Pharmacological Modulation of the the ANS

Question 1

Name some uses of adrenoceptor agonists.

Answer 1

• EYE DROPS: Ephedrine/ Brimonidine
• ASTHMA INHALERS: Salbutamol
• CARDIAC STIMULANT: Adrenaline/ Dobutamine
• ACUTE ANAPHYLAXIS (EG. BEE STING): Adrenaline

Question 2

What are sympathomimetics?

Answer 2

Drug that recreates the stimulation of a sympathetic nerve

Question 3

Give examples of muscarinic agonists.

Answer 3

-pilocarpine: used to treat glaucoma and dry mouth, used in sweat tests
-bethanecol: used to occasionally aid bladder and gastric emptying

Question 4

Give examples of nicotinic agonists.

Answer 4

-succinylcholine: is a high affinity agonist used in surgery for depolarising paralysis

Question 5

What are cholinesterase inhibitors and what are some examples?

Answer 5

-Inhibit the break down of Ach so there is an increase in [Ach] so there is greater stimulation of nAchRs

-They are short lasting or long-lasting (parathion insecticide)
- EXAMPLES: tacrine, donepezil, rivastigmine: used for dementia, neuromuscular diseases

Question 6

When are muscarinic blockers/antagonists used?

Answer 6

-in premedication before anaesthesia: to decrease secretions and to sedate
-in the heart: to increase AV conduction
-to cure motion sickness

Question 7

When are nicotinic blockers/antagonists used and what are some examples?

Answer 7

-muscle relaxants are direct nAchR blockers: tubocurarine
-depolarising blockers are direct nAchR agonists: suxamethonium

Question 8

What are the main uses of β1 receptor blockers?

Answer 8

-for the heart: atenolol slows down HR which reduces arrhythmia
-in kidneys: atenolol triggers the JGA mechanism

Question 9

What are parasympathomimetics?

Answer 9

Compound that mimics the stimulation of parasympathetic nerves

Question 10

What might be the benefits and drawbacks of taking Bethanecol (a muscarinic receptor agonist)?

Answer 10

PROS
- Minimally invasive
- Not seen as a last resort option

CONS
- Restrictions on quality of life e.g need constant access to the drug which may be a problem if, for example, they need to travel
- Side effects - Bethanecol mainly targets the M3 receptor to cause smooth muscle contraction of the bladder but it may also target other muscarinic receptors causing pain to the eyes, heart and stimulating these receptors. SOLUTION - Pharmacological treatment with more specific effects i.e specific to bladder smooth muscle