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Part 3 – PM3B > (PM3B) Adrenergic Therapeutics > Flashcards

(PM3B) Adrenergic Therapeutics Flashcards

1
Q

What are the stages in catecholamine synthesis?

A

(1) Tyrosine converted to DOPA via tyrosine hydroxyls
(2) DOPA converted to dopamine via DOPA decarboxylase
(3) Dopamine converted to noradrenaline via dopamine ß-hydroxylase
(4) Noradrenaline converted to adrenaline via phenylethanolamine N-methyltransferase

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2
Q

What molecule provides negative feedback in catecholamine synthesis?

A

Noradrenaline

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3
Q

Where is noradrenaline released?

A

ALL post-ganglionic sympathetic fibres

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4
Q

Where is adrenaline released?

A

Adrenal gland

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5
Q

On which molecule does noradrenaline provide negative feedback on, in catecholamine synthesis?

A

Tyrosine hydroxylase

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6
Q

Where does noradrenaline bind?

A

Either alpha/beta adrenoceptors

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7
Q

What are the adrenoceptor subtypes?

A

(1) alpha-1
(2) alpha-2
(3) beta-1
(4) beta-2
(5) beta-3

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8
Q

What subtypes of alpha-1 adrenoceptor are there?

A

(1) alpha-1A
(2) alpha-1B
(3) alpha-1D

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9
Q

What subtypes of alpha-2 adrenoceptor are there?

A

(1) alpha-2A/D
(2) alpha-1B
(3) alpha-1C

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10
Q

Where are alpha-1 adrenoceptors located?

A

Smooth muscle

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11
Q

Where are alpha-2 adrenoceptors located?

A

(1) Smooth muscle

(2) Nerve terminals

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12
Q

Where are beta-1 adrenoceptors located?

A

Heart

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13
Q

Where are beta-2 adrenoceptors located?

A

(1) Smooth muscle
(2) Heart
(3) Skeletal muscle
(4) Nerve terminals

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14
Q

Where are beta-3 adrenoceptors located?

A

(1) Skeletal muscle

(2) Fat

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15
Q

What is the function of alpha-1 adrenoceptors?

A

(1) Vasoconstriction
(2) Contraction – relax GIT
(3) Glycogenolysis

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16
Q

What is the function of alpha-2 adrenoceptors?

A

(1) Contraction

(2) Inhibition of neurotransmitter release

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17
Q

What is the function of beta-1 adrenoceptors?

A

Increase cardiac rate + force

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18
Q

What is the function of beta-2 adrenoceptors?

A

(1) Vasodilation

(2) Bronchodilation

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19
Q

What is the function of beta-3 adrenoceptors?

A

(1) Thermogenesis

(2) Lipolysis

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20
Q

Which G protein does the alpha-1 adrenoceptor act on?

A

G-alpha-q

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21
Q

Which G protein does the alpha-2 adrenoceptor act on?

A

G-alpha-i/o

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22
Q

Which G protein does the beta-1 adrenoceptor act on?

A

G-alpha-s

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23
Q

Which G protein does the beta-2 adrenoceptor act on?

A

G-alpha-s

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24
Q

Which G protein does the beta-3 adrenoceptor act on?

A

G-alpha-s

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25
Q

What is the response of alpha-1 adrenoceptor binding?

A

Increased IP3

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26
Q

What is the response of alpha-2 adrenoceptor binding?

A

Decreased cAMP

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27
Q

What is the response of beta-1 adrenoceptor binding?

A

Increased cAMP

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28
Q

What is the response of beta-2 adrenoceptor binding?

A

Increased cAMP

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29
Q

What is the response of beta-3 adrenoceptor binding?

A

Increased cAMP

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30
Q

For which adrenoceptor subtype does noradrenaline have the greatest potency?

A

alpha-1

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31
Q

For which adrenoceptor subtype does noradrenaline have the poorest potency?

A

beta-2

beta-3

32
Q

What are some selective agonists of alpha-1 adrenoceptors?

A

(1) Phenylephrine

(2) Methoxamine

33
Q

What are some selective agonists of alpha-2 adrenoceptors?

A

(1) Clonidine

(2) Brimonidine

34
Q

What are some selective agonists of beta-1 adrenoceptors?

A

(1) Dobutamine

(2) Xamoterol

35
Q

What are some selective agonists of beta-2 adrenoceptors?

A

(1) Salbutamol
(2) Terbutaline
(3) Ritodrine

36
Q

What are some selective agonists of beta-3 adrenoceptors?

A

Mirabegron

37
Q

What are some selective agonists of alpha-1 adrenoceptors?

A

(1) Doxacin

(2) Terazosin

38
Q

What are some selective agonists of alpha-2 adrenoceptors?

A

(1) Yohimbine

(2) Idazoxan

39
Q

What are some selective agonists of beta-1 adrenoceptors?

A

(1) Atenolol
(2) Metoprolol
(3) Bexatolol

40
Q

What are some selective agonists of beta-2 adrenoceptors?

A

Butoxamine

41
Q

What are some selective agonists of beta-3 adrenoceptors?

A

None/ unknown

42
Q

Where is tyrosine hydroxylase found?

A

ONLY in noradrenergic neurones

43
Q

What are the stages of adrenergic transmission?

A

(1) Tyrosine converted to noradrenaline
(2) Noradrenaline packaged into vesicles
(3) Noradrenaline vesicles move into synaptic cleft via exocytosis
(4) Noradrenaline binds to postsynaptic cell receptors/ uptake 1 transport system/ uptake 2 transport system/ alpha-2 adrenoceptor on presynaptic membrane

44
Q

What is given in event of cardiac arrest? Why?

A

Adrenaline

1 in 10000 dilution

IV

Causes vasoconstriction via alpha-1 and beta adrenoceptor stimulation

45
Q

What is given in event of cardiogenic shock?

A

ß1-selective adrenoceptor agonist

Dobutamine

Increased cardiac output

46
Q

What is given to treat asthma?

A

ß2-selective agonists

e. g. salbutamol/ terbutaline (short-acting)
e. g. salmeterol/ formoterol (long-acting)

47
Q

What is given to treat an overactive bladder (incontinence), with specific regard to adrenergic transmission?

A

ß3-selective agonist

Mirabegron

Only when anti-muscarinic drugs are ineffective/ contraindicated

48
Q

What effects does the adrenaline in an EpiPen have on the adrenergic receptors during anaphylaxis?

A

(1) Bronchodilation via ß2 adrenoceptor

(2) Increased BP via alpha-1 adrenoceptor

49
Q

What is the treatment of glaucoma using adrenoceptor agonists?

A

Adrenaline/ brimonidine/ apraclonidine

  • selective alpha2-agonists
  • used to reduce intraocular pressure
  • used when ß-blockers are inappropriate
50
Q

What is local anaesthesia using adrenoceptor agonists?

A

Adrenaline

  • prolongs LA action
  • e.g. lidocaine in dental procedures
  • e.g. bupivacaine in spinal anaesthesia
51
Q

What is the use of adrenoceptor agonists in labour?

A

ß2-selective agonists

e.g. ritodrine/ salbutamol

Smooth muscle relaxant

Inhibit sympathetic-induced contraction of uterus

Prevention of premature labour from 24-33 weeks

52
Q

How long can ß2-selective agonists prolong premature labour for?

A

Maximum 48 hours

53
Q

Which ß2-selective agonists can prolong premature labour for?

A

(1) Ritodrine

(2) Salbutamol

54
Q

How many weeks gestation is considered premature?

A

24-33 weeks

55
Q

What are the effects of alpha-adrenoceptor antagonists on blood pressure?

A

Doxazosin/ terazosin

Cause vasodilation

Decrease arterial BP

Not first line

Treatment of hypertension

56
Q

What are the effects of alpha-adrenoceptor antagonists on benign prostatic hyperplasia?

A

alpha-1A adrenoceptor selective antagonists
- e.g. alfuzosin/ indoramin/ tamsulosin

Relaxes smooth muscle in bladder + prostate

Treats enlargement of prostate + improves urinary retention

57
Q

What are the cardiovascular effects of beta-adrenoceptor antagonists?

A

Non-selective = propranolol/ timolol

ß1-selective = metoprolol/ atenolol

Important drugs in the treatment of:

  • angina
  • MI
  • dysrhythmia
  • heart failure
  • hypertension
58
Q

What are the effects of beta-adrenoceptor antagonists on glaucoma?

A

Topical ß-blocker

Betaxolol – ß1-selective

Act to reduce production of aqueous humour
- reduce intraocular pressure

can also use carteolol/ timolol eye drops

59
Q

What are the effects of beta-adrenoceptor antagonists on migraines?

A

Propranolol/ metaprolol

Migraine prophylaxis

60
Q

What are some side-effects of beta-adrenoceptor antagonists?

A

(1) Cardiac depression/ bradycardia
(2) Fatigue + tiredness
(3) Cold extremities – reduced blood flow

61
Q

Can cardioselective beta-adrenoceptor antagonists be taken in a patient with asthma or COPD?

A

No

Contraindicated

62
Q

What are some contraindications for beta-adrenoceptor antagonists?

A

(1) Cardioselective beta-blockers in patients with asthma or COPD
(2) Eye drops used for glaucoma for patients with cardiovascular disease

(3) Patients prone to hypoglycaemia
- ß2-receptors control glucose release from the liver

(4) Liver disease

63
Q

Give an example of an adrenoceptor partial agonist.

A

Clonidine

64
Q

What is clonidine?

A

alpha-2 partial agonist

Used in treatment of hypertension

65
Q

What is the mechanism of action of clonidine?

A

(1) Activation of alpha-2 adrenoceptor
(2) Causes negative feedback on noradrenaline release in presynaptic membrane
(3) Down-regulation of noradrenaline reduce alpha-1-mediated vasoconstriction

66
Q

What is the mechanism of action of alpha-2 partial agonists?

A

(1) Activation of alpha-2 adrenoceptor
(2) Causes negative feedback on noradrenaline release in presynaptic membrane
(3) Down-regulation of noradrenaline reduce alpha-1-mediated vasoconstriction

67
Q

Give two examples of indirect sympathomimetics that are used therapeutically as nasal decongestants.

A

(1) Ephedrine

(2) Pseudoephedrine

68
Q

What is the mechanism of action of ephedrine?

A

(1) Acts as substrate for uptake transport system in presynaptic membrane
(2) Leads to noradrenaline release
(3) Causes vasoconstriction
(4) Reduces nasal blood flow + oedema (congestion)

69
Q

What is the mechanism of action of pseudoephedrine?

A

(1) Acts as substrate for uptake transport system in presynaptic membrane
(2) Leads to noradrenaline release
(3) Causes vasoconstriction
(4) Reduces nasal blood flow + oedema (congestion)

70
Q

What is the mechanism of action of indirect sympathomimetics?

A

(1) Acts as substrate for uptake transport system in presynaptic membrane
(2) Leads to noradrenaline release
(3) Causes vasoconstriction
(4) Reduces nasal blood flow + oedema (congestion)

71
Q

Other than ephedrine and pseudoephedrine, name substrates of uptake transport system 1 in the presynaptic membrane.

A

(1) Tyramine

(2) Amphetamine

72
Q

When are substrates of uptake transport system 1 used therapeutically?

A

(1) Narcolepsy
(2) ADHD
(3) Appetite suppression

73
Q

What other actions do substrates of uptake transport system 1 have therapeutically?

A

Pyschoactive agents

e.g. cocaine/ tricyclic antidepressants

Treatment of depression

74
Q

What are the enzymes responsible for catecholamine metabolism (breakdown)?

A

(1) Monoamine oxidase (MAO)
- MAO-A
- MAO-B
- found in mitochondria in sympathetic nerve terminals/ liver/ intestinal epithelium

(2) Catechol-O-methyl-transferase (COMT)

75
Q

What is the significance of COMT and MAO?

A

Enzymes

Responsible for catecholamine metabolism (breakdown)

76
Q

What is an MAOI?

A

Monoamine oxidase inhibitor

77
Q

What are some therapeutic uses of MAOIs?

A

(1) Anti-depressant
- e.g. phenelzine
- if SSRIs/ TCAs are ineffective

(2) Parkinson’s disease
- MAO-B selective
- prevention of dopamine breakdown
- slows disease progression
- e.g. selegiline/ rasagiline

Part 3 – PM3B (32 decks)

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