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NAS > Autonomic Pharmacology > Flashcards

Autonomic Pharmacology Flashcards

1
Q

At which points can drugs target autonomic transmission

A

Synapse
Along axon - not specific
At target organ

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2
Q

Where are Muscarinic receptors present?

A

At effector organs of parasympathetic ns

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3
Q

Where are nicotinic receptors present in sympathetic and para ns

A

In ganglion

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4
Q

Structure of nicotinic cholinergic receptor

A

Transmembrane
5 subunits
2 ACh molecules need to bind

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5
Q

What is hexamethonium

A

A methonium derivative
Selective antagonist for neuronal sub type of nicotinic receptor
Not competitive
Blocks all the effects of autonomic stimulation (all preganglionic fibres are cholinergic)

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6
Q

Why is hexamethonium not used anymore

A

Not specific enough
Has too many side effects

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7
Q

What NT is released on to muscarinic receptors

A

ACh

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8
Q

How many transmembrane segments do muscarinic receptors have

A

7

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9
Q

How many subtypes of muscarinic receptors

A

5
First 3 (M1-3) are important in the periphery

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10
Q

Why are muscarinic drugs described as “parasympathomimetic drugs”

A

Mimic the effects of parasympathetic NS activation

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11
Q

Where were muscarinic drugs found

A

In family of fungi

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12
Q

General Effects of parasympathomimetics

A

Cardiovascular - decreased HR
Smooth muscle - contracts
Exocrine glands - secrete eg. Sweat, salivation, bronchial secretion

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13
Q

Source of muscarinic poisoning

A

Muscarinic agonists in Many mushrooms

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14
Q

Adverse effects of poisoning by muscarinic agonists

A

Bradycardia so decreased BP
Increased gut motility
Bronchoconstriction
Pupillary constriction
Salivation
Lacrimation

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15
Q

Treatment of muscarinic poisoning

A

Muscarinic antagonist (atropine)

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16
Q

Example of muscarinic agonist tht treats glaucoma and how it works

A

Pilocarpine
Route of administration: Topical to the eye
Action: on M3 receptors on ciliary muscles, improving aqueous humour drainag, dropping intraocular pressure

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17
Q

Types of muscarinic antagonists and where they act

A

Antagonists specific to muscarinic receptor they act on
M1 - stomach and salivary glands
M2 - cardiac
M3 - smooth muscle

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18
Q

Less specific antagonists like are used more widely

A

Atropine
Hyoscine
Cyclopentolate

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19
Q

Clinical uses of antimuscarinic drugs

A

Stop parasympathetic NS
- Asthma (ipratropium)
- Treat bradycardia (atropine)
- During operations (atropine)
- Dilate pupils (tropicamide)
- Urinary incontinence (oxybutynin)
- Motion sickness

20
Q

Why is atropin used in operations

A

Skeletal NMJ blocking agent given to cause paralysis
Stop cholinergic transmission
After operation need to reverse paralysis with acetylcholinesterase inhibitor
This increases ACh at NMJ
Excessive ACh in the lungs and heart
Atropine used to block muscarinic receptors in airways

21
Q

5 main subtypes of adrenoceptors (sympathetic) and their role

A

Alpha 1 - contract smooth muscle
Alpha 2 - presynaptic auto inhibition, direct vasoconstriction, central inhibition of sympathetic outflow
Beta 1 - increases heart rate and contractility
Beta 2 - relax smooth muscle (bronchodilation, vasodilation)
Beta 3 - relax smooth muscle (bladder), lipolysis

22
Q

Main uses of alpha adrenoceptor receptor agonists

A
  • Vasoconstrictors (adrenaline/ noradrenaline) with local anaesthetic (keeps LA at target tissue). Alpha 1.
  • Nasal decongestants (phenylephrine). Alpha 1
  • Hypertension. Central alpha 2.
  • Facial erythema in rosacea (brimonidine). Alpha 2.
23
Q

How adrenoceptors produce intrinsic cascade

A

Receptor stimulated
Gq protein activated
Stimulates phospholipase C
Releases Ca from Intracellular stores
DAG activates and causes Intracellular cascade

24
Q

Signal transduction mechanisms for alpha 1 adrenoceptor

A

G protein: Gq
Target: phospholipase C
Transduction effect: increase IP3/ DAG

25
Q

What are some autonomic receptors

A

Nicotinic - ACh
Adrenoceptor - catecholamines
Muscarinic - ACh post ganglionic

26
Q

Signal transduction mechanisms for alpha 2 adrenoceptors

A

Gi
Decreases adenylyl cyclase
Decrease cAMP

27
Q

Signal transduction mechanism for all beta adrenoceptors

A

Gs
Increases AC
Increases cAMP

28
Q

Signal transduction mechanism for M1/ M3 muscarinic agonists and antagonists

A

Gq
Phospholipase C
Increases IP3/ DAG

29
Q

Signal transduction mechanism for M2 muscarinic agonists and antagonists

A

Gi
Decrease in Adenylyl cyclase
Decrease cAMP

30
Q

Main uses of alpha-adrenoceptor 1 antagonists

A

Block sympathetic transmission

  1. Doxazosin alpha 1 - To lower hypertension
  2. Tamsulosin alpha 1 - Treat benign prostatic hyperplasia
31
Q

Main uses of Beta adrenoceptor agonists

A

Stimulate sympathetic NS
- Cardiogenic shock (beta 1)
Adrenaline, dobutamine
- Anaphylactic shock (alpha/ beta)
Adrenaline
- Asthma (beta 2)
Salbutamol

32
Q

Main uses of beta adrenoceptors antagonists

A

Block sympathetic NS
Cardiac arrhythmias
Hypertension, angina (metoprolol)
Anxiety states
Heart failure
Glaucoma (timolol)

33
Q

3 ways Adrenergic transmission is continued

A
  1. Noradrenaline transporter blockers
  2. Monoamine oxidase inhibitors
  3. Indirectly acting sympathomimetic amines
34
Q

How do “inhibitors of noradrenaline uptake” work

A

NAT inhibitors enhance the effects of sympathetic activity
By blocking NAT (transporter)
NAd stays in extracellular space
Promotes sympathetic transmission

35
Q

What does NAT (noradrenaline transporter) transport

A

Cotransport Na+, Cl- and Catecholamine

36
Q

What is the main way for terminating the actions of NAd

A

NAd uptaken by NAT

37
Q

What drugs inhibit NAT (they enhance effects of sympathetic NS)

A

Cocaine
Tricyclic antidepressants (desipramine)

38
Q

What other transporters are NAT closely related to

A

Dopamine transporters
Serotonin transporters

39
Q

What is desipramine

A

Tricyclic antidepressant
NAT inhibitor
Major action is on CNS
Adverse effects: tachycardia, dsyrhythmia

40
Q

What is cocaine and its effects

A

Euphoria and excitement CNS action
NAT inhibitor
Causes tachycardia and increased BP
Type of Local anaesthetic

41
Q

How mono-amine oxidase inhibitors promote Adrenergic transmission

A

Most block MAO irreversibly
Used clinically as antidepressants
Increase levels of NAd, dopamine and 5-HT in brain and peripheral tissue
Adverse effects: postural hypotension, weight gain, restlessness, insomnia, cheese reaction

42
Q

Examples of mono-oxidase inhibitors

A

Phenelzine
Tranylcypromine
Iproniazid
Moclobemide

43
Q

How indirectly acting sympathetic amines promote Adrenergic transmission

A

They are structurally related to noradrenaline
Transported into nerve terminals (NAT) and into vesicles (VMAT)
Displace noradrenaline which leaks out via NAT
Long lasting effects that mimic those of NAd

44
Q

Examples of indirectly acting sympathetic amines

A

Amphetamine
Ephedrine
Tyramine

45
Q

What are some effects of NAd in the sympathetic NS

A

Bronchodilatation
Vasoconstriction
Raised BP

46
Q

What are receptors of sympathetic and parasympathetic

A

SNS - nicotinic and adrenoceptors
PNS - nicotinic and muscarinic

NAS (17 decks)

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