F1 What is a drug?

Question 1

what is a drug?

Answer 1

a substance that alters chemical reactions in the body to give a physiological result

Question 2

what 2 properties do drugs have?

Answer 2

• exerts a physiological effect
• a compound with a defined chemical structure

Question 3

what are the 4 major classes of protein targets?

Answer 3

• enzymes
• transporters
• ion channels
• receptors

Question 4

most drugs work at protein drug targets of various classes. give a drug that is an exception to this

Answer 4

Rennie
- contains bicarbonates that neutralise excess stomach acid

Question 5

what are receptors?

Answer 5

proteins in the body which respond to an endogenous messenger by initiating a signal

Question 6

give examples of endogenous messengers

Answer 6

hormones
neurotransmitters

Question 7

what are common characteristics of receptors?

Answer 7

• selective binding site for native hormone/transmitter
• act as molecular switches (have inactive and active states)
• signal is amplified

Question 8

what are the 2 types of receptor drug?

Answer 8

agonists and antagonists

Question 9

what do agonists do generally?

Answer 9

mimic/reproduce the effects of endogenous messengers

Question 10

what do antagonists do generally?

Answer 10

block the effects of endogenous messengers

Question 11

what type of drug targets enzymes, transporters and ion channels?

Answer 11

predominantly inhibitors

Question 12

what types of drug target receptors?

Answer 12

• at least 2 types of drug with opposing actions at the same target
• agonists and antagonists

Question 13

what factor determines the extent to which a drug binds to its target?

Answer 13

its local concentration

Question 14

what are the 2 branches of pharmacology?

Answer 14

• pharmacokinetics
• pharmacodynamics

Question 15

what are pharmacokinetics?

Answer 15

• how the body controls drug concentration at the site of action

Question 16

what are pharmacodynamics?

Answer 16

• the effect of the drug on the target cell/tissue

Question 17

what are is ADMETox and what does it stand for?

Answer 17

• Absorption, Distribution, Metabolism, Excretion, Toxicity
• the parameters for pharmacokinetics

Question 18

what do we mean by selectivity?

Answer 18

• drug targets the correct cell/tissue for a biological response
• drug interacts with the binding site of the correct molecular target

Question 19

what are on-target and off-target effects?

Answer 19

• on-target: an effect produced by intended interaction with the correct molecular target
• off-target: an effect produced by unintended interaction with a different molecular target

Question 20

what is the related neurotransmitter to adrenaline?

Answer 20

noradrenaline

Question 21

what are the receptors for adrenaline?

Answer 21

adrenoceptors

Question 22

what does adrenaline do when it binds to adrenoceptors in the airway?

Answer 22

• opens airways
• more gas into lungs for gas exchange
• enhances gas exchange (more oxygen and carbon dioxide transferred)

Question 23

what does adrenaline do when it binds to adrenoceptors in the heart?

Answer 23

• increased heart rate
• increased circulation of blood to muscles

Question 24

what must be considered when treating asthma in terms of the effect of adrenaline?

Answer 24

• mimic airway effects of adrenaline
• avoid other effects eg. on the heart

Question 25

why do the effects of adrenaline on the heart need to be avoided when treating asthma?

Answer 25

may cause palpitations

Question 26

how does salbutamol demonstrate selectivity generally?

Answer 26

• selective adrenoceptor agonist
• mimics the effect of adrenaline on airways but not the heart
• activates adrenoceptors in the lungs better than the heart

Question 27

how is the administration of salbutamol in an inhaler important for pharmacokinetics?

Answer 27

• targets the delivery to the airways and limits the systemic exposure of salbutamol
• this means it is less likely to reach other adrenoceptors (eg. in the heart) and cause side effects

Question 28

what doe the strength of interaction between a drug and its protein target depend on?

Answer 28

• depends on the drug ‘fitting’ into the 3D protein binding site
• the better the ‘fit’ the higher affinity the drug has for its target

Question 29

what does a higher affinity between a drug and its target mean?

Answer 29

the drug will produce its effects at a lower concentration

Question 30

is drug selectivity concentration-dependent?

Answer 30

• yes
• all drugs will interact with additional binding sites at higher concentrations which can lead to unwanted side effects