Pharmacodynamics

Question 1

Pharmacodynamics

Answer 1

The effect a drug has on the body

Question 2

Physiological communication of medications

Answer 2

1. Stimulus
2. First messenger NT/Hormone
3. Target receptors within cells
4. Intracellular secondary messenger
5. Response

Question 3

where do drug actions take part

Answer 3

• Ion channels
• Receptors
• Enzymes
• Transport proteins

Question 4

Ion channels as drug targets

Answer 4

Ion channel blockade or opening is useful in controlling functions of cells such as muscles or nerves.

e.g. Sodium entry into the cell excites it leading to contraction in mus

Question 5

What is lignocaine

Answer 5

Blocks sodium entering the cell and reduces muscle excitability (heart) and stops nerves conducting (central and peripheral nervous system)

Question 6

Transport Proteins as drugs

Answer 6

Some inhibit transport proteins. Some examples can Ion transport pumps, diuretics, digoxin and selective serotonin reupatke inhibitor

Others drugs use transport proteins as carriers:
L-Dopa (Parkinson’s disease medication) is transported into the body and brain by the large neutral amino acid (LNAA) transporter.

Question 7

What are receptors

Answer 7

Specefic proteins capable of binding a specific group of drugs or endogenous substances.

Receptors can be :
1. Extracellular- bind neurotransmitters
2. Intracellular- Bind steroids

Question 8

Ligand

Answer 8

A substance that binds to a receptor.
Can be found in the body(endogenous) or enter the body (exogenous) to bind with a receptor.

Drugs are exogenous ligands as they come from outside the body

e.g. histamine is a ligand at histamine receptors

Question 9

Effect of Aldosterone

Answer 9

• Aldosterone binds to an intracellular receptor called mineralocorticoid receptor
• Allows nucleus to produce more proteins
• These allow it to regulate the levels of Sodium in the adrenal gland

Question 10

Receptor theory

Answer 10

• Receptors bind ligands by weak bonds
• Characteristics of shapes and charge give rise to concept of affinity
• Affinity- How well it binds to the receptor

Question 11

Agonists

Answer 11

• drugs with high affinity and high intrinsic activity.
• Mimic the effect of natural ligand

Question 12

Antagonists

Answer 12

• drugs with high affinity but no intrinsic activity
• Binding of the drug to the receptor results in no effect
• (receptor is inhibited)

Question 13

Kinds of Antagonisms

Answer 13

Competitive Antagonists
Non-Competitive Antagonists
Partial Agonists

Question 14

Competitive antagonists

Answer 14

these compete for the same receptor as an agonist

Question 15

Non-competitive antagonist

Answer 15

these drugs bind to a place other than the endogenous ligand binding site and incapacitate the receptor.

Question 16

Partial Agonists

Answer 16

These act on a receptor but without the maximum effect

Question 17

Classification of receptors

Answer 17

• Receptors are classified by their structure or which ligand binds to them.
• Receptors are subdivided into subtypes
• Subtypes bind similar ligands but generate different effects
  • Example, beta receptors
    
    • beta1 in the heart
    • beta2 in the lungs

Question 18

Drug Selectivity

Answer 18

Drugs may have more than one effect. This is because the same drug may bind to different receptors therefore resulting in a multitude of effects

Question 19

Drug Potency Vs Efficacy

Answer 19

Potency- strength of the drug/amount of the drug needed to ilicit a certain effect

Efficacy is the maximal possible effect of drug . (Depends on receptor affinity and number)

Look at PPT to understand this

Question 20

Receptor Down Regulation

Answer 20

• If Drug is agonistic then receptor down regulation may occur
• Body perceives potential for too much effect as too many ligands
• So receptors on membrane reduce for ligand binding
• Less effect (may or may not be right :) )

Question 21

Consequences

Answer 21

If drug stopped suddenly the body is “starved” of ligand effect, this may give rise to withdrawal or a crisis effect in the body

Question 22

Receptor Up Regulation

Answer 22

• If the receptor-drug effect is antagonistic then receptor up regulation may occur.
• Body think the effect is too little
• Increase in receptors available for ligand binding

Question 23

Consequences

Answer 23

overt effect of that ligand in the body, which may be harmful and sometimes fatal.