💊Pharmacology💊 - Pharmacodynamics & Pharmacokinetics

Question 1

What is the difference between pharmacology and therapeutics?

Answer 1

Pharmacology is the study of drug action, how a drug interacts with living organisms and how this influences physiological function
Therapeutics is concerned with drug prescribing and the treatment of disease, more focused on the ‘patient’

Question 2

What is the difference between pharmacodynamics and pharmacokinetics?

Answer 2

Pharmacodynamics deals with ‘what the drug does to the body’ and pharmacokinetics deals with ‘what the body does to the drug’

Question 3

What 3 things must be considered when evaluating the effect a drug has on the body?

Answer 3

Where is the effect produced?
What is the target for the drug?
What is the response that is produced after interaction with this target?

Question 4

What must a drug do in order to have an effect?

Answer 4

Be bound to a target

Question 5

Are drugs often limited to just 1 effect on the body?

Answer 5

No!

Question 6

What effect does cocaine have?

Answer 6

Produces a euphoric high
Also, can be an effective local anaesthetic

Question 7

Where in the body is the euphoric effect produced by cocaine?

Answer 7

The nucleus accumbens

Question 8

What is the specific cellular target of cocaine?

Answer 8

Dopaminergic neurones in the nucleus accumbens

Question 9

What is the specific molecular target of cocaine?

Answer 9

The dopamine reuptake protein on the pre-synaptic terminal of dopaminergic neurones

Question 10

What is the response that is produced after cocaine’s interaction with it’s target?

Answer 10

Cocaine will BLOCK the dopamine reuptake protein. This means that dopamine is not removed from the synapse as quickly, and is thus more available to bind to the dopamine (D1) receptor. Activation of this receptor is what causes euphoria

Question 11

What are the 4 different types of drug targets?

Answer 11

Receptors
Enzymes
Ion channels
Transport proteins

Question 12

What type of target does aspirin bind to?

Answer 12

Enzyme

Question 13

What is the effect of aspirin?

Answer 13

Aspirin binds to the ‘enzyme’ cyclooxygenase and blocks the production of prostaglandins

Question 14

What type of target do local anaesthetics bind to?

Answer 14

Ion channels

Question 15

What is the effect of local anaesthetics?

Answer 15

Local anaesthetics block sodium ‘ion channels’ and thus prevent nerve conduction

Question 16

What is the target of Prozac (anti-depressant)?

Answer 16

Carrier proteins

Question 17

What is the effect of Prozac?

Answer 17

Prozac (Anti-depressant) block serotonin ‘carrier proteins’ and prevent serotonin being removed from the synapse

Question 18

What is the target of nicotine?

Answer 18

Receptor

Question 19

What is the effect of nicotine?

Answer 19

Nicotine binds to and activates the nicotinic acetylcholine ‘receptor’

Question 20

Why is selectivity important for a drug?

Answer 20

So that it only effects the desired target
Minimal side and adverse effects

Question 21

Which 3 molecules are very structurally similar and are found in synapses?

Answer 21

Dopamine, noradrenaline, serotonin

Question 22

What problem does these 3 molecules being very structurally similar pose?

Answer 22

A drug that can interact with the receptor for one of them may be able to interact with receptors for the other two

Question 23

What is the significance of drug dose on its specificity?

Answer 23

The higher the dose, the more likely a drug is to have an effect at a secondary target site
Site A sees an effect at a low dose, then as dose increases a threshold is reached where an effect is now seen at site B

Question 24

What are the different types of drug-receptor interactions?

Answer 24

Electrostatic interactions
Hydrophobic interactions
Covalent bonds
Stereospecific interactions

Question 25

Describe electrostatic interactions

Answer 25

This is the most common mechanism and includes hydrogen bonds and Van der Waals forces

Question 26

Describe hydrophobic interactions

Answer 26

This is important for lipid soluble drugs

Question 27

Describe covalent bonds

Answer 27

these are the least common as the interactions tend to be irreversible

Question 28

Describe stereospecific interactions

Answer 28

A great many drugs exist as stereoisomers and interact stereospecifically with receptors

Question 29

What is the affinity of a drug?

Answer 29

The affinity of a drug determines strength of binding of the drug to the receptor, affinity is strongly linked to receptor occupancy

Question 30

What is the efficacy of a drug?

Answer 30

The ability of an individual drug molecule to produce an effect once bound to a receptor

Question 31

What is the difference between affinity and efficacy?

Answer 31

Affinity refers to the likelihood that a molecule of a drug will be bound to a receptor, the efficacy refers to whether the binding of a drug has an effect or not. When a drug occupies a receptor, it does not necessarily produce one standard unit of response

Question 32

What type of molecule would have high affinity but no efficacy?

Answer 32

A receptor antagonist When bound to that receptor, it is effectively blocking that receptor

Question 33

What type of molecule would have affinity but sub-maximal efficacy?

Answer 33

A partial agonist When bound it can produce a partial response, but not a maximal response

Question 34

What type of molecule would have high affinity and high/maximal efficacy?

Answer 34

A (full) agonist When bound to a receptor, produces a maximal response

Question 35

What is the potency of a drug?

Answer 35

The concentration or dose of a drug required to produce a defined effect

Question 36

What is the standardised measure of potency?

Answer 36

The concentration or dose of a drug required to produce a 50% tissue response

Question 37

What are the 4 major pharmacokinetic factors?

Answer 37

Absorption Distribution Metabolism Excretion

Question 38

Define absorption

Answer 38

The passage of a drug from the site of administration into the plasma

Question 39

What is bioavailability?

Answer 39

The fraction of the initial dose that gains access to the systemic circulation

Question 40

What is the significance of distribution in pharmacokinetics?

Answer 40

Different tissues will be exposed to different amounts of the drug depending on several factors

Question 41

What are the factors that effect distribution of a drug in body tissues?

Answer 41

Regional blood flow Plasma protein binding Capillary permeability Tissue localisation

Question 42

How does regional blood flow effect drug distribtution?

Answer 42

Different tissues receive a greater proportion of blood flow, so these tissues will receive more exposure to the drug

Question 43

How does plasma protein binding effect drug distribution?

Answer 43

Drugs with a higher affinity to plasma proteins are unable to diffuse out of blood (only free drug molecules can) so are not able to reach their target sites

Question 44

Why is metabolism important in drug pharmacokinetics?

Answer 44

To make drugs less lipid soluble, allowing for easier excretion

Question 45

What are the two phases in drug metabolism?

Answer 45

Phase 1 – main aim is to introduce a reactive group to the drug Phase 2 – main aim is to add a conjugate to the reactive group Both stages together act to decrease lipid solubility which then aids excretion and elimination

Question 46

What is the purpose of phase 1 of drug metabolism?

Answer 46

The end result of phase 1 metabolism is to produce metabolites with functional groups that serve as a point of attack for the conjugating systems of phase 2

Question 47

What is the purpose of phase 2 of drug metabolism?

Answer 47

The attachment of a substituent group, and the resulting metabolite is nearly always inactive and far less lipid soluble than the phase 1 metabolite

Question 48

What are the main routes of drug excretion?

Answer 48

The lungs (such as alcohol, this forms the basis of the breathalyser test) Breast milk ( this is why care needs to be taken that drugs excreted in milk do not affect the baby) **Kidneys** (in urine) **Liver** (in bile)

Question 49

What are the 3 major mechanisms of excretion from the kidney?

Answer 49

Glomerular filtration Active tubular secretion (or reabsorption) Passive diffusion across tubular epithelium