Receptor Pharmakology

Question 1

Affinity

Answer 1

How well do drugs bind to its target
How selective is the drug to its target?
KD = Disassociation constant = concentration at which 50% receptors are bound

Question 2

Efficacy

Answer 2

How much effect do the drugs have?
Emax = maximum response of the drug

Question 3

Potency

Answer 3

How much drug is needed for response?
E50 = concentration at which 50% response is elicited

Question 4

Autonomic nervous system

Answer 4

The parasympathetic and sympathetic nervous system

Question 5

Somatic nervous system

Answer 5

motor effect

Question 6

Parasympathetic nervous system

Answer 6

Cranial and sacral
Effect at Heart, glands, eye, SM, gut, airway
- Decrease HR
- Contraction

Question 7

Sympathetic nervous system

Answer 7

Thoracic and Lumbar
Effect at sweat glands, Heart, glands, SM, vascular, gut
- Increase HR
- Dilatation

Question 8

Muscarinic receptors

Answer 8

Activated by Ach, pilocarpine, induces:
- Salivation
- Lacrimation
- Urination
- Defecation
- Bradycardia

Question 9

Nicotinic receptors

Answer 9

Activated by ACh, nicotine, induces:
- Action Potential initiation
- Skeletal muscle contraction if at the somatic pathway

Question 10

Atropine

Answer 10

Muscarinic antagonist
- Anti- SLUD
- Dilated Iris
- Tachycardia
- If drug crosses BBB, agitation, restlessness, disorientation, coma

Question 11

d-tubocurarine

Answer 11

Nicotinic antagonist at NMJ (competative reversible)
- Muscle relaxation
- Blocks suxamethonium, therefore blocks depolarisation)

Question 12

Hyoscine

Answer 12

Muscarinic antagonist
Used for motion sickness

Question 13

Ipratropium

Answer 13

Muscarinic antagonist
Used for asthma patients; bronchodilatation

Question 14

Alpha 1 Adrenoceptors

Answer 14

• constrict blood vessel
• pupil dilation
• constriction of GIT sphincters

⚡️NA > Adr
✅ Phenylephrine
🅱️ Prazosin

Question 15

Alpha 2 Adrenoceptors

Answer 15

Inhibit neurotransmitter release

⚡️NA < Adr
✅ Clomidine
🅱️ Yohimbine

Question 16

Beta 1 Adrenoceptor

Answer 16

• Increase HR & force
• Renin secretion of kidneys

⚡️NA = Adr
✅ Dobupamine
🅱️ Metoprolol

Question 17

Beta 2 Adrenoceptor

Answer 17

• dilate Skeletal blood vessels
• Bronchodilatation

⚡️NA &laquo_space;Adr
✅ Salbutamol
🅱️ Non clinically used

Question 18

Autacoids

Answer 18

Defence mediators - formulation and release associated with infection and inflammation
Histamine, Bradykinin, Eicosanoids (Prostaglandin, leukotrienes); mediators are labile or rapidly broken down close to their site of release, therefore usually only act locally

Question 19

Histamine

Answer 19

Stored and released from mast cells & basophils
Can also be released from Enterochromaffin-like cells that regulate stomach acid secretion

Interact with H1-4 GPCRs

Question 20

Antihistamine

Answer 20

H1R antagonism

Question 21

H2R antagonism

Answer 21

Peptic ulcer disease

Question 22

H3R antagonism

Answer 22

Narcolepsy: a chronic neurological disorder that affects the brain’s ability to control sleep-wake cycle

Question 23

H4R antagonism

Answer 23

No known clinical effect therefore use yet

Question 24

Bradykinin

Answer 24

Local peptide mediator in pain and inflammation generated after plasma exudation during inflammation
- Dilate arterioles & venules
- Release Prostaglandins and Nitric oxides
- Simulation of sensory nerve endings = pain

Question 25

Eicosanoids (Leukotrienes, prostaglandins)

Answer 25

Derived from arachidonic acid
LOX = inflammatory pathway in inflammatory cells
COX = inflammatory pathway in most cells
- Inflammation
- vasodilation
- increased vascular permeability
- Enhance action of bradykinin and histamine (dilation)

Question 26

Glucocorticoids

Answer 26

Anti-inflammatory
Inhibit eicosanoid synthesis by inhibiting COX/PLA2 induction
- inhibition of cytokines and adhesion molecule expression