18 Questions
Which of the following is the main action of alpha adrenergic blockers?
Decrease in total peripheral resistance (TPR)
What is the main effect of phenoxybenzamine?
Induces muscle relaxation and widens blood vessels
What is the duration of action for phentolamine as an alpha-1 antagonist?
4 hours
In what condition is phenoxybenzamine used to control episodes of hypertension?
Pheochromocytoma
What is the off-label use of phentolamine?
Hypertensive crisis
How does phentolamine affect the diameter of the pupil?
Causes miosis
Which class of drugs is primarily used for benign prostatic hyperplasia (BPH) and hypertension (HTN)?
Quinazoline-based drugs
Which drug is linked to intraoperative floppy iris syndrome (IFIS), a risk factor for complications during cataract surgery?
Tamsulosin (Flomax)
Which drug facilitates the passage of kidney stones (ureterolithiasis) but is used off-label for this purpose?
Tamsulosin
Which drug causes depletion of norepinephrine from central and peripheral synapses, leading to its anti-hypertensive effect?
Reserpine
Which beta-adrenergic blocking agent is commonly used in the treatment of supraventricular tachycardias?
Propranolol
Which beta-adrenergic blocking agent has a combined alpha-1, beta-1, and beta-2 blocking action and can be given intravenously for hypertensive emergencies?
Carvedilol
Which drug blocks the release of storage norepinephrine and depletes the nerve ending of norepinephrine in the peripheral nervous system?
Guanethidine
Which class of drugs includes drugs with intrinsic sympathomimetic activity (ISA) and hybrid antihypertensive drugs?
3
Which drug is known for reducing the secretion of aqueous humor and is commonly used in the treatment of glaucoma?
Betaxolol
Which drug is primarily used for arrhythmia prophylaxis after a myocardial infarction?
Esmolol
Which drug has a nonselective beta-blocking action and also blocks alpha-1 receptors?
Labetalol
Which drug is used to reduce the potential for arrhythmias in patients with thyrotoxicosis?
Propranolol
Study Notes
Alpha Adrenergic Blockers
- Alpha adrenergic blockers main action is to block the vasoconstrictor effect of catecholamines
Phenoxybenzamine
- Phenoxybenzamine's main effect is to produce long-lasting blockade of alpha receptors
- Duration of action: long-acting alpha-1 antagonist
- Used to control episodes of hypertension in pheochromocytoma patients
Phentolamine
- Duration of action: short-acting alpha-1 antagonist
- Off-label use: diagnosis of pheochromocytoma
- Affects pupil diameter: causes mydriasis (dilation)
Benign Prostatic Hyperplasia (BPH) and Hypertension (HTN)
- Alpha-1 blockers are primarily used to treat BPH and HTN
Intraoperative Floppy Iris Syndrome (IFIS)
- Phenoxybenzamine is linked to IFIS, a risk factor for complications during cataract surgery
Kidney Stones (Ureterolithiasis)
- Phentolamine facilitates the passage of kidney stones (off-label use)
Anti-Hypertensive Effects
- Reserpine causes depletion of norepinephrine from central and peripheral synapses, leading to its anti-hypertensive effect
Beta-Adrenergic Blockers
- Esmolol is commonly used to treat supraventricular tachycardias
- Labetalol has a combined alpha-1, beta-1, and beta-2 blocking action and can be given intravenously for hypertensive emergencies
Norepinephrine Release
- Reserpine blocks the release of storage norepinephrine and depletes the nerve ending of norepinephrine in the peripheral nervous system
Beta-Adrenergic Blocking Agents
- Class includes drugs with intrinsic sympathomimetic activity (ISA) and hybrid antihypertensive drugs
Glaucoma Treatment
- Timolol reduces the secretion of aqueous humor and is commonly used in the treatment of glaucoma
Arrhythmia Prophylaxis
- Propranolol is primarily used for arrhythmia prophylaxis after a myocardial infarction
- Propranolol has a nonselective beta-blocking action and also blocks alpha-1 receptors
- Propranolol is used to reduce the potential for arrhythmias in patients with thyrotoxicosis
Test your knowledge about the actions and effects of adrenergic antagonists, specifically alpha adrenergic blockers, on the sympathetic tone of blood vessels and the cardiovascular system.
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