Week 3- Individual Variation Flashcards
What determines the intensity of the drug response?
The concentration of a drug at its sites of action
Which two groups are more sensitive to drugs?
Infants and the elderly
Diseases of which two organs can cause the accumulation of drug to toxic levels?
Kidney and liver
Explain pharmacodynamic tolerance
Adaptive responses occur with long-term administration requiring higher drug levels to get the same response.
Explain metabolic tolerance.
Because of increased drug metabolism, an increased dosage is needed to maintain therapeutic drug levels.
Which drug commonly demonstrates tachyphylaxis over a short time of administration?
Nitroglycerin patches
Define the placebo effect.
The placebo effect is defined as that component of a drug response that is caused by psychological factors.
What are the three types of pharmacogenomics alterations?
Immune response, metabolism, and target.
Why do some patients have no pain relief from codeine?
A variant cytochrome P450 is unable to convert codeine to morphine.
How does starvation increase the free drug concentration level of some drugs?
Decreased binding to albumin increases the drug level in the bloodstream.
How does the change in glomerular filtration in the third trimester affect drug clearance?
The increased glomerular filtration increases the renal excretion of drugs.
How does intestinal motility affect drug levels in a pregnant woman?
Slowed motility allows more drug to be absorbed.
List 4 types of drugs and explain their likelihood of crossing the placenta.
Lipid-soluble – easy, Ionized – difficult, Highly polar – difficult, Protein-bound - difficult
What percentage of birth defects is caused by drugs?
Less than 1%.
What is the risk of malformations by a teratogen?
10%
How many weeks after conception do gross malformations begin to occur? In what trimester?
2 weeks. First trimester (3-8 weeks).
From what week are the developmental processes of the brain affected?
Week 9
When is the best time for a breastfeeding mother to take a short-acting drug to limit drug levels in the breast milk?
Immediately after breastfeeding
What FDA drug classification has adequate studies in pregnant women to demonstrate no risk to fetus of woman?
Class A
Is a lack of teratogenesis in animals proof of safety in humans?
No
What type of drugs readily enters breast milk?
Lipid-soluble drugs
When should a nursing mother take a medicine in order to minimize transfer of the drug into the breast milk?
Immediately after breastfeeding
Pediatrics refers to patients under what age?
16 years
Define neonates and infants.
Neonates – first 4 weeks, Infants – weeks 5 through 1 year
Discuss the effect of blood flow on the absorption of IM medications in neonates and infants.
Neonates – slower than infants and adults due to slow and erratic blood flow, Infants – more rapid than neonates or adults
Discuss how decreased protein binding in neonates and infants affect drug distribution.
Low albumin levels provide fewer binding sites which increases the free drug levels.
An immature blood-brain barrier in the infant increases the likelihood of what kind of effects?
Sensitivity to CNS effects of drugs
The infant’s hepatic metabolism reaches an adult level at what age?
One year.
When does the infant’s GFR reach adult levels?
One year.
A child’s hepatic metabolism peaks at what age? The child’s metabolism is greater than an adult during what ages?
Two years. 1-12 years.
How do sulfonamides cause neurological toxicity in infants under 2 months old?
Sulfonamides displace the bilirubin from the plasma proteins. Bilirubin crosses the blood-brain barrier causing neurological toxicity.
What drug is implicated with Reye’s syndrome when administered in children with chicken pox or influenza?
Aspirin
What is the most accurate method of determining dosage in children?
Body Surface Area (BSA)
A decrease in lean body mass in the elderly is associated with what change in total body water? How does this total body water change affect water-soluble drug concentrations?
A decrease in lean body mass is associated with a decrease in total body water. This decrease in total body water will increase a concentration of water-soluble drugs.
The elderly show what change in hepatic metabolism of drugs?
A decrease in hepatic metabolism of drugs
What is the most important cause of adverse reactions in the elderly?
Decreased renal excretion
What lab most accurately assesses renal clearance?
Creatinine clearance
What labs are frequently used instead of creatinine clearance to monitor renal function?
Blood urea nitrogen (BUN), Creatinine
Drugs with what type of therapeutic indexes are most likely to cause adverse reactions?
Drugs with low therapeutic indexes
How do multiple drugs affect the risk of drug interactions?
Increases the risk of drug interactions
