Part 1

Question 1

Define a receptor

Answer 1

Target proteins through which endogenous regulatory ligands produce an effect

Question 2

List the 4 types of drug targets

Answer 2

Enzymes
Physiologic receptors
Ion channels
Carrier transporters

Question 3

Examples of common drug targets

Answer 3

Acetylcholine, adrenergic receptors , histamine, opioid, steroid, cytokine

Question 4

Explain how methotrexate is used to fight cancer

Answer 4

Methotrexate binds to the target receptor, dihydropholate reductase which is important for the synthesis of purines which are building blocks of RNA and DNA. This reduces the rapid division of cells in cancer

Question 5

Name 2 physiologic receptors and their agonists and antagonists

Answer 5

B-adrenoceptor
Agonist- noradrenaline, isoprenaline
Antagonist- propranolol

Opioate
Agonist- morphine
Antagonist- neloxone

Question 6

Effects of adrenaline (epinephrine) on the heart

Answer 6

Adrenaline binds

Question 7

List ion channels and their blockers and modulators

Answer 7

Voltage gated Na channels
Blockers - local anaesthetics, tetrodoxin
Modulator- veratridine

GABA gated Cl channels
Blockers-picrotoxin
Modulators-benzodiazepines

Question 8

Which animal has tetrodoxin

Answer 8

Fugu(pupperfish)

Question 9

Give examples of the types of transmembrane receptors

Answer 9

• Ligand-gated ion channel- cholinergic nicotinic receptors eg acetylcholine
• G-protein coupled- a and b adrenoceptors eg noradrenaline
  *Enzyme-linked receptors- insulin eg insulin
• Intracellular receptors- steroid receptors eg oestrosdial

Question 10

Define activation of receptor

Answer 10

When the drug is bound to receptor and causes the receptor to elicit a cellular response

Question 11

Differentiate between agonist and antagonist

Answer 11

Agonist- a drug that binds to a receptor and causes the receptor to become activated
Have high efficacy

Antagonist- a drug that binds to a receptor but does not cause activation and prevents the agonist from binding
Have zero efficacy

Question 12

Efficacy

Answer 12

Ability to produce desired outcome

Question 13

Affinity

Answer 13

The degree to which the drug binds to receptor
How much the drug wants to bind to receptor

Question 14

Potency

Answer 14

How strong or effective the drug is

Question 15

Differentiate between partial and full agonists

Answer 15

Partial- drugs with intermediate levels of efficacy such that even at 100% occupancy of the receptors, the drug only causes tissue response of submaximal effect
Full agonists- Have enough efficacy to cause maximal tissue response

Question 16

Define the law of mass action

Answer 16

The rate of a chemical reaction is proportional to the concentration of reaction substances

Question 17

KD

Answer 17

The amount of the drug that is not bound

Question 18

Explain the lower the KD the higher the affinity

Answer 18

Because when KD is low then there are few drugs that are not bound meaning most of the drugs are bound so there is high affinity
Also binding (occupation) always associated with affinity

Question 19

Equilibrium association constant

Answer 19

Reciprocal of dissociation contant
How much of the drug is bound
The higher the KA the higher the affinity

Question 20

List drug transport proteins and their inhibitors

Answer 20

Noradrenaline transporter- tricylclic antidepressants
Proton pump-omeprazole

Question 21

Name enzymes and inhibitors

Answer 21

Cyclo-oxygenase - aspirin and other NSAIDS
HMG-CoA reductase-simivistatin
Dihydrofolate reductase- methotrexate