s2-L16-principles of pharmacology-part 1

Question 1

Explain receptor concept
-how do drugs produce their effects?
-Define response in terms of a drug.

Answer 1

-drugs produce their effects by combining with specific receptor sites in cells.
-response is a function of the number of occupied receptors.

Question 2

3 ways of how cell function is altered by drugs

Answer 2

-altered membrane potential
-altered enzyme activity
-altered gene expression

Question 3

2 examples of drugs that affect the cell function directly.

Answer 3

-tetrodotoxin (TTX)-puffer fish 🐠 - blocks V.G.Na.channels inhibiting nerve signal transmission, stops A.P leading to paralysis.
-aspirin-inhibits cyclooxygenase (COX) enzyme which produces prostaglandins in inflammation.
-acridine dyes (binds to DNA, prevent DNA replication)

Question 4

How do most drugs affect these cell functions?

Answer 4

via (physiological) receptors - it mimics or blocks the body’s natural signalling process.

Question 5

Name 4 ways the drug can target things.

Answer 5

-to enzymes - cyclooxygenase, the aspirin receptor
-to ion channels - Ca2+ channels blocked by nifedipine-relaxation in blood vessels
-transporters(pumps) - noradrenaline transporter blocked by cocaine
- physiological receptors - receptors for hormones, NTMs - acetylcholine, histamine, insulin.

Question 6

What are drug receptors ? where are they found?

Answer 6

-A specialised protein in the body that interacts with drugs to produce a biological effect.
-located on cell membranes/inside the cell

Question 7

how are drug receptors classified and how are they named? just one interaction or more?

Answer 7

• receptors are classified on the basis of the selective action of drugs.
• named according to the transmitter or hormone with which they interact
• most transmitters /hormones interact with more than one type of receptor

real differences in protein structure underline differences between subtypes

Question 8

what does muscarinic mean

Answer 8

from 🍄

Question 9

Define receptor superfamilies

Answer 9

Are large groups of related receptors that share structural and functional characteristics.

Question 10

Name types of superfamilies receptors and examples for them.

Answer 10

-integral ( or ligand-gated) ion channels - nicotinic receptor
-G protein coupled receptors - muscarinic receptor, adrenoreceptors
-integral tyrosine kinases - insulin receptor
-steroid receptors on DNA - oestrogen receptor
- cytokine receptors - prolactin receptor, growth hormone receptor

Question 11

Define quantitative pharmacology

Answer 11

-assume drugs acts by entering in to a simple chemical relation with certain receptors in cells and that there is a simple relation between the amount of drug fixed by these receptors and the action produced.

Question 12

Define affinity and what does it controls/governs?

Answer 12

-the strength of the interaction between a drug and its receptor. It describes how tightly a drug binds to its target.

-Affinity governs binding

Question 13

How is affinity measured ?

Answer 13

can be measured using a drug’s dissociation constant from its receptor, the Kd

Question 14

Define Kd(drug dissociation constant)

Answer 14

represents the drug concentration at which, at equilibrium, half the receptor population will be bound with drug

lower Kd or Ka means stronger binding

Question 15

Define efficacy and what does it controls/governs?

Answer 15

-refers to the max effect a drug can produce, regardless of dose.
OR
-how well a drug achieves its intended therapeutic effect once it binds to its target
OR
-a measure of the degree to which an agonist produce a response when binding a given proportion of receptors.

-Efficacy governs activation

Question 16

What is the efficacy value for full agonists and partial agonists?

Answer 16

-Full agonist -> efficacy = 1
-Partial agonist -> efficacy <1, but greater than 0

Question 17

Define Occupancy(p)

Answer 17

Fraction of receptors occupied by agonist is defined as p.

Question 18

Define agonists in simple terms

Answer 18

Drugs can act as agonists, activating receptors to produce a response.
-agonists bind to a receptor/target and produce a response.

Question 19

Define antagonists in simple terms

Answer 19

Drugs can act as antagonists, blocking receptors to prevent a response.

Question 20

the interaction between a drug and its receptors determine what 3 things?

Answer 20

selectivity
potency
duration of action

Question 21

Define EC50

Answer 21

effective drug concentration to produce 50% of the maximum response.

Question 22

What does EC50 allows the measure of…?

Answer 22

Potency

Question 23

Define Potency

Answer 23

the amount of drug required to produce a particular level of effect/response.

Question 24

does all the receptors have to occupied for the drug to work fully efficiently?

Answer 24

NO

Question 25

What is an inverse agonist and what does it have and what does it do?

Answer 25

-A drug that produces a negative efficacy, less than 0. -such drugs inhibit any intrinsic receptor activity that might exist in the absence of a ligand.

Question 26

what does negative efficacy governs?

Answer 26

de-activation of R in A+R equation OR reduce the activity of biological reaction

Question 27

What is the value of efficacy for antagonists?

Answer 27

zero efficacy

Question 28

Antagonists can do what to agonists and what are some types of antagonists?

Answer 28

-Antagonists block or reduce the response to an agonist -various different types like competitive, irreversible, other.