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Drugs in Pharmacology > 83 - Drugs in ANS Adrenergic drugs > Flashcards

83 - Drugs in ANS Adrenergic drugs Flashcards

1
Q

Where are the sites of actions for adrenergic drugs?

A
  1. Sympathetic postganglionic synapse >release NA to alpha and beta receptors
  2. Sympathetic nicotinic receptors at adrenal medulla > release adrenaline to alpha and beta receptors
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2
Q

What are the principle pathways and actions of a1 adrenoceptors?

A

Gq protein
Phospholipase C > IP3
increase intracellular Ca2+ release

Vasoconstriction

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3
Q

What are the principle pathways and actions of a2 adrenoceptors?

A 
Gi/o protein
reduce cAMP
reduce PKA
reduce intracellular Ca2+ release
reduce intracellular K+

Inhibit transmitter release

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4
Q

What are the principle pathways and actions of b1 adrenoceptors?

A

Gs protein
increase cAMP
increase PKA

Increase cardiac rate and force

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5
Q

What are the principle pathways and actions of b2 adrenoceptors?

A

Gs protein
increase cAMP
increase PKA

vasodilation
bronchodilation

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6
Q

What are the principle pathways and actions of b3 adrenoceptors?

A

Gs protein
increase cAMP
increase PKA

Lipolysis

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7
Q

_______ are examples of adrenergic drugs.
________ is able to activate a1,a2 and b1 receptors.
________ is able to activate all a1,a2,b1 and b2 receptors.
_______ is able to activate only beta receptors.

A

Catecholamines;

noradrenaline;
adrenaline (one more methyl group);

Isoprenaline

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8
Q

NA, Adr and Iso activate which common receptor?

What is the effect upon the activation of this receptor?

A

Beta 1 receptors

Increase chronotropic effect (increase heart rate) and iontropic effect (increase force of contraction) > increase cardiac output

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9
Q

Na and Adr activates _______ receptors that causes vasoconstriction.

Adr and Iso activates ____receptors to cause vasodilation.

A

a1 ;

b2

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10
Q

Name the adrenoceptor agonist for a1 receptors.

A

Phenylephrine

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11
Q

Name the adrenoceptor agonist for a2 receptors.

A

Clonidine (“close” > Gi protein)

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12
Q

Name the adrenoceptor agonist for b1 receptors.

A

Dobutamine

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13
Q

Name 2 adrenoceptor agonists for b2 receptors.

A

Salbutamol
Terbutaline
Ritodrine

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14
Q

Name the adrenoceptor agonist for b3 receptors.

A

BRL 3744

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15
Q

What are the 4 a1 antagonists?

A
  1. Phentolamine (拉麵)
    - competitive reversible
  2. Phenoxybenzamine (惡死benz)
    - irreversible
  3. Terazosin (Terror 祖先)
    - long-acting
  4. Tamsulosin
    - selective on a1A receptors
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16
Q

Name an a2 antagonist.

A

Yohimbine

yo 人叫人 not to close

17
Q

What are the 1st, 2nd and 3rd generation beta blockers?

A

1st: Propranolol (b1,b2)

2nd: Metoprolol + atenolol
(b1>b2, cardioselective)

3rd: Celiprolol (b1 blocker, weak b2 agonist)

Carvedilol (b1/2 blocker, a1 blocking activity)

18
Q

How is catecholamines produced?

flow chart

A

Tyrosine > DOPA > Dopamine (DA) > noradrenaline > adrenaline

19
Q

How is NA at the synaptic cleft be removed except binding to a/b receptors? (2 ways)

A
  1. taken up by noradrenaline transporter (NET)
    > Monoamine oxidase (MAO) to become metabolites

//> VMAT (such that NA is stored rather than metabolised by MAO)

  1. bind to a2 receptors at presynpatic cell > produce negative feedback
20
Q

_________ inhibits the vesicular monoamine transporter (VMAT) for noradrenaline.

A

Reserpine

> NA in cytoplasm is metabolised by MAO > depletes the storage granules of NA with high or repeated doses

21
Q

Adrenergic neuron blocking drugs like _________ are concentrated in the cytoplasm via ________.
What are their function?

A

Guanethidine

NET (Noradrenaline transporter)

Functions:

  • inhibit exocytosis of NA
  • uptaken into synaptic vesicles to displace NA
  • weak local anaesthetic activity
22
Q

Repeated

Which drug can be used as a selective a2 receptor agonist to inhibit the release of NA at the presynaptic cell?

A

Clonidine

23
Q

___________enters the NA biosynthetic pathway to
form a false transmitter __________that replaces NA.

It has a more potent agonist than NA for the negative feedback but
is a less potent agonist than NA on the end-organ.

A

a-methyl-DOPA;

a-methyl-NA

24
Q

Indirect acting sympathomimetics like _______ can be used to displace NA from vesicles, allowing it to be released.

This reduces NA re-uptake , which has a weak adrenoceptor agonist action.

  • Competitive inhibition on MAO too.
A

Tyramine

inhibits MAO and release NA from vesicles

25
Q

_______________ can be used to inhibit the NET, thus potentiate noradrenergic transmission and actions of other adrenoceptor agonists that are substrates of the NET.

A

Noradrenaline reuptake inhibitors (NRI)

26
Q

Give 3 examples of noradrenaline reuptake inhibitors.

A
  1. Cocaine (also local anaesthetic)
  2. Phenoxybenzamine (potent a1 blocker)
  3. Imipramine (weak a1 blocker)
27
Q

What drugs can be used to treat hypertension?

Class > e.g.

A
  1. a1 adrenoceptor antagonists
    - terazosin (long acting) better than prazosin (short-acting) [terror> 怕祖先]
  2. b1 adrenoceptor antagonists
    - reduce CO and renin release from JG cells in kidney
  • propranolol
  • metoprolol and atenolol
  • celiprolol and carvedilol
  1. Clonidine (a1 antagonist) and a-methyl DOPA (forms false transmitter)
  • reduce sympathetic tone to heart and blood vessels
  • inhibit peripheral sympathetic synaptic activities , reduce sympathetic outflow of the brain.
28
Q

What drug can be used in angina pectoris?

  • feeling of tightness, squeezing, or pain in the chest due to heart not getting enough oxygen-rich blood
A

beta 1 block by propranolol

  • reduces cardiac work and hence O2 consumption
29
Q

What drug can be used in atrial tachycardias?

A

too fast > slow down

b1 block by propanolol slows down ventricular rate

*Excessive dose may cause heart failure

30
Q

What drug can be used in heart failure?

A

b1 agonists
Dobutamine
increase CO

31
Q

What drug can be used in anaphylactic shock (acute anaphylaxis)?

  • type 1 hypersensitivity reaction that can be very rapid onset (few minutes) and life-threatening
A

Intramuscular injection of adrenaline

a1 and b1 agonist improve cardiovascular function
+
b2 agonist dilates the airways

32
Q

What drug can be used in Phaeochromocytoma?

  • tumour in adrenal medulla
  • large amount of catecholamines are secreted, bp may rise to a high level
A 
a1 antagonist
phenoxybenzamine
\+
b1 antagonist
atenolol

surgical removal of the tumour usually requires pre-treatment with the above drug combination

33
Q

What drug can be used in benign prostatic hyperplasia?

- Progressive enlargement of the prostate
due to overgrowth of normal cells
(Increased prostatic and
urethral smooth muscle
tone, driven by the
sympathetic system, cause
difficulty in voiding urine)
A

Tamsulosin

a1a blockers

on prostatic/urethral smooth muscle to facilitate urination

34
Q

What drug can be used in nasal congestion?

A

a1 agonists
like phenylephrine

contracts blood vessels in the nasal cavity to exert nasal decongestant action

35
Q

What drug can be used in asthma?

A

b2 agonists

  • salbutamol
  • relieve bronchospasm
36
Q

What drug can be used in premature labour?

A

Ritodrine
b2 agonist

  • given by intravenous to reduce uterine contraction

“rine”> “uterine”

37
Q

What drugs can be used in to cause Mydrisasis (dilation of pupil) Opthalmological examination?

A
  1. Contract circular iris muscle by parasympathetic nerve to produce miosis (constriction of pupil)
    - m3 antagonists (tropicamide) > myadriasis
  2. Contract radial iris muscles by sympathetic nerve/ a1 agonists
    - phenylephrine
    > myadriasis
38
Q

Cheese reaction. Cheese contains a lot of _____, which is a substrate of MAO.

MAO in the gut wall and liver normally metabolises it before it reaches the systematic circulation.

What will be the effect if MAOI is present?

A

tyramine

  • no MAO to metabolise tyramine > provoke sudden and dangerous rise in bp
    because it inhibits MAO and release NA from vesicles

Drugs in Pharmacology (5 decks)

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