Faster topical absorption
- Irregular intramuscular absorption
Pediatric - Distribution
Total body water
- 70-80% in full-term infants
- 85% in premature newborns
- 64% in children 1-12
The greater TBW = lower fat content
Protein binding decreased because of decreased protein made in immature liver
Immature BBB = more drugs cross into brain
Pediatric - Metabolism
Immature liver = decreased drug metabolism
Older children = increased metabolism = higher doses
Pediatric - Excretion
Kidney immaturity affect glomerular filtration rate and tubular secretion
Decreased perfusion rate of the kidney = less drugs excreted
Pediatric - Dosages
Mostly always uses weight dosages
Drugs ordered as mg/kg
Geriatric Considerations
20-40% of all prescribed medications
> 40% of OTC drugs
Polypharmacy - multiple medications
- chronic illnesses and conditions
Geriatric - Physiological
Cardiovascular = decreased CO and BF to organs
Decreased absorption and distribution
GI = increased pH and decreased peristalsis
Liver = decrease cytochrome P450 and decrease metabolism
Kidney = decreased excretion of water soluble drugs
Geriatric - Absorption
Increased gastric pH Slowed gastric emptying Decreased peristalsis Reduced blood flow Reduced absorptive surface area (flattened intestinal villi)
Geriatric - Distribution
Total body water (TBW) lower
Increased fat content
Decreased albumin by liver= decreased protein binding
Geriatric - Metabolism
Less microsomal enzymes affecting drug metabolism
Reduced blood flow to liver
Prolonged half-life and drug accumulation
Geriatric - Excretion
Decrease glomerular filtration rate (40-50%) due to decreased blood flow
Leads to decreased excretion which also leads to drug accumulation
Decreased number of intact nephrons
