Podcast
Questions and Answers
What is a common side effect of non-selective alpha-adrenergic antagonists like Phenoxybenzamine?
What is a common side effect of non-selective alpha-adrenergic antagonists like Phenoxybenzamine?
- Reduced heart rate
- Enhanced ejaculation
- Reflex tachycardia (correct)
- Increased blood pressure
What distinguishes alpha1-selective antagonists from non-selective ones like Phentolamine?
What distinguishes alpha1-selective antagonists from non-selective ones like Phentolamine?
- They are irreversible antagonists
- They cause more reflex tachycardia
- They cause less tachycardia than non-selective antagonists (correct)
- They are less effective in treating hypotension
Which alpha1-adrenoceptor subtype primarily mediates contraction of prostate smooth muscle?
Which alpha1-adrenoceptor subtype primarily mediates contraction of prostate smooth muscle?
- α2B
- α1A (correct)
- α2A
- α1B
What is the primary action of Phentolamine as an adrenergic blocker?
What is the primary action of Phentolamine as an adrenergic blocker?
What effect does nasal stuffiness have in patients administered with non-selective alpha-blockers?
What effect does nasal stuffiness have in patients administered with non-selective alpha-blockers?
What is the primary use of epinephrine in cases of cardiac arrest?
What is the primary use of epinephrine in cases of cardiac arrest?
Which of the following β2-adrenoceptor agonists is primarily used for treating asthma and COPD?
Which of the following β2-adrenoceptor agonists is primarily used for treating asthma and COPD?
What effect do blockers of α- and/or β-adrenoceptors have on catecholamines?
What effect do blockers of α- and/or β-adrenoceptors have on catecholamines?
What is the primary therapeutic action of glucocorticoids in respiratory conditions?
What is the primary therapeutic action of glucocorticoids in respiratory conditions?
Which drug is an irreversible non-selective α-adrenoceptor blocker?
Which drug is an irreversible non-selective α-adrenoceptor blocker?
Which of the following is a common side effect of β1 and β2 blockers?
Which of the following is a common side effect of β1 and β2 blockers?
What is the characteristic action of clonidine as an α2-adrenoceptor agonist?
What is the characteristic action of clonidine as an α2-adrenoceptor agonist?
Which statement is true about the effects of phenoxybenzamine?
Which statement is true about the effects of phenoxybenzamine?
What is the effect of phentolamine on blood pressure?
What is the effect of phentolamine on blood pressure?
Which therapeutic use involves the use of prazosin?
Which therapeutic use involves the use of prazosin?
How does terazosin alleviate urinary obstruction in benign prostate hypertrophy?
How does terazosin alleviate urinary obstruction in benign prostate hypertrophy?
What is the primary mechanism of action for phezocrine in treating pheochromocytoma?
What is the primary mechanism of action for phezocrine in treating pheochromocytoma?
After administering phentolamine, what change occurs when epinephrine is introduced?
After administering phentolamine, what change occurs when epinephrine is introduced?
Which medication is notable for causing less hypotension compared to terazosin?
Which medication is notable for causing less hypotension compared to terazosin?
What symptom does Raynaud's syndrome treatment specifically target?
What symptom does Raynaud's syndrome treatment specifically target?
What action results from α1-adrenoceptor stimulation at the bladder neck?
What action results from α1-adrenoceptor stimulation at the bladder neck?
What is a common side effect of α1-adrenoceptor antagonists related to blood vessels?
What is a common side effect of α1-adrenoceptor antagonists related to blood vessels?
Which of these medications is a reversible (competitive) β-adrenoceptor blocker?
Which of these medications is a reversible (competitive) β-adrenoceptor blocker?
For which condition is propranolol specifically noted to be used as a prophylactic treatment?
For which condition is propranolol specifically noted to be used as a prophylactic treatment?
What effect does blocking β1-adrenoceptors generally have on heart rate and cardiac contractility?
What effect does blocking β1-adrenoceptors generally have on heart rate and cardiac contractility?
Which β-blocker has partial β-agonistic activity?
Which β-blocker has partial β-agonistic activity?
Which of the following conditions could β-adrenoceptor antagonists potentially worsen?
Which of the following conditions could β-adrenoceptor antagonists potentially worsen?
What is a characteristic effect of labetalol compared to other β-blockers?
What is a characteristic effect of labetalol compared to other β-blockers?
What is one of the common side effects of β-blockers that have high lipid solubility?
What is one of the common side effects of β-blockers that have high lipid solubility?
What is the mechanism by which Clonidine reduces blood pressure?
What is the mechanism by which Clonidine reduces blood pressure?
Which side effect is associated with the use of Reserpine?
Which side effect is associated with the use of Reserpine?
Why are ganglionic blockers seldom used in clinical practice?
Why are ganglionic blockers seldom used in clinical practice?
What is the role of Guanethidine in the treatment of hypertension?
What is the role of Guanethidine in the treatment of hypertension?
What is the primary action of α-methyl dopa in the body?
What is the primary action of α-methyl dopa in the body?
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.
