Pharmacology - chapter 2 - Drug Receptor interactions and pharmacodynamics

Question 0

Name the four major receptor families.

Answer 0

1 Ligand-gated ion channels(cholinergic nicotinic receptors)
2 G protein-coupled receptors(alpha & beta adrenoreceptors)
3 Enzyme-linked receptors(insulin receptors)
4 intracellular receptors(steroid receptors)

Question 1

Pharmacodynamics =

Answer 1

what the drug does to the body

Question 2

Name two important features of signal transduction

Answer 2

1 the ability to ampilfy small signals

2 mechanisms to protect the cell from excessive signals

Question 3

handy biproduct of amplification?

Answer 3

Only a small percentage of receptors for a specific ligand need to be occupied to elicit maximal response. This leaves “spare receptors”. E.g 99% of insulin receptors are said to be spare receptors.

Question 4

Dose-response relationship:

Difference between potency and efficiacy?

Answer 4

Potency - amount of drug needed to produce an effect of a given magnitude, 50% of maximum is used to determine potency.

Efficacy - the ability of a drug to elicit a response when it intereacts with a receptor.

Question 5

which is more thereapeutically beneficial, a drug with high potency or one with high efficiacy?

Answer 5

The one showing more efficacity

Question 6

Agonist?

Answer 6

binds with a receptor and produces an effect.

Question 7

Full agonist?

Answer 7

a drug that bind with the receptor and produces a maxima biologic response that mimics that of the endogenous ligand.

Question 8

phenylephrine is an agonist at…

Answer 8

alpha 1 receptors

Question 9

partial agonist?

Answer 9

have efficiacies greater than zero, but less than that of a full agonist. Under certain conditions a partial agonist may act as an antagonist of a full agonist.

Question 10

Inverse agonist?

Answer 10

force constituitively active receptors into an inactive state

Question 11

Antagonists?

Answer 11

have affinity for a receptor but do not produce a biological response. Antagonists have no intrinisic activity and therefor produce no effect by them self.

Question 12

competitive antagonist?

Answer 12

if both antagonist and agonist bind to the same site on a receptor, they are said to be competitive.

Question 13

terazosin competes with endogenous ……………….. at ……………….receptors

Answer 13

terazosin competes with endogenous norepinephrine at alpha1 adrenoreceptors

Question 14

Irreversible antagonists, two mechaisms of binding?

Answer 14

1 bind strongly anf covalently to the active site of a receptor
2 bind to an allosteric site

Question 15

A fundamental difference between competitive and non-competitive antagonists is….

Answer 15

that competitive antagonists bind reduce agonist potency, whereas non-competitive antagonists reduce agonist efficiacy.

Question 16

Fuctional antagonism?

Answer 16

ehn antagonsit bind to a completely different receptor, eliciting effects that are functionally opposite of the agonist

Question 17

What are quantal doses?

Answer 17

Quantal dose-response relationships is the magnitude of the dose on the proportion of a population that responds to a given drug.

Question 18

Therapeutic index?

Answer 18

Therapeutic index = Toxic dose in 50% of population divided by the drug dose that produces the desired effect in 50% of the population.

Therapeutic Index = ToxicDose50 / EffectiveDose50

Question 19

Small therapeutic index?

Answer 19

small increases in doses can produce undesirable side-effects

Question 20

large therapeutic window?

Answer 20

Exessive doses can be given without producing any side-effects.

Question 21

Penicillin Therapeutic Index?

Answer 21

Large. Often tenfold of minimally required dose.

Question 22

Warfarin Therapeutic Index?

Answer 22

Small. As the dose is increased a higher fraction of patients respond. However, at higher doses, the anticoagulative properties increase the risk for hemorrhage. Warfarin have a small therapeutic window.