Pharmacokinetics

Question 1

What three modifications encompass Phase I Biotransformation?

Answer 1

Oxidative, Reductive and Hydrolytic

Question 2

What is the purpose of Phase I Biotransformation?

Answer 2

expose a functional group

Question 3

What organelle are Cyt p450 enzymes located?

Answer 3

endoplasmic reticulum

Question 4

What is the function of Phase II reactions?

Answer 4

make a compound for water soluble

Question 5

The clearance of drug by the kidney depends on what three variables?

Answer 5

GFR

being bound to plasma proteins

pH or urine

Question 6

What are the two mechanisms by which drugs can be excreted via the intestines?

Answer 6

secreted directly into bile

secreted by GI enterocytes

Question 7

What is the equation for Volume of Distribution?

Answer 7

[blood]/[body]

Question 8

What three types of drugs have large Vd’s?

Answer 8

lipophilic

non-ionizable

low binding to plasma proteins

Question 9

What is zero order elimination?

Answer 9

capacity to clear drug is at saturation

Question 10

What is first order elimination?

Answer 10

clearance system is not saturated

Question 11

What is the equation for half life of drug?

Answer 11

(0.693)(Vd)/clearance

Question 12

Drug will accumulate in the body if the dosing interval is shorter than how many half-lifes of the drug?

Answer 12

4 half-lifes

Question 13

What is the equation for accumulation factor?

Answer 13

1/fraction lost in one dosing interval

Question 14

What is bioavailability?

Answer 14

the amount of drug that reaches systemic circulation

Question 15

What is the equation for extraction ratio?

Answer 15

clearane/flow

Question 16

What is the therapeutic window?

Answer 16

[drug] between MEC and toxic effects

Question 17

What is the equation for steady state concentration?

Answer 17

dosing rate / clearance

Question 18

What is the definition of steady state concentration?

Answer 18

[drug] where elimination is equal to the bioavailability

Question 19

What is the equation for bioavailability?

Answer 19

f x (1-ER)

Question 20

Do cytochrome ezymes act more during Phase I or Phase II metabolism?

Answer 20

Phase I

Question 21

Is capacity limited essentially first-order or zero-order kinetics?

Answer 21

zero-order

Question 22

Is flow limited essentially first-order or zero-order kinetics?

Answer 22

first-order

Question 23

Is half-life variable for a drug that is processed by first-order or zero-order kinetics?

Answer 23

zero

Question 24

After how many 1/2 lifes will a drug be negligible?

Answer 24

4-5 half lifes

Question 25

What is steady state depedent on?

Answer 25

drug half life

Question 26

What is the Katzung definition of steady state?

Answer 26

condition where the average total amount of drug in the body does not change over time

Question 27

What is the mnemonic for drugs that follow zero-order kinetics?

Answer 27

P's & WHEATS

Question 28

What do the P's of P's & WHEATS stand for?

Answer 28

phenytoin and phenylbutazone

Question 29

What does the W of P's & WHEATS stand for?

Answer 29

warfarin

Question 30

What does the H of P's & WHEATS stand for?

Answer 30

heparin

Question 31

What does the E of P's & WHEATS stand for?

Answer 31

ethanol

Question 32

What does the A of P's & WHEATS stand for?

Answer 32

aspirin

Question 33

What does the T of P's & WHEATS stand for?

Answer 33

theophylline and Talbutamide

Question 34

What does the S of P's & WHEATS stand for?

Answer 34

salicyclates

Question 35

What three groups are added to during Phase II Metabolism?

Answer 35

acetylation sulfation glucoronydation

Question 36

What is the equation for clearance?

Answer 36

elimination/[Drug]

Question 37

Which order of kinetics does capacity eliminated excretion follow?

Answer 37

zero-order

Question 38

Flow dependent elimination mimmics which order of elimination?

Answer 38

first-order

Question 39

Accumulation of drugs in the body will be detectable if dosing interval is shorter than how many half lives?

Answer 39

4

Question 40

What is the equation for loading dose?

Answer 40

(Vd)([Desired Concentration])/F

Question 41

What are the units for clearance?

Answer 41

mL/min/Kg

Question 42

What is the equation for Dosing Rate?

Answer 42

Clearance x Desired Concentration

Question 43

What is the equation for Dosing Rate-Oral?

Answer 43

Dosing Rate ss/ F-oral