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Pharm Exam 1 > Autonomic Pharmacology Part II > Flashcards

Autonomic Pharmacology Part II Flashcards

1
Q

What neurotransmitter is released at target organs in the sympathetic nervous system?

A

Norepinephrine - activates alpha and beta receptors

or

circulating epinephrine from adrenal gland

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2
Q

All adrenergic receptors are

A

G protein-coupled receptors that work by activating secondary messengers within the cell

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3
Q

Alpha receptors

A

Alpha 1 = causes calcium release inside the cell

  • Smooth muscle contraction
  • Stimulates “tone” on the postsynaptic side

Alpha 2 = presynaptic; inhibits neurotransmitter release

  • Works via negative feedback
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4
Q

Beta Receptors

A
  • Beta 1 = increases HR
    • Both beta 1 and 2 are found on the heart but Beta 1 is the most important for HR increase
  • Beta 2 = triggers relaxation of smooth muscles along respiratory tract and certain blood vessels
    • found in airways and BV that cause relaxation, particularly BV in skeletal muscles
  • Beta 3 = leads to lipolysis, breakdown of triglycerides in adipocytes (releases energy reserves)
    • This is about getting more fuel, this releases more energy into the blood for more movement and fuel the fight or flight response, glucose and adipose mobilization
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5
Q

Dopamine, norepinephrine and epinephrine are all derived from?

A

Tyrosine

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6
Q

How does the catecholamines differ?

A

by functional group

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7
Q

How do norepinephrine and epinephrine differ?

A

Where they are released

NE - sympathetic neurons

Epi - adrenal gland when SNS is activated

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8
Q

Are Ne and Epi equivalent?

A

Relatively

The exception is that NE has a low potency at beta 2 receptors

Epi activates all alpha and betas; however, NE doesn’t activate beta 2

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9
Q

Draw the diagram showing epinephrine and norepinephrine actions on receptors

A

Epinephrine: agonist at ALL ANDROGENIC RECEPTORS

  • little change in blood pressure due to the fact that it activates a wide range of areas

Norepinephrine: Minimal activity at Beta 2 adrenergic receptors

  • Large increase in Blood pressure because it acts on specifically beta 1 receptors
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10
Q

Blood pressure =

A

cardiac output x vascular resistance (TPR)

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11
Q

Does epinephrine cause a large change in blood pressure?

A

No, but norepinephrine has a large increase (doesn’t activate Beta 2 for vasodilation)

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12
Q

Enhancing/decreasing sympathetic NS is known as

A

Increase = sympathomimetic

Decrease = sympatholytic

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13
Q

What are the drug mechanisms?

A
  1. Block adrenergic receptors - using antagonist
  2. Activate adrenergic receptors - using agonists
  3. Block uptake transporters
  4. Increase release of neurotransmitters - increase NE
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14
Q

What is known as the prototypical adrenergic agonist since it activates all receptors?

A

Epinephrine

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15
Q

What are the main effects of SNS activation?

A

Vasoconstriction in most tissues - alpha 1

Vasodilation in skeletal muscles - Beta 2

Increase HR and contractility - Beta 1

Dilate/relax bronchial smooth muscle - beta 2

Mydriasis - dilate pupil - alpha 1

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16
Q

What system is responsible for attention, arousal, wakefulness, anxiety, memory formation/ retention and vigor?

A

Noradrenergic system in the brainstem

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17
Q

T/F peripheral norepinephrine and epinephrine can cross the blood-brain barrier

A

FALSE but many adrenergic drugs do and can regulate brain adrenergic receptors to produce therapeutic or side effects

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18
Q

Cardiac output =

A

stroke volume x HR

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19
Q

Mean arterial pressure =

A

cardiac output x total peripheral resistance

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20
Q

Alpha 1 adrenergic agonists are used clinically for

A

vasoconstriction - increasing TPR (CO goes down to maintain MAP)

mydriasis for eye exam

21
Q

Alpha 2 adrenergic agonist are used to

A

reduce blood pressure

location is usually presynaptic; inhibits neurotransmitter release (works via negative feedback)

if vasodilation, TPR goes down; then the CO goes up (SNS activates increasing CO, maintaining MAP)

22
Q

Phenylephrine

A

Alpha 1 selective - activation

used as a decongestant

reflex response - decreases SNS and increases PSNS - vagus nerve activity

Reflex bradycardia = reflex that is happening due to vasoconstriction that is occurring

23
Q

Histamine does what to the body

Blood pressure

Sympathetic nerve activity

Vagus nerve activity

Heart rate

A

Causes vasodilation

Alpha antagonist - or alpha-blocker would give a similar but milder effect

Blood pressure - decreases BP

Sympathetic nerve activity - increased activity

Vagus nerve activity - decreased activity

Heart rate - increase HR

Reflex tachycardia

24
Q

Alpha-adrenergic agonists

A

Major Uses

  • Alpha 1 - selective
    • Vasoconstriction
    • To cause mydriasis for eye exam
  • Alpha 2 - selective: reduce blood pressure

Drugs:

  • Epinephrine
    • used as vasoconstriction in combination with local anesthetics (also levonordefrin)
  • Phenylephrine (PE) - another vasoconstrictor
    • Alpha 1 - selective - sometimes used as a local vasoconstrictor
    • Used as a decongestant - PE is Sudafed
      • Causes vasoconstriction in the nose
  • Oxymetazoline
    • Somewhat alpha 1 - selective, primarily acts on alpha 1 because it is applied directly to tissue
    • Decongestant nasal spray - vasoconstriction
  • Clonidine
    • Alpha 2 selective
    • Decreases sympathetic outflow, reduces blood pressure
    • still in use but not a first line agent
      • Sometimes used for hypertension
        • used when someone is resistant to other hypertension medication
25
Q

Oxymetazoline

A

somewhat alpha - 1 selective

primarily acts on alpha 1 because it is applied directly to tissue

Decongestant nasal spray - vasoconstriction

26
Q

Clonidine

A

Alpha 2 selective

Decreases sympathetic outflow, reduces blood pressure

27
Q

Prazosin

A

Alpha 1 selective antagonist

Antihypertensive

28
Q

Tamsulosin

A

Alpha 1 selective antagonist

Relaxes prostatic smooth muscle in benign

Prostatic hyperplasia (BPH)

29
Q

What could be the consequence of an alpha-blocker that is non-selective

A

Can cause tachycardia by blocking presynaptic alpha 2 receptors

leads to increased NE release which can then stimulate beta receptors

30
Q

Alpha blocker side effects

A

Orthostatic hypotension (decreases in BP due to changes in body position - sit to stand, common for people taking alpha blockers)

Reflex tachycardia (less prevalent with alpha-1 selective drugs, drop in TPR and therefore body would try and increase CO)

Nasal congestion (like phenylephrine - opposite of this)

31
Q

What are the major uses of beta-adrenergic agonists?

A

Beta 1 - stimulate cardiac output (rarely used)

Beta 2 - relax bronchial smooth muscle (very commonly used) = used primarily in asthma

32
Q

Which drug works by activating alpha - 1 receptors?

A

oxymetazoline

33
Q

Albuterol

A

Beta 2 selective agonist for acute asthma exacerbations (rescue inhaler)

Short-acting drug, reacts quickly and lasts for a few hours

34
Q

Salmeterol

A

Long-acting beta 2 selective agonist used for asthma

lasts for 12-24 hours

35
Q

Major uses of “beta blockers” = beta adrenergic receptor antagonists

A
  • Nonselective or beta 1 selective agents
    • Decrease cardiac work (rate, force of contraction)
      • Anti-arrhythmic - decrease excitability of the myocytes of the heart
      • Antihypertensive (cardiac effect plus reduced renin)
      • Anti-angina - reduces the workload of the heart, decreases the O2 requirement of the heart
      • Treatment of heart failure
    • Decrease intraocular pressure (glaucoma)
  • Beta 2 - selective: none in clinical use, although nonselective drugs do block beta 2
    • causes constriction of the airways, opposite of albuterol inhalers for asthma
36
Q

Beta-blocker (beta-adrenergic receptor antagonists) major side effects

A

Related to Beta 1 blockade: hypotension, heart failure

Related to Beta 2 blockade: hypoglycemia, bronchoconstriction

37
Q

Propranolol

A

Non-selective beta blockers (-olol)

  • Decreased cardiac output by blocking beta 1 receptors in the heart
  • May produce bronchoconstriction by blocking beta 2 receptors in the lungs
    • contraindicated in asthmatics - inhaler will not work
  • May impair glucose mobilization by blocking Beta 2 receptors in the liver
    • impairs recovery from hypoglycemia in diabetics on insulin
  • Inexpensive
    • lots of history of use and therefore predictable, commonly used beta blocker
38
Q

Metoprolol

A

Beta 1 selective (cardioselective) beta blockers

  • Similar usage and effects compared to propranolol
  • Avoids bronchoconstriction and hypoglycemia
  • Maybe more expensive
39
Q

Acebutolol

A

Other beta blockers

  • Has intrinsic sympatheticmimetic activity (ISA)
  • Functions as partial agonist
  • Avoids bradycardia that occurs in some patients
    • this drug still gives heart SNS but also blocks the full agonist effects of EPI and NE, not as strong as an effect as a full beta blocker
    • on their own they can act as a weak agonist but can also block the receptor site
40
Q

Labetalol

A

other beta blockers

  • Blocks beta 1 , beta 2 and alpha 1
    • Neat thing is that this also blocks alpha 1
  • Useful in hypertension
    • affects both CO and peripheral resistance and therefore can treat hypertension - not a common drug
41
Q

Unopposed alpha stimulation

A

Beta receptors blocked while alpha are being stimulated

Leads to large increase in vascular resistance; reflex bradycardia

This is why the use of EPI is contraindicated for people on beta blockers

42
Q

How does cocaine act on receptors?

A

Indirect or mixed acting Sympathomimetics (indirect because they do not directly activate NE) they enhance sympathetic effects - sympathomimetrics

inhibits NET and NE reuptake

NET = NE reuptake terminal raise NE levels in the synapse

43
Q

How does amphetamine act on receptors?

A

Enhances NE release and blocks reuptake

44
Q

How does ephedrine/pseudoephedrine act?

A

Enhances NE release and has direct agonist activity

Agonist on alpha and beta receptors

45
Q

Abuse potential is increased in drugs that

A

readily enter the CNS

block dopamine reuptake

46
Q

Risk is highest with (direct/indirect) sympathomimetic drugs since adrenergic receptors are non-selectively activated

A

indirect

47
Q

Sympathomimetic toxidrome

A

MATHS

Mydriasis

Agitation, arrhythmia, angia

Tachycardia

Hypertension, hyperthermia

Seizure, sweating

48
Q

Sympathomimetic drugs should be avoided or used only with extreme caution in individuals with pre-existing cardiovascular disease: such as

A

hypertension

angina pectoralis (coronary heart disease)

History of myocardial infarction (MI; heart attacks)

Cardiac arrhythmias

Pharm Exam 1 (5 decks)

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