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Questions and Answers
What is a common side effect of non-selective alpha-adrenergic antagonists like Phenoxybenzamine?
What distinguishes alpha1-selective antagonists from non-selective ones like Phentolamine?
Which alpha1-adrenoceptor subtype primarily mediates contraction of prostate smooth muscle?
What is the primary action of Phentolamine as an adrenergic blocker?
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What effect does nasal stuffiness have in patients administered with non-selective alpha-blockers?
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What is the primary use of epinephrine in cases of cardiac arrest?
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Which of the following β2-adrenoceptor agonists is primarily used for treating asthma and COPD?
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What effect do blockers of α- and/or β-adrenoceptors have on catecholamines?
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What is the primary therapeutic action of glucocorticoids in respiratory conditions?
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Which drug is an irreversible non-selective α-adrenoceptor blocker?
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Which of the following is a common side effect of β1 and β2 blockers?
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What is the characteristic action of clonidine as an α2-adrenoceptor agonist?
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Which statement is true about the effects of phenoxybenzamine?
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What is the effect of phentolamine on blood pressure?
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Which therapeutic use involves the use of prazosin?
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How does terazosin alleviate urinary obstruction in benign prostate hypertrophy?
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What is the primary mechanism of action for phezocrine in treating pheochromocytoma?
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After administering phentolamine, what change occurs when epinephrine is introduced?
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Which medication is notable for causing less hypotension compared to terazosin?
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What symptom does Raynaud's syndrome treatment specifically target?
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What action results from α1-adrenoceptor stimulation at the bladder neck?
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What is a common side effect of α1-adrenoceptor antagonists related to blood vessels?
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Which of these medications is a reversible (competitive) β-adrenoceptor blocker?
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For which condition is propranolol specifically noted to be used as a prophylactic treatment?
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What effect does blocking β1-adrenoceptors generally have on heart rate and cardiac contractility?
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Which β-blocker has partial β-agonistic activity?
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Which of the following conditions could β-adrenoceptor antagonists potentially worsen?
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What is a characteristic effect of labetalol compared to other β-blockers?
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What is one of the common side effects of β-blockers that have high lipid solubility?
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What is the mechanism by which Clonidine reduces blood pressure?
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Which side effect is associated with the use of Reserpine?
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Why are ganglionic blockers seldom used in clinical practice?
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What is the role of Guanethidine in the treatment of hypertension?
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What is the primary action of α-methyl dopa in the body?
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Study Notes
Cardiac Arrest and Epinephrine
- Cardiac arrest leads to cessation of heart muscle contractions.
- Epinephrine is administered to restore heart rate (HR) after cardiac arrest.
Actions of β2-Adrenoceptor Agonists
- Salbutamol and terbutaline are used for asthma and COPD to dilate bronchioles and stabilize mast cells, reducing histamine and leukotriene release.
- Glucocorticoids like betamethasone are primary therapies to decrease edema and bronchial hyperactivity.
- Salbutamol and terbutaline can also be used to manage premature labor.
Adrenoceptor Blockers
- Blockers can inhibit both endogenous and exogenous catecholamines.
- α1 and α2 blockers (e.g., labetalol) act differently by blocking selective receptor subtypes.
Irreversible α-Adrenoceptor Blockers
- Phenoxybenzamine is a non-selective irreversible α-adrenoceptor blocker, binding covalently to α1 > α2 receptors.
- Effects last for days, requiring new receptor synthesis for recovery.
- Side effects include hypotension, reflex tachycardia, nasal congestion, headache, and ejaculation inhibition.
Reversible α-Adrenoceptor Blockers
- Phentolamine is a non-selective reversible antagonist with minimal clinical importance.
- Alpha1-selective antagonists like prazosin, doxazosin, and terazosin have reduced reflex tachycardia compared to phentolamine.
Therapeutic Uses of α1-Adrenoceptor Antagonists
- Prazosin is used for hypertension by blocking α1 receptors in arterioles.
- Phenoxybenzamine can be used preoperatively for pheochromocytoma to lower blood pressure.
- Low doses of α1-antagonists are used for Raynaud’s syndrome to reduce arteriolar vasospasm.
- Terazosin manages benign prostatic hyperplasia (BPH) by easing urinary flow through α1A blockade.
Side Effects of α1-Adrenoceptor Antagonists
- May cause tachycardia due to increased sympathetic activity.
- Side effects include orthostatic hypotension, headaches, and nasal stuffiness.
β-Adrenoceptor Blockers
- Non-selective β-blockers include propranolol and pindolol; β1 selective blockers include metoprolol.
- These agents do not affect baseline blood pressure in healthy individuals but prevent HR and cardiac output increases during exercise.
Uses of β-Adrenoceptor Antagonists
- Hypertension treatment through decreased sympathetic nerve activity and cardiac output.
- Management of angina, myocardial infarction, chronic heart failure, arrhythmias, glaucoma, hyperthyroidism, migraines, and acute panic symptoms.
Toxicities of β-Adrenoceptor Antagonists
- May lower HR excessively, particularly in patients with bradycardia or AV block.
- High lipid-solubility β-blockers (e.g., propranolol) may cause sedation and depression.
- Caution in patients with acute heart failure, asthma, and insulin-dependent diabetes.
Labetalol
- Labetalol is a non-selective blocker effective in severe hypertension and hypertensive crises without causing reflex tachycardia.
- Orthostatic hypotension is a common side effect; contraindicated in asthma patients.
Adrenergic Neuron Blockers
- Clonidine and α-methyl dopa decrease blood pressure via α2-adrenoceptor stimulation, reducing sympathetic discharge.
- Reserpine impairs the uptake of neurotransmitters into storage vesicles; rarely used due to significant side effects.
- Guanethidine reduces norepinephrine release from storage vesicles and is used for severe hypertension.
Ganglionic Blockers
- Hexamethonium blocks neuronal nicotinic receptors affecting ganglionic transmission.
- Usage is rare due to significant side effects, including alterations in autonomic tone.
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Description
This quiz covers the critical aspects of cardiac arrest, focusing on the use of epinephrine to restore heart rate. It also delves into the actions of β2-adrenoceptor agonists, particularly in the treatment of asthma and COPD. Test your knowledge on these essential pharmacological interventions.
