chapter 4 - week 1 Flashcards
drug therapy during pregnancy, factors affecting safety
Drugs cross the placenta primarily by diffusion.
Factors affecting safety:
* Drug properties
* Fetal gestational age
* Maternal factors
“Motherisk” program
US Food and Drug Administration (FDA) has implemented pregnancy safety categories.
* These are used in Canada
drug therapy during breastfeeding
Breastfed infants are at risk for exposure to drugs consumed by the mother
Consider risk–benefit ratio
neonatal and pediatric condsiderations with absorption
- Gastric pH less acidic until 1 to 2 years of age
- Gastric emptying slowed
- First-pass elimination reduced
- Reduced bile salt formation decreases bioavailability
- Intramuscular absorption faster and irregular
neonatal and pediatric condsiderations with distrution
- Total body water differences result in increased distribution and dilution of water-soluble drugs.
- Greater total body water means lower fat content.
- Decreased level of protein binding
- Immature blood–brain barrier means more drugs enter the brain.
neonatal and pediatric condsiderations with metabolism
Liver immature; does not produce enough microsomal enzymes
Older children may have increased metabolism, requiring higher doses or more frequent administration than infants.
Other factors: liver enzyme production, genetic differences, and substances to which the mother may have been exposed during pregnancy
Neonatal and pediatric considerations with excretion
Kidney immaturity affects glomerular filtration rate and tubular secretion.
Decreased perfusion rate of the kidneys may reduce excretion of drugs.
factors affecting pediatric drug dosages
Skin is thin and permeable.
Stomach lacks acid to kill bacteria.
Lungs have weaker mucus barriers.
Body temperatures are less well regulated, and dehydration occurs easily.
Liver and kidneys are immature, impairing drug metabolism and excretion.
methods of dosage calculations of pediatric patients
Body surface area method
Uses the West nomogram
Always use weight in kilograms, not pounds.
Always use height in centimeters, not inches.
Body weight dosage calculations
Uses mg/kg
general considerations for pediatric patients
- Prepare all equipment and supplies first.
- Have caregivers stay as appropriate.
- Assess for comfort methods before, during, and after drug administration.
considerations for older adult patients
older adults: older than the age 65
* High use of medications
* Polypharmacy
* Nonadherence
* Increased incidence of chronic illnesses
* Sensory and motor deficits
older adult considerations with absorptsion
Gastric pH less acidic
Gastric emptying slowed
Movement through gastrointestinal (GI) tract slowed because of decreased muscle tone and activity
Blood flow to GI tract reduced
Absorptive surface of GI tract reduced
older adult considerations with distrubuation
- 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)
older adult considerations with excertion
- Decreased glomerular filtration rate
- Decreased number of intact nephrons
older adult considerations with metabolism
- Aging liver produces fewer microsomal enzymes, affecting drug metabolism.
- Blood flow to the liver is reduced.
- Leads to a prolonged half-life of many drugs
- Potential for accumulation if not monitored
Older Adults: Beers Criteria for Prevention of Adverse Drug Events
A listing of drug and drug classes to be avoided in older adults
Identified disease states considered to be contraindications for some drugs
Three categories:
* Potentially inappropriate drugs and classes in older adults
* Potentially inappropriate medications to avoid with certain diseases
* Medications to be used with caution in older adults