Adrenergic Agonist and Antagonists Flashcards

1
Q

What are the prototype non-competitive and competitive alpha adrenergic blockers?

A
Non-competitive = phenoxybenzamine
Competitive = phentolamine
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2
Q

Describe the mechanism of action for phenoxybenzamine (include receptor affinity, receptor binding, and metabolism)

A

Phenoxybenzamine preferentially binds alpha 1 over alpha 2 covalently. Can aldo bind H1, AChR, and serotonin receptors with high doses.
Half-time = 24 hours

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3
Q

Describe the pharmacologic effects of phenoxybenzamine on the CNS, cardiovascular system, eye, and penis

A

CNS - weakness, nausea, and vomitingCardiovascular - vasodilation through blocking alpha 1 and reflex tachycardia by blocking of presynaptic alpha 2 receptors near the heart
Eye - miosis
Penis - inhibition of ejaculation

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4
Q

What are the clinical uses (4) of phenoxybenzamine

A
  1. Pre-operative management of pheochromocytoma with propanolol or other beta blocker
  2. PVD
  3. Raynaud Syndrome
  4. Acrocyanosis
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5
Q

Describe the mechanism of action for phentolamine in reference to receptors bound

A

Phentolamine will bind alpha 1 and alpha 2 equallyCan also bind to H1 receptors in the gastric mucosa

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6
Q

Descirbe the effects of phentolamine on the cardiovascular system and GI tract

A

CV - causes vasodilation through alpha 1 and sometimes reflex tachycardia through the same mechanisms as phenoxybenzamine
GI - increases gastric motility and pepsin and HCl release

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7
Q

What are the clinical uses of phentolamine (3)?

A
  1. Surgical management of pheochromocytoma to prevent hypertensive crises
  2. Aid in withdrawal from clonidine
  3. Treat necrosis induced by local NE administration
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8
Q

What are the side effects phentolamine (4)?

A
  1. Nausea
  2. Vomiting
  3. Tachycardia
  4. Orthostatic hypotension
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9
Q

What type of adrenergic antagonists are ergot alkaloids from rye fungus?

A

Non-selective alpha blockers.

Some stimulation of serotonin receptors

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10
Q

What kind of antagonist is prazosin?

A

Selective alpha1 antagonist

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11
Q

What are the clinical uses and side effects of prazosin?

A

Used to treat hypertension, and does not cause relfex tachycardia
Syncope is the common side effect due to orthostatic hypotension

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12
Q

What type of drug is tamulosin?

A

Selective alpha 1A antagonist

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13
Q

What are the clinical uses and side effects of tamulosin?

A

This drug is specific for prostatic smooth muscle and is used to treat BPH
The specificity of the drug eliminates orthostatic hypotension

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14
Q

Describe the mechanism of action of propanolol

A

Non-selective competitive beta blocker

Note: this is a lipid soluble drug that is able to enter the CNS –> drowsiness

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15
Q

What are the effects of propanolol on the CV system, Respiratory system, and metabolism?

A

Cardiovascualr - decreases CO, HR, and AV nodal conduction and inhibits vasodilation.
Note: prolonged use can cause decreases in TPRRespiratory - block bronchodilation
Note: avoid in asthmatics eedeot
Metabolism - block glycogenolysis and lipolysis

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16
Q

Describe the absorption and metabolism of propranolol?

A

This drug is absorbed orally, but variably susceptible to the first-pass effect. Each patient needs to be dosed individually

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17
Q

What are the cardiovascular uses (4) of propanolol?

A
  1. Hypertension
  2. Angina pectoris
  3. Arrhythmia
  4. Reduction of mortality after acute MI by decreasing the likelihood of ventricular arrhythmia and recurrent ischemia
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18
Q

What are the non-cardiovascular clinical uses (4) of propanolol?

A
  1. Management of preoperative pheochromocytoma along with phenoxybenzamine
  2. anxiety
  3. migraine headaches
  4. thyrotoxicosis - hyperthyroidism patients have lots of beta receptors
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19
Q

What are the common (6) and severe (6) side effects of propanolol use?

A
Common
1. dizziness
2. drowziness
3. diarrhea
4. depression
5. constipation 
6. nausea
Severe
1. fever
2. rash
3. purpura
4. potentiate hypoglycemia
5. increase VLDL and HDL
6. interfere with SGOT and BUN assays
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20
Q

What are the four contraindications for propanolol use?

A
  1. Overt heart failure
  2. Cardiogenic shock
  3. Asthma
  4. AV nodal block
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21
Q

What is metoprolol and what is it used for?

A

Cardioselective Beta 1 antagonist used to treat hypertension

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22
Q

What is atenolol and what is it used for?

A

Cardioselective Beta 1 blocker used in the treatment of chronic stable angina and hypertension
Note: decreased risk of bronchospasm and does not prolong recovery from insulin-induced hypoglycemia

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23
Q

What is acebutolol and what is it used for?

A

A cardioselective beta blocker for hypertension and dysrrhythmias

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24
Q

What is betaxolol and what is it used for?

A

A beta 1 blocker for hypertension and glaucoma

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25
Q

What are the five catecholamines and describe there metabolism, distribution, and route of administration?

A
  1. Epinephrine
  2. Norepinephrine
  3. Isoproterenol
  4. Dopamine
  5. Dobutamine
    These drugs are quickly metabolized, do not cross the BBB, and must be administered any other way than orally
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26
Q

Describe the three modes of action for catecholamines?

A

Direct - binds to adrenergic receptors
Indirect - induces the release of norepinephrine or inhibits its reuptake
Mixed - does both direct and indirect

27
Q

Generally describe the effects of alpha receptor stimulation

A

Alpha 1 - Contraction of smooth muscle
Alpha 2 - inhibition of insulin release, relaxation of intestinal smooth muscle, and inhibition of presynaptic NE release

28
Q

Generally describe the effects of beta receptor stimualtion

A

Beta 1 - increases cardiac output and renin release
Beta 2 - increases glycogenolysis, insulin release, and smooth muscle relaxation
Beta 3 - lipolysis

29
Q

Describe the receptor affinity for epinephrine

A

Epinephrine has affinity for all adrenergic receptors. Affinity at low doses is greater for beta 2 than alpha 1, but vice versa at higher doses

30
Q

Describe the effects of epinephrine on the cardiovascular system

A

Increased CO, HR, contractility, conduction
Blood flow
1. skeletal muscle undergoes vasodilation at low doses and constriction at high doses
2. Vasoconstriciton of vessels in kidneys, mucosa, skin, and lungs
3. vasodilation of coronary arteries
Systolic blood pressure will be slightly increased while diastolic blood pressure is decreased. Overall blood pressure remains unchanged or slightly increased.

31
Q

What are the four clinical uses of epinephrine?

A
  1. pediatric asthma
  2. topical hemolytic - only works on capillaries and arterioles
  3. anaphylactic shock
  4. prolongation of local anesthetic duration
32
Q

What are the adverse effects and contraindications of epinephrine?

A

Side effects - Headache, anxiety, and fearNote: when mixed with halothane, arrhythmias can occur
Contraindications - hypertension, angina pectoris, shock, hyperthyroidism, and degenerative heart disease

33
Q

Describe the receptor affinity of norepinephrine

A

High affinity for alpha 1, alpha 2, and beta 1….beta 3?

Note: very weak at beta 2

34
Q

Describe the cardiovascular and metabolic effects of norepinephrine

A

Causes increase in blood pressure, heart rate, and cardiac output. Followed by reflex bradycardia resulting in slow forceful heart rate.
Blood pressure is increased by vasoconstriction.alpha 1 stimulation modestly increases glycogenolysis, but beta 3 stimulation increases lipolysis

35
Q

Describe the use, side effects, and contraindications of norepinephrine

A

Used as a pressor agent for spinal anesthesia
Side effects - headache, anxiety, and slow forceful heart rate
Contraindications - same as epinephrine

36
Q

What receptors does isoproterenol interact with?

A

All beta receptors

37
Q

What are the cardiovascular and metabolic effects of isoproterenol?

A

Cardiovascular - increased heart everything with vasodilation in skeletal muscle. Increase in systolic and decrease in diastolic blood pressures with a net decrease or no change in BP.
Metabolism - activation of lipolysis, but glycogenolysis is opposed by induced insulin release

38
Q

What are the clinical uses (3) and side effects (5) of isoproterenol?

A
Clinical Uses
1. bronchial asthma
2. heart block
3. cardiogenic shock following MI
Side effects
1. tachycardia
2. headache
3. arrhythmia
4. angina pectoris
5. flushing of the skin
39
Q

Describe the receptor affinity of dopamine

A

Agonist at beta 1 and D1 at low doses, and effecting alpha 1 at higher doses

40
Q

What are the cardiovascular effects and clinical uses of dopam ine?

A

Causes a mild increase in cardiac output. Main effect is increased blood flow to the mesenteric and renal vascular beds.
Note: this effect can be overriden with higher doses stimulating alpha 1 or chlorpromazineClinical uses - cardiogenic shock (increase CO and blood flow to vital organs) and chronic CHF (increase CO without increasing TPR)

41
Q

What is dobutamine and what effects does it have?

A

Dobutamine is a beta 1 selective partial agonist with mild positive inotropic and chronotropic effects

42
Q

What are the clinical uses of dobutamine?

A

Used to treat acute MI and chronic CHF with less chance of arrhythmia

43
Q

Describe the mechanism of action, pharmacologic effects, and clinical uses of phenylephrine

A

Phenylephrine is a selective alpha 1 agonist which causes vasoconstriction and reflex bradycardia. Reflex can be blocked by atropine.
The clinical uses include nasal decongestant, infiltration with anesthetic, pressor agent for spinal anesthesia, and paroxysmal atrial tachycardia.
Note: Pressor agent causes reflex bradycardua for the atrial tachycardia

44
Q

Name (3) beta adrenergic agonists used to treat asthma. What is their mechanism of action, pharmacologic effects, and side effects?

A

Albuterol - used for bronchial asthma, side effects include tachycardia, hypoglycemia, hypokalemia, and muscle tremors
Salmeterol and formoterol - are longer lasting agents which can be used for phrophylaxis of asthma
MOA - bind to beta 2 with a ten fold selectivity compared to beta 1. Long duration of action, but may develop tolerance quickly
All of these will cause bronchodilation

45
Q

What the fuck is tyramine and why do you care?

A

Tyramine is a compound found in beer, red wine, and cheese (I love cheese). Normally this little fucker is degraded by GI and hepatic MAO, but little bitches taking MAOIs will feel the effects of tyramine.
Tyramine will enter the presynaptic nerve terminal and displace NE. Ya bitch!

46
Q

What is the MOA of cocaine, tricyclic antidepressants, and SNRIs

A

They block the action of NET maintaining high concentration of NE in the synapse

47
Q

What is the MOA of amphetamines and their pharmacologic effects?

A

Amphetamines indirectly cause the release of NE and inhibit its reuptake into the nerve terminal.
Pharmacologic effects
CNS - Improves concentration, confidence, alertness, and fatigue
CV - positively affects inotrope and vasoconstriction, negative effect on chronotropeUrinary sphincter contraction

48
Q

What are the clinical uses (3), side effects (6), and toxicity signs (3 and 3)/treatment for amphetamines?

A

Clinical Uses - ADHD, obesity, and narcolepsy
Note: tolerance to appetite suppression and mood effects develops quicklyside effects - insomnia, delerium, nausea, vomiting, anxiety, and arrhythmia
Acute toxicity - convulsions, coma, and death
Chronic toxicity - abnormal mental state, weight loss, and psychotic reactionsToxicity treatment - Amphetamines are weak bases and can be removed quicker by making the urine acidic with ammonium chloride

49
Q

Describe the MOA, metabolism, and pharmacologic effects of ephedrine

A

MOA - mixed action: direct action at beta receptors and indirect release of NE
Metabolism - not degraded by COMT or MAO, useful orally and long lasting
Pharmacologic effects - A modest CNS stimulant which causes increase in inotrope and weak vasoconstriction but no change in HR. Moderate sustained bronchodilation

50
Q

What is tachyphylaxis and what drug does this pertain to?

A

Reduced efficacy with repeated useEphedrine

51
Q

What are the clincial uses (3) and adverse effects (3) of ephedrine?

A

Clinical uses - pressor agent for spinal anesthesia, nasal decongestant, and treatment of severe acute bronchospasm
Adverse effects - insomnia, anxiety, and palpitations

52
Q

Name the four zolines (ZOLTAN!!). What are they used for and how do they work

A

Naphazoline, tetrahydrozoline, xylometazoline, and oxymetazoline
These are alpha one agonists used to treat nasal decongestion

53
Q

What should be noted about tetrahydrozoline and xylometazoline

A

Tetrahydrozoline may cause sedation or shock in children (finally they’ll shut the fuck up!) and possibly rebound congestion
Xylometazoline can distribute systemically and should be used cautiously in hypertensive patients

54
Q

What is the mechanism of action, clinical use, and side effect of guanethidine?

A

MOA - competes with NE at NET for uptake into the presynaptic terminal where it binds to chrommafin vesicles (?that’s probably what they’re called?) displacing NE and inhibiting its release
Clinical Uses - was used to treat essential hypertension in the medieval times
Adverse effects - orthostatic hypotension

55
Q

What does reserpine do and what would you use it for?

A

Blocks VMAT’s pussy with it’s black dick so DOPA cannot enter the chrommafin vesicle (again ??). Last line agent for hypertension

56
Q

What is the MOA and pharmacologic effects of clonidine?

A

Clonidine binds slectively to alpha 2 receptors and activates them
When administered through IV clonidine causes increase in BP through peripheral alpha receptors and then a decrease through the central receptors. When administered percutaneous or orally the drug causes decreased cardiac output and preload.

57
Q

What are the clinical uses (2) and adverse effects (4) of clonidine?

A

Clinical uses - last line agent for essential hypertension and adjunct in narcotic withdrawal
Adverse effects - dry mouth, sedation, impotence, and hypertensive crises with sudden withdrawal

58
Q

Why would I ever use methyldopa?

A

If you have a preggers woman with hypertension

59
Q

What is fenoldopam?

A

This is a D1 agonist used to treat cardiogenic shock

60
Q

What is the sequence of effects in NE administration?

A

High action at Beta 1 and Alpha 1 receptors, with low affinity for Beta 2 receptors.
Blood pressure and peripheral resistance increase –> increased vagal tone causing a slowing of the heart rate regardless of the effects at Beta 1

61
Q

What are the effects of low epinephrine infusion?

A

Mean pressure remains so there is no increased vagal tone causing a slowed HR. Peripheral resistance will decrease slightly.

62
Q

What are the effects of low isoproterenol infusion?

A

No effect on systemic pressure, but resistance drops while HR increases

63
Q

What are examples of 3rd generation beta blockers

A

Carvedilol and labetalol

Note: have effects at Beta 1, Beta 2, ad Alpha 1