unit 4.7 chapter 20 adrenergic blocking drugs

Question Answer
adrenergic blockers also referred to as sympatholytics – because they lyse, or inhibit SNS stimulation
a2 are located in the actual nerves that stimulate the presynaptic effector cells
a2 receptor cells are inhibitory in nature
a-blockers work either by direct competition with norepinephrine or by a noncompetitive process
a- blockers have a greater affinity for the a-adrenergic receptor than norepinephrine does, and therefore can chemically displace norepinephrine molecules from the receptor
selective adrenergic blockade lease to vasodilation, reduced blood pressure, constriction of pupil, reduced smooth muscle tone in organs such as bladder and prostate
a- blocker drugs alfuzosin, doxazosin, prazosin, and terazosin
a-blockers action cause both arterial and venous dilation, which reduces systemic vascular resistance and BP
a-blockers are used to treat hypertension, benign prostatic hyperplasia(BPH to decrease resistance to usinary outflow)
tamosulosin and alfouzosin are exclusively used to treat benign prostatic hyperplasia (BPH)
used to prevent skin necrosis and sloughing after the extravasation (infiltration) of vasopressors such as norephinephrine and epinephrine
when epinephrine and norepinephrine extravasate (leak out of the blood vessel int the surrounding tissue) they can cause vasoconstriction and ultimately tissue death or necrosis, if the vasoconstriction is not reversed quickly an entire limb can be lost
contraindications of a-blocking drugs include drug allergy, and peripheral vascular disease, may also include liver or kidney disease, coronary artery disease, peptic ulcer, and sepsis
ADE of a- blockers first dose phenomenon – sudden drop in BP. Orthostatic hypotension-
B-adrenergic blocking drugs block SNS stimulation of the B-adrenergic receptors by competeing with norepinephrine and epinephrine
B-blockers can either be selective of nonselective, depending on the type of B-adnergic receptor they antagonize
B1-blockers that are selective for the heart are called cardioselective _-blockers or B1-blocking drugs
other B-bockers block both B1- and B2 adrenergic receptors and are referred to as nonselective B-blockers
intrinsic sympathomimetic activity drugs not only block B-adregenergic receptors but also partially stimulate them (acebutolol, pindolol)
cardioselective B1-blockers block the B1-receptors on the surface of the heart – reduces myocardial stimulation, which in turn reduces heart rate, slows conduction through AV and SA node
the result of B2 receptor blockage smooth muscle contraction of the bronchioles, narrowing of the airways leading to shortness of breath
when B2 stimulation is blocked the muscles are then stimulated by unopposed sympathetic activity at the B1 receptors which causes them to contract – this causes systemic vascular resistance
catecholamines also promote glycogenolysis – the production of glucose from glycogen dn mobilize glucose in response to hypoglycemia
non-selective B-blockers impair the process of glycogenolysis from catecholamines and impede the secretion of insulin from the pancreas, which causes elevation of blood glucose level
B-blockers can cause the release of free fatty acids from adipose tissue, which may result in moderately elevated blood levels of triglycerides and reduced levels of HDL
B-blocker indications include angina, myocardial infarction, cardiac dysrhythmias, hypertension, and heart failure
B-blockers posess anti-ischemic, antiatherogenic, and antidysrythmIc properties
B-blockers work by dec the demand of myocardial energy and O2 consumption, which helps to shift the supply ad demand ratio to the supply side = more O2 to reach heart
B-blockers are also considered to be cardioprotective because they inhibit stimulation by the circulating catecholamines
Myocardial infarction causes catecholamines to be release
unopposed stimulation by catecholamines would further increase the heart rate and the contractile force, thereby increasing myocardial oxygen demand
the AV node normally receives impulse stimulation from the SA node and slows it down so that the ventricles have time to full before they are stimulated to contract
conduction in the SA node also spontaneously depolarizes at the most frequent rate is slowed by B-blockers
B-Blockers also slow conduction through the AV node
the effects on the conduction system of the heart make B-blocker drugs useful in the treatment of various types of irregular heartbeat rhythms called dysrhythmias
the form of heart failure that includes the component of diastolic disfunction responds favourably to B-blockers
because of their lipophilicity some B-blockers can easily gain entry into the CNS and are used fr the prophylaxis of migraine headaches rather than for acute attacks
contraindications for B-blockers allergy, acute decompensated heart failure, cariogenic shock, heart block or bradycardia, pregnancy, severe pulmonary disease, Rauaud's disease
ADE of B-blockers can be caused by acute withdrawal of the drug – can exacerbate underlying angina and precipitate a MI
B2-receptor blocking can cause hypoglycemia – due o B2 receptors inducing glucose production ad pancreatic release of glucagon and delivering glucose to the system
B-blockers can also cause delayed recovery rom hypoglycaemia in patients with type 1 diabetes
B-blockers can interfere with normal responses to hypoglycaemia, such as tremor, tachycardia and nervousness masking the signs and symptoms of hypoglycemia
non-selective B-blockers are thought to contribute to the development of hyperglycaemia buy impairing the release of insulin from the pancreatic B-cell
a- receptor blockig effects blood vessels
B1 receptor blocking affect heart rate
B2 blocking affects bronchial smooth muscle
non-selective adrenergic blocker will have the following actions a-blocking leading to blockade of the sympathetic stimulation of blood vessels, resulting in vasodilation and decrease in BP
second action of non selective adrenergic blocking drugs B1-blocking-effecting heart contractility, and conduction = bradycardia, decrease contractility and conduction
third action of non selective adrenergic blocking drug B2- blocking leading to blockade on bronchial smooth muscle with the net effect on the bronchoconstriction.
B- blockers may precipitate bradycardia, hypotension, or increased airway resistance.
patient with a history of asthma, emphysema, bronchitis or any condition unbolting increased airway resistance or branchochonstriction can not take B2-blockig drugs without experiencing further bronchoconstriction and negative effects on their underlying disease condition
important to also assess intake and output, daily weights, breath sounds, and blood glucose levels(Especially if the patient has diabetes)
patients taking a-blockers need to aboid alcohol, excessive exercise, exposure to hot climates, and use of saunas or hot tubs, hot showers and baths (anything that causes vasodilation)
phentolamine mesylate (Rogitine) classification a- blocker that reduces systemic vascular resistance and is sometimes used to treat hypertension
phentolamine mesylate (Rogitine) used to treat high BP caused by pheochromocytoma and also in the diagnosis of catecholamine secreting tumour
phentolamine mesylate (Rogitine) is also used to treat extravasation or vasoconstriction IV drugs (norepinephrine, epinephrine, dopamine) = vasodilation and increased blood flow to ischemic tissue
phentolamine mesylate interacts with drugs alcohol, and erect dysfunction meds (causing hypotensive effects)
tamsulosin hydrochloride classification is an a-blocker used primarily to treat BPH and is exclusively indicated for male patients
tamosulin hydrochloride action block a-adrenergic receptors in the smooth muscle within the prostate and bladder = relaxation of smooth muscle fibres and improved urinary flow
atenolol (Tenormin) classification cardioselective B-blocker that is commonly used to prevent future MI, and hypertension and angina
carvedilol classification non selective B-blocker and a1-blocker and a calcium channel blocker (At high doses)
carcedilol primarily used for heart failure, but also beneficial in the treatment of hypertension and angina
esmolol hydrochloride (Brevibloc) classification strong short acting B1-blocer primarily used in acute situations to provide rapid temporary control od the vernacular rate in tachydysrhythmias
laberalol hydrochloride (Trandate) can block both a- and b- receptors – used in treatment of severe hypertension and hypertensive emergencies to lower BP before damage occurs
metropolol tartare (Lopressor) classification is a B1-blocker that is a favourite for cardiologists in MI
propranolol hydrochloride (Inderal) classification prototypical nonselective B1 and B2 blocker.
Propranolo hydrochloride used in treatment of tachydysrhythmias associated with cardiac glycoside intoxication and for treatment of hypertrophic sub aortic stenosis…
sotalol hydrochloride (Rylosol) classification nonselective B-blocker that has potent antidysrhythmic properties.
sotalol hydrochloride (Rylosol) used in management of difficult to treat dysrhythmias -only used in select patients due to ADE

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