Pharmacokinetics and pharmacodynamics questions

Question 1

In zero-order kinetics, the rate of elimination of a drug is proportional to the drug concentration

Answer 1

False.
A constant amount of drug is eliminated per unit
time.

Question 2

A non-competitive antagonist binds irreversibly to the receptor

Answer 2

True.

Question 3

A competitive antagonist shifts the dose response curve to the left

Answer 3

False. The presence of a competitive antagonist (inhibitor) would shift the dose response curve to the right, with no change in the efficacy (plateau). The rightward shift is caused by competition for the same number of receptors.

Question 4

The higher the affinity of a drug for its receptor, the higher its potency

Answer 4

False. Potency is inversely proportional to affinity.

Question 5

Bioavailability (F) refers to the fraction of the dose of a drug absorbed into the systemic circulation

Answer 5

True

Question 6

Drugs with a high apparent volume of distribution (> 500ℓ) are confined to the plasma

Answer 6

False. Drugs which are lipid insoluble, such as neuromuscular blockers, remain in the blood, and have a low Vd.

Question 7

A greater proportion of an acidic drug is in its unionized form in an acidic medium

Answer 7

True

Question 8

Topically administered drugs undergo first-pass metabolism in the liver

Answer 8

False. 1st pass metabolism - Refers to the
elimination that occurs when a drug is first absorbed from the intestine & passes through the liver via the portal circulation

Question 9

In first order kinetics, the rate of elimination is proportional to the plasma drug concentration

Answer 9

True

Question 10

The time to steady state depends on the half-life of a drug

Answer 10

True

Question 11

Drug clearance is dependent on the route of administration

Answer 11

False. Clearance of a drug is independent of

the dose and route of administration

Question 12

A non-competitive antagonist shifts the dose response curve of the agonist to the left

Answer 12

False. Shifts to the right

Question 13

The maximal efficacy of a drug is reduced by competitive antagonists

Answer 13

False. The maximal efficacy of a drug is reduced by non-competitive antagonists

Question 14

Intravenously administered drugs have a higher first pass metabolism than orally administered drugs

Answer 14

False. IV drugs aren’t affected by first pass metabolism

Question 15

Active transport is a saturable process

Answer 15

True.

Question 16

Drugs with a high volume of distribution are confined to the plasma

Answer 16

False

Question 17

The non-ionized form of a drug diffuses across cell membranes to a greater extent than the ionized form.

Answer 17

True

Question 18

ED50 is the dose at which half the drug is eliminated

Answer 18

False. The ED50 (median effective dose) is the dose of a medication that produces a specific effect in 50% of the population that takes that dose

Question 19

A partial agonist at a receptor has more intrinsic activity than a full agonist at the same receptor

Answer 19

False. Partial agonist has affinity and less intrinsic activity

Question 20

a competitive antagonist binds reversibly to a receptor

Answer 20

True

Question 21

A non-competitive antagonist increases the maximal effect (Emax) of a drug

Answer 21

False. The maximal efficacy of a drug is reduced by non-competitive antagonists

Question 22

The lower the dissociation constant (Kd), the more potent the drug

Answer 22

True

Question 23

Intravenous drugs have bioavailability of 50%

Answer 23

False. 100% Bioavailability

Question 24

Topical administration is a type of parenteral administration

Answer 24

False. Parenteral includes: IV, SC and IM

Question 25

Sodium bicarbonate increases the pH of the stomach

Answer 25

True

Question 26

Drugs with an extensive first pass effect require high I.V. doses as compared with oral doses.

Answer 26

False. First pass metabolism affects oral drugs. So oral drugs with high first pass effect would require higher dose as compared with IV

Question 27

Hepatic drug metabolism involves the conversation of water soluble into lipid soluble.

Answer 27

False. Lipid into water soluble soluble.

Question 28

Alkalizing the urine enhances excretion of acidic drugs.

Answer 28

True

Question 29

Facilitated passive diffusion is a saturable process

Answer 29

True

Question 30

The plasma-protein bound fraction of a drug undergoes glomerular filtration.

Answer 30

False. Glomerular filtration: molecules below 20 kDa pass into filtrate. Drug must be free, not protein
bound.

Question 31

The time required to reach steady state is approximately 2 half lives.

Answer 31

False. Approximately 4/5

Question 32

Second messengers relay signals from receptors on the cell surface to target molecules inside the cell

Answer 32

True

Question 33

Bio availability refers to the elimination rate of a drug per unit time

Answer 33

False. Bioavailability is the fraction if drug absorbed into systemic circulation.

Question 34

Rifampicin is a cytochrome P450 enzyme inhibitor

Answer 34

False. Rifampacin is a cytochrome P450 enzyme inducer.

Question 35

lipophilic drugs have a high volume of distribution

Answer 35

True