M-Chapter 7: Adrenergic Antagonists Flashcards
(10 cards)
A 60-year-old female patient started on a new
antihypertensive medication recently. Her blood
pressure seems to be under control, but she complains
of fatigue, drowsiness, and fainting when she gets up
from the bed (orthostatic hypotension). Which of the
following drugs is she most likely taking?
A. Metoprolol.
B. Propranolol.
C. Prazosin.
D. Clonidine.
C. α-Blockers (prazosin) are more likely to cause orthostatic hypotension compared to β-blockers (metoprolol, propranolol) and α2 agonists (clonidine).
A 30-year-old male patient was brought to the ER with
amphetamine overdose. He presented with high blood
pressure and arrhythmia. Which of the following is
correct regarding this patient?
A. Amphetamine can activate all types of adrenergic
receptors.
B. β-Blockers are the ideal antidotes for amphetamine
poisoning.
C. α-Blockers can normalize the blood pressure in this
patient.
D. Miosis could be a possible symptom of
amphetamine poisoning.
A. Amphetamine is an indirect adrenergic agonist that mainly enhances the releaseof norepinephrine from peripheral sympathetic neurons. Therefore, it activates all types of adrenergic receptors (that is, α and β receptors) and causes an increase in blood pressure. Since both α and β receptors are activated by amphetamine, α-blockers or β-blockers alone cannot relieve the symptoms of amphetamine poisoning. Since amphetamine causes sympathetic activation, it causes mydriasis, not miosis.
A new antihypertensive drug was tested in an animal
model of hypertension. The drug when given alone
reduces blood pressure in the animal. Norepinephrine
when given in the presence of this drug did not cause
any significant change in blood pressure or heart
rate in the animal. The new drug is similar to which
of the following drugs in terms of its pharmacological
mechanism of action?
A. Prazosin.
B. Clonidine.
C. Propranolol.
D. Metoprolol.
E. Carvedilol.
E. Norepinephrine activates both α1and β1receptors and causes an increase in heart rate and blood pressure. A drug that prevents the increase in blood pressure caused by norepinephrine should be similar to carvedilol that antagonizes both α1and β1
receptors. Prazosin is an α1antagonist, clonidine is an α2 agonist, and propranolol and metoprolol are β antagonists, and these drugs cannot completely prevent the cardiovascular effects of norepinephrine.
A β-blocker was prescribed for hypertension in a female
asthma patient. After about a week of treatment, the
asthma attacks got worse, and the patient was asked
to stop taking the β-blocker. Which of the following
β-blockers would you suggest as an alternative in this
patient that is less likely to worsen her asthma?
A. Propranolol.
B. Metoprolol.
C. Labetalol.
D. Carvedilol.
B. The patient was most likely given a nonselective β-blocker (antagonizes both β1
and β2receptors) that made her asthma worse due to β2antagonism.
An alternative is to prescribe a cardioselective (antagonizes only β1) β-blocker that does not antagonize β2receptors in the bronchioles. Metoprolol is a cardioselective β-blocker. Propranolol, labetalol, and carvedilol are nonselective β-blockers and could worsen the asthma.
A 70-year-old male needs to be treated with an
α-blocker for overflow incontinence due to his enlarged
prostate. Which of the following drugs would you
suggest in this patent that will not affect his blood
pressure significantly?
A. Prazosin.
B. Doxazosin.
C. Phentolamine.
D. Tamsulosin.
E. Terazosin.
D. Tamsulosin is an α1antagonist that is more selective to the α1receptor subtype (α1A) present in the prostate and less selective to the α1receptor subtype (α1B) present in the blood vessels. Therefore, tamsulosin does not affect blood pressure significantly. Prazosin, doxazosin, terazosin, and phentolamine antagonize both these
subtypes and cause significant hypotension as a side effect.
A 50-year-old male was brought to the emergency room
after being stung by a hornet. The patient was found to
be in anaphylactic shock, and the medical team tried
to reverse the bronchoconstriction and hypotension
using epinephrine. However, the patient did not fully
respond to the epinephrine treatment. The patient’s wife
mentioned that he is taking a prescription medication
for his blood pressure, the name of which she does not
remember. Which of the following medications is he
most likely taking that could have prevented the effects
of epinephrine?
A. Doxazosin.
B. Propranolol.
C. Metoprolol.
D. Acebutolol.
B. Epinephrine reverses hypotension by activating β1receptors and relieves bronchoconstriction by activating β2receptors in anaphylaxis. Since epinephrine was not effective in reversing hypotension or bronchoconstriction in this patient, it could be assumed that the patient was on a nonselective β-blocker (propranolol). Doxazosin (α1-blocker), metoprolol, or acebutolol (both β1-selective blockers) would not have completely prevented the effects of epinephrine.
Which of the following is correct regarding α-adrenergic
blockers?
A. α-Adrenergic blockers are used in the treatment of
hypotension in anaphylactic shock.
B. α-Adrenergic blockers are used in the treatment of
benign prostatic hyperplasia (BPH).
C. α-Adrenergic blockers may cause bradycardia.
D. α-Adrenergic blockers are used in the treatment of
asthma.
E. α-Adrenergic blockers reduce the frequency of
urination.
B. α-Adrenergic blockers are used in the treatment of BPH because of their relaxant effect on prostate smooth muscles. Being antihypertensive agents, they are notuseful in treating hypotension in anaphylaxis. α-Adrenergic blockers generally cause reflex tachycardia (not bradycardia) due to the significant drop in blood pressure caused by them. α-Adrenergic blockers have no significant effects on bronchial tissues and are not useful in treating asthma. They increase (not reduce) the frequency of urination by relaxing the internal sphincter of the urinary bladder, which is controlled by α1 receptors.
Which of the following is correct regarding β-blockers?
A. Treatment with β-blockers should not be stopped
abruptly.
B. Propranolol is a cardioselective β-blocker.
C. β-Blockers may cause orthostatic hypotension.
D. Cardioselective β-blockers worsen asthma.
E. β-Blockers decrease peripheral resistance by
causing vasorelaxation.
A. If β-blocker therapy is stopped abruptly, that could cause angina and rebound hypertension. This could be due to the up-regulation of β receptors in the body.
β-Blockers do not cause direct vasorelaxation. Therefore, they do not decrease peripheral resistance and are less likely to cause orthostatic hypotension. Propranolol is a nonselective β-blocker (not cardioselective). Cardioselective β-blockers antagonize only β1 receptors and do not worsen asthma as they do not antagonize β2 receptors.
Which of the following drugs is commonly used topically
in the treatment of glaucoma?
A. Atropine.
B. Timolol.
C. Tropicamide.
D. Scopolamine.
B. β-Blockers reduce the formation of aqueous humor in the eye and therefore reduce intraocular pressure, thus relieving glaucoma. Timolol is a nonselective β-blocker that is commonly used topically to treat glaucoma. Atropine, tropicamide, and scopolamine are anticholinergic drugs that might worsen glaucoma.
Which of the following is correct regarding carvedilol?
A. Carvedilol is a cardioselective β-blocker.
B. Carvedilol is safe for use in asthma patients.
C. Carvedilol has α1-blocking activity.
D. Carvedilol is contraindicated in the treatment of
stable chronic heart failure.
C. Carvedilol is a nonselective β-blocker with α1-blocking activity. Since it also blocks β2 receptors in the lungs, carvedilol could exacerbate asthma. Carvedilol is not used in patients with acute exacerbation of heart failure but is used in the treatment of stable, chronic heart failure.
