8. Drugs & Receptors Flashcards Preview

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Flashcards in 8. Drugs & Receptors Deck (26)
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0

How is molarity calculated?

Grams per litre/molecular weight

1

How is concentration in grams per litre calculated?

Molarity x molecular weight

2

What is the binding of a receptor governed by?

The affinity of the ligand and receptor

3

What is activation of a receptor governed by?

The intrinsic efficacy

4

What is efficacy?

The cell and tissue independent factors between a ligand binding and a response

5

Agonists have:
affinity and efficacy?
affinity only?
efficacy only?
none?

Agonists have both affinity and efficacy

6

Antagonists have:
Affinity and efficacy?
Affinity only?
Efficacy only?
None?

Antagonists have only affinity

7

How can drug receptor binding be measured?

Radioligands

8

What is Bmax?

The maximum binding capacity

9

What is Kd?

The dissociation constant, it is a measure of affinity
Measured as the concentration of drug at half max occupancy of receptors

10

A high Kd means what?

A low affinity for the receptor

11

A drug receptor binding curve on a logarithmic x axis will give you what graph shape?

Sigmoidal

12

How do you measure the EC50 and what does it represent?

Effective concentration giving 50% of the max response
This shows potency which is a combination of affinity and efficacy

13

Which has greater affinity for Beta 2 receptors, salbutamol or salmeterol?

Salmeterol

14

What enhances the utility of salbutamol?

Inhaled directly into the lungs hence straight onto beta 2 receptors

15

What is the problem with giving asthma drugs IV?

Salmeterol cannot be given IV, salbutamol can but has poor selectivity for beta 2 receptors, hence it agonises beta 1 as well, speeding up the heart.

16

Less than 100% receptor occupancy giving a 100% response leads to what?

Spare receptors

17

Does number of receptors have an effect on potency?

Yes

18

What is a partial agonist?

A drug that cannot produce a maximal effect even with full receptor occupancy

19

Can a partial agonist be more potent than a full agonist?

Yes as potency is dependant of affinity and efficacy

20

What is buprenorphine used for?

Buprenorphine is a partial agonist which has higher affinity but lower efficacy than the full agonist morphine. This means it can be used to out compete morphine with less of the respiratory depression that opioids cause.

21

What is IC50?

The concentration of antagonist that gives 50% inhibiton

22

What is naloxone?

High affinity opioid antagonist which is used to reverse respiratory depression as it will displace other opioids

23

What does the agonist response graph look like with increasing amounts of irreversible competitive antagonist?

Shifts it to the right as spare receptors are filled, then down as there are insufficient receptors for a full response

24

What is phenoxybenzamine?

Irreversible alpha 1 adrenoreceptor blocker used in hypertension episodes in pheochromocytoma

25

Name a non competitive antagonist used to analgesia

Ketamine