Pharmacokinetics 3

Question 1

For most drugs, the rate of metabolism depends on two factors:

Answer 1

the concentration of a drug at the site of metabolism
the intrinsic rate of the metabolic process

Question 2

The concentration of a drug at the site of metabolism is influenced by

Answer 2

blood flow to the site of metabolism

Question 3

The intrinsic rate of the metabolic process is influenced by

Answer 3

genetics and enzyme activity

Question 4

Zero order kinetics describes the situation where there is more

Answer 4

drug than enzyme

Question 5

Examples of drugs that undergo zero order kinetics include

Answer 5

aspirin, phenytoin, alcohol, warfarin, heparin, and theophylline

Question 6

First order kinetics describes the situation where there is

Answer 6

less drug than enzyme (no saturation occurs)

Question 7

Which drugs follow first order kinetics?

Answer 7

nearly all the drugs we administer

Question 8

If an enzymatic pathway that obeys first order kinetics becomes saturated, then the kinetics can

Answer 8

change from first order to zero order

Question 9

Which process is a phase 2 reaction?
a. reduction
b. conjugation
c. oxidation
d. hydrolysis

Answer 9

B. conjugation

Question 10

Drug metabolism is divided into

Answer 10

three phases

Question 11

Phase 1 of drug metabolism includes

Answer 11

modification (oxidation, reduction, and hydrolysis)

Question 12

Phase 2 of drug metabolism includes

Answer 12

conjugation

Question 13

Phase 3 of drug metabolism includes

Answer 13

excretion

Question 14

Sites of metabolism include

Answer 14

the kidneys, plasma, lung, and intestines

Question 15

The ______ is the primary metabolic organ

Answer 15

liver

Question 16

________ is the enzymatic process of altering a molecule’s chemical structure

Answer 16

metabolism

Question 17

The purpose of metabolism is to change a

Answer 17

lipid-soluble, pharmacologically active compound into a water-soluble, pharmacologically inactive byproduct

Question 18

Describe oxidation.

Answer 18

removes electrons from a compound

Question 19

Describe reduction.

Answer 19

adds electrons to a compound

Question 20

Describe hydrolysis.

Answer 20

adds water to a compound to split it apart (usually an ester)

Question 21

A phase 2 reaction

Answer 21

conjugates a highly polar, water-soluble substrate to the molecule

Question 22

A phase 3 reaction involves

Answer 22

ATP dependent carrier proteins that transport a drug across a cell membrane

Question 23

Describe enterohepatic circulation.

Answer 23

some conjugated compounds are excreted in the bile, reactivated in the intestine, and then reabsorbed into the systemic circulation

Question 24

What drugs undergo enterohepatic circulation?

Answer 24

diazepam and warfarin

Question 25

Identify the drugs that undergo perfusion-dependent hepatic elimination. select 3 a. diazepam b. fentanyl c. rocuronium d. lidocaine e. propofol f. remifentanil

Answer 25

fentanyl (b) lidocaine (d) propofol (e)

Question 26

Drugs that undergo capacity-dependent hepatic elimination include

Answer 26

diazepam & rocuronium

Question 27

Hepatic clearance is the product of

Answer 27

liver blood flow and hepatic extraction ratio

Question 28

The extraction ratio is a measure of how much

Answer 28

drug is delivered to the clearing organ vs. how much drug is removed by that organ

Question 29

An extraction ratio of 1.0 means that

Answer 29

100% of the drug delivered to the clearing organ is removed

Question 30

An extraction ratio of 0.5 means that

Answer 30

50% of the drug delivered to the clearing organ is removed

Question 31

For a drug with a high hepatic extraction ratio (>0.7), clearance is dependent on

Answer 31

liver blood flow

Question 32

Examples of drugs where clearance is dependent on liver blood flow include

Answer 32

fentanyl, sufentanil, morphine, ketamine, and propofol

Question 33

For a drug with a low hepatic extraction ratio (<0.3), clearance is dependent on

Answer 33

the ability of the liver to extract the drug from the blood

Question 34

Examples of drugs where clearance is dependent on the ability of the liver to extract the drug from the blood inlcude

Answer 34

rocuronium, diazepam, and methadone

Question 35

When administered orally, high extraction ratio drugs are subject to

Answer 35

first-pass metabolism

Question 36

Hepatic extraction ratio is

Answer 36

how much drug is removed by the liver

Question 37

The extraction ratio is a measure of

Answer 37

how much drug is delivered to the clearing organ vs. how much drug is eliminated by that organ

Question 38

The extraction ratio equation is

Answer 38

Extraction ratio= (arterial concentration- venous concentration)/arterial concentration

Question 39

Hepatic clearance is categorized as

Answer 39

perfusion-dependent elimination or capacity-dependent elimination

Question 40

Increased liver blood flow leads to

Answer 40

increased clearance

Question 41

Does hepatic enzyme activity have an effect on drugs that have perfusion-dependent elimination?

Answer 41

No

Question 42

Does hepatic enzyme activity have an affect on drugs that undergo capacity-dependent elimination?

Answer 42

Yes! - changes in hepatic enzyme activity or protein binding have a profound impact on the clearance of these drugs

Question 43

Do alterations in liver blood flow affect clearance for capacity dependent elimination drugs?

Answer 43

minimally because only a small amount of drug is removed per unit time

Question 44

If enzyme induction occurs, how does this affect capacity-dependent drugs?

Answer 44

it increases clearance

Question 45

Drugs with low hepatic extraction ratios include

Answer 45

rocuronium diazepam lorazepam methadone thiopental theophylline phenytoin

Question 46

Drugs with intermediate hepatic extraction ratios include

Answer 46

midazolam vecuronium alfentanil methohexital

Question 47

Drugs with high hepatic extraction ratios include

Answer 47

fentanyl sufentanil morphine meperidine naloxone ketamine propofol lidocaine bupivacaine metoprolol propranolol alprenolol nifedipine diltiazem verapamil

Question 48

Enterohepatic circulation describes

Answer 48

a process where the liver excretes a substance into the bile, and then that substance is reabsorbed from the small intestine and transported back to the liver

Question 49

Drugs that undergo enterohepatic circulation tend to

Answer 49

have a long duration of effect

Question 50

What drugs undergo enterohepatic circulation?

Answer 50

diazepam, warfarin