Session 2 - Pharmacodynamics

Question 1

Define drug action

Answer 1

Interaction at cellular level between a drug and cellular components.

Question 2

Define drug effect

Answer 2

The response resulting from the the drug action which may affect local function or wider body function.

Question 3

Explain specific drug action

Answer 3

Effects produced by interaction of the drug with a specific site, either on the cell membrane or inside the cell. Eg receptor activation

Question 4

Name 4 types of drug action

Answer 4

• Stimulation
• Inhibition/Depression
• Replacement
• Cytotoxic

Question 5

Explain and give an example of the drug action “stimulation”

Answer 5

Selective enhancement of the level of activity of specialised cells

Eg adrenaline and heart

Question 6

Explain and give an example of the drug action “inhibition/depression”

Answer 6

Diminution of activity of specialised cells

Eg diazepam

Question 7

What are type of structure is the cell membrane

Answer 7

Phospholipid bilayer

Question 8

Name 3 targets of drug action

Answer 8

• Receptors
• Enzymes
• Transport or uptake inhibitors

Question 9

Explain how drugs interact with receptors

Answer 9

Specific proteins situated on cell membranes .

Each are able to react with ligans (eg hormones, neurotransmitters and nutrients).

Drugs with similar chemical shape bind to these receptors. Eg adrenaline and the heart by mimicking the shape of the ligans

Question 10

What are ligans

Answer 10

Endogenous substances such as hormones and neurotransmitters

Question 11

Receptor activation - name 3 ways in which ligands can act

Answer 11

• Agonist
• Antagonist
• Partial Agonist

Question 12

What is an agonist ?

Answer 12

Drugs that occupy receptors and activate them

Question 13

What is an antagonist ?

Answer 13

Drugs that occupy receptors but do NOT activate them. Antagonists block receptor activation from agonists.

Question 14

Name an antagonist and how it works

Answer 14

Beta blocker (bisoprolol) blocks receptors so that a ligans (adrenaline) can not activate the receptor which in turn works to lower blood pressure.

Question 15

Explain a partial agonist

Answer 15

Only has a partial efficiency at the receptor, triggers a response lower than a full agonist at tech receptor

Question 16

Example of an agonist action

Answer 16

Activates or enhances cellular activity

Morphine and insulin

Question 17

Define affinity

Answer 17

The force of attraction between the drug and a receptor

Question 18

Define efficacy

Answer 18

Drugs ability to activate a response once bound to the receptor

Question 19

Difference between potency and efficacy

Answer 19

Potency is how much drug is needed to produce an effect that’s required.

Efficacy is the capacity of drug to activate a receptor.

Question 20

If two drugs are in competition for the same receptor which is going to win ? This is known as competitive antagonism

Answer 20

The one with the higher affinity

Question 21

Non competitive antagonism

Answer 21

Counter the effect of another drug or natural chemical but not competing for the receptor

Question 22

What acid is involved in response to an inflammatory response ?

Answer 22

Arachidonic acid

Question 23

What are enzymes ?

Answer 23

Biological catalysts, they speed chemical reactions and are not changed them selves.

Question 24

Explain ACE inhibitor hypertension medicine in terms of pharmacodynamics

Answer 24

Renin is released by the kidneys.

Renin converts angiotensinogen produced by the liver to angiotensin 1.

Angiotensin converting enzyme (ACE) forms angiotensin 2 which causes the arteries to narrow.

ACE inhibitors stop the ACE activity, and therefore relaxes the arteries and lowers blood pressure.

Question 25

What is activated in response to arachidonic acid ?

Answer 25

Cox- 1 enzyme

Cox - 2 enzyme

Question 26

Explain the cyclooxygenase pathway

Answer 26

Arachidonic acid is realised in response to irritation or injury. In response to arachidonic acid COX 1 and COX 2 catalyse the formation of prostaglandins within the body.

Question 27

Cox 1 catalyses prostaglandins that are responsible for what ?

Name 3

Answer 27

Homeostatic effects

1 - renal homeostasis
2 - Gastric mucosal production
3 - platelet function

Question 28

Cox 2 is responsible for catalysing prostaglandins that are responsible for what ?

Name 3

Answer 28

Inflammatory effects

1- pain
2- inflammation
3- fever

Question 29

Which enzyme is expressed constantly ? Cox 1 or cox 2 and why ?

Answer 29

Cox 1 - as it is responsible for homeostatic effects

Question 30

Which enzyme is only expressed during irritation or injury ? Cox 1 or cox 2 and why ?

Answer 30

Cox 2 as it has inflammatory effects.

Question 31

Name the 3 targets for drug action.

Answer 31

• Receptors
• Enzymes
• Transport or uptake inhibitors

Question 32

Define an enzyme

Answer 32

A biological catalyst catalyst that increases the chemical reaction in the body.

Question 33

Define receptors

Answer 33

A macro molecular structure found within a cell or on its plasma membrane that is able to react with ligans.

Question 34

Explain transport/uptake inhibitors in terms of SSRIs

Answer 34

Serotonin is released into the synaptic cleft.
Under normal circumstances, some of the serotonin is taken back into the presynaptic nerve ending.
SSRIS inhibit this mechanism therefore serotonin levels are increased in the synaptic cleft and more serotonin is available to bind to receptors

Question 35

What does SSRIs stand for.

Answer 35

Selective serotonin reuptake inhibitors.

Question 36

Name to SSRIS

Answer 36

Fluoxetine and citalopram

Question 37

Define competitive antagonism in terms of morphine naloxone.

Answer 37

Naloxone has a higher affinity to receptors than morphine therefore naloxone can reverse the effects of morphine on the body.

Question 38

Define non competitive antagonism.

Answer 38

Counter the effect of another drug or natural chemical but not competing for the same receptors.