19. PATIENT CHARACTERISTICS & PK Flashcards
(38 cards)
List pharmacokinetic factors that affect the dosage regimen
ADME
List clinical factors that affect the dosage regimen
- patient factors: age, weight, race, sex disease, etc.
- therapy factors: drugs, convenience, compliance
List activity/toxicity factors that affect the dosage regimen
- therapeutic window
- adverse effects
- toxicity
- concentration/response relationship
List other factors that affect the dosage regimen
- route of administration
- dosage form
- tolerance/sensitivity
- pharmacogenomics
- drug interactions
- cost
What should ALWAYS be kept in mind when dosing pediatric patients?
CHILDREN ARE NOT SMALL ADULTS
Describe the Vd difference between adults and pediatric pts
- younger patients have higher VD (“water balloon”)
- increased absorption of hydrophilic drugs
T/F: pediatric patients are homogenous
FALSE!
differentiate throughout development
What is a issue with dosing pediatric patients?
limited information about peds dosing (missing in ~75% of drugs)
What route of administration is rarely used in peds pts?
IM
Describe the topical absorption difference between adults and pediatric pts
increased topical absorption in peds pts (higher conc) due to thinner skin
Describe the protein binding difference between adults and pediatric pts
Decreased protein binding in newborns & infants
What is the most reliable route of administration for peds pts?
rectal
Describe aging effects that can impact distribution
- Decreased lean body mass
- Decreased total body water
- Increased body fat
with advancing age
Describe impacts on elimination due to aging
- AGE-RELATED CHANGE IN RENAL FUNCTION!
- Reduced muscle mass (decreased SeCr)
Why is it important to consider the effects of aging when using the SeCr of older adults?
Estimation of renal function using SeCr may be less reliable in older adults due to reduced muscle mass
Why is it important to consider the effects of aging when dosing renally eliminated drugs in older adults?
- Decreased renal Cl of drugs that are eliminated by glomerular filtration and active tubular secretion with increasing age
- Lower dosing for renally eliminated drugs
List some PK (ADME) differences between men & women
- Women typically have higher concentrations of drug and therefore a greater chance for adverse effects
- Women have greater CYP3A activity (20-50% higher than men)
- Women tend to have slower GFR & secretion
- Men have slightly higher CYP2C19 & 2E1 activity
Explain why women have a higher risk of developing cardiac arrythmias vs. men
Longer QT prolongation
Explain why women have higher concentrations of drug than men
- Women have a higher % of body fat compared to men
- Women have greater Vd for lipophilic drugs
- Women have smaller Vd for hydrophilic drugs & smaller plasma volumes
Higher exposure if not corrected for body weight
What is a “sex difference”?
Differences cause by biological hormones
What is a “gender difference”?
lifestyle differences (due to gender norms)
T/F: The FDA considers “sex” and “gender” to be interchangeable
TRUE
Describe differences in distribution caused by pregnancy
- Increase in total body water & expanded plasma volume = increased Vd of hydrophilic drugs
- Increased body fat = increased Vd of lipophilic drugs
Describe differences in elimination caused by pregnancy
- Increased hepatic blood flow = Increased elimination of high hepatic extraction drugs
- Increased renal blood flow & GFR = Increased elimination of renally eliminated drugs
