principles

Question 1

What three types of biochemical reactions are involved in phase I metabolism of drugs?

Answer 1

Reduction, oxidation, and hydrolysis

CYTP450 mediated

Question 2

What is the formula that describes the therapeutic index (TI) of a drug?

Answer 2

TD50/ED50

Question 3

In pharmacodynamics, the addition of a noncompetitive agonist ____ (increases/decreases/does not change) the efficacy of the agonist.

Answer 3

decreases

Question 4

What are three drugs that exhibit zero-order elimination?

Answer 4

Phenytoin and ethanol—aspirin at toxic concentrations (a pea is round like the 0 in zero order)

Question 5

define potency

Answer 5

Amount of drug needed for a given effect

Question 6

define efficacy

Answer 6

maximum effect of a drug

Question 7

Drug A has a therapeutic index of 5 μg/ml, whereas Drug B has a therapeutic index of 30 μg/ml. Which drug would be safer for your patient?

Answer 7

Drug B

Question 8

In first-order elimination of drugs from the body, what is the relationship between the rate of elimination and the drug concentration?

Answer 8

Rate of elimination is directly proportional to the drug concentration—a constant fraction (rather than a constant amount) is eliminated

Question 9

What reactions occur in phase II metabolism

Answer 9

glucorindation
acetylation
sulfonation

elderly has “gas”

Question 10

How does the potency of a partial agonist relate to the potency of a full agonist of the same receptor?

Answer 10

A partial agonist may be more potent than, less potent than, or equally as potent as a full agonist

Question 11

A 20-year-old man has been taking amphetamines. What substance should you give to enhance the renal clearance of this weakly basic drug?

Answer 11

ammonium chloride

Question 12

The lowest effective dose of drug X is 200 mg/dL. If given at 600 mg/dL, drug X is lethal. What is the therapeutic window of drug X?

Answer 12

400

600-200 = 400

Question 13

Phase I metabolism of drugs yields ____ (nonpolar/slightly polar/very polar) molecules that are ____ (inactive/often still active).

Answer 13

Slightly polar; often still active

Question 14

Phase II metabolism of drugs yields ____ (nonpolar/slightly polar/very polar) molecules that are ____ (inactive/often still active).

Answer 14

very polar, inactive

Question 15

A patient is on norepinephrine, but the physician also gives phenoxybenzamine. What type of antagonist is phenoxybenzamine on α-receptors?

Answer 15

noncompetitive antagonist

Question 16

Describe how affinity and vmax increase on a graph

Answer 16

Vmax inc as you go down
affinity inc as you go left (Km dec)

“Cali is greater than here”

Question 17

Do: competitive or noncompetitive inhibitors cross eachother on a graph?

Answer 17

competitors cross eachother! aka they have the same vmax but different Kms

Question 18

What type of agonist or antagonist is overcome by the addition of more substrate

Answer 18

reversible competitive inhibitors

Question 19

Reversible Competitive inhibitors affect efficacy or potency?

Answer 19

decrease potency

Question 20

What is the formula for Vd

Answer 20

amount of drug in body/ plasma concentration

Question 21

what is the formula for clerance

Answer 21

Vd x Ke

Question 22

What is the formula for T 1/2

Answer 22

0.7 x Vd/ CL

Question 23

What is the formula for loading dose

Answer 23

target plasma concentration x Vd/ bioavailability

Question 24

what is the formula for maintenance dose

Answer 24

target plasma concentration x CL x dose interval / bioavailability

Question 25

Half life is a property of ____

Answer 25

first order drugs

Question 26

how many half lives does it take to reach steady state

Answer 26

4-5

Question 27

name an example of a competitive antagonist pair

Answer 27

Benzos with flumazenil

Question 28

name an example of a partial agonist pair

Answer 28

morphine is full with buprenorphine - partial

Question 29

How is a partial agonist different from a full agonist

Answer 29

lower efficacy