Symp Nervous System II by Prof. Krouse Flashcards
What does Phenoxybenzamine treat?
What is its mechanism of action?
What is its unique aspect in this mechanism of action?
pheochromocytoma, acute/chronic hypertension
Nonselective alpha antagonist – causes a drop in BP
irreversible covalent bond
What does Phentolamine treat?
What is its mechanism of action?
Is it competitive and reversible?
What is its toxicity profile?
pheochromocytoma
Non selective alpha antagonist – causes drop in BP followed by a reflex tachycardia
Yes
hyptotension, tachycardia, arrythmias, myocardial infarction
What does Prazosin treat?
What is its mechanism of action?
What is unique about its effect?
Hypertension and BPH
Alpha1 selective antagonist
No reflex tachycardia
Why doesn’t reflex tachycardia occur in patient who use prazosin?
Phentolamine (non-selective, alpha1- and alpha2-blocker) causes a fall in BP with reflex tachycardia. Whereas Prazosin and Terazosin are selective alpha1-blockers. It is thought that since they leave the presynaptic alpha2-receptors operational, this prevents the reflex tachycardia.
What is the toxicity profile of alpha blockers?
- postural hypotension (very marked) all agents
- reflex tachycardia, arrhythmias, myocardial infarction
- ↓ plasma lipids
- impotence (significant with phenoxybenzamine)
- headache, dizziness, nausea, drowsiness
Propranolol is used to treat?
Selective or Non Selective X Blocker?
LA or no LA action?
Partial agonist activity?
Hypertension, angina, arrythmias
Non selective Beta Blocker
LA-action
No ISA
What is Pindolol treat?
What’s special about its developmental history?
Does it stabilize the membrane?
Hypertension, angina
1st drug developed as a partial agonist (ISA)
Yes
What is the difference between Metoprolol and Atenolol? What are their similarities?
Metoprolol has LA-action; atenolol does not.
Both are B1 selective blockers used to treat hypertension, angina, and arrythmias.
Both lack ISA.
What does timolol treat?
Chronic treatment of Glaucoma
What are the similarities between Labetalol and Carvedilol?
What are their differences?
Both are A AND B blockers used to treat hypertensive crises.
Labetalol has some B-agonist activity.
What drug would you use for arrythmia?
B1 selective blocker like Metoprolol
What drug would use for angina? How does it work?
Any (Non-selective or selective) beta blocker
decreases O2 demand more than 02 supply
Which beta blockers would you use to treat CHF?
Carvedilol, labetalol, metoprolol
In what situations is a beta blocker for CHF contraindicated?
unstable CHF, significant bronchospasm, bradycardia or depression
Why is propranolol never used in acute hypertensive crises?
What is the one exception to this rule?
The main problem with pheochromocytoma is the high BP not the tachycardia. If a
beta-blocker is given alone, you allow the alpha1-activity of the catecholamines to act
unopposed. This would increase the BP still further. Beta-blockers can safely be given after the
BP has been stabilized with an alpha-blocker.
Labetalol (beta- and alpha-blocker) can be given alone to treat the crisis
