Key terms

Question 1

Oral bioavailability

Answer 1

AUC = Area under curve

AUD oral/AUC IV

Question 2

Bioavailability

Answer 2

Fraction of a dose which finds its way into a body compartment, usually the circulation. Total area under the curve

Question 3

1st order kinetics

Answer 3

The rate of elimination is proportional to level of drug. A constant fraction of drug is eliminated in a unit of time

Question 4

Zero order kinetics

Answer 4

Rate of elimination is constant

Question 5

Loading dose

Answer 5

Vd x [Drug]target

Question 6

What is volume of distribution equivalent to?

Answer 6

Dose / [Drug]t0

Question 7

How do you work out the elimination rate constant (k)?

Answer 7

Look at the slope of the curve

Question 8

How do you work out half life?

Answer 8

Vd/Cl

Question 9

What is t1/2 proportional to?

Answer 9

Vd

Question 10

What is t1/2 inversely proportional to?

Answer 10

Cl (1/clearance) which = GFR

Question 11

What is EC50?

Answer 11

The effective concentration giving 50% of maximal response. (You find 50% effect and then follow it across to the concentration)

It is a measure of potency

Question 12

What is Km?

Answer 12

Substrate concentration giving 1/2 maximum reaction velocity (Vmax/2)

Question 13

What is the efficacy of a drug?

Answer 13

The ability of an activated receptor to generate response/the ability of a receptor to become activation.

Question 14

What is Bmax?

Answer 14

The maximal binding capacity. Seen on a Drug-receptor interaction (binding) curve.

Question 15

What is KD?

Answer 15

Dissociation constant. The concentration of a drug/ligand/antagonist needed for 50% occupancy of receptors. It is a measure of the affinity of a drug.

Question 16

What is the affinity of a drug?

Answer 16

The likelihood of the drug to bind to it’s target.

Question 17

What is potency?

Answer 17

A measure of both affinity and efficacy. Useful for comparisons.
EC50 is a measure of potentcy

Question 18

What is Emax?

Answer 18

The maximum response. Seen on a conc/dose response curve.

Question 19

What is IC50?

Answer 19

The conc of antagonist that gives 50% of maximal inhibition.

Question 20

What is LD50?

Answer 20

Lethal dose in 50% of the population

Question 21

What is ED50?

Answer 21

Effective dose in 50% of the population.

Question 22

What is the therapeutic window?

Answer 22

The range of doses that can effectively

treat a condition while remaining safe

Question 23

How do you work out the therapeutic index?

Answer 23

Toxic dose/Effective dose

Question 24

Rate of elimination

Answer 24

CL/kD

Question 25

Drug selectivity

Answer 25

The more the selective a drug is for its target, the less chance that it will intact with different targets and have less desirable effects.

Question 26

Drug specificity

Answer 26

Targeting drugs against specific receptor subtypes allows drugs to be targeted against a specific organ.

Question 27

If a drug is both a partial agonist and antagonist what determines how it behaves?

Answer 27

The proportion of active to inactive sites.