Drug Receptors and Pharmacodynamics - SRS

Question 1

What the body does to drugs is called?

Answer 1

Pharmacokinetics

Question 2

What the drug does to the body is called?

Answer 2

Pharmacodynamics

Question 3

What are the five types of Drug-receptor interactions?

Answer 3

1. Agonist
2. Antagonist
3. Allosteric Modulators
4. Constitutive Activity
5. Intrinsic Efficacy

Question 4

How does an agonist work?

Answer 4

Binds to and activates a ligand, mimicking the endogenous ligand by directly or indirectly stimulating the same response typically produced by the endogenous ligand.

Question 5

What are the types of agonists?

Answer 5

Full agonist

Partial agonist

Inverse Agonist

Question 6

What does a full agonist do?

Answer 6

Binds and activates receptor-effector system to max extent of the system.

Question 7

Partial agonists activate receptor systems at a submaximal level, how does this effect impact the system in the presence or absence of a full agonist?

Answer 7

Presence of - Partial agonists act as competitive antagonists by reducing the response, thus, partial agonists are also partial antagonists.

Absence of - Partial agonists act as agonists and increase the response.

Question 8

Inverse agonists do what?

Give an example.

Answer 8

Bing the receptor but produce a physiological response that is opposite to that normally elicited.

Agonists of the GABA receptor cause sedation, while inverse agonists cause agitation and anxiety.

Question 9

Most antagonists bind receptors in a reversible way… how would you overcome this competitive antagonism?

Answer 9

Increase the agonist concentration

Question 10

In the absence of an agonist, what is the term used to refer to antagonists?

Answer 10

Neutral antagonism

Question 11

How do allosteric modulators work?

Can you overcome the effect of these by increased agonist concentration?

Answer 11

Bind the receptor at a site different than the agonist binding site, either facilitating or inhibiting the agonist action.

NO.

Question 12

What is “Intrinsic efficacy”?

Answer 12

Ability of a drug to elicit a physiologic effect after binding to and activating a receptor-effector system. This is independent of binding affinity.

Question 13

How do noncompetitive antagonists frequently bind receptors?

Answer 13

Irreversibly

Question 14

What determines the duration of the therapeutic response for non-competitive antagonists?

Answer 14

Mostly on the rate of receptor molecule turnover, less so the rate of drug elimination.

Question 15

Define drug potency

Answer 15

The Amount of a drug needed to produce a particular effect.

Question 16

What is Maximal efficacy?

Answer 16

Limit of the dose-response relation on the response axis.

Question 17

What are the components of Quantal Dose Effec curves we need to know?

Answer 17

1. Median effective dose - Dose at which 1/2 of individuals exhibit the specified quantal response.
2. Median Toxic dose - dose at which 1/2 of individuals experience a specified toxic effect.
3. Therapeutic index
4. Therapeutic window

Question 18

How do you calculate the therapeutic index?

Answer 18

LD₅₀/ED₅₀

Question 19

What is an idiosyncratic response?

Answer 19

An unexpected response that is infrequently observed in most patients.

Question 20

What is tolerance?

Answer 20

When responsiveness diminishes as a consequence of continued drup administration.

Question 21

What is tachyphylaxis?

Answer 21

When responsiveness diminishes rapidly after administration of a single dose.

Question 22

What is drug selectivity?

Answer 22

Propensity of the drug to elicit a therapeutic effect versus toxic or adverse effects.