Week 4A PO

Question 1

compartment
1
2

Answer 1

extravascular (IM injection, SC, GI tract)

central (plasma, blood, serum

Question 2

bolus dose goes into the

Answer 2

extravascular ‘gut’ compartment

Question 3

what is ka

Answer 3

first order transfer rate constant bw gut and central compartment

Question 4

usually absorption process is faster than

Answer 4

elimination process, not always the case

ka is faster than k

Question 5

slower exponential

faster exponential

Answer 5

k (elimination rate constant)

ka

Question 6

the peak and later decay arises from

Answer 6

difference between two exponential terms

Question 7

CL, V, k, F, and ka

Answer 7

• depend on drug and patient
• may depend on age, weight, sex, genetics or state of health
• dose, F, and ka are parameters associated w/ dosage form

Question 8

F may be reduced by

Answer 8

poor solubility, drug instability

Question 9

what happens to the Rate of drug absorption and elimination

Answer 9

• Rate of
A : absorption >> elimination
B : absorption = elimination (dC/dt= 0)
C : absorption < elimination
D : elimination >> absorption

Question 10

by reducing absorption rate constant/smaller ka value

Answer 10

time occurs later/is increased, and peak concentration is lower/decreases

Question 11

changing F values is equivalent to

Answer 11

changing the dose

• the higher the F value, the higher the concentration values at each time point. shifts curve up and down.
• tmax is unchanged bc k and ka remain the same

Question 12

• assuming ka &laquo_space;k, then:

Answer 12

• k = klate
absorption becomes rate-limiting and the late phase after the peak has the half-life of absorption
- Penicillin G

Question 13

Cresidual =

Answer 13

C late - C plasma (mg/L)

Question 14

most often ka&raquo_space; k

Answer 14

• ka = klate
-the late phase after the peak has the half-life of
elimination

Question 15

if the constants are very similar (ka = k) then

Answer 15

another model is required

Question 16

F should be determined by comparison with another route of administration, cannot determine with CL or V alone, nor can we be certain that ka»k

Answer 16

• if the other dosage form is an IV dose then F is absolute bioavailability
• if other dosage form is another oral or other non IV product, then F is relative bioavailability

Question 17

MRT (mean residence time)

Answer 17

-average time for drug molecules to reside in the body
-depends on route of administration, assumes drug is eliminated from central compartment
= aumc/auc

Question 18

at zero moment its

at first moment

Answer 18

auc

aumc (area under moment curve)

Question 19

Assume a child received 20 dimes for his birthday and
immediately places them in his piggy bank. Over the next month, he periodically removes 1 or more dimes from the piggy bank to purchase candy. Specifically, 3 days after placing the coins in his bank he removes 5 dimes, on day 10 he removes 4 dimes, on day 21 he removes 6 dimes and on day 30 he removes 5 dimes. At the 30th day after placing the coins in his bank, all of the coins have been removed. Hence, the elimination of the deposited dimes is complete. The MRT of the dimes in the piggy bank is simply the sum of the times that coins spend in the bank divided by the number of dimes placed in the bank

Answer 19

MRT =
(3×5) + (10× 4) + (21×6) + (30×5) divided by 20
MRT = 16.55 days

not all the dimes were there for 16.55 days its just the average.

Question 20

K late equation

Answer 20

= ln C1 - ln C2/ (t2-t1)

Question 21

Vss = CL x (MRToral - MAT) so

Answer 21

MRToral = MRTiv + MAT