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97 Cards in this Set
- Front
- Back
What is pheochromocytoma?
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A condition with an adrenal gland tumor that secrete catecholamines.
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How do A&B blockers work?
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They prevent interaction of endogenous norepi or other sympathomimetics with adrenergic receptors.
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What effect does norepi blockade have?
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It decreases the effect of SNS homeostatic mechanisms.
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What are some side effects of alpha blockers?
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1. Impotence
2. Postural hypertension 3. Reflex tachycardia |
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How do alpha blockers work?
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They prevent catecholamines or sympathomimetics from provoking alpha responses.
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How do alpha blockers affect insulin?
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Inhibition of insulin secretion is abolished; therefore insulin is secreted.
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What effect does beta stimulus have on the heart?
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It causes cardiac stimulation.
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What are the hemodynamic effects of blocking the alpha receptor?
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1. Vasodilation
2. Hypotension 3. Increased heart rate 4. Decreased peripheral vascular resistance |
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Name some competitive alpha antagonists.
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1. Phentolamine
2. Prazosin 3. Yohimbe |
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What alpha antagonist forms a covalent bond?
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1. Phenoxybenzamine
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Which alpha blockers are nonselective?
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1. Phentolamine
2. Phenoxybenzmine |
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Which alpha blockers are selective?
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1. Prazosin
2. Yohimbe |
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Which alpha receptor is prazosin selective towards?
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Postsynaptic alpha 1
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Which alpha receptor is yohimbe selective towards?
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Presynaptic alpha 2
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List the alpha antagonists.
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1. Phentolamine
2. Phenoxybenzamine 3. Yohimbe 4. Prazosin |
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What is the mechanism of action of phentolamine?
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Produces peripheral vasodilation and decreased SBP.
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What effect does phentolamine have via A1 blockade?
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Direct action in vascular smooth muscle.
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What effect does phentolamine have via A2 blockade?
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1. Neural release of norepi
2. Increased heart rate 3. Increased cardiac output |
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What are some parasympathetic side effects of phentolamine?
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1. Hyperperistalsis
2. Abdominal pain 3. Diarrhea |
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How is phentolamine metabolized?
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By the liver.
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What are the clinical uses of phentolamine?
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1. Acute hypertensive emergency
2. Pheochromocytoma 3. Autonomic nervous system hyperreflexia 4. Local administration for sympathomimetic that is administered accidentally |
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Although phenoxybenzamine is a non-selective alpha blocker, it has a greater affinity for?
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Postsynaptic A1 receptors.
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What are the cardiovascular effects of phenoxybenzamine?
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1. Orthostatic hypertension
2. Marked decrease in SBP with inhaled anesthetics 3. Increased cardiac output 4. Neonatal hypertension and respiratory distress for the first 72 hours of life |
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What are some non-cardiac effects of phenoxybenzamine?
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1. Prevents inhibition of insulin secretion by epi
2. Miosis 3. Sedation in chronic tx 4. Nasal stuffiness |
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What is epi's effect on insulin?
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Epi usually inhibits the release of insulin release so that more glucose goes to the brain during fight or flight situations.
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What are the clinical uses of phenoxybenzamine?
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1. Pre-op med for pheochromocytoma
2. Reynaud's syndrome (increases cutaneous blood flow) |
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What are clinical uses of yohimbe?
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1. Idiopathic orthostatic hypotension
2. Impotence |
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What side effects may occur with increased doses of yohimbe?
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1. Tachycardia
2. Hypertension 3. Rhinorrhea 4. Dissociative states (crosses BBB) |
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What effect does yohimbe have on anesthesia?
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The actions on presynaptic alpha 2 receptors decreases anesthetic requirements.
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What are clinical uses of prazosin?
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1. Raynaud's syndrome
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What effect does Prazosin have on the cardiovascular system?
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Produces dilation of arterioles and veins.
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How is prazosin metabolized?
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By the liver.
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How do beta blockers work?
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1. Bind selectively to beta-adrenergic receptors
2. Prevent effect of catecholamines and sympathomimetics on: a. heart b. smooth muscle of airway c. blood vessels |
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Should beta blocker be continued during the perioperative period?
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Yes
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What is considered the standard beta blocker?
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Propanolol
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Beta blockers are competitive inhibitors; what does this mean?
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They are reversible - large amounts of agonists would replace them at the receptor sites.
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What happens with chronic tx or beta blockers?
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Up-regulation of beta adrenergic receptors.
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What type of receptors are beta adrenergic receptors?
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G protein coupled receptors.
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What percentage of beta blockers are B1 vs B2?
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75% are B1
20% are B2 |
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Beta blockers are derivatives of what drug?
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Isoproterenol
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What beta blockers are non-selective?
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1. Propanolol
2. Nadalol 3. Timolol 4. Pindolol |
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What beta blockers are cardio-selective?
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1. Atenolol
2. Acebutolol 3. Betaxolol 4. Bisoprolol 5. Metoprolol 6. Esmolol |
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Where do cardio-selective beta blockers bind?
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B-1 receptors
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What does the selectivity of beta blockers depend on?
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The dose given. You will lose selectivity with large doses.
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What are the effects of B1 blockade?
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1. Slows sinus rate
2. Slows conduction through AV node 3. Decreases contractility 4. Increases diastolic perfusion time |
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What things should you consider with B1 selective blockers?
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1. Reactive airway
2. PVD |
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What determines adequate tx with propanolol?
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A resting heart rate of 55-60 bpm.
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What are the B1 cardiac effects of propanolol?
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1. Decreased HR
2. Decreased myocardial contractility 3. Decreased cardiac output |
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What are the B2 cardiac effects of propanolol?
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1. Increased peripheral vascular resistance
2. Increased coronary vascular resistance |
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What are the pharmacokinetics of propanolol?
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1. 90-95% hepatic first pass effect with oral dose
2. 90-95% extensively bound to protein 3. Hepatic metabolism |
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What effect does propanolol have on local anesthetics?
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It decreases the clearance of amides by decreasing hepatic blood flow and liver metabolism.
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What effect does propanolol have on opioids?
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It decreases pulmonary first-pass uptake of fentanyl.
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Which beta blocker is most recommended by cardiologists?
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Metoprolol
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What is a clinical use for timolol?
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Its used in glaucoma to decrease production of aqeous humor
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What side effects are caused by systemic absorption of timolol?
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1. Bradycardia
2. Airway resistance |
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What type of beta blocker is metoprolol?
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1. Selective B1 with intact B2 blockade
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Which is the most selective B1 beta blocker?
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Atenolol
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What are clinical uses of atenolol?
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1. Prevention of MI
2. Hypertension |
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How is atenolol administered for prevention of MI?
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Via IV before and immediately after surgery.
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What are some pharmacologic features of esmolol?
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1. Rapid onset
2. Short onset 3. Rapid hydrolysis via plasma esterases 4. Elimination half time of 9 minutes 5. Does not cross BBB |
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What are some clinical uses of esmolol?
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1. Adverse increases in SBP and HR during surgery
2. Laryngoscopy and intubation 3. Resection of pheochromocytoma 4. Thyrotoxicosis 5. PIH 6. Cocaine and epi cardiovascular toxicity |
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Where do beta blockers exert their most prominent pharmacologic effects and side effects?
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On the cardiovascular system.
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Can beta blockers cause hypoglycemia?
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Yes
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What are some contraindications to administering beta blockers?
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1. Preexisting AV heart block
2. Cardiac failure not caused by tachycardia 3. Hypovolemia 4. COPD 5. Diabetes |
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What is the specific reason for avoiding beta blockers in diabetics?
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They may mask signs of hypoglycemia by blunting tachycardia reflex.
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What are some general side effect of beta blockers?
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1. N&V
2. Diarrhea 3. Thrombocytopenia |
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What are some cardiac side effects of beta blockers?
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1. Decreased phase 4 depolarization
2. Poor LV ejection due to peripheral vasoconstriction 3. Increased effects with exercise 4. Increased pressor effect of epi 5. Accentuation vasospasm in Raynaude's disease |
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What are the usual clinical manifestations of excessive myocardial depression caused by beta blockers?
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1. Bradycardia
2. Low cardiac output 3. Hypotension 4. Cardiogenic shock |
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What meds should be used to treat excessive myocardial depression by beta blockers?
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1. Atropine (incremental doses of 7 mcg/kg IV)
2. Isoproteronol (cont. gtt) 3. Dobutamine 4. Glucagon (1-10 mg IV) 5. Calcium Chloride (250-1000 mg IV) |
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What should be done if beta blocker induced bradycardia does not respond to medication?
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1. Placement of a transvenous artificial pacemaker
2. Possible hemodialysis |
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How do beta blocker affect potassium?
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1. Inhibits uptake of potassium into skeletal muscle
2. Hyperkalemia with non-selective beta blockers. |
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How do beta blockers interact with anesthesia?
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1. Myocardial depression with inhaled agents (esp with timolol)
2. Additive cardiovascular effects: Ketamine>Enflurane>Halothane>Opioids>Isoflurane |
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What effect may chronic tx with propanolol cause to the nervous system?
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Fatigue and lethargy
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What effect do beta blockers have on the fetus?
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They may cross the placenta and affect the newborn:
1. Bradycardia 2. Hypotension 3. Hypoglycemia |
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What can happen with acute withdrawal of beta blockers?
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Excess SNS reactivity for 24-48 hours dues to up-reguation.
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What are some general clinical uses of beta blockers?
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1. Tx of essential hypertension
2. Management of angina pectoris 3. Tx of acute coronary syndrome 4. Perioperative beta-receptor blockade 5. Tx of intraoperative MI 6. Suppression of cardiac dysrhythmias 7. Management of CHF 8. Prevention of excessive SNS activity 9. Preoperative prep of hyperthyroid pts |
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Name the combined alpha & beta blockers?
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1. Labetolol
2. Carvedilol |
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Which receptors does labetolol work on?
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1. Selective alpha1
2. Non-selective beta |
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How does the sparing of presynaptic A2 receptors by labetolol exert an affect?
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Released norepi can continue to inibit further release of catecholamines via negative feedback resulting from stimulation of A2 receptors.
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How is labetolol metabolized?
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Conjugation of glucuronic acid.
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What are the cardiovascular effects of labetolol?
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1. Decreased SBP without reflex tachycardia
2. Vasodilation via A1 and B2 |
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What are the clinical uses of labetolol?
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1. Hypertensive emergencies
2. Severe hypertension 3. Rebound hypertension 4. Pheochromocytoma 5. Angina |
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What are the side effects of labetolol?
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1. Orthostatic hypotension
2. Bronchospasm 3. CHF 4. Heart block 5. Fluid retention |
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Which receptors does Carvedilol work on?
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1. Non-selective beta
2. A1 |
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What are the clinical uses of carvedilol?
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1. Mild to moderate CHF due to ischemia or cardiomyopathy
2. Essential HTN |
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What are 2 major cardiovascular actions of competitive alpha blockers?
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1. Decreased BP secondary to vasodilation
2. Reflex tachycardia |
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How does phentolamine produce tachycardia?
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Release of norepi from sympathetic postganglionic nerve terminals owing to A2 blockade.
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How does A2 receptor blockade of sympathetic nerve terminals by an alpha blocker like phentolamine alter the release of norepi?
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It increases the release of norepi.
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What two alpha blockers can be used preoperatively to control blood pressure in the pt undergoing surgery to remove a pheochromocytoma?
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1. Phenoxybenzamine
2. Prazosin |
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Why is prazosin a better choice of treating pts with CHF than a non-selective alpha blocker?
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Prazosin:
1. Produces vasodilation without increase release of norepi 2. Less likely to evoke tachycardia secondary to increased release of norepi |
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List 5 side effects of beta blockers.
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1. Heart block
2. Worsening of CHF 3. Bronchospasm 4. Coronary artery constriction 5. Inhibition of insulin release |
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How does propanolol decrease myocardial oxygen consumption?
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1. Decreasing HR
2. Decreasing myocardial contractility |
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What is the purpose of given a beta blocker to anginal pts?
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They prevent increases in heart rate; this action keeps oxygen requirement reduced and prevents angina.
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What are 3 manifestations of abrupt withdrawal of beta blockers?
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1. Tachycardia
2. Hypertension 3. Angina |
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Why do tachycardia and HTN develop after abrupt withdrawal of a beta blocker?
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Cardiac beta receptors are up-regulated as a result of chronic beta blockage and are highly sensitive to catecholamines.
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What drugs are not appropriate for treating supraventricular tachycardia in the pt with bronchospastic disease? Why?
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Non-selective beta blockers, because B2 receptor blockage produces bronchoconstriction.
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Norepi released from sympathetic postganglionic nerve terminals has its actions terminated primarily by what mechanism normally?
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Reuptake.
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