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Pharm 2024 > PPT 10 Adrenergic Antagonists > Flashcards

PPT 10 Adrenergic Antagonists Flashcards

1
Q

What are the effects of alpha(α) blockers on blood pressure and heart rate

A

alpha-blockers inhibit the α1 receptors on blood vessels, causing vasodilation and reduced BP

No direct effects on HR but Reflex Tachycardia can occur by body trying to compensate

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2
Q

What effect will occur if alpha-blocker given in absence of an agonist?

A

Without an agonist to block, an α-blocker will have little to no immediate effect on blood pressure or heart rate because it is not counteracting the activation of α-adrenergic receptors

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3
Q

What effect will occur if alpha-blocker given in presence of an agonist?

A

Normally, an agonist like norepinephrine would bind to α1 receptors on blood vessels, causing vasoconstriction, which raises blood pressure. An α-blocker prevents this binding, leading to vasodilation and a reduction in blood pressure

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4
Q

What is the mechanism of action of alpha antagonists?

A

bind to alpha receptors and block the normal endogenous ligand

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5
Q

What are the two types of alpha antagonists?

A

Reversible - competitive, safer
Irreversible - non-competitive, form covalent bonds; recovery requires new receptors

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6
Q

What are the examples of reversible alpha antagonists?

A

Phentolamine, Tolazoline, Prazosin, and Labetalol

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7
Q

What is an example of an irreversible alpha antagonist?

A

Phenoxybenzamine

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8
Q

Non-selective α antagonists are useful in the treatment of _______

A

pheochromocytoma (tumor that results in over-production of epinephrine)

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9
Q

Drugs that end in -osin are used to treat _______ and ______

A

Hypertension and benign prosthetic hyperplasia

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10
Q

Alpha 2 antagonists have _______ effect clinically

A

little - Ergotamine and Yohimbine

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11
Q

How do primary dopamine receptor antagonists work? Name the 2 examples given in lecture

A

decrease dopamine in CNS, reduce delusions/anxiety
Chlorpromazine and Haloperidol

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12
Q

How will alpha selectivity affect HR in alpha antagonists?

A

Mixed antagonist - increase HR
Alpha 1 selective - no affect on HR

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13
Q

What are the different types of competitive antagonism for beta blockers?

A
  • Most are pure antagonist
  • Some partial agonists
  • Some inverse agonists
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14
Q

ADME of beta blockers

A
  • A: well absorbed orally; peak 1-3 hours
  • D: rapid; most half-lives 3-10 hours
  • M: major first-pass metabolism – low bioavailability
  • E: varied mechanisms depending on the agent
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15
Q

Change in FORCE of muscular contractions

A

Inotropic

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16
Q

Change in RATE of muscular contractions

A

Chronotropic

17
Q

Pressors vs depressors

A
  • Pressors – vasoconstriction (raise BP)
  • Depressors – vasodilation (lower BP)
18
Q

What effect can B-blockers have on respiratory system?

A

Increased airway resistance, inhibits B2 vasodilation

19
Q

What effect can B-blockers have on the eye?

A

decrease IOP by decreasing production of aqueous humor

20
Q

what effect can B-blockers have on metabolism?

A

inhibits lipolysis
inhibits glycogenolysis

chronic use inc VLDL, dec. HDL

21
Q

Which Beta-blockers are best for patients with COPD and/or diabetes? why?

A

metoprolol (Lopressor) and atenolol (tenormin)
Mainly B1 specific, no effect on B3

22
Q

What are the clinical indications from lecture that B-blockers are used for?

A

HTN, ischemic heart disease, cardiac arrhythmia, obstructive cardiomyopathy, dissecting aortic aneurysm

23
Q

Which B-blocker are all B-blockers compared to?

A

Propanolol

24
Q

What effect can B-blockers have on the heart?

A

negative inotropic and negative chronotropic

25
Q

What effect can B-blockers have on skeletal blood vessels?

A

opposes B2 mediated vasodilation, increasing peripheral resistance acutely, and decreases peripheral resistance chronically

26
Q

What effect can B-blockers have on the kidneys?

A

Suppression of renin-angiotensin (beta receptors in the kidney)

27
Q

List the mechanism of action and clinical uses of phentolamine

A

Alpha blocker
Competitive antagonist of α1 and α2, reduction in peripheral resistance and causes cardiac stimulation
Treatment of HTN linked to pheochromocytoma and for male erectile dysfunction

28
Q

List the mechanism of action and clinical uses of phenoxybenzamine

A

Alpha blocker
Treatment for pheochromocytoma, marked effect on orthostatic BP
Covalently bound (irreversible), somewhat selective for α1, inhibits NE reuptake

29
Q

List the mechanism of action and clinical uses of labetolol

A

mixed alpha and beta blocker, used to treat HTN

30
Q

List the mechanism of action and clinical uses of drugs that end in -osin

A

Alpha blocker
Prazosin, Terazosin, Doxazosin, Alfuzosin, Tamulosin (Flowmax)
Treatment of HTN and BPH, α1 selective so no tachycardia

31
Q

What are alpha 2 selective blockers used for?

A

Yohimbine and Ergotamine - little use clinically, possible future drug target

32
Q

What is the mechanism of action of propanolol?

A

mixed beta antagonist, extensive first-pass metabolism

33
Q

How is the makeup of labetalol different?

A

racemic mixture, 2 centers of asymmetry = 4 different isomers - 2 are completely inactive, 1 is alpha blocker, 1 is beta blocker

34
Q

Which beta blocker is good for intraoperative tachycardia?

A

Esmolol. - ultra short-acting and beta 1 selective

35
Q

What are the partial beta agonists?

A
  • Nebivolol - selective β1 antagonism
  • Nadolol - long duration of action, nonselective
  • Pindolol, Acebutolol, Carteolol, Penbutolol - treat HTN and angina; less likely to cause bradycardia and cholesterol abnormalities
36
Q

What are the clinical indications for alpha blockers?

A

HTN, treatment of pheochromocytoma (tumor that results in over-production of epinephrine)

37
Q

What are the adverse effects of alpha blockers?

A
  • Cardiac stimulation
  • Abdominal pain, N/V/D
  • Postural hypotension
38
Q

What are the adverse effects of beta blockers?

A
  • Bradycardia
  • Rash, fever, other allergies in susceptible
  • CNS effects - sedation, sleep disturbances, depression
  • Worsening of asthma
  • Hypoglycemia in diabetics
  • Discontinue use gradually
39
Q

Explain the following sentence: Phentolamine converts a pressor (epinephrine) into a depressor. Describe the effects of phentolamine by itself vs with epinephrine

A

Phentolamine is a competitive antagonist - not much change by itself
Epinephrine before phentolamine - presser effects
Epinephrine after phentolamine - depressor effects

Pharm 2024 (28 decks)

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