Pharmacodynamics

Question 1

What is the definition of pharmacodynamics?

Answer 1

What the drug (chemical) does to the body and how the body responds

Interaction between chemical compounds of the body and foreign chemicals

Question 2

What are the 4 ways in which drugs tend to work?

Answer 2

1) replace missing chemicals/act as their substitutes
2) stimulate particular cell activities
3) slow down/inhibit particular cell activities
4) interfere with function of foreign cells

Question 3

What are the 4 types of proteins drugs mainly exert their effects on?

Answer 3

1) receptors
2) enzymes
3) ion channels
4) carrier (transporter) molecules

Question 4

Define receptor…

Answer 4

Protein molecule

Has a specific shape/3D structure

Only substances that fit precisely can interact (complementary)

Enable natural substances e.g. NT/hormones to influence activity of the cell- influence may be stimulate or inhibit process inside cell

Question 5

What is a ligand?

Answer 5

Molecule/chemical that binds to a receptor

Question 6

What are target cells?

Answer 6

Cells with the appropriate receptor to detect/respond to hormones, mediators and NT

Question 7

Define specificity…

Answer 7

Ability of the drug to combine with one particle type of receptor

No drug acts with complete specificity- this causes unwanted side effects

Question 8

Define efficacy…

Answer 8

Measure of the bound ligand to activate a response

Question 9

Define affinity…

Answer 9

Interaction between drug and binding site

Closer the fit and greater number of bonds leads to higher affinity of the drug for the receptor

Question 10

What is the effect of an Agonist drug?

Answer 10

Activate or stimulate their receptors

Trigger a response to increase or decrease cell activity

Question 11

What is the effect of an Antagonist drug?

Answer 11

Block the access/attachment of body’s natural agonists (NT) to receptors

Prevent/reduce cell responses to natural agonists

Question 12

Define agonist…

Answer 12

Mimic action of endogenous (naturally occurring) ligands

Question 13

Define antagonist…

Answer 13

Block action of endogenous ligands

Question 14

What is the function of a reversible competitive antagonist?

Answer 14

Competes with the agonist for the agonist binding site on the receptor- blocks it, stopping agonist binding

Increasing agonist conc. can overcome blocking effect , restoring response

Question 15

What is the function of irreversible, competitive antagonists?

Answer 15

Forms covalent bonds to agonist binding site so block cannot be overcome

Question 16

What are the functions of non-competitive antagonists?

Answer 16

Bind to a site other than agonist binding site

Often causes conformational change in receptor, reducing ability of the agonist to bind to its binding site- reduces response to agonist

Question 17

What are the functions of alpha-receptors?

Answer 17

Associated mainly with increased contractibility of vascular smooth muscle and intestinal relaxation

Question 18

What are the functions of beta-receptors?

Answer 18

Associated with vasodilation and relaxation of non-intestinal smooth muscle and cardiac stimulation

Question 19

What is an enzyme?

Answer 19

A protein which acts as a biological catalyst

Controls rate at which reactions occur

Remain unchanged

Question 20

What is the function of the active site?

Answer 20

Where chemical reactions occur

Where the enzyme interacts with its substrate

The prime target for drugs acting on enzymes

Question 21

What is the function of non steroidal anti-inflammatory drugs (NSAIDS)?

Answer 21

Drugs that block activity of an enzyme

Inhibit enzyme cyclo-oxygenase (COX)- block its activity

Question 22

What is the function of COX?

Answer 22

Responsible for formation of some important chemical mediators e.g. Prostaglandins- play key role in inflammation and pain

Question 23

What is the function of acetylcholinesterase inhibitors?

Answer 23

Used to improve/stabilise symptoms of Alzheimer’s disease

Breaks acetylcholine in the synapse- if you inhibit breakdown of acetylcholine more NT would remain in synapse, enhancing memory

Question 24

What is the function of Acetylcholine?

Answer 24

NT helping with memory and thinking

Question 25

What are the functions of calcium channel blockers?

Answer 25

Act as vasodilators- blocking intracellular calcium required for contraction of arteriolar smooth muscle

Reduce aldosterone production (adrenal cortex)

Lowers BP

Slows HR

Reduce force of contraction in cardiac smooth muscle

Negative chronotrophic effect- atrial fibrillation possibly causing heart block

Question 26

What does vasodilation cause in calcium channel blockers?

Answer 26

Causes reduction in peripheral vascular resistance- reduced BP

Question 27

What are the functions of sodium channels?

Answer 27

Vital for propagation of AP along nerve cells

Question 28

What happens if sodium channels are blocked?

Answer 28

Prevents sensation of pain

Delay in conductance, decrease in excitability and prevents sensations of pain

Question 29

What are the functions of potassium channel blockers?

Answer 29

Prolongs repolarisation (going back to resting state)

Question 30

What are the functions of potassium channel openers?

Answer 30

Used to rest hypertension and angina- relax smooth muscle- vasodilation

Question 31

What is the function of GABA?

Answer 31

Most common NT

Acts to reduce excitability in CNS

Reduced signalling in the brain

Sedating NT

Question 32

What are the functions of Benzodiazepines?

Answer 32

Act as modulators of GABA receptors, potentiating effect of the receptor

Question 33

What is the function of Serotonin?

Answer 33

In the CNS it is a mood enhancer

Increasing levels in synaptic cleft available to bind to postsynaptic receptors causing mood enhancement

Question 34

What is the function of Selective Serotonin Reuptake inhibitors?

Answer 34

Prevent reuptake of Serotonin from synaptic cleft back into the pre-synaptic neurone