AGENTS, CONTROLLING THE FUNCTIONS OF THE PERIPHERAL NERVOUS SYSTEM - Adrenoreceptor antagonist drugs Flashcards
Which drugs is a nonselective alfa receptor antagonist?
Phentolamine
Indicate the alfa1-selective antagonist
Prazosin
Which agents is an alfa2–selective antagonist?
Yohimbine
Indicate the irreversible alfa receptor antagonist
Phenoxybenzamine
Which drugs is an nonselective beta receptor antagonist?
Propranolol
Indicate the beta1-selective antagonist
Metoprolol
Which of the following agents is a beta2–selective antagonist?
Butoxamine
Indicate the beta adrenoreceptor antagonist, which has partial beta–agonist activity
Pindolol
Which drugs is a reversible nonselective alfa, beta antagonist?
Labetalol
Indicate the indirect-acting adrenoreceptor blocking drug
Reserpine
The principal mechanism of action of adrenoreceptor antagonists is
Reversible or irreversible interaction with adrenoreceptors
Characteristics of alfa-receptor antagonists include
- They cause a fall in peripheral resistance and blood pressure
- They cause epinephrine reversal (convert a pressor response to a depressor response)
- They may cause postural hypotension and reflex tachycardia
Characteristics of alfa-receptor antagonists do not include
Bronchospasm
Which drugs is an imidazoline derivative and a potent competitive antagonist at both alfa1 and alfa2 receptors?
Phentolamine
Characteristics of phentolamine include
- Reduction in peripheral resistance
- Tachycardia
- Stimulation of muscarinic, H1 and H2 histamine receptors
Characteristics of phentolamine do not include
Stimulation of responses to serotonin
The principal mechanism of phentolamine-induced tachycardia is
Antagonism of presynaptic alfa2 receptors enhances norepinephrine release, which causes cardiac stimulation via unblocked beta receptors
Nonselective alfa-receptor antagonists are most useful in the treatment of
Pheochromocytoma
The main reason for using alfa-receptor antagonists in the management of pheochromocytoma is
Blockade of alfa2 receptors on vascular smooth muscle results in epinephrine stimulation of unblocked alfa2 receptors
Which drugs is useful in the treatment of pheochromocytoma?
Phentolamine
Indicate adrenoreceptor antagonist agents, which are used for the management of pheochromocytoma
Αlfa-receptor antagonists
The principal adverse effects of phentolamine include
- Diarrhea
- Arrhythmias
- Myocardial ischemia
The principal adverse effects of phentolamine do not include
Bradycardia
Indicate the reversible nonselective alfa-receptor antagonist, which is an ergot derivative
Ergotamine
Indicate an alfa-receptor antagonist, which binds covalently to alfa receptors, causing irreversible blockade of long duration (14-48 hours or longer)
Phenoxybenzamine
Compared with phentolamine, prazosin has all of the following features
- Highly selective for alfa1 receptors
- The relative absence of tachycardia
- Persistent block of alfa1 receptors
Compared with phentolamine, prazosin has not features
Irreversible blockade of alfa receptors
True or False. ALFA1a subtype mediates both vascular and prostate smooth muscle contraction
FALSE
True or False. There are at least three subtypes of alfa1 receptors, designated alfa1a, alfa1b and alfa1d
TRUE
True or False. ALFA1a subtype mediates prostate smooth muscle contraction
TRUE
True or False. ALFA1b subtype mediates vascular smooth muscle contraction
TRUE
Indicate an alfa1 adrenoreceptor antagonist, which has great selectivity for alfa1a subtype
Tamsulosin
Subtype-selective alfa1 receptor antagonists such as tamsulosin, terazosin, alfusosin are efficacious in
Benign prostatic hyperplasia (BPH)
Indicate an alfa receptor antagonist, which is an efficacious drug in the treatment of mild to moderate systemic hypertension
Prazosin
Which alfa receptor antagonists is useful in reversing the intense local vasoconstriction caused by inadvertent infiltration of norepinephrine into subcutaneous tissue during intravenous administration?
Phentolamine
Beta-blocking drugs-induced chronically lower blood pressure may be associated with theirs effects on
- The heart
- The blood vessels
- The renin-angiotensin system
Characteristics of beta-blocking agents include
- They occupy beta receptors and competitively reduce receptor occupancy by catecholamines or other beta agonists
- They do not cause hypotension in individuals with normal blood pressure
- They can cause blockade in the atrioventricular node
Characteristics of beta-blocking agents do not include
They induce depression and depleted stores of catecholamines
Beta-receptor antagonists have all of the following cardiovascular effects
- The negative inotropic and chronotropic effects
- Vasoconstriction
- Reduction of the release of renin
Beta-receptor antagonists have not the following cardiovascular effects
Acute effects of these drugs include a fall in peripheral resistance
Beta-blocking agents have all of the following effects
- Bronchoconstriction
- Decrease of aqueous humor prodaction
- “membrane-stabilizing” action
Beta-blocking agents have all of the following effects except
Increase plasma concentrations of HDL and decrease of VLDL
Beta-receptor antagonists cause
Inhibition of glycogenolysis
Propranolol has all of the following cardiovascular effects
- It decreases cardiac work and oxygen demand
- It inhibits the renin secretion
- It increases the atrioventricular nodal refractory period
Propranolol has all of the following cardiovascular effects except
It reduces blood flow to the brain
Propranolol-induced adverse effects include
- Bronchoconstriction
- “supersensitivity” of beta-adrenergic receptors (rapid withdrawal)
- Sedation, sleep disturbances, depression and sexual dysfunction
Propranolol-induced adverse effects do not include
Hyperglycemia
Propranolol is used in the treatment all of the following diseases
- Cardiovascular diseases
- Hyperthyroidism
- Migraine headache
Propranolol is used in the treatment all of the following diseases except
Bronchial asthma
Metoprolol and atenolol are members of
The beta1-selective group
Which beta receptor antagonists is preferable in patients with asthma, diabetes or peripheral vascular diseases?
Metoprolol
Indicate a beta receptor antagonist, which has very long duration of action
Nadolol
Indicate a beta1-selective receptor antagonist, which has very long duration of action
Betaxolol
Which drugs is a nonselective beta-blocker without intrinsic sympathomimetic or local anesthetic activity and used for the treatment of life-threatening ventricular arrhythmias?
Sotalol
Indicate a beta receptor antagonist with intrinsic sympathomimetic activity
Oxprenolol
Pindolol, oxprenolol have all of the following properties
- They are nonselective beta antagonists
- They are less likely to cause bradycardia and abnormalities in plasma lipids
- They are effective in hypertension and angina
Which drugs has both alfa1-selective and beta-blocking effects?
Labetalol
Characteristics of carvedilol include
- It has both alfa1-selective and beta-blocking effects
- It attenuates oxygen free radical-initiated lipid peroxidation
- It inhibits vascular smooth muscle mitogenesis
Characteristics of carvedilol do not include
It is a beta1-selective antagonist
Indicate the adrenoreceptor antagonist drug, which is a rauwolfia alkaloid
Reserpine
Characteristics of reserpine include
- It decreases cardiac output, peripheral resistance and inhibits pressor reflexes
- It may cause a transient sympathomimetic effect
- It depletes stores of catecholamines and serotonin in the brain
Characteristics of reserpine do not include
It inhibits the uptake of norepinephrine into vesicles and MAO
Indicate a beta-blocker, which is particularly efficacious in thyroid storm
Propranolol
Beta-receptor blocking drugs are used in the treatment all of the following diseases
- Hypertension, ischemic heart disease, cardiac arrhythmias
- Glaucoma
- Hyperthyroidism
Beta-receptor blocking drugs are used in the treatment all of the following diseases except
Pheochromocytoma
Beta-blocker-induced adverse effects include
- Bronchoconstriction
- Depression of myocardial contractility and excitability
- “supersensitivity” of beta-receptors associated with rapid withdrawal of drugs
Beta-blocker-induced adverse effects do not include
Hyperglycemia