Flashcards in Adrenergic Antagonists Deck (92):
What is a synonym for adrenergic antagonists?
What are the 2 broad classes of alpha-receptor antagonists?
Who do alpha-receptor reversible antagonists compete with?
Describe the mechanism of alpha-receptor reversible antagonists
block receptor and dissociate if agonist is present in high enough concentration
What is a alpha-receptor reversible antagonist duration of action dependent on?
drug's affinity for receptor
1/2 life of drug in the body
How do alpha-receptor irreversible antagonists bind?
form covalent bonds = permanent block
What is the alpha-receptor irreversible antagonist duration of action dependent on?
dependent on synthesis of new receptors (up to several days)
What do alpha-antagonists do in the cardiovascular system?
block alpha1-mediated vasoconstriction --> vasodilation --> decrease in peripheral vascular resistance and decrease in BP
What is a side effect of alpha-antagonists in the cardiovascular system?
orthostatic hypotension (body's ability to adjust peripheral vascular resistance has been blocked
reflex tachycardia (response to maintain cardiac output; compensatory mechanism to drop in BP)
What are some other effects of alpha1 antagonists?
block mydriasis --> mitosis
block nasal vasoconstriction --> sinus congestion
block alpha-mediated urinary retention --> facilitates urination
What is phenoxybenzamine and what does it do?
irreversible blockade of alpha1 receptors (more so than alpha2 receptors)
What is the effect of phenoxybezamine?
blocks vasoconstriction --> vasodilation
also blocks presynaptic alpha2 receptors (blocks reuptake of norepinephrine (not as potent an effect))
What is phenoxybezamine used to treat?
conditions of excessive catecholamine release --> pheochromocytoma (adrenal gland tumor)
What are the symptoms of pheochromocytoma that are treated by phenoxybezamine?
over secretion of norepinephrine and epinephrine --> hypertension, headaches, palpitations, sweating
What is phentolamine?
reversible blockade of alpha1 receptors and presynaptic alpha2 receptors
What is the effect of phentolamine?
alpha1 blocking = decrease peripheral vascular resistance
alpha2 blocking due to increase in cardiac stimulation --> increase HR increase cardiac workload, potential for arrhythmias (due to increase norepinephrine activity b/c blocked norepinephrine reuptake)
What is phentolamine used for?
management of pheochromocytoma
What are some other examples of alpha1 antagonists?
What is a side effect of prazosin?
What is tamsulosin used for?
What is the effect of tamsulosin?
relaxation of arterial/venous smooth muscle --> HTN
relax smooth muscle in prostate (most selective for this)
Some drugs have alpha1 antagonistic as a secondary mechanism of action, in these drugs what is the side effect that you'll most likely see?
What are some examples of drugs that have alpha1 antagonistic side effects and what are they usually used for?
Haloperidol = antipsychotic
Chlorpromazine = antipsychotic
Trazodone = sleep aid and antidepressant
Ergotamine and dihydroergotamine = migranes
How do beta-receptor antagonists bind to their receptors?
Are beta-receptor antagonists pure antagonists?
Most are, however some do have some beta-agonist activity (but usually only w/ low concentrations of endogenous catecholamines)
some have local anesthetic properties
Can beta-receptor antagonists be selective?
Yeah, differ in affinity and selectivity for blocking beta1 or beta2
However, selectivity will decrease w/ higher doses
Are there pharmacokinetic differences between beta-receptor antagonists?
Yeah, differences between distribution, 1/2 life, and elimination route
What are beta antagonists usually called in the cardiovascular system?
What are beta antagonists used for in the cardiovascular system?
control high BP
What is the mechanism of action of beta-antagonists in the control of high BP?
complex and unclear mechanism
suppression of renin release
debatable first-line agent for high BP
What is the mechanism of action of beta antagonists in the control of angina, CHF, MI?
part of first-line therapy
reduce cardiac workload (negative inotropic, negative chronotropic effects)
slow AV node conduction --> decrease HR
suppress renin release
What is the net effect of beta-antagonists in the treatment of angina, CHF, or MI?
reduce peripheral vascular resistance, BP, overall workload of the heart
Why is it surprising that beta-antagonists (or blockers) decreases BP?
block peripheral Beta2 receptors --> expect inhibit vasodilation BUT w/ long term use BP decreases (unclear mechanism)
What can enhance vasodilation properties of beta antagonists?
drugs that also block alpha1 receptors
nonselective agents --> greater drop in BP b/c block vasoconstriction
What is an example of a nonselective adrenergic antagonist that is used to treat high BP?
labetolol --> blocks alpha and beta; blocks vasoconstriction
Why are beta antagonists used to treat angina?
help pts by improving balance between oxygen supply and demand
Describe the mechanism of beta blockers when treating angina
block adrenergic effects of sympathetic nervous system --> reduce cardiac workload --> reduce demand of oxygen
improves exercise tolerance by preventing heart from working to hard
Why are beta antagonists contraindicated for use in pts w/ asthma and COPD?
No pure beta1 blockers available --> inadvertently block beta2 receptors (which facilitate bronchodilation)
Which class of drugs would you want to use to treat COPD and asthma instead of beta antagonists?
Which opthalmic disease are beta blockers used to treat?
open-angle glaucoma --> reduce production of aqueous humor --> reduce intraocular pressure
What are some examples of beta blockers that are used to treat glaucoma and how are they given?
What are some side effects of beta blockers?
block glucose mobilization
worsen high cholesterol
intrinsic sympathomimetic activity
local anesthetic activity
What does it mean to block glucose mobilization?
reduce energy availability
inhibit sympathetic-mediated stimulation of lipolysis
partial inhibitor of glycogenolysis --> block body's availability to make glucose when needed (hypoglycemia)
Why would you want to use caution with beta blockers use in an insulin dependent diabetics?
beta blockers mask symptoms of hypoglycemia --> pts won't know when sugars drop
Hypoglycemic symptoms= tachycardia/sweating
What are some of the cholesterol issues caused by beta blockers?
some types of stored cholesterol levels are altered --> increase cardiovascular risk and coronary artery disease
increase VLDL (very low density lipoproteins aka bad kind)
decrease HDL (high density lipoproteins aka good kind)
Which types of beta blockers can cause cholesterol issues?
Both selective and nonselective beta blockers
Which types of beta blockers have intrinsic sympathomimetic activity (ISA)?
beta blocker that has partial beta agonist activity (structural thing)
What is a good thing about about intrinsic sympathomimetic activity?
may decrease negative features of beta blockers --> i.e. bronchoconstriction and bradycardia
What is a bad thing about intrinsic sympathomimetic activity?
may reduce the therapeutic effects of beta blockers --> especially cardioprotective benefits
What are 3 examples of beta blockers with intrinsic sympathomimetic activity?
What is another term for local anesthetic action of beta blockers?
What is the mechanism of local anesthetic action of beta blockers?
blockade of Na+ channels in axon of nerves --> prevent electrolytic excitation of the nerve/depolarization/transfer of sensation info
What are some examples of beta blockers with local anesthetic action?
What are the 7 major uses of beta blockers?
Ischemic heart disease
When are beta blockers considered a first line option in treating hypertension?
in patients w/ compelling indications (comorbidities)
What are the comorbidities that indicate use of beta blockers in treatment of hypertension?
What are considered the most important beta blockers used for hypertension?
Name the other beta blockers used for hypertension?
Would you use beta blockers to treat hypertension if a patient didn't have the comorbidities?
No --> beta blockers aren't considered first line for these patients
What causes ischemic heart disease?
cholesterol plaques in cardiac arteries--> decrease blood flow and oxygen delivery
What types of symptoms would pts with ischemic heart disease have?
Poor exercise tolerance
What are the effects of beta blockers in patients with ischemic heart disease?
decrease cardiac workload (slow HR, decrease strength of heart squeeze) --> less demand for O2 (limited supply meets less demand)
When are beta blockers considered first line to treat ischemic heart disease?
pts @ risk or after MI
history of angina
history of left ventricular dysfunction
What are the 2 beta blockers used to treat ischemic heart disease?
What is an arrhythmia?
abnormal electrical rhythm w/in the heart muscle
decrease heart functionality
can be fatal
What types of arrythmias are beta blockers used to treat?
What are the physiologic effects of beta blockers that are useful in the treatment of arrhythmias?
extend the resting period of AV nodal cells
slow ventricular response to electrical stimulation --> stop abnormal rhythm (hopefully)
Are beta blockers the first line treatment of arrhythmias?
No, usually used after other meds have failed
What are the 2 beta blockers that are used to treat arrythmias?
Which type of heart failure are beta blockers used for?
CHRONIC heart failure
What are some examples of beta blockers that are used to treat chronic heart failure?
What type of eye disease are beta blockers used to treat?
What is the method of administration of beta blockers when treating glaucoma?
administered directly to the eye
What are the effects of beta blocks in the eye (aka why are they used to treat glaucoma)?
inhibits the production of aqueous humor
What are some examples of beta blockers that are used to treat glaucoma?
What are some of the side effects of beta blockers that are used to treat glaucoma?
cardiac/pulmonary effects --> systemic absorption
What is hyperthyroidism (very general), and what can it lead to?
lead to excessive catecholamine action --> tachycardia
What are the effects of beta blockers that are useful in treating hyperthyroidism?
decrease symptoms by blocking adrenergic receptors
decrease conversion of thyroxine (T4) --> triiodothyronine (T3) (t3 = active thyroid hormone)
What is an example of a beta blocker that is used to treat hyperthyroidism?
Which beta blockers are used to treat migraine headaches?
How do beta blockers treat migraine headaches?
reduce frequency and/or intensity
What is a synonym of performance anxiety?
How do beta blockers treat performance anxiety?
eliminate symptoms induced by stress and anxiety:
reduce palmar sweating
What are some complications of liver disease?
portal vein hypertension
What are some effects of beta blockers that are useful in treating hepatic diseases?
can have targeted effect to reduce the elevated BP
What are 2 beta blockers that are used to treat hepatic disease?
What are some major side effects of beta blockers?
Worsening of asthma (beta2 in lungs)
worsen cardiac output in pts w/ heart failure
exacerbation of hypoglycemia in diabetics
What are some of the minor/less common side effects of beta blockers?
Overall why do you want to use caution with the use of beta blockers?
the response of pts to beta blockers can be unpredictable
What is the most important thing about stopping the use of beta blockers?
NEED TO TAPER PTS OFF BETA BLOCKERS
Why do you need to taper pts off of beta blockers?
abrupt discontinuation can lead to rebound hypertension (esp. in pts being treated for ischemic heart disease or hypertension)