M&R 8.1 - Drugs and Receptors Flashcards Preview

ESA 2 > M&R 8.1 - Drugs and Receptors > Flashcards

Flashcards in M&R 8.1 - Drugs and Receptors Deck (21):
1

What is meant by the affinity of a drug?

The ability of a drug to bind to its biological target e.g. a receptor

2

What is meant by the efficacy of a drug?

The ability of a drug to generate a response upon binding

3

What is meant by intrinsic efficacy?

The ability of an agonist to activate a receptor

4

What does efficacy depend on?

- Efficacy

- Influential factors to the response e.g. cell-tissue dependent factors

5

What is Kd?

- The concentration of a drug/ligand supplying 50% of the receptors (dissociation constant)

- Measurement of affinity

- Lower Kd = Higher affinity

6

What is Bmax?

- The maximum binding capacity between a ligand and its receptors

- Indicates number of receptors

7

When would radioligands be used?

- To obtain information about binding

- Low radioligand = low binding

8

When would a concentration-response curve be used?

When measuring a response in cells/tissues

9

When would a dose-response curve be used?

When measuring a response in a whole animal

10

What is Emax?

Maximum response of a drug

11

What is EC50?

- The effective concentration giving 50% of the maximal response

- A measure of potency

12

What is potency?

- A combination of both affinity and efficacy

- The concentration of a drug required to give 50% of the maximal response

13

What does potency depend on?

- Affinity

- Efficacy

- Needs to generate a MEASURABLE RESPONSE

14

What is the relevance of measuring efficacy in relative terms?

- Agonists with different Emax = different efficacy

BUT

- Agonists with same Emax may have different efficacy as affinity could differ

15

How does dose differ to concentration?

- Dose = concentration of the drug at a site of unknown action (mg or Mgk-1)

- Concentration = known concentration of a drug at a site of action

16

What is an agonist?

- A molecule that activates a receptor

- Fits binding site fully

17

What are the features of an agonist?

Have:

- Intrinsic efficacy

- Efficacy

- Affinity

18

What is an antagonist?

A molecule that blocks the ability of an agonist by blocking the binding site without causing a conformational change

19

What are the features of an antagonist?

- ONLY HAS AFFINITY

- Doesn't cause a response so has no intrinsic efficacy

20

How does Salbutamol compare with Salmeterol?

- Salbutamol has a higher affinity for Beta-2 adrenoceptors than Beta-1

- Salbutamol has a Beta-2 selective efficacy

- Salmeterol has a higher affinity for Beta-2 adrenoceptors than Beta-1

- Salmerterol has no selective efficacy (prevents side effects and Beta1 activation through affinity)

21

How is the route of administration of Salbutamol significant?

- Gives another element of selectivity

- Limits Beta-1 activation and other side effects

- Can be given by drip to a severely ill patient but that then loses the selectivity

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