Theme 4 - Pharamcodynamics

Question 1

Define pharmacodynamics

Answer 1

Study of drug effect and mechanism of action (what drug does to body)

Question 2

Define “drug”

Answer 2

A chemical substance of known structure, other than a nutrient or an essential dietary ingredient, which, when administered to a living organism, produces a biological effect.

Question 3

Define “medicine”

Answer 3

The dosage forms in which drugs are administered (capsules, tablets, mixtures), contain more than one drug as well as inactive substances necessary during its manufacturing process.

Question 4

What are the 5 Targets of drug action?

Answer 4

Simple chemical neutralisation
Enzyme inhibitors
Receptor occupying drugs
Modulators of certain transport systems
Ion channel interaction

Question 5

Define the term “receptor”

Answer 5

A protein macromolecule with positions in its 3D structure that is of such a nature that they have chemo recognising properties for a specific endogenous molecule or a specific drug (it is also stereospecific)

Question 6

What are the 4 receptor types?

Answer 6

1. Ligand-gated ion channels (ionotropic receptors)
2. G-protein-coupled receptors (metabotropic receptors)
3. Kinase-linkedreceptors
4. Nuclear receptors

Question 7

Give examples of drug-receptor binding interaction

Answer 7

 Enzyme-substrate binding
 Binding of fatty acids and drugs to plasma proteins (albumin)
 Binding of antigens to antibodies

Question 8

What are the 4 main types of drug-receptor bonds?

Answer 8

Covalent, electrostatic, hydrophobic, cation-π

Question 9

Which receptors are Class I receptors related to?

Answer 9

nicotinic acetylcholine receptor

Question 10

What do class I receptors have in common with regards to the number of subunits?

Answer 10

All have the same number of subunits

Question 11

How do Class I receptors function?

Answer 11

By the fast opening of an ion channel

Question 12

What are Class II receptors coupled to?

Answer 12

second messenger system

Question 13

At what rate do Class II receptors operate?

Answer 13

rate much slower than class I receptors

Question 14

What does the protein composition of all class II receptors have?

Answer 14

7 membrane crossing segments

Question 15

What is the relationship between amino acid sequences of class II receptors?

Answer 15

they are all similar

Question 16

What is Receptor equilibrium?

Answer 16

A receptor exists in a dynamic equilibrium in two states Ri (active state) and R* (inactive state)

Question 17

What is intrinsic activity?

Answer 17

The ability to elicit a response after binding to a receptor

Question 18

What is a full agonist?

Answer 18

When the concentration of the agonist is increased, the biological response will increase until the maximal response has been reached

Question 19

What is a partial agonist?

Answer 19

Will not be able to produce 100% of the biological response of the agonist even at very high concentrations

Question 20

What is an Antagonist?

Answer 20

Antagonists block or reverse the effect of agonists, have no intrinsic activity

Question 21

What is a Competitive antagonist?

Answer 21

A competitive antagonist competes with the agonist for binding to the receptor. It has affinity for the receptor, but no intrinsic activity

Question 22

What is a Non-competitive antagonist?

Answer 22

Antagonists that binds to a different part of the receptor than agonists, there is no competition for the same binding site.

Question 23

What is an Irreversible competitive antagonist?

Answer 23

The antagonist competes directly with the agonist for receptor binding. However, the binding forces between the antagonist and receptor are so strong that the antagonist- receptor complex is irreversible.

Question 24

What is a Physiological antagonist?

Answer 24

Drugs cause opposite effects on the same system having different receptors.

Question 25

What is a chemical antagonist?

Answer 25

These antagonists bind to the active drug and inactivate

Question 26

What is the receptor reserve?

Answer 26

The maximum response can be obtained without the agonist occupying all the receptors. This excess of receptors is in reserve.

Question 27

What is the down-regulation of receptor numbers?

Answer 27

chronic stimulation by agonists cause a decrease in receptor numbers

Question 28

What is the up-regulation of receptor numbers?

Answer 28

chronic inhibition by antagonists cause an increase in receptor numbers

Question 29

What is a second messenger system?

Answer 29

A second system that communicates with the interior of the cell.