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Flashcards in Pharmacodynamics Deck (40)
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1

How does a drug exert its effects?

By binding to a target receptor

2

What proportion of targets do G protein-coupled receptors account for?

30%

3

List the order of molarity starting with picomolar.

Picomolar
Nanomolar
Micromolar
Millimolar
Molar

4

Define what a ligand is.

A molecule that binds specifically to a receptor

5

How does an agonist act at a receptor?

An agonist activates a receptor

6

How many moles is 1 micromolar?

10-6 M

7

How do antagonists function?

They block the binding site of endogenous molecules, meaning the receptor cannot be activated

8

Define the term efficacy.

A molecules efficacy is its ability to evoke a response in the cell its acting on

9

Do antagonists have any affinity and/or efficacy?

Antagonists have affinity as they can bind their target, but they have no efficacy, as they do not evoke any response in the cell

10

Do agonists have any affinity and/or efficacy?

Agonists have affinity as they bind their target, and they have efficacy, as their binding evokes a response in the cellular target

11

How can you measure drug-receptor interactions by binding?

By measuring the binding of a radioligand, which you can measure

12

How are high affinity drugs pharmacologically useful?

You will not need a high amount of the drug as its affinity for its target is already high

13

What is Bmax? What is Emax?

Bmax is the number of molecules that lead to maximal binding, while Emax is the number of molecules that lead to a maximal effect

14

What is the difference between concentration and dose?

Concentration is the amount of drug given to a known site of action, while dose is the concentration of drug given to a site of unknown action

15

What is the EC50?

The EC50 is a measure of the effective concentration of a ligand that gives 50% of the maximal response/effect - the EC50 is a measure of potency

16

Other than affinity and intrinsic efficacy, what else might affect a molecules potency (EC50)?

The number of receptors a cell contains

17

What are receptors termed that are bound by their ligand but have no effect on a ligands efficacy within the cell?

Spare receptors

18

Other than affinity and intrinsic efficacy, what else might affect a molecules potency (EC50)?

The number of receptors a cell contains

19

What are receptors termed that are bound by their ligand but have no effect on a ligands efficacy within the cell?

Spare receptors

20

What receptors are the therapeutic target in asthma? What does binding cause?

B2-adrenoreceptors - binding of an agonist causes relaxation

21

Describe the mechanism of action of salbutamol.

Salbutamol acts as a B2 adrenoreceptor agonist - it stimulates a G protein cascade through adenyl cyclase to increase levels of cAMP, activating protein kinase A - this leads to a series of events which leads to bronchodilation, widening the bronchial passages

22

What is the difference between a partial agonist and a full agonist?

A partial agonist has less efficacy than a full agonist

23

What is the role of spare receptors?

They increase sensitivity

24

What happens to spare receptors when a cell is over-stimulated?

The cell will remove receptors from its surface if over-stimulated - the cell is therefore less sensitive as a higher concentration will need to bind in order to bring about a response - this is seen in drug addiction

25

What happens respectively to receptor number in low activity and high activity?

In low activity receptor numbers generally tend to increase (receptors are up-regulated), while in high activity receptor numbers are generally decreased (they are down-regulated)

26

What is down-regulation of receptors (due to over-stimulation) otherwise called in drug addicts?

Tolerance

27

What is withdrawal/abstinence syndrome?

Neonatal abstinence withdrawal syndrome results from the cessation of the administration of drugs by the mother - this may lead to the child experience withdrawal symptoms as if they had been taking the drug themselves

28

List 3 examples where a partial agonist may be relevant?

- due to an absence/low levels of an endogenous ligand
- when concentrations/doses of a full agonist are too high (acting as an antagonist)
- to induce a more specifically controlled response

29

Give an example of a partial agonist. What receptors are their target?

Opioids are partial agonists - these usually target u-opioid receptors

30

What are the effects of opioids?

Pain relief
Euphoria
Respiratory depression (leading to death)