Chapter 1 - Basic Concepts Part 2

Question 1

explain what half life is

Answer 1

time needed for the drug concentration in the plasma to decrease by 50%

Question 2

what is “F”

Answer 2

fraction of administered dose absorbed

measure of extent of administered dose that actually reaches systemic circulation

Question 3

what is lag time?

give an example of a dosage form that may have lag time

Answer 3

time that elapses btwn extravascular administration and when the drug appears in systemic circulation

example is enteric coating - delayed release

Question 4

what is MAT

Answer 4

mean absorption time

average time for all the drug molecules to be absorbed (only applies to extravascular)

Question 5

what is MRT

Answer 5

mean residence time

average amt of time for all the drug molecules of a dose to reside in the body

Question 6

what is Ka/Km/Ke

Answer 6

Ka - rate constant of absorption

measure of the rate at which the drug is absorbed after it has become available for absorption

Km = rate metabolism
Ke = rate elimination

Question 7

term for the steady-state concentration of the drug in plasma

Answer 7

Css – plateau level for chronic drugs

Question 8

what do K12 and K21 mean

Answer 8

rate constants of TRANSFER

ie - between plasma and the tissues

Question 9

Vd

Answer 9

volume of distribution - volume of body fluid in which the drug is either dissolved or distributed

Question 10

for any extravascular drug, what must happen before the drug gets into systemic circulation

Answer 10

ABSORPTION

Question 11

another term for site of action

Answer 11

receptor site

Question 12

another name for biophase

Answer 12

receptor site – drug that is causing therapeutic effect

Question 13

drug in plasma is assumed to be in equilibrium with drug where?

Answer 13

drug in biophase

Question 14

true or false

extravascular routes of administration do not go through 1st pass effect (except oral)

Answer 14

true

extravascular except oral bypasses 1st pass

Question 15

true or false

a prodrug is not a drug

Answer 15

TRUE - it itself as no activity

Question 16

true or false

a drug can either be activated or deactivated through the liver

Answer 16

true - case of prodrug

Question 17

“central compartment”

Answer 17

plasma

drug only absorbs in plasma NOT BLOOD

Question 18

*****average volume of plasma in a normal 70kg (154lb) adult

Answer 18

3 LITERS

Question 19

AROUND __% of body weight is water

Answer 19

60%

Question 20

for an IV injection, what is the typical minimum Vd

Answer 20

3 LITERS

BUT as the plasma distributes to other tissues, Vd will keep increasing

Question 21

“central compartment”

Answer 21

plasma

Question 22

how is some alcohol excreted

Answer 22

pulmonary - that’s why breathalyzers are a thing

Question 23

marker to indicate therapeutic levels at receptor site

Answer 23

we use plasma levels

Question 24

3 meds that we don’t need to measure plasma concentration of drug to evaluate therapeutic effect

Answer 24

blood pressure meds
diabetes meds
anticoagulants

Question 25

true or false drug in central compartment immediately distributes to tissue

Answer 25

false takes time initially, amount in tissue will be zero

Question 26

relationship between concentration at plasma/central compartment vs tissue

Answer 26

INDIRECT relationship when conc at central compartment high, conc at tissue site is low. needs time to distribute there

Question 27

name the 2 types of pharmacokinetics

Answer 27

linear pharmacokinetics nonlinear pharmacokinetics

Question 28

true or false we measure drug concentration at the receptor site

Answer 28

FALSE we measure plasma conc

Question 29

true or false most drugs exhibit nonlinear pharmacokinetics

Answer 29

FALSE - most are linear

Question 30

in linear pharmacokinetics, what 2 things are proportional to the dose what is NOT affected by the dose

Answer 30

cmax cp (plasma conc) as dose increases, plasma conc and cmax also increase pharmacokinetic parameters are NOT AFFECTED by the dose, except for cmax and AUC

Question 31

true or false in linear pharmacokinetics, as the dose increases, t1/2 also increases

Answer 31

FALSE - does not change

Question 32

a drug follows linear pharmacokinetics. 50mg dose produces a maximum Cp (plasma concentration) of 10mcg/L what will be the Cp if the dose is doubled?

Answer 32

Cp will be 20mcg/L

Question 33

is the Cmax of a particular drug identical in all patients?

Answer 33

NO - individual variations exist however, if it follows linear kinetics, should still follow this

Question 34

true or false in non-linear pharmacokinetics, Cp is NOT proportional to the dose

Answer 34

TRUE

Question 35

is "dose-dependent pharmacokinetics" considered linear or nonlinear kinetics?

Answer 35

nonlinear because if you change the dose, EVERYTHING CHANGES (including t/12, AUC)

Question 36

which is more difficult to dose correctly - linear or nonlinear pharmacokinetics

Answer 36

nonlinear is more difficult to dose

Question 37

"capacity-limited" pharmacokinetics

Answer 37

non-linear pharmacokinetics

Question 38

true or false in non-linear pharmacokinetics, "the extent of absorption is not proportional to the dose"

Answer 38

true

Question 39

true or false in non-linear kinetics, elimination follows 1st order kinetics

Answer 39

FALSE - does not

Question 40

true or false in linear kinetics, we expect the Css and Cmax to double if the dose doubles

Answer 40

true

Question 41

true or false in non-linear kinetics, the amount of drug excreted in the urine is NOT proportional to the dose administered

Answer 41

true

Question 42

true or false for non-linear kinetics, the half life does not change if the dose changes

Answer 42

FALSE - it does either increases or decreases -- not predictable (normally it would increase)

Question 43

true or false in non-linear kinetics, the AUC is NOT proportional to the amount of drug available for absorption

Answer 43

true

Question 44

true or false in non-linear kinetics, the cmax is not proportional to the dose

Answer 44

true

Question 45

a drug follows non-linear kinetics. the cmax has increased MORE THAN EXPECTED when the dose was increased name a possible mechanism for this what is the term for this phenomenon

Answer 45

the process of removing the drug from the body has become saturated, meaning that whatever amount of drug is administered will be in the body and not able to be eliminated significant, unexpected increase in concentration this is Michaelis Menten/saturable pharmacokinetics

Question 46

a drug follows non-linear kinetics. the cmax has increased LESS than what was expected with the amount of dose given. name 2 possible mechanisms for this

Answer 46

1. the drug is highly protein bound - as more dose is given, it just saturates the plasma proteins more (or faster elimination) 2. Autoinduction of metabolism

Question 47

define clinical pharmacokinetics

Answer 47

applying pharmacokinetic principles to therapeutic management of individual patients

Question 48

goal of clinical pharmacokinetics

Answer 48

increased effectiveness and/or decreased toxicity

Question 49

what is the difficulty with clinical pharmacokinetics

Answer 49

every individual has a variation in drug response, despite the drug and dosage form being exactly the same

Question 50

4 general factors that result in each patient having different reactions to each drug, despite the drug, dose, route, dosage form, etc being exactly the same

Answer 50

-patient factors -severity of disease -other drugs given at same time -environmental factors

Question 51

true or false the concentration of drug in plasma is DIRECTLY RELATED to the concentration at the site of action

Answer 51

true

Question 52

true or false patient's genetics do not change their response to drugs

Answer 52

FALSE - usually does

Question 53

true or false the therapeutic Cp is the same for all patients

Answer 53

false

Question 54

since each patient responds differently, drug manufacturers publish what 4 values based on studies of a large population of humans studies

Answer 54

maintenance dose half life Vd Cp (therapeutic drug plasma conc)

Question 55

pharmacodynamics is the relationship between ____ and ____

Answer 55

the drug conc at site of action and the magnitude of the effect produced (both the intensity and time of effect. effect can either be good or bad (toxic)

Question 56

true or false pharmacokinetics and pharmacodynamics are identical

Answer 56

FALSE - complementary

Question 57

________- deals with the interaction between the drug and its receptors

Answer 57

pharmacodynamics

Question 58

what is the 1 parameter that both pharmacodynamics and pharmacokinetics have in common

Answer 58

receptor site concentration

Question 59

*drug solubility is the principle determinant of oral absorption because...

Answer 59

it is the principle determinant of drug dissolution rate

Question 60

true or false drug solubility is the principle determinant of intestinal membrane permeability

Answer 60

FALSE - principle determinant of drug dissolution rate lot of other factors determine permeability -- solubility still does too, but NOT the principle determinant

Question 61

true or false as the particle size decreases, the dissolution rate increases, surface area increases, and the radius increases

Answer 61

FALSE all are true except for the radius one as particle size decreases, radius decreases too