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Final Test: Dynamics II > Sympathomimetics I: Receptors and Endogenous Agonists > Flashcards

Sympathomimetics I: Receptors and Endogenous Agonists Flashcards

1
Q

What is purpose of SNS?

A
  • controlling heart rate
  • contractility
  • blood pressure
  • vasomotor tone
  • carbohydrate
  • fatty acid metabolism
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2
Q

How does stimulation of the SNS occur?

A
  • in response to physical activity
  • psychological stress
  • allergies
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3
Q

How are drugs used to influence the SNS?

A
  • treatment of hypertension
  • shock
  • cardiac failure and arrhythmias
  • asthma
  • emphysema
  • allergies and anaphylaxis
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4
Q

What are sympathomimetics?

A
  • compounds that mimic the endogenous catecholamines (norepinephrine, epinephrine, and dopamine)
  • from the sympathetic post ganglionic axon terminal
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5
Q

How can you determine effect of a particular sympathomimetic agent?

A
  • action depends on adrenergic receptor subtype expressed by the organ
  • know receptor subtypes and characteristics
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6
Q

Know the basic chemical structures of direct acting agonist

A

see page 2

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7
Q

What is the parent sturcure of sympathmimetics?

A
  • phenylethylamine is the parent structure
  • all synthetic dervative have basic core structure
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8
Q

Describe the structure of endogenous neurotransmitters such as NE, Epi, and DA and what is the importance of different substiutents.

A
  • they all have -OH substituents atthe 3 and 4 position of pheny ring;
  • lose of these -OH groups = loss of direct receptors activation
  • the -OH groups, prevent access to the CNS (polar)
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9
Q

What sturcute is best for activitiy of sympathomimetics?

A
  • 2 carbons between the phenyl ring and the amine= best for activity
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10
Q

What does increasing the size of the alkyl group do to activity?

A
  • increasing the size of the alkyl group on the amine increases activity at the beta receptors
  • why Epi has the highest affinity
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11
Q

How does the lack of -OH affect metabolism and duration of action?

A
  • absence of -OH groups stops metabolism by COMT
  • loss of direct sympathomimetic activity
  • enhance oral availability and duration of actions
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12
Q

what are some example of sympathmimetics that lack -OH?

A
  • amphetamine
  • methamphetamine
  • ephedrine
  • phendimetrazine
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13
Q

What other substitution effect MAO metabolism?

A
  • substitution on alpha carbon prevents metabolism by MAO
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14
Q

What are the rank order of potency for alpha receptors?

A

epi> NE>> >>Isoproteranol

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15
Q

What are the two alpha receptors activated by therapeutic levels of epi and NE?

A

alpha 1 & alpha 2

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16
Q

How does the alpha-1 receptor activation impact the vasculature?

A

its on smooth muscle:

  • surrounding arterioles
  • supplying the skin
  • kidney
  • intestinal mucosa
  • veins

Ex. activated on arterioles—–> vasoconstriction—->>increase in blood presure

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17
Q

How does alpha 1 receptor activation impact the heart?

A
  • no direct affect on heart;
  • reflex bradycardia may occur in response to increased blood pressure
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18
Q

How does alpha 1 receptor activation activate the eye?

A

the eye-mydriasis (dilation)

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19
Q

How does alpha-1 receptor activation impact the GI tract?

A

contraction of the sphincters; inhibits movement

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20
Q

How does alpha-1 activation impact the sex organs?

A

it promotes ejaculation

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21
Q

How does alpha-1 receptor activation impact the urinary tract?

A
  • contraction of the trigone and sphincter
  • decreases voiding
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22
Q

How does alpha-1 receptor activation impact secretion?

A
  • it stimulates salivation and sweating
  • inhibiting nasal mucous producation (blood vessel constriction)
  • stimulation pilerection
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23
Q

How does the alpha-2 receptor activation affect the vasculature?

A
  • activation of post-synaptic alpha 2 receptors on the veins and the arterioles cause contraction of the smooth muscle
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24
Q

How does alpha-2 receptor activation impact the pancreas?

A
  • decreases insulin—-> elevating glucose levels in the blood
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25
Q

How does alpha-2 receptor activation impact the nose?

A
  • decreases mucous secretion
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26
Q

How can presynaptic activation of alpha-2 receptors be considered sympatholytic?

A
  • amount NE release from terminals is lowerd by via inhibitory autoreceptors (an adrenergic neuron)
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27
Q

How can alpha-2 receptor activation also inhibit ACh?

A
  • block ACh via alpha 2 receptors—-> inhibitory heteroreceptor (cholinergic neuron)
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28
Q

What is the rank order of potency for beta receptors?

A

isoproteranol> Epi>>>>NE

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29
Q

How do the actions of NE compare to Epi on beta receptors?

A
  • NE and Epi stimulate equally
  • NE has little effect on beta-2 receptors @ normal doses
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30
Q

What is beta-1 receptor activation on the heart?

A
  • Epi and NE increase the force of myocardial cells and the rate sinoatrial cells
  • the rhythm of the contraction:: increasing the rate of relaxation—->shortens systole, fraction in diastole is increased—> increased filling of the ventricles= overall output is increase
  • response is followed by reflex bradycardia
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31
Q

How does beta-1 receptor activation impact the kidneys?

A
  • increases renin secretion—> increase of angiotensin—->vasoconstriction
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32
Q

How does activation of beta-1 impact fat cells?

A

enhance lipolysis

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33
Q

How does beta-2 activation impact vasculature?

A
  • activation of beta-2 receptors (blood vessels supplying the skeletal muscle, liver, and gut )—–> vasodilaiton of vessels—> increased blood flow to regions
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34
Q

What does beta-2 receptor activation impact the lungs?

A

bronchodilation

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35
Q

How does beta-2 receptor activation impact the GI system?

A
  • lowers frequency and amplitude of contractions
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36
Q

How does beta-2 receptor activation impact the uterus?

A

decreases the tone and contractions during preganacy

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37
Q

How does beta-2 receptor activation impact the bladder?

A

relaxes the detrosor muscle

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38
Q

How does beta-2 activation impact the eye?

A
  • elaxes the ciliary muscle (distance vision)
  • lowers aqueous humor formation with an increase in outflow
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39
Q

How does activation of beta-2 receptors impact the metabolism?

A

stimulated glucagon secretion (results in increased glucose output) and an increased in blood glucose, lactic acid and free fatty acid. Activation of lipase (increas in cAMP levels and PKA activation) results in a break down of triglycerides to free fatty caids. In liver cells activation of phosphorylase catalyzes the breakdone of glycogen to glucose.

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40
Q

What is another commerical name for epiephrine?

A

Adrenaline

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41
Q

What are some names of the form of epinephrine that can be inhaled and what are they used to treat?

A

1) bronkaid Mist
2) Primatene Mist
3) Asthma Haler

and they are used to treat

1) asthma
2) pulmonary obstructive diseases: bronchospasms, emphysema, and bronchitis

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42
Q

How does epinephrine work?

A

its a selective beta2 agonist primiarily used in the chronic treatment of asthma.

its has a longer duration of action and minimal cardiac stimulatory effects

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43
Q

What is the mechanism of action for epinephrine in the inhalation form?

A

it involves the stimulation of beta-2 receptors which results in tralazation of bronchial smooth muscle.

Epi also inhibits the release of mediators from mast cells that produce bronchial constriction

decrease bronchial secretion and this relieves congestion

44
Q

What are the names of epinephrine in the parenteral form and and is the use?

A

1) adrenaline
2) EpiPen
3) Sus-phrine

used for emergency treatment of allergic reactions

Drugs of choice:

acute hypotension

cardiac arrest and syncope

ocular surgery

superfical hemorrhage

its short acting (minutes in duration)

45
Q

What is the mechanism of action of epinephrine in the parenteral form in regards to acute hypotension, cardiac arrest,

A

activation of alpha-1 receptors: vasoconstriction in the vessels of the skin, mucosa, and vascular beds of the kidney

activation of beta-1 receptors: the heart increase cardiac output

stimulation of beta-1 receptors: on the heart increase cardiac output

activation of beta-1 receptors in the heart: increase in heart rate and force of contraction

activation of B2 receptors: result in dilation of blood vessels supplying the skeletal muscle

46
Q

What is the correlation between epinephrine and blood presure?

A

it differs with the dose of epinephrine

47
Q

What happens to epinephrine when given at low doses?

A

at low doses decrease peripheral resistance occurs along with a decrease in diastolic pressure and a small increase in the systolic pressure

48
Q

What are the effects of epinephrine at high doses?

A

at high doses an increas in peripheral resistance occurs with an elevation in both systolic and diastolic pressure

Compared to…..

the decrease in blood pressure at low doses is a result of greater sensitvity to vasodilating beta-2 receptors than vasoconstricing alpha receptors to the effects of epi at that dose

49
Q

What is can be epinephrine be given as an adjunct with?

A

its an adjunct to local anesthetic

50
Q

How should local anesthetic be dosed?

A

give local anesthetic with very diluted epinephrine (1:1000,000)

51
Q

How does local anesthetic and epinephrine work together?

A

the epinephrine greatly increase the duraton of the local anesthetic

this allows the local anesthetic to remain in the area for a longer period of time to exert an effect; if epinephrine was not present would be absorbed quickly from site of administration and degraded

more important for short acting and intermediate acting local anesthetic such as procaine and lidocaine

52
Q

What does epinephrine + local anesthetic do at injection?

A

vasoconstricts blood vessels–at the site of local injection

53
Q

What is the mechanism of action for epinephrine in allergic recations?

A

mechanism of action involves the stimulation of beta-2 receptors, resuling in the relaxation of bronchial smooth muscle

epinephrine also inhibits the release of mediators form mast cells that produce bronchial constriction

due to powerful bronchodilator effects, relieves all known histamine or allergic bronchoconstriction

54
Q

What is the mechanism of action when epinephrine is used for surgical aid and control peripheral resistance?

A

it activates the alpha-1 receptors to constrict blood vessels of the skin; reduces bleeding in eye surgery via alpha-1 action and mydriasis

55
Q

What concentration of epinephrine should be used for surgical aid and to control peripheral resistance?

A

a very diluted soultion (1: 100,000)

56
Q

What is the diluted epinephrine 1:100,000 also used for?

A

used in the past as an opthalmic agent to treat open angle glaucoma to increase outflow of aqueous humor and or desensitization of beta-2 receptors

57
Q

What are the side effects of epinephrine?

A

tachycardia, hypertension, anxiety fear, tension, headahe and nervousness

58
Q

What are the contraindication of epinephrine?

A

most forms of hypertension and most forms of shock

59
Q

How fast does epinephrine work and how long does it last?

A

it has a rapid onset of action and brief duration of action–rapid degradation

60
Q

How can epinephrine be given in emergency situations?

A

it can be given intravenously, subcutaneously, by endotracheal tube, or by inhalation

61
Q

Why is oral adminstration of epinephrine not good?

A

its ineffective-because its inactivated by intestinal enzymes

62
Q

How is epinephrine metabolized and how does the body get rid of it?

A

its metabolized by COMT and MAO; only the metabolites are excrited in the urine

63
Q

What are the drug interactions with epinephrine?

A

the alpha blockers block the effects of epi

64
Q

inhalation anesthetic + epi?

A

increase risk of arrhythmias and sensitization of the myocardium

65
Q

local anesthetics + epi?

A

may cut off blood flow to the skin

66
Q

TCA + Epi?

A

increase the risk of hypertension and tachycardia (block uptake)

67
Q

insulin + Epi?

A

effect of insulin is reduced b/c more glucose is liberated; diabetes may need to increase insulin

68
Q

Beta-blockers + Epi?

A

inhibition of Epi’s effects; hypertension could result due to the loss of beta-mediated vasodilation and alpha-1 receptor effects

69
Q

Cocaine + Epi?

A

potentiation of cardiovascular effects and potential for hypertensive crisis

70
Q

Epi + digitalis ?

A

increased risk for arrhythmias

71
Q

Epi + ergot derivatives?

A

hypertension (sertonin agonist-constric vessels)

72
Q

Xanthines + Epi?

A

increased CNS stimulation-additive toxic effects

73
Q

What happens when epinephrine is used too often?

A

potential for tolerance to develop

74
Q

Whats another name for norepinephrine?

A

levophed

75
Q

what is norepinephrine mostly used for?

A

its used for restoration of blood pressure in acute hypotensive states

76
Q

how is norepinephrine administered, how fast does it act, and what is the duration of its action?

A

its given IV with a rapid onset of action; the duration of action is 1-2 minutes following the end of infusion

77
Q

In what case would norepinephrine be poorly absorbed?

A

if its given by SC injection

78
Q

How is the action of norepinephrine terminated?

A

it is destroyed in the gut if given orally and it is metabolized by COMT and MAO; reuptake is also possible for termination of action

79
Q

What is norepinephrine effect on the activation of alpha-1 receptors and how does this impact blood presure ?

A

lead to vasconstriction, increased blood pressure, and an increase in total peripheral resistance.

Note- NE has little effect at beta-2 receptors which vasodilates skeletal muscle vessels.

therefore increases in blood pressure is higher for NE than Epi

80
Q

What are some other actions of norepinephrine?

A

other actions results in reduction in blood flow to the SKM and skin

some decrease in insulin secretion which can result in hyperglycemia

81
Q

What are the side effects of norepinephrine?

A

sympathetic effects at other organs

blandhing and sloughing of skin along injected vein (etravasation and produced by extreme vasoconstriction)

irregular heart beat–arhythmias more likely with large dose

reflex slowing of the heart

anxiety and CNS stimulation

82
Q

What are the conindications with norepinephrine?

A

1) sympathomimetics
2) local anesthetics
3) TCA
4) beta blockers
5) digitalis
6) ergot alkalodis
7) methyldopa

83
Q

What is the contraindication of norepinephrine and sympathomimetics?

A

amphetamines/cocaine-potentiation of NE effects- especially CNS stimulation

84
Q

What is the contraindication of norepinephrine with local anesthetics?

A

sensitization of the myocardium to sympathomimetics

85
Q

What is the contraindication of norepinephrine to TCA?

A

it potentiates the cardiovascular effects, resulting in tachycardia and arrhythmias

86
Q

What is the contraindication of beta-blockers with norepinephrine?

A

blockade of beta mediated therapeutic effects; unopposed alpha-receptor stimulation resulting in hypertension and bradycardia

87
Q

What is the contraindication of digitalis to norepinephrine?

A

can cause arrhythmias

88
Q

What is the contraindication of ergot alkaloids to norepinephrine?

A

causes hypertension

89
Q

What is the contraindication of methyldopa to norepinephrine?

A

enhanced increase in blood pressure

90
Q

What is dopamine?

A

its the immediate precursor of NE and Epi

91
Q

What is the function of dopamine?

A

it acts centrally in the regulation of movement

92
Q

How is dompamine administered?

A

its administered orally- a substrate for both MAO and COMT

93
Q

What are the effects of distinct receptor subtypes?

A

effects are mediated by distinct receptor subtypes; at low concentration the primary effect is on D1 receptors which leads to vasodilation

94
Q

What is dopamine used to treat?

A

used in the management of states of low cardiac output such as severe congestive heart failure- it dilates renal and splanchnic beds

used to treat cardiogenic and septic shock

95
Q

What are some related drugs to dopamine?

A

related drugs include fenoldopam (corlolpam)- selective D1 receptor agonist which is used to lower blood pressure in severe hypertension

dopexamine (dopacard) is a synthetic analog of dopamine with intrinsic activity at both dopamine and beta2 receptors

96
Q

In what type of patients does dopamine produce favorable hemodynamic actions?

A

in patients with severe congestive heart failure, sepsis, and shock

97
Q

What is concept behind reflex bradycardia?

A

all systems have a set point–if the system deviates it tries to make up for that to return to the poin

98
Q

What system is the blood presure important to and what is blood pressure?

A

its very important to the vasculature

blood pressure is cardiac output X total peripheral resistance

99
Q

What things can sympathomimetics increase? and how does this impact the baroreceptor?

A

they can increase the cardiac output and the total peripheral resistance;

the increased BP sensed by baroreceptors—-> the baroreceptor signal to the PSNS neurons of the vagus to fire and release ACh into the heart—> the ACh release causes the heart to slow down ande decrease the cardiac output—> decreases the BP

the TPR does not change because the vasculature is not enervated by PSNS

100
Q

Name the catecholamines and their receptors

A

1) epinephrine- alpha1 & 2, beta-1 & 2
2) norepinephrine- alpha 1& 2, beta-1
3) isoproterenol- beta 1 & 2
4) dopamine- beta -1
5) dobutamine- beta-1

101
Q

Name the catecholamines and what are their receptors.

A

1) phenylepherine- alpha-1
2) clonidine- alpha-1
3) metaproterenol- beta-2 > beta-1
4) terbutaline, ritrodrine, albuterol- beta-2
5) amphetamine- alpha, beta, and central nervous system
6) ephedrine- alpha, beta, and central nervous system

102
Q

What are the major effects of the alpha-1 receptors?

A

vasoconstriction; increased PR; increased blood pressure; mydriasis; increased closure of internal bladder sphincter

103
Q

What are the major effects of alpha 2 recepectors?

A

inhibition of NE, inhibition of insulin release

104
Q

What are the major effects of beta-1 receptors?

A

tachycardia, increased lipolysis, increase myocardial contractility, increase renin release

105
Q

What are the major effects of beta-2 receptors?

A

Final Test: Dynamics II (11 decks)

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