HOW DRUGS ACT

Question 1

What is pharmacology?

Answer 1

The branch of medicine and biology concerned with the study of drug action

Question 2

What is a dose?

Answer 2

The amount of active ingredient

Question 3

What is pharmacokinetics?

Answer 3

What the body does to the medication 
Absorption 
Distributions
Metabolism
Excretion

Question 4

What is pharmacodynamics?

Answer 4

What the medication does the the body and its mechanism

Question 5

What are the 4 main types of drug targets?

Answer 5

Receptors, enzymes, carrier molecules and ion channels

Question 6

What is a ligand?

Answer 6

A molecule which produces a signal by binding to a site on a target protein

Question 7

What is affinity?

Answer 7

The strength of non-covalent bonds between drug and receptor

Question 8

What’s the dissociation constant?

Answer 8

The concentration at which half the drug is bound to the receptor at equilibrium

Question 9

What is the difference between agonist and antagonist?

Answer 9

An agonist is a drug that produces a positive effect when bound to a receptor whilst the antagonist reduces the effect of the agonist at the given receptor

Question 10

Where does a non-competitive antagonist bind to?

Answer 10

An allosteric site where it can cause a conformational change to the quaternary structure so the agonist cannot bind

Question 11

What’s the difference between a reversible and irreversible agonist?

Answer 11

A reversible agonist binds non-covalently whilst the irreversible agonist binds covalently

Question 12

What is an inverse agonist?

Answer 12

A drug that produces a negative effect when bound to a receptor

Question 13

What is a second messenger?

Answer 13

Intracellular signalling molecules released by the cell in response to exposure to extracellular signalling molecules

Question 14

What is efficacy (Emax)?

Answer 14

The maximum response achievable from a drug

Full agonists produce an Emax of 199 and antagonists produce an Emax of 0

Question 15

What is potency?

Answer 15

The dose of the drug required to produce a specific effect of given intensity

Question 16

What is effective concentration 50 (EC50)?

Answer 16

The concentration of a drug that induces a half-maximal response

Question 17

What is the therapeutic window?

Answer 17

The range of doses that produces the therapeutic response without causing any significant adverse effects
It’s usually the ratio between minimum effective concentration and minimum toxin concentration

Question 18

What is LD50?

Answer 18

Lethal dose 50- the maximum dose of the medication where 50% of a population die

Question 19

What is ED50?

Answer 19

The median effective dose

The dose that produces a specific effect in 50% of the population who take the dose

Question 20

What is the therapeutic index?

Answer 20

A quantative measurement of the relative safety of the drug

Question 21

What are the 4 main types of receptors?

Answer 21

Ligand-gated ion channels
G-protein coupled receptor
Receptor kinases
Nuclear receptors

Question 22

Describe a ligand gated ion channel?

Answer 22

Several subunits with an extracellular, transmembrane and intracellular domain. It has a pore down the centre which opens as the ligand binds

Question 23

Describe a G-protein-coupled receptor?

Answer 23

A long protein with an extracellular domain and a transmembrane domain which crosses into the membrane 7 times before ending inside the cell. As the ligand binds, the G protein is cleaved and the second messengers are able to be phosphorylation to get a biological response

Question 24

What are the subunits of a G-protein-coupled receptor?

Answer 24

S subunit= stimulates adenylyl cockade and increase cAMP formation
I subunit and O subunit = inhibits adenylyl Cyclades and reduces cAMP formation
Q subunit = targets phospholipase C which increases the production of second messengers
Gamma subunits = block the activity of alpha subunits

Question 25

Describe kinase linked receptors?

Answer 25

A single pass transmembrane protein that has an extracellular ligand-binding domain linked to an intracellular domain by a transmembrane helix. The intracellular domain tends to have enzyme activity (usually a kinase)
When the ligand binds, it triggers a conformational change in the enzymatic domain to form high-affinity binding site for second messengers

Question 26

Describe nuclear receptors?

Answer 26

They associate with ligand which initiates changes in gene transcription by binding to hormone response elements in gene promoters and recruiting activating or repressing factors

Question 27

What is tachyphylaxis?

Answer 27

When an agonist binds to a receptor but the biological response is reduced over time. It’s an acutely, sudden decrease in response to the drug after administration

Question 28

What is receptor desensitisation?

Answer 28

When the biological response to a drug diminishes when it’s given repeatedly- it’s a more gradual lose than tachyphylaxis

Question 29

What is drug tolerance?

Answer 29

The body’s adaptation to repeated presence of a drug so a new homeostatic point is set and larger doses are required to give the original effects

Question 30

What are some possible merchandises of desensitisation and tolerance to drugs?

Answer 30

A decrease in the number of receptors
Receptors may become uncoupled from intracellular signalling pathways so second messengers can’t be activated
Exhaustion of intermediate messenger molecules
Metabolic breakdown of medication
Physiological adaptations of the body

Question 31

How can we treat dependence?

Answer 31

With an agonist that may have milder side effects or an antagonist

Question 32

What are the 2 types of adverse drug reactions?

Answer 32

Type A which is related to the pharmacological properties so are predictable and understandable, they are usually related to the dose given or susceptibility of the patient

Type B are unrelated to the drug’s principle mode of action so have more unpredictable side effects