Test 5 Review Flashcards
(110 cards)
Intrapatient therapeutic variability
Different response in the same patient at different times
Interpatient therapeutic variability
Different response between different people
Pharmacokinetic variability
Varying of delivery, removal, efficacy, and toxicity of drug (body does to drug)
-dangerous to drugs with a narrow therapeutic index (more likely to be fatal)
What plays a vital role in pharmacokinetic variability?
Genetic effect
Why is body weight and composition a source of pharmacokinetic variability?
Obese person has a higher volume of distribution for lipophilic drugs (dissolve in fat and spread farther) so they need a smaller dose
How to find dose required?
(Avg dose/70kg) x weight in kg
Why is age a source of pharmacokinetic variability?
Very young or old people have a worse immune system and enzymes are too weak to absorb the medication correctly
Why are infants and children at higher risk of greater bioavailability?
They have increased permeability of membranes such as the BBB, they have increased water content, decreased blood flow, metabolism, and renal clearance
Why do the elderly have risk of greater bioavailability?
Decreased liver and kidney function and a higher plasma concentration (liver can’t metabolize well and kidney can’t eliminate well)
Why is sex a source of pharmacokinetic variability?
Women have higher fat content, therefore more volume of distribution for lipophilic drugs
Why does pregnancy and lactation affect pharmacokinetic variability?
Teratogenicity (drugs crossing placenta and affecting fetus) and it is unknown how some drugs will affect a pregnancy
Fetal Alcohol Syndrome-FAS
Woman either drinks during pregnancy or takes a drug that affects the child, resulting in a malformed face “teratogenic effect”
Why does health and disease affect pharmacokinetic variability?
Kidney and liver disease will affect variability, dehydration, malnutrition, etc
Pharmacodynamic variability
What the drug does to the body
-variable drug effects due to difference in structure and function of target organs or patient disease
Why is sex a source of pharmacodynamic variability?
Females are more responsive to pain medications
Why is idiosyncrasy a source of pharmacodynamic variability?
Idiosyncrasy is an unpredictable and unusual response that is undocumented, usually a genetic predisposition, so it can affect what the drug does to the body
Why are circadian rhythms a source of pharmacodynamic variability?
Because chemicals like histamine and sex hormones are highest at night, and cortisol is highest in the morning so they can affect what the drug does to the body
Why does drug tolerance a source of pharmacodynamic variability?
If someone is tolerant to a drug they need more and more, so an increased dose can affect what the drug does to the body
Tachyphylaxis
Rapidly increasing response to a drug after administering a few doses
Why is receptor regulation by drugs a source of pharmacodynamic variability?
It can result in either tolerance or a more pronounced effect, so it can influence what the drug does to the body
-receptor up and receptor down regulation
Receptor up regulation
Number of receptors increase with continuous administration of drug, resulting in too many places for the drug to attach, causing a rebound (more pronounced) drug effect
Receptor down regulation
Number of receptors decrease with continuous administration, results in not enough places for the drug to attach leading to tolerance
Why is drug resistance a source of pharmacodynamic variability?
Because 3 types of resistance lead to absorption and elimination problems, affecting what the drug does to the body
Intrinsic resistance
Resistance to causing activity when attached to a receptor, leads to decreased absorption or increased elimination, and decreased response to the drug