32 - Drugs Affecting Nervous System

Question 1

Exception to the rule that sympathetic nervous system releases noradrenaline to target

Answer 1

Sweat glands, where sympathetic nervous system releases ACh onto muscarinic AChR

Question 2

Botulinumtoxin function

Answer 2

Stops membrane fusion between ACh vesicles and synaptic membrane by degrading SNARE proteins on vesicle.

Question 3

Effect of botulism

Answer 3

Flaccid paralysis

Question 4

What is targeted by botulinumtoxin?

Answer 4

Has selectivity for uptake into cholinergic neurons. Mechanism not known.

Question 5

Conditions that are treatable with botulinumtoxin
1)
2)

Answer 5

1) Blepharospasm - Overactive blink response, makes someone functionally blind. Botox relaxes muscles involved in blinking.
2) Excessive underarm sweating - Botox inhibits ACh function of muscarinic receptors in sweat glands

Question 6

Selectivities of anticholinesterase drugs

Answer 6

Selective between NMJ and postganglionic parasympathetic juncitons

Question 7

Examples of anticholinesterase drugs
1)
2)
3)

Answer 7

1) Edrophonium
2) Neostigmine/pyridostigmine
3) Donepezil

Question 8

Edrophonium

Answer 8

Anticholinesterase drug
Short duration
Used to diagnose myasthenia gravis

Question 9

Neostigmine/pyridostigmine

Answer 9

Medium-duration anticholinesterase drug
Used to treat symptoms of myasthenia gravis
Used to reverse effect of non-depolarising neuromuscular blockers

Question 10

Donepazil

Answer 10

Anticholinesterase

Enters CNS, used to treat symptom of Alzheimer’s (reduction in ACh signalling in CNS)

Question 11

Myasthenia gravis

Answer 11

Autoimmune disease, where antibodies are made against nicotinic receptors on skeletal muscle motor endplates.
Leads to blockage, C’ disruption of post-synaptic membrane –> Loss, internalisation of nicotinic receptors

Question 12

What can be used to treat myasthenia gravis symptoms?

Answer 12

Anticholinesterse drugs.
Reduces degradation of ACh on motor endplate.
This isn’t a cure, as the number of functional nicotinic receptors decreases with time, so eventually anticholinesterase drugs won’t have an effect.

Can also use immunosuppressants to slow release of anti-nicotinic Ig

Question 13

Test for myasthenia gravis

Answer 13

Tensilon test

Question 14

Tensilon test

Answer 14

Diagnostic test for myasthenia gravis
Administer edrophonium (trade name Tensilon), see if motor weakness lessens

Question 15

Type of ACh receptors in autonomic ganglia

Answer 15

Nicotinic N (Nn) ACh receptors

Question 16

Use of autonomic nicotinic ACh agonists

Answer 16

Smoking cessation

Use nicotine patches, varenicline

Question 17

Clinical uses of somatic nicotinic ACh antagonists

Answer 17

Pre-surgical muscle relaxation (EG: non-depolarising: tubocurarine, vecuronium)

Question 18

Example of a ganglionic nicotinic ACh antagonist

Answer 18

Hexamethonium

Question 19

Autonomic muscarinic agonism effects
1)
2)
3)
4)
5)

Answer 19

1) SLUD - salivation, lacrimation, urination, defecation
2) Sweating
3) Bronchoconstriction
4) Bradycardia
5) Vasodilatation (non-neural effect)

Question 20

Example of a therapeutic autonomic muscarinic agonist

Answer 20

Pilocarpine, for treating glaucoma

Question 21

Autonomic muscarinic antagonism effects
1)
2)
3)
4)

Answer 21

1) Decreased salivation, lacrimation, urination, defecation
2) Reduced sweating
3) Tachycardia
4) Bronchodilation

Question 22

Examples of anti-muscarinic drugs
1)
2)
3)

Answer 22

1) Atropine
2) Hyoscene
3) Ipratropium

Question 23

Atropine
1)
2)
3)
4)
5)
6)

Answer 23

1) Anti-muscarinic
2) Reduces secretions (for surgery)
3) Bronchodilation
4) Bradycardia
5) Pupil dilation (for examining eye)
6) Treating AChE-inhibitor poisoning (EG: with organophosphates)

Question 24

Hyoscene

Answer 24

Anti-muscarinic

For motion sickness

Question 25

Ipratropium

Answer 25

Anti-muscarinic

For treating COPD

Question 26

Drugs that block NA reupatake

Answer 26

Cocaine

Tricyclics

Question 27

How is NA metabolised?

Answer 27

After being reuptaken, is degraded by monoamine oxidase

Question 28

Indirectly-acting sympathomimetics

Answer 28

Enters synaptic vesicle containing NA.

Displaces NA in vesicle, leading to release of NA into synaptic cleft

Question 29

Name for drugs that displace NA from vesicle

Answer 29

Indirectly-acting sympathomimetics

Question 30

Examples of indirectly-acting sympathomimetics
1)
2)
3)

Answer 30

1) Amphetamines
2) Ephedrines
3) Tyramine

Question 31

Tyramine
1)
2)
3)

Answer 31

1) An indirectly-acting sympathomimetic
2) Found in old cheeses, vegemite, salami
3) Can cause unwanted cardiovascular effects (EG: hypertension) in patients taking MAOI

Question 32

Example of an alpha, beta, and alpha and beta specific adrenoceptor agonist

Answer 32

1) Alpha - Phenylephrine
2) Beta - Isoprenaline
3) Alpha/beta - Adrenaline

Question 33

Why is salbutamol and not isoprenaline used to treat asthma?

Answer 33

Isoprenaline is more potent vaodilator (beta2), but also is a stronger beta1 agonist (cardiovascular effects). Salbutamol is a much more potent agonist of beta2 receptors than beta1.

Question 34

Beta1 and beta2 adrenoceptor antagonist

Answer 34

Propranolol

Question 35

Beta1 adrenoceptor agonism effect

Answer 35

Increased heart rate, force of contractility

Question 36

Beta1 adrenoceptor agonist

Answer 36

Dobutamine (useful in heart failure)

Question 37

Beta1 adrenoceptor antagonist

Answer 37

Atenolol (useful in hypertension)

Question 38

Alpha 1 and 2 adrenoceptor antagonist

Answer 38

Phentolamine (vasodilation)

Question 39

Alpha1 adrenoceptor agonist

Answer 39

Phenylephrine (nasal decongestant)

Question 40

Alpha1 adrenoceptor antagonist

Answer 40

Prazosin (treat hypertension)

Question 41

Alpha2 adrenoceptors

Answer 41

Pre-junctional receptors.

Inhibit neurotransmitter release.