Chapter 5 - Distribution Flashcards
true or false
if a drug is highly protein bound, the half life will be short
false - prolonged
if a drug is highly protein bound, is this linear or nonlinear pharmacokinetics
nonlinear
as free drug is excreted and leaves circulation, what happens to protein bound drug?
the bound drug will release from its protein and go into circulation to maintain equilibrium
true or false
a drug can bind to proteins not only in the plasma, but in the tissue as well
true
but more focused on plasma proteins
true or false
both free and bound drug can be distributed and eliminated
false - only free drug
are we able to measure the amount of FREE DRUG in a patient
no – just the total amount
measuring just free drug is too much $$
how much plasma is in an average 70kg male
3L
3 areas that drug can be distributed
plasma
other body areas (adipose tissue, protein, bone, etc)
plasma proteins
name 3 plasma proteins
albumin, alpha glycoprotein, lipoprotein
ACIDIC DRUGS principally bind to what plasma protein
albumin
BASIC DRUGS primarily bind to what plasma protein
all 3 - albumin, lipoprotein, and alpha glycoprotein
minimum VD in an average person
3L
true or false
in a normal person, the concentration of plasma proteins usually fluctuates
FALSE - usually constant
if a patient has a certain disease state - changes
what will happen if a patient has NO plasma proteins
the entire dose will be free
true or false
high plasma protein binding = linear kinetics
FALSE - nonlinear
*just an important note
ONLY FREE DRUG CAN HAVE THERAPEUTIC EFFECT!!!!!
What is a disadvantage of drug being distributed to other tissues (aside from the target tissue)
side effects
formula to determine the fraction of free drug (a)
a = Cfree/C bound + Cfree
as alpha decreases, what happens
the amount of free drug increases significantly - need to reduce dose
true or false
if the alpha value decreases, we need to increase the dose of the drug
FALSE
there will be more free drug, so need to decrease the dose
after the drug molecules have entered the bloodstream, the pattern of DISTRIBUTION is determined by what
PERFUSION to each tissue
4 factors that affect drug distribution
-rate of flow of blood
-partition characteristics of the drug between plasma and tissue
-partition coefficient of drug into various tissues
-volume or mass of the tissue
if Vd is low, where will the drug remain
drug remains in the plasma and keeps circulating
rate of renal plasma flow
this is also known as the rate of…
590-695mL/min
rate of filtration
how many perfusion groups are there
4
true or false
most drugs are water soluble and dissolve in the plasma
true
total body water is ____ +____
extracellular fluid + intracellular fluid
**true or false
our body water content is lowest in infancy
false - highest in infancy. continues to decrease with age. gets to be 58% (~60%) when we get from 16 yrs - adulthood
true or false
water content does not change with age
false - it does
*around ___% of our body weight is water
60%
70kg adult. what vol of total water to use for calculation
41L
3L of the 41L of total body water is ___
plasma
true or false
it is not possible for the Vd of a drug to be below 3L
true
“the fluid portion of blood”
plasma
“the fluid portion of blood in combo with the formed elements - RBC, WBC, platelets
WHOLE BLOOD
what is “serum”
the product that’s left after fibrinogen, a soluble protein, is removed from the plasma
the drug concentration in the ______ correllates to the therapeutic effect
(whole blood, plasma, or serum)
plasma
are glucose levels checked using whole blood, plasma, or serum?
whole blood
“whole blood with the formed elements removed”
plasma
“plasma with the fibrinogen removed”
serum
what is the easiest way to measure drug concentration - whole blood, plasma, or serum
whole blood
however — not good. not very accurate.
are SOLUBLE PROTEINS included in the plasma?
yes - but not the formed elements
true or false
plasma is whole blood without solid matter and without dissolved matter
FALSE - without solid manner but has manner dissolved in the blood
true or false
if the Vd is high, the drug concentration in the plasma is likely low
true
define volume of distribution
the volume of fluid in which the drug appears to be distributed
true or false
the volume of distribution is a true physical volume
FALSE - not a true anatomical, physiological, or physical volume
it’s a calculated volume of the apparent volume - no true physiologic meaning
true or false
the volume of distribution has not true physiologic meaning
true – it’s a hypothetical volme of body fluid in which the drug appears to be dissolved or distributed
is it possible for the dose to be toxic for 1 patient and therapeutic to another?
YES
ie - if the drug distributes less in the tissues of 1 patient, (due to the 4 factors mentioned earlier) – more will be in the plasma. will need to decrease the dose for that patient
are we able to measure the drug concentration in the tissue?
no - only plasma
if you give a dose and the plasma concentration is low, what does this say about the vd
high vd - a lot is going to the tissues!
formula to find volume of distribution
V= Ab/C
Ab=total amount of drug in body
C = plasma concentration of the drug
volume of distribution is the size of a compartment to account for….
the TOTAL AMOUNT of drug in the body
true or false
protein binding only takes place in the plasma
FALSE - both in the plasma and the tissue
is there a difference in body composition between male and female
yes
3 components of our body composition
water
fat
fat-free solids
