Adrenergic Antagonists Flashcards
Review: What are the adrenergic receptor types?
- a1 & a2
- b1 & b2
- D
Review: Where are adrenergic receptors present?
- PNS
- CNS
Review: What do adrenergic receptors bind?
- E
- NE
- DA
- other sympathomimetics
Review: What are the adrenergic actions on the CV system?
- a1 vasoconstriction, increase BP
- b1 increase HR and CO
- b2 vasodilation, decrease BP
- central a2 vasodilation
Review: What are the adrenergic actions on the respiratory system?
- a1 decongestion
- b2 bronchodilation
Review: What are the adrenergic actions on the eyes?
- a1 mydriasis, decrease redness
- a2 decrease IOP
Review: What are the adrenergic actions on the GU tract?
- b2 delays fetal delivery
Review: What are the adrenergic actions on the secretory glands?
- b increase apocrine sweat glands and salivary glands
Review: What are the adrenergic actions on metabolism?
- overall increase energy (breakdown stores)
- b increase glycogenolysis and lypolysis
- a2 decrease lipolysis
- b2 increase insulin release
- a2 decrase insulin release
Review: What are the adrenergic actions on the CNS?
- feelings such as wakefulness, nervousness, anorexia, & euphoria
What are the two types of alpha antagonists?
- reversible
- irreversible
What is the half life of a reversible alpha antagonist?
- short
Describe the binding of reversible alpha antagonists?
- compete with agonists and endogenous catecholamines
- easily bumped off when [high] agonist
What is a reversible alpha antagonists duration of action dependent on?
- receptor affinity
- half life
What is the half life of an irreversible alpha antagonist?
- long
Describe the binding of irreversible alpha antagoinists
- form covalent bonds with receptor to permanently block it
What is an irreversible alpha antagonists duration of action dependent on?
- synthesis of new receptors
What is the effect of a-antagonists in the CV system?
- block a1 mediated vasoconstriction
- leads to decreased peripheral vascular resistance and decreased BP
What are the side effects of a-antagonists in the CV system?
- orthostatic HTN
- tachycardia
What is the effect of a-antagonists on the eyes?
- block mydriasis –> miosis
What is the effect of a-antagonists on nose?
- block nasal vasoconstriction –> sinus congestion
What is the effect of a-antagonists on GU tract?
- block a-mediated urinary retention –> facilitates urination
What are examples of general a-antagonists?
- phenoxybenzamine (Dibenzyline)
- phentolamine (OraVerse)
What are the effects of phenoxybenzamine, a general a-antagonist?
- irreversible blockage of a1>a2
- blockade of vasoconstriction leading to vasodilation
- blocks presynaptic a2 receptors
What can general a-antagonist be used to treat?
- excessive catecholamine release (pheochromocytoma)
What are the effects of phentolamine, a general a-antagonist?
- reversible blockade of a1 and presynaptic a2
- a1 blocking effects include decrease peripheral vascular resistance
What are the general classes of a1 antagonists?
- suffix: -osin
What class is tamsulosin and how does it work?
- a1 antagonist
- relaxes arterial and venous smooth muscle and smooth muscle in prostate
What is a treatment for BPH?
- tamsulosin
What is a side effect of a1 antagonists?
HTN
How do b-receptor antagonists bind?
- reversibly
What is a “beta blocker”?
- b-antagonist in the CV system
What are beta blockers used for?
- controlling high BP
- angina, CHF, MI
How do beta blockers work?
- reduce cardiac workload by blocking peripheral b2 receptors to cause vasodilation
How do beta blockers help angina patients?
- improve the balance between O2 supply and depand
Beta blockers block the _________ effects that would occur under _________ conditions.
- adrenergic
- sympathetic
What are contraindicated in patients with asthma and COPD and why?
- beta blockers
- no pure b1 blockers available therefor condition could be worsened by ‘dirty’ actions of beta blockers
What clinical use do beta blockers have on the eye?
- tx open angle glaucoma
- decreases production of aqueous humor which reduces IOP
What are examples of beta blockers used for glaucoma?
- betaxolol (Betoptic)
- timolol (Timoptic)
- carteolol (Ocupress)
What are some unexpected effects of beta blockers?
- block glucose mobilization, consistent with a1
- worsen high cholesterol, not usually an issue since they are usually on a 2nd rx to lower cholesterol
- intrinsic sympathomimetic activity
- local anesthetic activty
What is a metabolic effect of beta blockers?
- block glucose mobilization
What are the effects of beta blockers on cholesterol?
- increase VLDL
- decrease HDL (not good)
Define intrinsic sympathomimetic activity (ISA)
- partial agonist of a beta blocker
What are the effects of ISA?
- decrease likelihood of negative features of beta blockers (i.e. bronchoconstriction and bradycardia)
- reduce therapeutic effects of beta blockers with ISA activity
What are drugs with ISA activity?
- labetalol
- pindolol
- acebutolol
How do beat blockers achieve local anesthetic qualities?
- block Na+ channels in nerve axons, prevents depolarization and transfer of information
What are the clinical indications for beta blocker use?
- HTN
- ischemic heart dz
- arrhthmias
- heart failure
- glaucoma
- migraine H/A
- performance anxiety
What determines if a patient should be using beta blockers for HTN as their 1st line option?
- “compelling indications”
- i.e. heart failure, post-MI, angina, diabetes and more
What are the #1 and #2 beta blockers for HTN?
- metoprolol (Lopressor, Toprol)
- atenolol (Tenormin)
How do beta blockers treat ischemic heart disease?
- b1 blockers decrease cardiac workload via decreased HR and strength of squeeze
- results in less O2 demand making the available O2 enough
What are beta blockers that are used to treat ischemic heart disease?
- propranolol (Inderal)
- metoprolol (Loressor)
Define arrhytmia
- abnormal electrical rhythms in cardiac m.
How do beta blockers treat arrhythmias?
- suppress supraventricular and ventricular arrhythmias
- extend resting period of AV node
- slows ventricular response
What are examples of beta blockers that treat arrhythmias?
- metoprolol (Lopressor)
- sotalol (Betapace)
What is the general effect of beta blockers on the heart?
- decrease HR
T/F: Beta blockers are useful in patients with acute heart failure.
- False, chronic
What is the effect of beta blockers on the eye?
- decrease aqueous humor to decrease IOP
How are beta blockers useful to treat hyperthyroidism?
- decrease symptoms by blocking adrenergic receptors
- decrease the conversion of T4 to T3
How are beta blockers helpful in treating migraine H/As?
- reduce frequency and/or intensity
How are beta blockers helpful in treating performance anxiety?
- slows HR
- reduces palmar sweating
How are beta blockers helpful in treating hepatic disease?
- reduce elevated BP, specifically in portal vein
What are the major unwanted side effects of beta blockers?
- bradycardia
- worsening of asthma
- worsening of CO in patients with heart failure
- exacerbation of hypoglycemia in diabetics
What are the minor unwanted side effects of beta blockers?
- mild sedation
- vivid dreams
- depression
What drug typically gives minor unwanted side effects?
- propranolol
T/F: Beta blockers cannot be stopped abruptly.
- True
What is a risk of abruptly stopping a beta blocker?
- rebound HTN
How do you choose a beta blocker?
- *clinical studies**
- safety issues
- partial agonist activity
- differences in metabolism
- differences in elimination half-life
What metabolizes ACh?
- AChE
What metabolize NE, E, and DA?
- MAO
- COMT
What does NET do?
- decreases NE
- reuptakes NE
What occurs with a1 receptors are stimulated inthe CV system?
- vasoconstriction
What occurs with a2 receptors are stimulated in the CV system?
- peripheral: vasoconstriction
- central: vasodilation to lower BP
What occurs with b1 receptors are stimulated in the CV system?
- increase HR
- increase contractility
Where are b1 receptors mostly located in the CV?
- heart
What occurs with b2 receptors in CV system?
- vasodilation to decrease BP
Where are b2 receptors found in the CV system?
- peripherally
What is the effect of an adrenergic antagonist (a1 antagonist) on the CV system?
- vasodilation
What is the effect of an adrenergic antagonist (b1) on the CV system?
- decrease HR
- decrease contractility
What is the effect of an adrenergic antagonist on the lungs?
- bronchoconstriction
What is the effect of an adrenergic antagonist on glucose in blood?
- blocks mobility
- blocks lipolysis
- blocks availability of glucose