E1- Adrenergic Blocking Agents Flashcards
What are possible effects of alpha blockers?
Decrease BP Reflex tachycardia Miosis Make it easier to urinate Inhibit ejaculation EPI reversal
What are possible effects of beta blockers?
Decrease rate and force of contraction in the heart Decrease O2 demand of heart Decrease renin secretion Cause bronchoconstriction Decrease glycogenolysis and lipolysis Inhibit insulin secretion Decrease intraocular pressure
Why should beta blockers and EPI never be given to someone with pheochromocytoma without concomitant administration of an alpha blockers?
Beta blockers will inhibit the vasodilation caused by B2 receptors, increasing the pressor effect of EPI
What should not be used in they eye because they will anesthetize the cornea?
Beta blockers
What is the only noncompetitive irreversible alpha blocker?
Phenoxybenzamine
What type of antagonist shifts the dose-response curve to the right, but the maximum effect is the same?
Competitive
What type of antagonist shifts the dose-response curve to the right, and the maximum effect is diminished?
Non-competitive
What are the two drugs classified as non-selective alpha receptor blockers?
Phentolamine
Phenoxybenzamine
What is Phentolamine used for?
Rarely used for short-term tx of HTN crisis
-Pheochromocytoma
-Pts on MAOIs who ingest tyramine
-After abrupt withdrawal from clonidine
To prevent necrosis if vasoconstrictor like NE is accidentally injected into tissues
What are contraindications of Phentolamine?
Caution in pts with CAD
What are side effects of Phentolamine?
Hypotension
Tachycardia
Arrhythmias
MI
What is Phenoxybenzamine used for?
DOC for prevention of severe hypertension in pheochromocytoma before surgery
What are side effects of Phenoxybenzamine?
Orthostatic hypotension
Tachycardia
Inhibit ejaculation
What are the two drugs classified as selective alpha 1 receptor blockers?
Prazosin
Tamsulosin
What is Prazosin used for?
1st choice for men with BPH and HTN
What are contraindications for Prazosin?
Combination with ED drugs and nitrates can lead to severe HTN
What are side effects of Prazosin?
Orthostatic hypotension
- Dizziness
- “First dose phenomenon”
Tachycardia
What are the two drugs classified as non-selective beta receptor blockers?
Propranolol
Timolol
What is propranolol metabolized by?
P450s
What is propranolol used for?
Post MI Increase exercise tolerance in angina pts Arrhythmias Heart failure (early stages only) Control hyperthyroidism sxs Migraine prevention Decrease catecholamine-induced tremor and stage fright HTN (chronic use)
What are contraindications of propranolol?
Acute HF, asthma, AV block, bradycardia, cardiogenic shock, pheochromocytoma
In which pts should you caution propranolol use?
COPD
Diabetics
What are side effects of propranolol?
Bronchoconstriction in asthma and COPD Exacerbate HF in late stages Bradycardia Sedation/fatigue Recovery from hypoglycemia more difficult/masks sxs
What is Timolol used for?
Glaucoma
In which pts should you caution Timolol use?
Athmatics
What are the four drugs cardio-specific beta 1 receptor blockers?
Metoprolol
Betaxolol
Esmolol
Nebivolol
What is the most selective beta 1 blocker/antagonist?
Nebivolol
What is Metoprolol used for?
Decrease rate and force of contraction of heart HTN Post-MI Angina Heart failure Migraine prophylaxis
What are contraindications of Metoprolol?
Acute HF, AV block, bradycardia, cardiogenic shock, pheochromocytoma
What medication is similar to Propranolol but has better exercise tolerance in angina and is safer in diabetics and asthmatics?
Metoprolol
What are side effects of Metoprolol?
Dizziness, bradycardia, hypotension
What is Betaxolol used for?
Glaucoma
In which pts should you caution Betaxolol use?
Asthmatics
What is Esmolol used for?
Used in critically ill pts where you don’t want the risk of lasting Beta blocker effects
Emergency situation where rapid effect is needed
What is Nebivolol used for?
Direct vasodilation (release NO from endothelial cells)
What are the two drugs classified as combined alpha 1 and beta blockers?
Carvedilol
Labetalol
What is Carvedilol used for?
Vasodilation w/o reflex tachycardia
HTN
Heart failure (especially after MI)
What are side effects of Carvedilol?
Orthostatic hypotension
Bronchoconstriction (don’t use in asthmatics)
What is Labetalol used for?
Vasodilation w/o reflex tachycardia
Lower BP in HTN emergency
HTN in pregnancy
What are side effects of Labetalol?
Orthostatic hypotension
Bronchoconstriction (don’t use in asthmatics)
Hepatotoxicity
What is the order of glaucoma tx?
- Prostaglandin analogues – initial DOC
- Beta blockers
•Timolol
•Betaxolol - Selective alpha 2 agonist
- Carbonic anhydrase inhibitors
- Cholinergic agonist
•Pilocarpine (last choice b/c blurs vision)
What are the main 4 responses to alpha blockade?
- Decreased vasoconstriction
- Reflex tachycardia
- Orthostatic hypotension
- Epinephrine reversal
What is the DOC is pheochromocytoma?
Phenoxybenzamine
What is the first dose phenomenon and what drug is it associated with?
- Bad orthostatic hypotension and syncope 30-90 minutes after first dose
- Associated with Prazosin
What are the cardiovascular effects of B blockade?
- Decreased chronotropy, inotropy, and dromotrpy
- decreased renin
- decreased O2 demand
- Decreeased CO2
- Decreaed BP when used chronically
How does beta blockade affect the endocrine system?
- inhibits glycogenolysis
- inhibits insulin secretion
- May cause hyperglycemia
What are the CYP50 inactivating drugs that you shouldn’t give with propranolol?
Cimetidine and chlorpromazine
What are the CYP450 inducers that you shouldn’t give with propranolol?
Barbiturates, phenytoin, and rifampin
