Introduction into Pharmacokinetics

Question 1

What is pharmacokinetics?

Answer 1

the process by which a drug is absorbed, distributed, metabolized, and excreted

Question 2

Typically, what are drug concentrations measured in?

Answer 2

plasma

Question 3

What is oral availability (F)?

Answer 3

the fraction of the drug that reaches the systemic circulation after oral ingestion

Question 4

What is oral availability determined by?

Answer 4

absorption and first pass metabolism

Question 5

What does absorption refer to?

Answer 5

the ability of a drug to cross the gut wall into the portal vein

Question 6

What is first-pass metabolism?

Answer 6

the presystemic drug elimination

Question 7

Where can first-pass metabolism occur?

Answer 7

in the gut wall, portal vein, or the liver

Question 8

High rates of metabolism in the gut wall, portal vein, or liver result in what?

Answer 8

low oral availability

Question 9

What is the total amount of the drug in the systemic circulation defined by?

Answer 9

the area under the concentration time curve (AUC)

Question 10

What is bioavailability?

Answer 10

the fraction of a drug that is absorbed and available to produce its systemic effect

Question 11

What does it mean if bioavailability is low?

Answer 11

it means that few drug molecules go to the plasma, meaning low drug effect

Question 12

What leads to low drug availability?

Answer 12

high metabolism or low absorption

Question 13

What percent bioavailability do you want to make sure you get an effect and that it is safe?

Answer 13

60-70%

Question 14

What is plasma concentration (Cp) directly proportional to? inversely proportional?

Answer 14

dose rate, clearance

Question 15

What is the steady state concentration (Cpss) determined by?

Answer 15

the maintenance dose rate and the clearance

Question 16

For drugs with a high fu (unbound fraction) will renal impairment or liver impairment decrease the clearance?

Answer 16

renal impairment

Question 17

For lipophilic drugs with low fu, will renal impairment or liver impairment decrease the clearance?

Answer 17

liver impairment

Question 18

What must be adjusted to allow for impaired drug clearance?

Answer 18

dosage

Question 19

How are drugs eliminated?

Answer 19

by excretion unchanged through the kidneys, or by metabolism to an inactive product usually in the liver

Question 20

What does fraction excreted unchanged (fu) define?

Answer 20

renal elimination

Question 21

What does (1-fu) describe?

Answer 21

metabolic elimination

Question 22

What are the different types of clearances?

Answer 22

whole body (blood, plasma), organ clearance, and in vitro clearance

Question 23

What is the objective of the interspecies dose extrapolation?

Answer 23

to ensure similar exposure (AUC) between species

Question 24

What is the assumption with the interspecies dose extrapolation?

Answer 24

that the axposure response relationship is not species specific

Question 25

Drug exposure is on the ______ _____.

Answer 25

causal chain

Question 26

Since little can be modified on the interactionof exposure and response (what happens inside the body), what can you do to optomize exposure?

Answer 26

change the amount of input of the drug