Exam 4 Flashcards
protein surfaces are mostly ___________ with _________ crevices (hydrophobic/hydrophilic)
hydrophilic, hydrophobic
_______ (high/low) protein content in blood plasma
high
protein binding results in non-uniform distribution of a drug in the body and hence affects which pharmacokinetic parameter?
Vd
the _______ (majority/minority) of drug molecules in plasma are bound to plasma proteins
majority
______ (free/bound) drug molecules are pharmacologically active and in equilibrium with other type of drug - free or bound
free
clinical labs report total plasma as the plasma drug concentration, what is the total plasma concentration equal to?
bound + unbound
this type of drug cannot easily pass through membranes, has a restrictive distribution and elimination, therapeutically inactive
bound drugs
this type of drug crosses cell membranes, has a larger distribution, therapeutically active
free/unbound drugs
major protein component of plasma and ECF, acidic and basic drugs bind to this
albumin
plasma protein that basic drugs bind to
AAGP
plasma proteins that lipophilic drugs bind to
lipoproteins
what percentage of plasma protein binding means low binding?
less than 50%
what percentage of plasma protein binding means high binding?
greater than 80%
what does fu mean?
fraction unbound drug in plasma
what does fut mean?
fraction unbound drug in tissues
what does fu equal (what’s the equation)?
[unbound]/[unbound]+[bound]
what does Vp mean?
plasma volume
what does Vt mean?
tissue volume
fu is _____ (higher, lower, constant) as Cp increases for drugs bound to albumin
constant
the number of albumin protein binding sites is _______ (greater/less) than the drug molecules available for binding
much greater than
at very ______ (high/low) Cp binding sites are saturated so fu increases as Cp increases
high
if the fu value is 0.01, what is the percent protein binding?
99%
if the fu value is 0.9, what is the percent protein binding?
10%
highly bound drugs have a ________ (high/low) fu, and drugs with this fu have a _______ (high/low) Vd
low, low
a greater Vd causes what change in Cp?
decrease in Cp because greater Vd means more moves into tissues so there is less drug in the plasma (decreased Cp)
changes in fu imply changes in the unbound drug concentration in plasma which can enter tissues and exert a pharmacological or toxicological effect but it can also be eliminated by what?
glomerular filtration
for drugs whose fu increases and are subject to _______ elimination, the increased unbound drug concentration is SOMETIMES cancelled out by the increase in elimination by GFT
restrictive
what is Ka?
affinity constant
a ______ (high/low) Ka value means strongly bound drugs (decreased fu) so larger dose needed
high
drug affinity (Ka and fu) is altered in what disease state?
uremia (consequence of severe renal disease)
any factor that alters protein binding becomes clinically important when a drug is _______ (highly/not highly) protein bound, when fu is _______ (greater than/less than) 0.1
highly, less than
_________ (increase/decrease) in albumin during hepatic failure, renal failure, burns, stress/trauma, pregnancy, decreased binding of phenytoin for example (decreased Cp)
decrease
______ (increase/decrease) in AAGP during myocardial infarction, renal failure, arthritis, surgery, increase in Cp of quinidine for example
increase
_____ (increase/decrease) in tissue binding affinity in uremia, increased Cp of digoxin for example
decrease
when 2 drugs compete for the same binding site, one drug kicks out the other drug
displacement
these drugs achieve high concentrations in plasma and bind to albumin/AAGP, displace other drugs from tissue sites
displacers
“non-synthetic” or “functionalization” reactions, introduce or uncover a hydrophilic functional group
phase I of biotransformation
“synthetic” or “conjugation” reactions, drug or drug metabolite is attached to endogenous water-soluble molecule
phase II of biotransformation
drug metabolite is eliminated from cell via transporters in cell membrane
phase III of biotransformation
the phases of biotransformation ______ (do/do not) imply sequence
do not