ADME
Absorption
Distribution
Metabolism
Elimination
Absorption
Measure of the rate and amount of drug that moves from administration site into the bloodstream
Bioavailability (F)
Fraction of drug that passes into the blood stream
For any administration, F is measured relative to the IV admin for the same drug
Formula for bioavailability (F)
F= AUC (non-IV type of admin)/ AUC (admin by IV) X 100%
If bioavailability = 60% what does that mean
60% of drug makes it to the blood stream
Determinants of drug absorption
Drug solubility
Drug concentration
Local blood flow
What is the major driving force for drugs to move into the vasculature
Concentration Gradient
Characteristics of blood flow as absorption
Can vary because of environment, fear level, exercise, IM vs SC
Can be the rate limiting step
What is the most common mechanism for drugs to pass through cell membranes
Passive diffusion
How does charge affect how fast drugs pass through barriers
Charged drugs move slower
Calculation of amount of drug delivered to a tissue
Drug delivery= concentration(plasma drug conc) X volume (blood flow)
What two factors affect drug distribution
amount of drug delivered to a tissue
Rate of passage through vascular wall
For highly lipophlic drugs what does distribution depend exclusively on
Tissue blood flow
Characteristics of plasma protein binding
Decrease apparent vol of distribution
Decrease intensity of clinical effects
Inc. Drug half life in plasma
Inc. incidence of drug interactions
Is drug-protein binding reversible
Yes
Is the degree of drug-protein binding a fixed constant
No
What is a source of clinically significant drug-protein interactions
May compete for binding sites and cause mutual displacement
