2.C

Question 1

What is a trend that is generally seen in drug plasma concentration vs effect (dose-response) graphs?

Answer 1

after a certain point, any further increase in drug plasma concentration will result in a non-proportional change in effect
=receptors are filled

Question 2

Describe the similarities and differences of the dose-response graph vs drug-receptor interaction.

Answer 2

similarities: follows the sae mathematical model
differences:
-they describe different things with different outcomes (physical binding of drug vs clinical effect)
-DR interaction accounts for patient PK variability but the dose-response curve has the valuable clinical outcome of effect
-

Question 3

What is the drug-receptor interaction graph a good predictor for?

Answer 3

if a drug has a narrow therapeutic window

Question 4

What is the dose-response graph a good predictor for?

Answer 4

if a drug has a wide therapeutic window
we know we have lots of room to play with, so PK changes are probably insignificant

Question 5

In which setting are we using drug-receptor interaction graphs? What about dose-response curve?

Answer 5

DR interaction used in the hospital realm when doing PK calculations for ill patients taking narrow TI drugs
dose-response curve used in community pharmacy as most drugs have wide therapeutic windows

Question 6

Why is it safe to rely on the dose-response graph in community pharmacy?

Answer 6

most of the time:
-extent of biological response is proportional to # of receptors occupied by drug
-maximum response is achieved when all receptors occupied
-binding of drug to receptor does not change the affinity of receptor for another drug

Question 7

What are the 4 factors that contribute to interindividual variability?

Answer 7

differences in drug concentration that reaches receptor
-interindividual variation in PK influence unbound [D] at receptor
variation in the concentration of an endogenous ligand
-relevant for drugs that antagonize endogenous ligands
alterations in the function or number of receptors
-genetics influence receptor # and efficiency of coupling
changes in components of response other than at receptor
-signal transduction

Question 8

Define saturation.

Answer 8

full receptor occupation
saturated=100% receptors occupied

Question 9

Define efficacy.

Answer 9

the maximum response achievable (Emax) from a drug
magnitude of response

Question 10

Define potency.

Answer 10

comparison of the concentration of drug needed to get a response in 50% of patients
measure of drug activity expressed in terms of the amount of drug needed to produce a pre-defined effect

Question 11

What can be used to indicate potency?

Answer 11

affinity

Question 12

What can you infer from a high EC50? What about a low EC50?

Answer 12

high EC50=low potency
-high concentration of drug needed to achieve effect in 50% of patients
low EC50=high potency
-little concentration of drug needed to achieve effect in 50% of patients

Question 13

What is the quantal-dose response?

Answer 13

the response is all-or-nothing events
binary
proportion/percentage of individuals who exhibit a pre-defined effect
characterized by an ED50 value

Question 14

What is the graded-dose response?

Answer 14

intensity of response varies with dose/concentration
shape of graph varies dependent upon potency and efficacy

Question 15

What are the pharmacodynamic interactions?

Answer 15

additive: combined effect of two drugs administered together that is equal to the sum of the individual response
synergism: combined effect of two drugs administered together that is greater than the sum of individual responses
potentiation: increase in effect of one effective drug when it is taken with an ineffective drug