Pharmacokinetics

Question 1

What are the routes of absorption for drugs?

Answer 1

Oral, sublingual, injection, inhalation, transdermal, topic and rectal

Question 2

What is the formula for bioavailability?

Answer 2

amount in blood/amount administered

Question 3

What are the factors affecting absorption?

Answer 3

Size, gastric emptying, polarity, pH and hepatic metabolism

Question 4

How do size and polarity affect absorption?

Answer 4

only small, non polar molecules can freely diffuse into tissues

Question 5

How does the pH of a drug affect how a drug is absorbed?

Answer 5

If the body tissue is a weak acid, only unionized acids can diffuse, weak bases cannot diffuse
and ion trapping

Question 6

What is ion trapping

Answer 6

fetal blood more acidic and can trap weak bases drug

Question 7

How does gastric emptying affect absorption

Answer 7

The presence of food and binding of minerals will slow absorption

Question 8

What is an example of a drug that can bind minerals?

Answer 8

Tetracycline can bind Ca2+ and reduce levels of both to be absorbed

Question 9

What is the role of P-glycoproteins in the absorption of drugs?

Answer 9

certain drugs react receptors to either increase or decrease the activity of them

Question 10

What is an important receptor for the absorption of drugs and what organs are they present in?

Answer 10

P-glycoproteins, found in small intestine, placenta, kidney, and liver

Question 11

What is the role of hepatic metabolism in absorption?

Answer 11

After metabolism, only 30% of drug is available

Question 12

What is the pro and con of IV route?

Answer 12

fastest but greatest risk of toxicity

Question 13

What are the factors affecting distribution?

Answer 13

blood flow, capillary size, protein binding, and tissue binding

Question 14

What is a real world example that illustrates the importance of blood flow for distribution?

Answer 14

Anesthesia-obese patients will need higher doses of it because it diffuses to fat instead of brain

Question 15

What is an example of where capillary size is important for distribution?

Answer 15

BBB has low permeability

Question 16

How does protein binding affect distribution and what is the most common blood protein?

Answer 16

If the protein is bound, it cannot diffuse freely

Question 17

What is the volume of distribution?

Answer 17

The dose administered/plasma concentration

Question 18

What does a high vs low volume of distribution value mean?

Answer 18

High-good for body, low-stuck with proteins

Question 19

What is the purpose of metabolism?

Answer 19

make drugs hydrophilic and less toxic

Question 20

What is a prodrug and what is an example?

Answer 20

drug that is activated by metabolism- coedeine

Question 21

What is phase 1 metabolism, and where does it occur?

Answer 21

oxidize drugs from electrons via NADPH in ER

Question 22

What are the three most prevalent enzymes for phase 1 metabolism?

Answer 22

CYP3A4
CYP2D6
CYP2C

Question 23

What is phase 2 metabolism?

Answer 23

The addition of a polar group for easier excretion

Question 24

What is clearance?

Answer 24

volume of blood from which a drug is irreversibly removed per unit of time

Question 25

What are the modes of excretion?

Answer 25

urine, feces, swear and breast milk

Question 26

What are the three modes of excretion in the kidneys?

Answer 26

Filtration, secretion and reabsorption

Question 27

What is the formula for finding out net excretion?

Answer 27

filtered + secreted - reabsorbed

Question 28

What is first order kinetics?

Answer 28

constant fraction of drug cleared epr unit of time, proportional to plasma concentration

Question 29

What is zero order kinetics?

Answer 29

constant amount of drug/unit of time

Question 30

What is the formula for half life

Answer 30

= 0.693 x Vd/Cl

Question 31

What are some things that can affect the effectiveness of drugs in patients?

Answer 31

drug interactions, age and genetics

Question 32

What are examples of drug interaction that could potentially harm the patient?

Answer 32

Drug X binds CYP450 better than Drug Y, drug Y cannot be metabolized and causes toxicity, allosteric binding that can cause increased or decreased metabolism of drug Y

Question 33

What are some things that come along with old age that affects drug ADME?

Answer 33

reduced peristalsis, reduced blood flow, increased gastric pH, higher proportion of fat, reduced metabolism due to reduced liver enzymes and renal function decreases

Question 34

What are some things that come along with young age that affects ADME?

Answer 34

reduced peristalsis, increased gastric pH, reduced plasma proteins, metabolism and renal function impaired due to incomplete maturation

Question 35

How can genetics affect ADME?

Answer 35

polymorphisms in metabolic enzymes-e.x. 10% variability in CYP2D6 in some populations

Question 35

What are common mutations that could help us in creating better drugs for cancer patients?

Answer 35

EGFR mutations- tyrosine kinase receptors bind drugs and so if we are able to genotype mutations, we could have better targeted therapies

Question 36

What are the effects of a pro drug on an slow/poor metabolizer?

Answer 36

You would not have the beneficial effects because it would take a longer time to activate

Question 37

What are the effects of a pro drug on an ultrafast metabolizer?

Answer 37

They would be at risk for increased toxicity and side effects