Pharmacology Flashcards
What the body does to the drug
Pharmacokinetics
What is the movement of drug into, through and out the body?
Pharmacokinetics
What is the flow of the drug?
ABDME
- Absorption
- Bioavailability
- Distribution
- Metabolism
- Excretion
Pharmacokinetics is determined by the drug’s
1) physiochemical properties
2) formulation
3) route of administration
How do drugs cross the membranes?
By: Passive diffusion Facilitated passive diffusion Active transport Pinocytosis
What are the 3 primary processes of pharmacokinetics?
IDE
Input
Distribution
Elimination
It is the amount of drug in the body in relation to the concentration of drug in the plasma.
Volume of Distribution
Where is the drugs with very high VD concentrated?
Extravascular tissue
than vascular compartment not homogeneously distributed
Why is VD generally uneven?
D/t the differences in blood perfusion, tissue binding, regional pH, and permeability of cell membranes.
What is the factor that predicts the rate of elimination in relation to the drug concentration?
Clearance
Clearance: first-order
Elimination - not saturable
Rate of elimination directly proportional to concentration
It is also known as:
Mixed-order Saturable Dose or conc dependent Nonlinear Michaelis Menten Elimination
Capacity-limited elimination
What is saturable and also called Vmax?
Maximum elimination capacity
It is the Km-drug conc at wc rate of elimination is 50% of Vmax.
Capacity limited elimination
Conc that are high relative to the elimination rate is almost independent of
Conc state of “pseudo-zero order” elimination
What if dosing rate exceeds elimination capacity?
Steady state cannot be achieved
Relationship of conc and dosing
Conc will keep rising as long as dosing continues
Where does the elimination of drugs depend?
Primarily on the rate of drug delivery to the organ of elimination
What is the main determinant of drug delivery?
Bld flow to the organ
Any conc of drug, most of the drug in bld perfusing the organ is eliminated on the
First pass of the drug through it
What is the time required to change the amount of drug in the body by one-half during elimination?
Half-life
Also time req to attain 50% of steady state or to decay 50% from steady state conditions after a change in the rate of drug administration
Half-life
Fraction remaining can be predicted from the dosing interval and t1/2
Drug accumulation
Fraction of unchanged drug reaching the systemic circulation following administration by any route
Bioavailability
What has the most rapid onset?
IV (100% Bioavailability)
Large volume, often feasible, may be painful, 75-100%, 90°
IM
- most common: deltoid (5mL)
- glutes (10mL)
Smaller vol than IM, may be painful, 75-100%, 45°
E.g vaxx, insulin
SC
Most convenient, 5-100%, first pass effect may be impt
Oral
Less first pass effect than oral, 30-<100%
Rectal
<100%, often very rapid onset
Inhalation
Usually very slow absorption, used for lack 1st pass effect, prolonged duration of action, 80-100%
Transdermal
What refers to extent and rate at wc active moiety (drug/metabolite) enters systemic circulation thus accessing site of action?
Bioavailability
What are drug products that contain the same active cmpd in the same amt and meet current official std?
Same cmpd, diff brand names
Chemical equivalence
What are drug products when given to same px in same dose result in equivalent concs of drug in plasma and tissues
Bioequivalence
What are drug products that when given to same px in same dose have same therapeutic and adverse effects?
Therapeutic equivalence
What is the principal site of drug met?
Liver
Inactive/weakly active subs that has an active metabolite
Prodrug
What is the goal of drug met/drug brkdwn?
Make drug easier to excrete
Formation of a new/modified fxnal grp or cleavage (oxidation, redxn, hydrolysis)
Phase I