PHARM A20/21: Drug Receptor Mechanisms

Question 1

What is the difference between selective and non selective ion channels?

Answer 1

Selective ion channels will only allow a specific ion to pass through following activation, while non-specific channels are less strict about what passes through

Question 2

What is Ka and Kd in the context of drug receptor reactions?

Answer 2

Ka is the association rat constant- the rate at which a ligand will bind the receptor; Kd= dissociation constant- rate at which a ligand will dissociate from the receptor

Question 3

What is the difference between affinity, efficacy, and potency? Which is most important in designing a drug?

Answer 3

Affinity is the chemical forces that cause a drug to associate with the receptor (how tightly it binds); Efficacy- how much effect the drug has on the receptor; Potency is the dose of drug necessary to produce a specified effect; Efficacy most important characteristic

Question 4

What factors are determinants of the response to a given drug?

Answer 4

Intrinsic efficacy and the number of receptors in target tissue

Question 5

What are spare receptors?

Answer 5

Receptors present that exceed the number necessary to produce a maximal response in a target tissue

Question 6

What is the difference between an orthosteric and allosteric drug?

Answer 6

Orthosteric drugs bind to the active site of a receptor, while allosteric molecules bind to a different site that changes the activity of the receptor

Question 7

What is an antagonist?

Answer 7

A drug that binds to a receptor but does not elicit a cellular response; prevent agonists from producing a response

Question 8

True or False: Antagonists alter the active state: inactive state equilibrium.

Answer 8

False

Question 9

What is an inverse agonist? How does it work?

Answer 9

A drug that binds to a receptor to produce an effect opposite that of an agonist- it stabilizes receptors in the inactive state and so there will be no spontaneous activity

Question 10

What is the threshold?

Answer 10

The dose that produces a just-noticeable effect

Question 11

What is ED50? The EC50%?

Answer 11

The dose that produces a 50% of maximum response; The blood concentration that produces 50% of maximal response

Question 12

What is the ceiling (ED99)?

Answer 12

Lowest dose that produces 50% of maximum response

Question 13

True or False: Partial agonists have both agonist and antagonist properties.

Answer 13

True

Question 14

How can the relative potency of two drugs be calculated?

Answer 14

Relative potency= ED50 drug B/ ED50 drug A

Question 15

What are physiologic antagonists?

Answer 15

Drugs that work through different mechanisms to produce opposing physiologic responses.

Question 16

What is competitive antagonist Inhibition?

Answer 16

Increasing doses of antagonist with a fixed dose of agonist

Question 17

What is the IC50/ ID50?

Answer 17

IC50 is the concentration in dose of the antagonist that produces a 50% decrease in the effect of the agonist

Question 18

What is a quantal dose-response curve?

Answer 18

Used when the dose of a group to produce a specified effect in a single patient is measured

Question 19

What are the two different types of Quantal-Dose Response Curves and what do they measure?

Answer 19

1) Quantal dose response curves plot dose on the x axis and % responders on the Y axis 2) Cumulative Quantal Dose- Response Curve plots the cumulative response off all doses up to a particular level

Question 20

How can the safety index be measured? What is the range required by the FDA?

Answer 20

Safety Index= LD1 (lethal dose for 1%) / ED99 (effective dose for 99%); FDA want index of greater than 10

Question 21

How is the therapeutic index calculated?

Answer 21

LD50/ED50

Question 22

What are Biologic Response Modifiers (aka Biologics)?

Answer 22

Wide range of biologic products ranging from vaccines, blood and blood components, gene therapy, recombinant proteins

Question 23

What value of safety index indicates that the drug is not safe?

Question 24

What are the two major types of Drug-Drug interactions?

Answer 24

Pharmacodynamic interactions and pharmacokinetic interactions

Question 25

What describes the nature of the interaction between caffeine and acetominophen?

Answer 25

Potentiation

Question 26

What are the types of pharmacokinetic interactions?

Answer 26

Interactions affecting absorption, distribution, metabolism, and excretion.