Drug Absorption #1 Flashcards
biopharmaceutics deals with factors that influence….
bioavailability
What factors can affect bioavailability? (4)
- drug
- patient specifically
- form
- route of administration
T/F The amount of drug in the blood will effect the amount of drug that gets to the site of action.
TRUE
Cmax
the highest concentration achievable from a single dose
Tmax
how long from administrations before the maximum concentration is achieved
Increased rate?–»
Cmax: Increase
Tmax: Decrease
AUC: no effected
Increased extent?–>
Cmax: Increase
Tmax: no effect
AUC: Increase
T/F Cmax and Tmax are usually visually determined
TRUE
AUC is determined by using the …..
Trapezoidal rule–>
Area= 1/2 (a +b) * c (sum of the two parallel sides * distance between the sides * 1/2
____ is determined using the last two concentration values collected
K el(Elimination constant)
K el or elimination is ___ order, so you have to change it to ____
FIRST; log
T/F Once the drug is released from the dosage form, it has to be dissolved before it can cross the membrane
TRUE
By what mechanism are most drugs given orally absorbed?
passive diffusion
Why do we have carriers in the GI tract?
to move nutrients through the membrane (these can not passively move across)
Rate of diffusion (dc/dt) determines….
how slow or rapidly the drug moves into the blood
P (3)
- partition coefficient
- measure of lipid solubility
- a constant
A LARGER P = …..
Higher Lipid solubility
Partition coefficient equation
ratio of relative solubility of a drug in lipid (/) relative solubility in water
D
diffusion coefficient
-a constant
A
area of surface at which diffusion is occurring
-a constant
h
thickness of the membrane
-a constant
C ad
concentration of drug at the site of administration
C p
concentration of drug in the plasma
T/F Diffusion is a random process
TRUE
Drug diffusing into the blood after being administered is driven by
kinetic energy (random movement of molecules)
Direction in which the molecules move depends on…..
the concentration gradient (usually from high to low concentration)
Permeability depends on ____ and _____ properties
solute and membrane
Drug Absorption is GENERALLY a _____ order process
FIRST
Which law can be used to determine the rate of diffusion?
Fisk Law of Diffusion
