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Pharmacology > Adrenergic Agonists > Flashcards

Adrenergic Agonists Flashcards

1
Q

Catecholamines

A

general term for neurotransmitters/hormones in the sympathetic NS

named after their structure
catacholamines:
dopamine, neorepinephrine, epinephrine

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2
Q

4 Categories of Adrenergic Receptors

A

Alpha 1, Alpha 2, Beta 1, Beta 2, Dopamine

all are G-protein couples cell membrane bound receptors

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3
Q

Alpha 1 Receptors

A

Coupled with Gq proteins to phospholipase C
When activated, results in activation of protein kinas es

kinases activate other enzymes that result in physiologic actions–>see positive action

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4
Q

Alpha 2 Receptors

A

Couples with G1 proteins to adenylyl cyclase
when activated, results in inhibitory activity that decreases cAMP
decreased cAMP=reduces transduction of activating types of enzymatic messages

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5
Q

Beta Receptors

A

coupled with Gs proteins to adenylyl cyclase
increases conversion of ATP to cAMP
activated multiple kinases that activate additional enzymes leading to physiologic actions (stimulate kinase to result in some kind of effect)

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6
Q

Dopamine Receptors

A

D1=receptors stimulate adenylyl cyclase=increased cAMP

D2=receptors inhibit adenylyl cyclase=decreases cAMP

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7
Q

Variations in Adrenergic Receptor Response

A

selectivity
regulation
polymorphism
catecholamine metabolism

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8
Q

Adrenergic Receptor Selectivity

A

Sympathomimetic drugs–>able to bind to one subgroup of receptors without binding to other (a drug can bind to alpha 1 receptors but not alpha 2 or beta)

degree of binding is drug concentration dependent
low concentration= selective
high concentration=nonselective binding

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9
Q

Adrenergic Receptor Regulation

A

receptors up or down regulate over time which results to changes of the deugs response to sympathomimetic drugs

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10
Q

Desensitization

A

aka tachyphylaxis

occurs after long term exposure to catecholamines. Results in decrease responsiveness of that cell/tissue to additional stimulation

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11
Q

Mechanisms of Desensitization

A

altered transcription or translation of DNA/RNA

modification of receptors from interactions with enzymes or other proteins

long term exposure to agonist (tachypholyxis)

interactions or messages from other receptors

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12
Q

Desensitization for Theraputic Benefit

A

desensitixation of receptor desired

Ex. Drug Z binds to alpha 1 receptors and causes an exaggeration of the expected physiologic response
But the body doesnít like exaggerated drug-induced responses and wants to maintain homeostasis in the target organ, meaning less neurotransmitter will be available to bind to those alpha 1eceptors
This results in the actual desired effect of the drug, which is a decrease in alpha 1 activity in a specific target organ

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13
Q

Variations in Receptor Polymorphism

A

individuals amino acid differences aloter receptor response–>alter degree of susceptibility to desensitization and alter degree or responsiveness to drugs–>some theraputic drugs work in some pt’s but not others

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14
Q

Termination of NT’s action

A
  • NE transporter (NET)–brings NE back to the presynaptic neuron
  • movmenet of NE out of synaptic cleft into bloodstream
  • Metabolism by COMT (catecholamine-O-methyltransferase)

Metabolism by monoamine axodase (MAO)

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15
Q

Norepinephrine Transporter (NET)

A

Removes 90% of released NE (most common way)

presynaptic pump that moves NE out of synapse and back into the neruon (NE will then be recycled or metabolized by MAO)

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16
Q

NET as Theraoutic Target

A 
inhibits NET (atomoxetine and cocaine)
leads to increased stimulation of adrenergic receptors
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17
Q

Catechol-O-methyl Transferase (COMT)

A

metabolizes all catecholamines–>terminates actions of NE, Epi, DA
drugs can inhibit COMT and prolong effect of the catecholamine
ex:Enatacopne (will inhibit COMT=increases DA)

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18
Q

Monoamine Oxidase (MAO)

A 
metabolizes Monoamines (NE, EPi, Serotonin, DA)
two forms A&B
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19
Q

Sympathomimetics

A

Drugs that mimic actions of NE, Epi, DA

2 forms-Direct & indirect agonists

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20
Q

Direct Agonist Sympathomimetics

A

structure allos for binding to adrenergic receptors resulting in activation

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21
Q

Indirect gonists

A

not interacting with receptor
cause release of stored catecholamines
inhibits reuptake of catechalomine already released

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22
Q

Structure of Sympathomimetics

A

similar structure to catecholamines, enough that NE receptors will allow it to bind

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23
Q

Benzene Ring Substitution

A

dding Hydroxyl groups–>maximizes a and b activity

adding hydroxyl to 1 reduces adrenergic potency

absence of OH will allow it to corss BBB and enter CNS

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24
Q

Amino Group Substitutions

A

increases Beta activity (decrease Alpha activity)

isopropyl on amino Nitrogen increases beta activity

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25
Q

Alpha Carbon Substitutions

A

block oxidation by MAO=prolonged duration of action (longer 1/2 life)
adding methyl group at alpha carbon increases ability to act as indirect sympathomimetics

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26
Q

Beta Carbon

A

less significant impact on activity

adding hydroxyl enables direct agonist activity

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27
Q

Sympathomimetic Effcts on Cardiovascular System

A

outcome is dependent on:

  • selectivity for alpha and beta receptors
  • agonist or antagonist
  • action of body’s compensatory mechanism to maintain homeostasis

will effect HR, CO, BP, Venous return

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28
Q

Alpha 1 Cardiovascular Effects

A

Alpha 1 are in vascular beds ina rteries

activation of alpha 1=vasoconstriction=increase BP=the body will try and maintain normal range so it will slow HR and decrease CO (CO stays constant)

ex: Phenylephrine

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29
Q

Alpha 2 Cardiovascular Effects

A

in vascular beds and in CNS
Localy administration or HIGH dose=activation by alpha 2 agonists=vasoconstriction

Systemic administration=activation of central alpha 2 receptors=decrease in sympathetic activity=decrease in BP

ex:clonidide (to tx HTN)

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30
Q

Beta 1 Cardiovascular Effects

A

in heart
increase contractility and increase HR=increase in CO

stimulates heart

31
Q

Beta 2 Cardiovascular Effects

A

in vasculature

vasodilation=drop in BP

32
Q

Dopamine Effects on Cardiovascular System

A

stimulation of D1=vasodilation (renal, splanchnic, coronary, cerebral)

also binds to alpha and beta receptors and response is dose dependent

33
Q

Low Dose DA on CV

A

activates Beta 2 receptors=vasodilation=lower Bp

34
Q

Medium Dose DA on CV

A

activates Beta 1 receptors=increases CO

35
Q

High Dose DA on CV

A

Activates Alpha 1 receptors=causes vasoconstriction=Increases BP

36
Q

Sympathomimetics Effects on the Lungs

A

Beta 2 receptors → bronchodilation

37
Q

Sympathomimetics Effect on the Eye

A

alpha receptors in radial muscle=mydriasis

can reduce IOP by increase outflow of aqueous humor

38
Q

Sympathomimetics Effects on the GU System

A

alpha receptors= promote urine retention and mediate ejaculation

39
Q

Sympathomimetics Effect on Salivary Glands

A

Beta receptors=increase salivation

40
Q

Sympathomimetics Effect on Apocrine sweat Glands

A

(palms of hands)

increase sweat production

41
Q

Sympathomimetics Effect on Metabolism

A

increase glycogenolysis in liver via beta receptors and increase serum glucose
Beta receptors=increase lipolysis
Alpha 2 receptors= decrease lipolysis
Beta 2 receptors=promote K+ reuptake
Beta 2 receptors= increase insulin release from islet cells
Alpha 2 receptors= decrease insulin release from islet cells

42
Q

Epinephrine

A

“adrenaline”

agonist at alpha and beta receptors

43
Q

Effect of Epinephrine

A 
potent vasoconstrictor and cardiac stimulant 
increases BP (alpha 1)
increases Hr and CO (B1 receptors)

in skeletal muscle causes vasodilation (B2) receptors

44
Q

Norepinephrine

A 
noradrenaline, Lvophed
alpha 1,2 and Beta 1 agonist
vasoconstrictor and cardiac stimulant 
increases BP (alpha 1)
increases HR and CO (beta 1)
45
Q

Phenylephrine (Neosynephrine)

A

Direct Alpha 1 agonist
not inactivated by COMT=prolongs duration of action
decongestant and raises BP

46
Q

Midodrine (Amantine)

A

increase BP and tx orthostatic hypotention

47
Q

Clonidine (catapres)

A

direct alpha 2 agonist, work in CNS to reduce BP and tx HTN

48
Q

Methyldopa (Aldomet)

A

direct alpha 2 agonist, work in CNS to reduce BP and tx HTN

49
Q

Guanfacine (Tenex)

A

direct alpha 2 agonist, work in CNS to reduce BP and tx HTN

50
Q

Guanabenz (Wytensin)

A

direct alpha 2 agonist, work in CNS to reduce BP and tx HTN

51
Q

Dexmedetomidine (Precedex)

A

direct alpha 2 agonist, acts in CNS for sedation

52
Q

Oxymetazoline (Afrin, Dristan)

A

alpha 1 action=vasoconstriction and used as decongestant

alpha 2 action has similar action to clonidine to decrease BP

53
Q

Isoproterenol (Isuprel)

A

Nonselective Beta agonist (B1 and B2)
B2=vasodilation (decreases diastolic BP)
B1=positive chronotropic and inotropic effects in heart (increase HR and CO)

54
Q

Dobutamine

A

Beta 1 selective agonist
increases CO w/o reflexive increase in HR
(+)isomer=B1 action and A1 antagonism=increase in CO and NO increase in BP

(-)isomer= a1 action which=vasoconstriction=increase BP

55
Q

beta 2 selective Agonists

A 
provide bronchodilation and useful in tx of asthma and COPD
Albuterol
Terbutaline
Metaproterenol 
Pirbuterol
Salmeterol
Formoterol
Ritodrine-->relaxes uterine smooth muscle during labor
56
Q

Mixed Acting Sympathomimetics

A

Provide Alpha and Beta effects=vasoconstriction, decongestion, bronchodilation, CNS-apetite supression

Ephedrine=bronchodilation
Pseudophredrine

57
Q

indirect Acting Sympathomimetics

A 
displace stored catecholamines
inhibit reuptake of NE by NET
Ex:
amphetamines
tyramine containing compounds
catecholaine reuptake inhibitors
58
Q

Amphetamines

A

causes release of stored NE and DA

CNS stimulation=increase mood and alertness and decreased appetite

59
Q

Modafinil (provigil)

A

indirect sympathomimetic

inhibits NE and DA transporters in CNS=increases wakefulness in pt’s with narcolepsy or shift work disorder

60
Q

Atomoxetine (Staterra)

A

Catecholamine Reuptake Inhibitor

selective inhibitor of NE reuptake with mostly CNS effect, used to tx ADHD

61
Q

Subutramine (Meridia)

A

Catecholamine Reuptake Inhibitor
seratonin and NE reuptake inhibitor
appetitie supressant

62
Q

Doluxetine (Cymbalta)

A

Catecholamine Reuptake Inhibitor
serotonina nd NE repuptake inhibitor
used an an antidepressant

63
Q

Cocaine

A

inhibits peripheral reuptake of NE by NET

inhibition of DA resuptake in pleasure center of brain=leads to very rapid addiction

64
Q

Sympathomimetic use to Tx Hypotension

A

use alpha 1 agonists to raise BP (by causing vasoconstriction)
NE and Phenylephrine
use of inotropic agents in shock syndromes
Dopamine, dobutamine

65
Q

Sympathomimetics to Tx HYPERtension

A

central acting alpha 2 agonists

clonidine (catapress)

66
Q

Sympathomimetics Management of Orthostatic Hypotension

A

tx with alpha 1 agonist like midodrine

67
Q

Sympathomimetic use in Emergency Cardiac Measures

A

Epinephrine –>redirects blood flow from less important areas to bran and heart using Alpha 1 and Beta 1

68
Q

Sympathomimetics in Surgical Apllication

A

Alpha 1
epinephrine to reduce blood loss at site of surgery

Epi, NE, Phenylephrine-locally acting alpha 1 agonists to slow diffusion of anesthetics away from site

69
Q

Sympathomimetics in Sinus Decongestants

A

use alpha 1 agonists in nasal sprays to cause vasoconstriction (Phenylephrine )neosynephrine) Oxymetazline (afrin)

70
Q

Sympathomimetics Pulmonary use

A 
Selective beta 2 agents=bronchodilation 
Albuterol (VentolinÆ, ProventilÆ)
Metaproterenol (AlupentÆ)
Pirbuterol (MaxairÆ)
Salmeterol (SereventÆ)
Formoterol (PerforomistÆ)
71
Q

Sympathomimetics Ophthalmic Applications

A

Alpha 1 agonist–>mydriasis (pupillary dilation)
reduce eye redness

Alpha 2–>reduce IOP w/glaucoma (apraclonidine, lopidine, bromonidie, alphagan)

72
Q

Sympathomimetics GU Application

A

Beta 2 selective–> relax uterus in premature labor (Ritodrine, Terbutaline)

73
Q

Sympathomimetics CNS Apllications

A

tx narcolepsy, appetitie supression, manage ADHD
Methylphenidate (RitalinÆ) Dextroamphetamine/amphetamine (AdderallÆ) Lisdexamfetamine (VynaseÆ) (prodrug for amphetamine)

74
Q

Sympathomimetics Sedation applications

A

Use Alpha 2 agonists

dexmedetomidine

Pharmacology (21 decks)

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