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microbiology & pharmacology > Pharmacology - chapter 6 - Adrenergic agonists > Flashcards

Pharmacology - chapter 6 - Adrenergic agonists Flashcards

0
Q

Describe the synthesis of norepinephrine.

A

Tyrosine is cotransported into the neuron along with sodium. There it is hydroxylated to DOPA - dihydroxypheynylalanine(rate-limiting step).
DOPA is then decarboxylated to form dopamine. Dopamine is transported into vesicles where it is hydroxylated to form norepinephrine.

Note: in the adrenal medulla, norepinephrine is methylated to yield epinephrine by phenyletanolamine N-metyltransferase(PMNT).

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1
Q

Where do you find the adrenergic neuron, and what is its primary neurotransmitter?

A

In the CNS and the sympathetic nervous system. The primary neurotransmitter of the adrenergic neuron is norepinephrine.

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2
Q

Reserpine?

A

Blocks amine transporter system than transport dopamine and norepinephrine into the synaptic vesicle.

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3
Q

What are the three ways by which norepinephrine is removed from the synaptic space under normal conditions?

A

1 Diffuse out of the synaptic space and into the general circulation.
2 Metabolized by Catechol O-methyltransferase on postsynaptic n.
3 Reuptaken and stored in presynaptic neuron.

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4
Q

Increased peripheral resistance, myadrisis, vasoconstriction, increased BP, increased tone of internal spchincter of the bladder… which receptor?

A

Alpha 1

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5
Q

Increased lipolysis, increased release of renin, increased myocardial contractility and tachycardia.. which receptor?

A

Beta uno

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6
Q

Inhibition of norepinephrine and ACh release, inhibition of insulin release… which receptor?

A

Alpha 2

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7
Q

Vasodilation, decreased TPR, bronchodilation, increased muscle and liver glycogenolysis, increased release of glucagon, relaxed uterine smooth muscle.. which receptor?

A

Beta 2

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8
Q

Alpha receptors: rank order of potency?

  • epinephrine
  • norepinephrine
  • isoproterenol
A

epinephrine > norepinephrine&raquo_space; isoproterenol

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9
Q

Beta receptors: rank order of potency?

  • epinephrine
  • norepinephrine
  • isoproterenol
A

isoproterenol > epinephrine&raquo_space; norepinephrine

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10
Q

What G-protein are alpha-1 receptors coupled with?

A

Gq protein that activate Phospholipase C pathway

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11
Q

Where are alpha-1 receptors primarily found?

A

on the postsynaptic membrane in effector organ

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12
Q

Where are the alpha-2 receptors primarily found?

A

On the presynaptic nerveendings, Beta cells of the pancreas and on certain vascular smooth muscle cells. ALpha-2 receptors are also found on the presynapthic parasympathetic membrane.

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13
Q

Tamsulosin?

A

Selective antagonist that binds to alpha-1a receptors in the urinary tract and the prostate gland.

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14
Q

Tamsulosin are used to treat.. ?

A

benign prostatic hyperplasia

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15
Q

Three ways of desensitizing receptors?

A

1 sequestration of the receptors
2 down-regulation(decreased synthesis and increased destruction)
3 inability to to couple with G-protein(phosphorylated receptor)

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16
Q 
Effects of epinephrine?
1 Cardiovascular
2 Respiratory
3 Glucose levels
4 Lipid metabolism
A

1 Cardiovascular - positive ionotrophic and chronotrophic effects by binding beta-1 receptors myocardium, beta-1 receptors in the kidney cause renin release, alpha-1 receptors cause constricion of vessels in the mucos membranes, skin and viscera. Beta-2 receptors cause vasodilation in the liver and skeletal muscle.
2 Respiratory - bronchodilation by binding beta-2 receptors.
3 Glucose - beta-2 activated glycogenolysis in liver and alpha-2 coupled inhibition of insulin release in pancreas = hyperglycemia.
4 Lipids - beta-1 activated lipolysis in adipose tissue. Increased cAMP levels stimulate gormone-sensitive lipase = elevated FFA & glycerol.

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17
Q

Hyperthyroidism and epinephrine?

A

increased synthesis of adrenergic receptors on the vasculature in the hyperthyroid patient may lead to hypersensitive response. So be careful.

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18
Q

Cocaine and epinephrine?

A

Cocaine prevents reuptake into presynaptic neuron.

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19
Q

Diabetics and epinephrine?

A

Since epinephrine increase the release of stored glucose it can exaccerbate the hyperglycemia in diabetics. Therefore insulin levels may have to be increased.

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20
Q

Levarterenol?

A

Levarterenol = norepinephrine

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21
Q

To what receptor do norepinehrine bind most avidly?

A

that would be to the alpha-adrenergic receptor. MMMMMYaaaaas.. hub hub hub.

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22
Q

Norepinephrine effects..?
1 cardiovascular
2 baroreceptor reflex
3 atropine treatment

A

1 cardiovascular - alpha-1 coupled vasoconstriction. NE cause greater vasoconstriction than does epinephrine. This is because it binds less than epinephrine to beta-2 receptors in skeltal muscles etc.
2 baroreceptor reflex - little if any cardiac stimulation is observed. This is due to that increased TPR causes a reflex bradycardia that counteracts the actions of NE on the heart.
3 atropine treatment - atropine blocks cholinergic muscarnic receptors so norepinephrine administration induce tachycardia.

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23
Q

Isoproterenol: receptors and primary effects?

A

Isoproterenol stimulates both beta-1 and beta-2 receptors. Isoproterenol causes intese stimulation of myocardium by binding beta-1 receptors. Beta-2 mediated vasodilation lowers TPR. Total effect = increased systolic pressure, lowered TPR and diastolic pressure.

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24
Q

Dopamine: where can we find this amazing neurotransmitter?

A

In the CNS, the basal ganglia and the adrenal medulla.

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25
Q

Effects of Dopamine on adrenergic receptors?

A

Dopamine binds alpha and beta receptors.

high doses induce vasoconstriction by binding alpha receptors
low doses stimulate beta-1 cardiac receptors.

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26
Q

Dopamine in mesenteric and renal vascular beds?

A

Dopamine binds to D1 and D2 receptor in the peripheral mesenteric and renal vasculature, producing vasodilation.

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27
Q

Dopamine therapeutical effects in treating shock?

A

Beta-1 receptors cause increased cardiac output.
Alpha-1 receptors cause vasoconstriction and increased TPR
Dopaminergic receptors increase blood flow to kidney and splanchnic
areas, increasing glomerular filtration rate.

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28
Q

Fenoldopam?

A

rapid acting agonist of peripheral dopaminergic receptors used to treat severe hypertension.

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29
Q

Dobutamine?

A

Beta-1 agonist used to treat congestive heart failure as well as ionotrophic support after cardiac surgery.

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30
Q

Oxymetazoline?

A

direct acting adrenergic agonist that stimulates alpha-1 & alpha-2 receptors. Used as nasal spray decongestant and as ophthalmic drops to relief redness(clear eyes).

31
Q

Phenylephrine?

A

direct acting synthetic adrenergic agonsit that bind primarily to alpha-1 receptors. Raise blood pressure. Used as nasal spray decongestant and as ophthalmic drops to cause myosis.

32
Q

Clonidine?

A

Alpha-2 agonist used in essential hypertension. It works centrally, decreasing sympathetic neuronal activity and adrenergic outflow.

33
Q

Albuterol and terbutaline?

A

Short-acting beta-2 agonists used primarily as bronchodilators. Terbutaline is used as a uterine relaxant to suppress premature labor.

34
Q

Monoamine oxidase inhibitors?

A

Inhibit MAO and its breakdown of monoamines(e.g. norepinephrine, dopamine, serotonin)

35
Q

MAOi and beta-2 agonists?

A

there should be a 2 week gap between the use of MAOi and bet-2 agonists, due to risk of adverse cardiovascular effects.

36
Q

Amphetamine?

A

blocks reuptake of norepinephrine - e.i. indirect adrenergic agonist.

37
Q

Tyramine?

A

Similar actions as amphetamine, not clinically useful. Significant compound if person use MAOi, as Tyramine is found in fermented food, aged cheese and Chianti wine.

38
Q

Cocaine?

A

Block Na/K ATPase required for cellular uptake norepinephrine.

39
Q

Ephedrine and pseudoephedrine?

A

mixed action adrenergic agents. Induce release of stored epinephrine as well as stimulate alpha & beta receptors. Ephedrine and Pseudoephedrine are not cathecols and thus poor substrates for COMT and MAO = long duration of action.

40
Q

Name five catecholamines?

A 
1 epinephrine
2 norepinephrine
3 isoproterenol
4 dopamine
5 dobutamine
41
Q

Four characteristics of catecholamines?

A

1 rapid onset of action
2 brief duration of action
3 not administered orally
4 do not penetrate BBB

42
Q

Non-catecholamines vs. catecholamines?

A

Non-catecholamines have longer duration of action and can be administered orally.

43
Q

type of beta receptor in adipose tissue?

A

Beta-3

44
Q

Name eight non-catecholamine adrenergic agonists.

A 
1 oxymetazoline work on alpha-1 
2 phenylephrine work on alpha-1
3 methoxamine work on alpha-1
4 clonidine work on alpha-2
5 albuterol & terbutarol work on beta-2
6 salmeterol & formoterol work on beta-2
7 amphetamine work on alpha, beta and in CNS
8 ephedrine & pseudoephedrine work on alpha, beta and CNS
45
Q

Name two sympathomimetic agents that can make noradrenaline leave the nerveterminal non-exocytotically?

A

Tyramine

Amphetamine

46
Q

Catecholamines –> aldehyde –> carboxylic acid

X? Y?

A

Catecholamines –> aldehyde –> carboxylic acid

X= MAO Y= ADH

47
Q

Major and minor metabolites excreted after degradation of NA?

A

Major: VMA
Minor: MHPEG

48
Q

VMA is primarily made in …………?

MOPEG is primarily made in ………….?

A

VMA –> Peripheral tissues

MOPEG –> CNS

49
Q

Autoinhibitory feedback in NA release, mechanism of action?

A

NA –> presynaptic alpha2 autoreceptor –> inhibtion of adenylate cyclase –> decreased cAMP levels –> Ca-channels closed –> no vesicle exocytosis

50
Q

Name two inhibitors of NA synthesis?

A

1 methyltyrosine blocks tyrosine hydroxylase

2 carbidopa blocks DOPA decarboxylase

51
Q

Amphetamine, ephedrine and tyramine are all…?

A

Indirect acting sympathomimetic drugs.

52
Q

Reserpine mechanism of action?

A

Blocks VMAT(vesicular monoamine transporter) - which will leave reabsorbed NA and dopamine to be degraded by MAO in cytoplasm = decreased NA sythesis and secretion.

53
Q

Beta 1-3 rceptors work by stimulating…?

A

Gs stimulate adenylate cyclase

54
Q

Alpha2 receptors work by inhibiting ……?

A

Gi inhibits adenylate cyclase

55
Q

Alpha1 receptors work by stimulating……?

A

Gq stimulate PLC

56
Q

Four main effects by alpha1 activation?

A

1 vasoconstriction
2 relaxation of GIT smooth muscle
3 salivary secretion
4 hepatic gluconeogenesis

57
Q

Four main effects of alpha2 activation?

A

1 inhibition of transmitter release(NA & ACh)
2 contraction of vascular smooth muscle
3 platelet aggregation
4 inhibition of insulin release

58
Q

Two main effects of beta1 activation?

A

1 increased cardiac rate and force

2 renin release

59
Q

Six main effects of beta2 activation?

A 
1 bronchodilation
2 vasodilation
3 relaxation of GIT smooth muscle
4 hepatic glycogenonlysis and gluconeogenesis
5 skeletal muscle glycogenolysis
6 muscle tremor
60
Q

Main effect of beta3 receptor activation?

A

Lipolysis

61
Q

Name four catecholamines?

A

adrenaline
noradrenaline
dopamine
isoprenaline

62
Q

name three alpha1 selective agonists?

A

phenylephrine
methoxamine
imidazolines(group)

63
Q

Name three alpha2 selective sympathomimetics that act centrally and decrease blood flow to the periphery?

A

1 Guanidine
2 Guanfacine
3 Guanabenz

64
Q

Name two beta1 selective agonist.

A

1 Dobutamine

2 xamoterol

65
Q

Name five beta2 selective agonists

A 
1 Salbutamol
2 Fenoterol
3 Salmeterol
4 Formeterol
5 Terbutaline
66
Q

Name two beta3 selective agonists

A

1 amibegron

2 solabegron

67
Q

Cinical use of sympathomimetics:

Four beta2-selective agonists used in asthma?

A

1 Salbutamol
2 Salmeterol
3 Formeterol
4 Terbutaline

68
Q

Clinical use of sympathomimetics:

Three drugs used in nasal decongestion?

A

1 oxymethazoline
2 xylomethazoline
3 phenylephrine

69
Q

Sympatholytics - alpha antagonists:

two non-selective?

A

1 phentolamine

2 tolazoline

70
Q

Sympatholytics - alpha antagonists:

Three alpha1-selective drugs?

A

1 prazosin
2 doxazosin
3 terazosin

71
Q

Sympatholytics - alpha antagonists:

Two alpha2-selective drugs?

A

1 yohimibine

2 idazoxan

72
Q

Sympatholytics - alpha antagonists:

Name a alpha1A-selective drug and its clinical application?

A

Tamsulosin, used in BPH

73
Q

Sympatholytics - beta antagonists:

common suffix?

A

-olol”

74
Q

Sympatholytics - beta antagonists:

Name three β-adrenergic antagonists with high lipophilicity, and one area of clinical use?

A

1 propanolol
2 penbutolol
3 carvediol

used in migraine prophylaxis and anxiety states

75
Q

Clonidine, receptor specificity?

A

alpha2 > alpha1

76
Q

Bromocriptine?

A

Natural ergot alkaloid and Dopamine agonist.

microbiology & pharmacology (32 decks)

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