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20 Cards in this Set
- Front
- Back
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Type of Adrenergic Antagonist?
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α-Blockers
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What is the effect of blocking α-receptors (i.e. activating α-blockers)?
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Blocking α receptors reduces sympathetic tone of blood vessels, results in decreased peripheral vascular resistance, vasodilation and lowered bp
Produces a reflex tachycardia |
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What are therapeutic uses of α-blockers (i.e. adrenergic antagonists)?
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o Treatment of urinary obstruction/retention
o Treatment of Hypertension o Treatment of Peripheral vascular disease o Treatment of Erectile dysfunction o Examples: Phenoxybenzamine |
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What are Competitive Antagonists?
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o Competitive antagonists bind same site as agonist
o Reversible antagonists will dissociate from receptor; block can be overcome with high concentrations of agonist o Irreversible antagonists do not dissociate and cannot be overcome with high concentrations of agonist; covalent bond |
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What is Echothiosulfate?
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is an irreversible Acetylcholine Esterase Inhibitor (AcHE)
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What type of drug is Phenoxybenzamine? What is it used to treat?
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Irreversible competitive/noncompetitive Adrenergic Antagonist;alpha-blocker
o Phenoxybenzamine is used to treat pheochromocytoma, a type of tumor that secretes catecholamines; phenoxybenzamine is given pre-operative to control hypertension and reverse some of the effects of excessive catecholamine secretion |
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What does Phenoxybenzamine do?
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inhibits reuptake of NE and blocks specific histamine, ACh and serotonin receptors
o Blocking α receptors prevents vasoconstriction by endogenous catecholamines, elicits a reflex tachycardia |
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What are the side effects of Phenoxybenzamine?
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postural hypotension, nasal stuffiness, nausea, vomiting
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What do prazosin, terazosin, doxazosin all treat? How?
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They treat hypertension;
they all are selective, competitive α1 blockers o All lower arterial blood pressure by causing relaxation of both arterial, venous smooth muscle o Unlike other α-blockers, have minimal effects on cardiac output and renal blood flow o Is a “first-dose” fainting effect due to lowered bp o When used alone (monotherapy) to treat hypertension, increases risk of congestive heart failure |
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What are Tamsulosin and Alfuzosin? What do they treat?
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o Both competitive α1 blockers
o Are used to treat benign prostatic hypertrophy (BPH), a condition characterized by enlarged prostate and interference with normal urine flow |
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Which neurotransmitter does an [alpha]-blocker reverse the actions of?
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Can reverse the agonist actions of EPI; EPI is a potent vasoconstrictor
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What does Yohimbine do? What is it used for?
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o Competitive α2 blocker, comes from bark of yohimbe tree
o Sometimes used as sexual stimulant o Works at level of CNS to increase sympathetic outflow to periphery o Is used as a vasodilator |
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What does a β-Blocker do?
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• All clinically available are competitive antagonists; bind at site where agonist binds
• Some are nonselective; cardio-selective ones bind to β1 receptors; are no selective β2 • All β blockers lower bp, various ones used to treat angina, cardiac arrhythmia, myocardial infarction, congestive heart failure, glaucoma, migraines • All can block actions of isoproterenol on heart |
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What is Propranolol? What does it do?
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o Prototype β-blocker, both β1, β2
o Diminishes cardiac output, lowers bp o Reduced bp causes decrease in renal perfusion o Extensively metabolized in liver, poor bioavailability |
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What is Nebivolol? What is it used to treat?
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is the most highly selective β1 antagonist; used to treat hypertension
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What drug are Metoprolol and Atenolol similar to?
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to Propranolol but have better bioavailability; may be safer in some patients who experience bronchoconstriction with Propranolol
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What kind of drugs are Acebutolol, atenolol, metoprolol, esmolol? What are they used to treat?
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o Selective β1 blockers primarily developed to eliminate unwanted side effect of bronco-constriction found with β2 blockers
o Are used to treat hypertension, particularly in patients with impaired pulmonary function o Used to treat angina |
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What are Partial Agonists?
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• They have the ability to weakly stimulate β1 and β2 receptors
• However, they have the ability to inhibit stimulation by more potent catecholamines such as NE and EPI |
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What kind of drugs are labetalol and carvedilol? What are they used to treat?
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reversible antagonists at both receptors
o Used to treat hypertension o They are different from other β-blockers in that they produce peripheral vasoconstriction, which is desirable for some patients |
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What are two examples of Indirect Antagonists?
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o Reserpine – blocks transport of DA into vesicles by the vesicular monoamine transporter (VMAT)
o Guanethidine – blocks release of NE that is stored in vesicles |
