Receptors

Question 1

_________ drugs facilitate receptor functions, while __________ drugs block receptor functions.

Answer 1

Agonist; antagonist

Question 2

T/F: An antagonist will block the agonist from causing a physiological effect.

Answer 2

True

Question 3

Pilocarpine and atropine produce their effects by acting on _________________ of salivary glands.

Answer 3

Muscarinic acetylcholine receptor proteins

Question 4

Muscarinic antagonists can produce __________.

Answer 4

Xerostomia

Question 5

Who came up with the receptor theory?

Answer 5

Langley studied curares antagonist activity on nicotine to muscle cells

Question 6

What is described by the equilibrium or dissociation constant ?

Answer 6

Drug concentration required for 1/2 maximal binding to the receptor (Kd)

Question 7

What is the general idea of uptake kinetics by a receptor?

Answer 7

Receptors will quickly become saturated to a point and will then slowly take up substrate (rectangular hyperbola)

Question 8

How would drugs with different Kd act differently in how they are bound by receptors?

Answer 8

A drug with a higher Kd would require higher concentrations to create the same effect as one with a lower Kd

Higher Kd = drug will come off of receptor more easily

Question 9

T/F: If X amount of drug produces a certain effect, 2X amount of drug will produce roughly twice as much of an effect.

Answer 9

FALSE

Depends on where you are on binding curve

If original amount is low - doubling may induce double the effect

If original amount is high - doubling may have very little additional effect

Question 10

Drugs exert their effects by __________.

Answer 10

Binding to a receptor

Question 11

The _________________ describing drug binding to its receptor is defined as the concentration of drug providing 1/2 maximal binding.

Answer 11

Dissociation constant

Question 12

Which type of curve allows for a more complete range of data to be shown?

Answer 12

Sigmoidal curve

Question 13

The law of mass action is a fine way to describe drug ___________, but does not accurately describe quantitiative aspects of drug _________.

Answer 13

Binding; action

Question 14

What is EC50?

Answer 14

This is the dose of drug that produces 1/2 the maximal effect

Question 15

Maximum drug effect is seen when drug concentrations greatly exceed the ________.

Answer 15

EC50

Question 16

T/F: There is a maximal pharmacological effect where once a drug reaches a certain level, more drug will not produce an additional effect.

Answer 16

True

Question 17

Is EC50 (1/2 maximal effect) the same as Keq (1/2 maximal binding)?

Answer 17

No because often EC50 is less than Keq (1/2 maximal effect is seen at less than 1/2 maximal binding)

Question 18

Why are partial agonists not as effective as full agonists?

Answer 18

Partial agonists activate a lower fraction of receptors, independent of their relative binding affinities

Question 19

What is the difference between binding affinity and efficacy?

Answer 19

Binding affinity: determines concentration dependence of drug action

Efficacy: the ability to confer the physiologic response

Question 20

Together, efficacy and binding affinity determine a drugs __________.

Answer 20

Potency

Question 21

Drugs with insufficient efficacy will be _____________ regardless of how well they bind to their receptor.

Answer 21

Partial agonists

Question 22

Drugs with no efficacy that bind to the receptor will be ____________.

Answer 22

Antagonists

Question 23

T/F: Receptors are characterized by their physiologic response, not their pharmacology.

Answer 23

False

Receptors are characterized by their pharmacology

Question 24

T/F: There are typically inhibitory receptors and excitatory receptors.

Answer 24

False

Receptors often have several functions

Question 25

Why is it important to know the different receptor families?

Answer 25

Underscores the need for receptor specific agonists and antagonists