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97 Cards in this Set

  • Front
  • Back
What is pheochromocytoma?
A condition with an adrenal gland tumor that secrete catecholamines.
How do A&B blockers work?
They prevent interaction of endogenous norepi or other sympathomimetics with adrenergic receptors.
What effect does norepi blockade have?
It decreases the effect of SNS homeostatic mechanisms.
What are some side effects of alpha blockers?
1. Impotence
2. Postural hypertension
3. Reflex tachycardia
How do alpha blockers work?
They prevent catecholamines or sympathomimetics from provoking alpha responses.
How do alpha blockers affect insulin?
Inhibition of insulin secretion is abolished; therefore insulin is secreted.
What effect does beta stimulus have on the heart?
It causes cardiac stimulation.
What are the hemodynamic effects of blocking the alpha receptor?
1. Vasodilation
2. Hypotension
3. Increased heart rate
4. Decreased peripheral vascular resistance
Name some competitive alpha antagonists.
1. Phentolamine
2. Prazosin
3. Yohimbe
What alpha antagonist forms a covalent bond?
1. Phenoxybenzamine
Which alpha blockers are nonselective?
1. Phentolamine
2. Phenoxybenzmine
Which alpha blockers are selective?
1. Prazosin
2. Yohimbe
Which alpha receptor is prazosin selective towards?
Postsynaptic alpha 1
Which alpha receptor is yohimbe selective towards?
Presynaptic alpha 2
List the alpha antagonists.
1. Phentolamine
2. Phenoxybenzamine
3. Yohimbe
4. Prazosin
What is the mechanism of action of phentolamine?
Produces peripheral vasodilation and decreased SBP.
What effect does phentolamine have via A1 blockade?
Direct action in vascular smooth muscle.
What effect does phentolamine have via A2 blockade?
1. Neural release of norepi
2. Increased heart rate
3. Increased cardiac output
What are some parasympathetic side effects of phentolamine?
1. Hyperperistalsis
2. Abdominal pain
3. Diarrhea
How is phentolamine metabolized?
By the liver.
What are the clinical uses of phentolamine?
1. Acute hypertensive emergency
2. Pheochromocytoma
3. Autonomic nervous system hyperreflexia
4. Local administration for sympathomimetic that is administered accidentally
Although phenoxybenzamine is a non-selective alpha blocker, it has a greater affinity for?
Postsynaptic A1 receptors.
What are the cardiovascular effects of phenoxybenzamine?
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
What are some non-cardiac effects of phenoxybenzamine?
1. Prevents inhibition of insulin secretion by epi
2. Miosis
3. Sedation in chronic tx
4. Nasal stuffiness
What is epi's effect on insulin?
Epi usually inhibits the release of insulin release so that more glucose goes to the brain during fight or flight situations.
What are the clinical uses of phenoxybenzamine?
1. Pre-op med for pheochromocytoma
2. Reynaud's syndrome (increases cutaneous blood flow)
What are clinical uses of yohimbe?
1. Idiopathic orthostatic hypotension
2. Impotence
What side effects may occur with increased doses of yohimbe?
1. Tachycardia
2. Hypertension
3. Rhinorrhea
4. Dissociative states (crosses BBB)
What effect does yohimbe have on anesthesia?
The actions on presynaptic alpha 2 receptors decreases anesthetic requirements.
What are clinical uses of prazosin?
1. Raynaud's syndrome
What effect does Prazosin have on the cardiovascular system?
Produces dilation of arterioles and veins.
How is prazosin metabolized?
By the liver.
How do beta blockers work?
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
Should beta blocker be continued during the perioperative period?
Yes
What is considered the standard beta blocker?
Propanolol
Beta blockers are competitive inhibitors; what does this mean?
They are reversible - large amounts of agonists would replace them at the receptor sites.
What happens with chronic tx or beta blockers?
Up-regulation of beta adrenergic receptors.
What type of receptors are beta adrenergic receptors?
G protein coupled receptors.
What percentage of beta blockers are B1 vs B2?
75% are B1
20% are B2
Beta blockers are derivatives of what drug?
Isoproterenol
What beta blockers are non-selective?
1. Propanolol
2. Nadalol
3. Timolol
4. Pindolol
What beta blockers are cardio-selective?
1. Atenolol
2. Acebutolol
3. Betaxolol
4. Bisoprolol
5. Metoprolol
6. Esmolol
Where do cardio-selective beta blockers bind?
B-1 receptors
What does the selectivity of beta blockers depend on?
The dose given. You will lose selectivity with large doses.
What are the effects of B1 blockade?
1. Slows sinus rate
2. Slows conduction through AV node
3. Decreases contractility
4. Increases diastolic perfusion time
What things should you consider with B1 selective blockers?
1. Reactive airway
2. PVD
What determines adequate tx with propanolol?
A resting heart rate of 55-60 bpm.
What are the B1 cardiac effects of propanolol?
1. Decreased HR
2. Decreased myocardial contractility
3. Decreased cardiac output
What are the B2 cardiac effects of propanolol?
1. Increased peripheral vascular resistance
2. Increased coronary vascular resistance
What are the pharmacokinetics of propanolol?
1. 90-95% hepatic first pass effect with oral dose
2. 90-95% extensively bound to protein
3. Hepatic metabolism
What effect does propanolol have on local anesthetics?
It decreases the clearance of amides by decreasing hepatic blood flow and liver metabolism.
What effect does propanolol have on opioids?
It decreases pulmonary first-pass uptake of fentanyl.
Which beta blocker is most recommended by cardiologists?
Metoprolol
What is a clinical use for timolol?
Its used in glaucoma to decrease production of aqeous humor
What side effects are caused by systemic absorption of timolol?
1. Bradycardia
2. Airway resistance
What type of beta blocker is metoprolol?
1. Selective B1 with intact B2 blockade
Which is the most selective B1 beta blocker?
Atenolol
What are clinical uses of atenolol?
1. Prevention of MI
2. Hypertension
How is atenolol administered for prevention of MI?
Via IV before and immediately after surgery.
What are some pharmacologic features of esmolol?
1. Rapid onset
2. Short onset
3. Rapid hydrolysis via plasma esterases
4. Elimination half time of 9 minutes
5. Does not cross BBB
What are some clinical uses of esmolol?
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
Where do beta blockers exert their most prominent pharmacologic effects and side effects?
On the cardiovascular system.
Can beta blockers cause hypoglycemia?
Yes
What are some contraindications to administering beta blockers?
1. Preexisting AV heart block
2. Cardiac failure not caused by tachycardia
3. Hypovolemia
4. COPD
5. Diabetes
What is the specific reason for avoiding beta blockers in diabetics?
They may mask signs of hypoglycemia by blunting tachycardia reflex.
What are some general side effect of beta blockers?
1. N&V
2. Diarrhea
3. Thrombocytopenia
What are some cardiac side effects of beta blockers?
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
What are the usual clinical manifestations of excessive myocardial depression caused by beta blockers?
1. Bradycardia
2. Low cardiac output
3. Hypotension
4. Cardiogenic shock
What meds should be used to treat excessive myocardial depression by beta blockers?
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)
What should be done if beta blocker induced bradycardia does not respond to medication?
1. Placement of a transvenous artificial pacemaker
2. Possible hemodialysis
How do beta blocker affect potassium?
1. Inhibits uptake of potassium into skeletal muscle
2. Hyperkalemia with non-selective beta blockers.
How do beta blockers interact with anesthesia?
1. Myocardial depression with inhaled agents (esp with timolol)
2. Additive cardiovascular effects:

Ketamine>Enflurane>Halothane>Opioids>Isoflurane
What effect may chronic tx with propanolol cause to the nervous system?
Fatigue and lethargy
What effect do beta blockers have on the fetus?
They may cross the placenta and affect the newborn:

1. Bradycardia
2. Hypotension
3. Hypoglycemia
What can happen with acute withdrawal of beta blockers?
Excess SNS reactivity for 24-48 hours dues to up-reguation.
What are some general clinical uses of beta blockers?
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
Name the combined alpha & beta blockers?
1. Labetolol
2. Carvedilol
Which receptors does labetolol work on?
1. Selective alpha1
2. Non-selective beta
How does the sparing of presynaptic A2 receptors by labetolol exert an affect?
Released norepi can continue to inibit further release of catecholamines via negative feedback resulting from stimulation of A2 receptors.
How is labetolol metabolized?
Conjugation of glucuronic acid.
What are the cardiovascular effects of labetolol?
1. Decreased SBP without reflex tachycardia
2. Vasodilation via A1 and B2
What are the clinical uses of labetolol?
1. Hypertensive emergencies
2. Severe hypertension
3. Rebound hypertension
4. Pheochromocytoma
5. Angina
What are the side effects of labetolol?
1. Orthostatic hypotension
2. Bronchospasm
3. CHF
4. Heart block
5. Fluid retention
Which receptors does Carvedilol work on?
1. Non-selective beta
2. A1
What are the clinical uses of carvedilol?
1. Mild to moderate CHF due to ischemia or cardiomyopathy
2. Essential HTN
What are 2 major cardiovascular actions of competitive alpha blockers?
1. Decreased BP secondary to vasodilation
2. Reflex tachycardia
How does phentolamine produce tachycardia?
Release of norepi from sympathetic postganglionic nerve terminals owing to A2 blockade.
How does A2 receptor blockade of sympathetic nerve terminals by an alpha blocker like phentolamine alter the release of norepi?
It increases the release of norepi.
What two alpha blockers can be used preoperatively to control blood pressure in the pt undergoing surgery to remove a pheochromocytoma?
1. Phenoxybenzamine
2. Prazosin
Why is prazosin a better choice of treating pts with CHF than a non-selective alpha blocker?
Prazosin:

1. Produces vasodilation without increase release of norepi
2. Less likely to evoke tachycardia secondary to increased release of norepi
List 5 side effects of beta blockers.
1. Heart block
2. Worsening of CHF
3. Bronchospasm
4. Coronary artery constriction
5. Inhibition of insulin release
How does propanolol decrease myocardial oxygen consumption?
1. Decreasing HR
2. Decreasing myocardial contractility
What is the purpose of given a beta blocker to anginal pts?
They prevent increases in heart rate; this action keeps oxygen requirement reduced and prevents angina.
What are 3 manifestations of abrupt withdrawal of beta blockers?
1. Tachycardia
2. Hypertension
3. Angina
Why do tachycardia and HTN develop after abrupt withdrawal of a beta blocker?
Cardiac beta receptors are up-regulated as a result of chronic beta blockage and are highly sensitive to catecholamines.
What drugs are not appropriate for treating supraventricular tachycardia in the pt with bronchospastic disease? Why?
Non-selective beta blockers, because B2 receptor blockage produces bronchoconstriction.
Norepi released from sympathetic postganglionic nerve terminals has its actions terminated primarily by what mechanism normally?
Reuptake.