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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
Alpha Carbon Substitutions
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
26
Beta Carbon
less significant impact on activity | adding hydroxyl enables direct agonist activity
27
Sympathomimetic Effcts on Cardiovascular System
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
28
Alpha 1 Cardiovascular Effects
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
29
Alpha 2 Cardiovascular Effects
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)
30
Beta 1 Cardiovascular Effects
in heart increase contractility and increase HR=increase in CO stimulates heart
31
Beta 2 Cardiovascular Effects
in vasculature | vasodilation=drop in BP
32
Dopamine Effects on Cardiovascular System
stimulation of D1=vasodilation (renal, splanchnic, coronary, cerebral) also binds to alpha and beta receptors and response is dose dependent
33
Low Dose DA on CV
activates Beta 2 receptors=vasodilation=lower Bp
34
Medium Dose DA on CV
activates Beta 1 receptors=increases CO
35
High Dose DA on CV
Activates Alpha 1 receptors=causes vasoconstriction=Increases BP
36
Sympathomimetics Effects on the Lungs
Beta 2 receptors → bronchodilation
37
Sympathomimetics Effect on the Eye
alpha receptors in radial muscle=mydriasis | can reduce IOP by increase outflow of aqueous humor
38
Sympathomimetics Effects on the GU System
alpha receptors= promote urine retention and mediate ejaculation
39
Sympathomimetics Effect on Salivary Glands
Beta receptors=increase salivation
40
Sympathomimetics Effect on Apocrine sweat Glands
(palms of hands) | increase sweat production
41
Sympathomimetics Effect on Metabolism
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
Epinephrine
"adrenaline" | agonist at alpha and beta receptors
43
Effect of Epinephrine
``` potent vasoconstrictor and cardiac stimulant increases BP (alpha 1) increases Hr and CO (B1 receptors) ``` in skeletal muscle causes vasodilation (B2) receptors
44
Norepinephrine
``` noradrenaline, Lvophed alpha 1,2 and Beta 1 agonist vasoconstrictor and cardiac stimulant increases BP (alpha 1) increases HR and CO (beta 1) ```
45
Phenylephrine (Neosynephrine)
Direct Alpha 1 agonist not inactivated by COMT=prolongs duration of action decongestant and raises BP
46
Midodrine (Amantine)
increase BP and tx orthostatic hypotention
47
Clonidine (catapres)
direct alpha 2 agonist, work in CNS to reduce BP and tx HTN
48
Methyldopa (Aldomet)
direct alpha 2 agonist, work in CNS to reduce BP and tx HTN
49
Guanfacine (Tenex)
direct alpha 2 agonist, work in CNS to reduce BP and tx HTN
50
Guanabenz (Wytensin)
direct alpha 2 agonist, work in CNS to reduce BP and tx HTN
51
Dexmedetomidine (Precedex)
direct alpha 2 agonist, acts in CNS for sedation
52
Oxymetazoline (Afrin, Dristan)
alpha 1 action=vasoconstriction and used as decongestant | alpha 2 action has similar action to clonidine to decrease BP
53
Isoproterenol (Isuprel)
Nonselective Beta agonist (B1 and B2) B2=vasodilation (decreases diastolic BP) B1=positive chronotropic and inotropic effects in heart (increase HR and CO)
54
Dobutamine
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
beta 2 selective Agonists
``` provide bronchodilation and useful in tx of asthma and COPD Albuterol Terbutaline Metaproterenol Pirbuterol Salmeterol Formoterol Ritodrine-->relaxes uterine smooth muscle during labor ```
56
Mixed Acting Sympathomimetics
Provide Alpha and Beta effects=vasoconstriction, decongestion, bronchodilation, CNS-apetite supression Ephedrine=bronchodilation Pseudophredrine
57
indirect Acting Sympathomimetics
``` displace stored catecholamines inhibit reuptake of NE by NET Ex: amphetamines tyramine containing compounds catecholaine reuptake inhibitors ```
58
Amphetamines
causes release of stored NE and DA | CNS stimulation=increase mood and alertness and decreased appetite
59
Modafinil (provigil)
indirect sympathomimetic | inhibits NE and DA transporters in CNS=increases wakefulness in pt's with narcolepsy or shift work disorder
60
Atomoxetine (Staterra)
Catecholamine Reuptake Inhibitor | selective inhibitor of NE reuptake with mostly CNS effect, used to tx ADHD
61
Subutramine (Meridia)
Catecholamine Reuptake Inhibitor seratonin and NE reuptake inhibitor appetitie supressant
62
Doluxetine (Cymbalta)
Catecholamine Reuptake Inhibitor serotonina nd NE repuptake inhibitor used an an antidepressant
63
Cocaine
inhibits peripheral reuptake of NE by NET | inhibition of DA resuptake in pleasure center of brain=leads to very rapid addiction
64
Sympathomimetic use to Tx Hypotension
use alpha 1 agonists to raise BP (by causing vasoconstriction) NE and Phenylephrine use of inotropic agents in shock syndromes Dopamine, dobutamine
65
Sympathomimetics to Tx HYPERtension
central acting alpha 2 agonists | clonidine (catapress)
66
Sympathomimetics Management of Orthostatic Hypotension
tx with alpha 1 agonist like midodrine
67
Sympathomimetic use in Emergency Cardiac Measures
Epinephrine -->redirects blood flow from less important areas to bran and heart using Alpha 1 and Beta 1
68
Sympathomimetics in Surgical Apllication
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
Sympathomimetics in Sinus Decongestants
use alpha 1 agonists in nasal sprays to cause vasoconstriction (Phenylephrine )neosynephrine) Oxymetazline (afrin)
70
Sympathomimetics Pulmonary use
``` Selective beta 2 agents=bronchodilation Albuterol (VentolinÆ, ProventilÆ) Metaproterenol (AlupentÆ) Pirbuterol (MaxairÆ) Salmeterol (SereventÆ) Formoterol (PerforomistÆ) ```
71
Sympathomimetics Ophthalmic Applications
Alpha 1 agonist-->mydriasis (pupillary dilation) reduce eye redness Alpha 2-->reduce IOP w/glaucoma (apraclonidine, lopidine, bromonidie, alphagan)
72
Sympathomimetics GU Application
Beta 2 selective--> relax uterus in premature labor (Ritodrine, Terbutaline)
73
Sympathomimetics CNS Apllications
tx narcolepsy, appetitie supression, manage ADHD Methylphenidate (RitalinÆ) Dextroamphetamine/amphetamine (AdderallÆ) Lisdexamfetamine (VynaseÆ) (prodrug for amphetamine)
74
Sympathomimetics Sedation applications
Use Alpha 2 agonists | dexmedetomidine

Pharmacology (21 decks)

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