Lecture 11 - How drug work: antagonists

Question 1

Recognise and list the characteristics of competitive antagonism

Answer 1

a. Receptor specificity
b. Reversible binding
c. Compete with agonist
d. Shift in dose-response curve (makes it shift to the right)
e. Efficacy unchanged
f. No effect on intrinsic activity
g. Surmountable antagonism (can be overcome by increasing agonist cause can eventually outcompete the antagonist)
h. Parallel shift in concentration-response curve (parallel rightward shift of curve without changing shape of curve)

Question 2

Recognize and list the general characteristics of partial agonists

Answer 2

a. Partial activation
b. Efficacy less than full agonists
c. Receptor binding with less affinity
d. Competitive antagonism (can act as one if full agonist is present)
e. Variable effects

Question 3

Pharmacologically important partial agonists

Answer 3

a. Buprenorphine
b. Salbutamol
c. Pindolol

Question 4

What is Buprenorphine

Answer 4

a. Used as initial treatment for opiate dependence
b. Less respiratory depression and euphoria if on relapse and use of potent opioid occurs

Question 5

What is Salbutamol

Answer 5

a. B2-adenoceptor selective partial agonist
i. Less downregulation of B2-adrenoceptors compared with full potent agonist

Question 6

What is Pindolo?

Answer 6

a. B-adrenoceptor (partial agonist) with “intrinsic sympathomimetic activity”
b. Lesser trough in cardiac contractility and rate

Question 7

What is the difference between competitive, non-competitive and functional antagonists?

Answer 7

the key differences among competitive, non-competitive, and functional antagonists lie in their mechanisms of action, binding reversibility, and effects on agonist concentration-response curves. Each type of antagonist has its own therapeutic and physiological implications.

Question 8

Describe drug selectivity

Answer 8

Fundamental aspect of drug development that aims to maximise the therapeutic benefit of a drug whilst minimising undesirable interactions with off-target molecules.

Question 9

Describe the aspects of pharmacodynamics

Answer 9

a. The study of how drugs interact with body and produce their effects
b. How drugs bind to their targets, influence biological processes and produce their therapeutic or adverse effects.

Question 10

Describe the adverse effects which underpin choice of drug dosage

Answer 10

Dose-response relationship, side effects, toxic effects, tolerance, cumulative effects, duration, patient factors etc.

Question 11

What is the Duty-cycle of GPCR

Answer 11

a. Bind agonist
b. Activation
c. Phosphorylation
d. Coated pits
e. Internalisation
f. Dissociation, dephosphorylation
g. Recycling