Chp 19 Adrenergic-Blocking Drugs Flashcards
How do adrenergic blockers work?
by binding to adrenergic receptors and inhibiting or blocking stimulation of the sympathetic nervous system. (opposite effect of adrenergic drugs)
What are adrenergic blockers also known as?
Adrenergic antagonists
sympatholytics
Alpha blockers, beta blockers, or alpha-beta blockers
How are adrenergic blockers classified?
by the type of adrenergic receptor they block (alpha1 and alpha2 receptors; beta1 and beta2 receptors)
What are the effects of alpha blockers?
they cause both arterial and venous dilation, reducing peripheral vascular resistance and BP.
What are alpha blockers used to treat?
- hypertension
- hyperplasia
- hypertension in patients with pheochromocytoma
- counteracting the effects of injected epinephrine and norepinephrine
What drug is used to counteract the effects of injected epinephrine and norepinephrine and how does it work?
Phentolamine - restores blood flow and prevents tissue necrosis
pheochromocytoma
a rare, usually noncancerous (benign) tumor that develops in an adrenal gland. Usually, this type of tumor affects one of your two adrenal glands, but it can affect both.
How does phentolamine work to diagnose the presence of pheochromocytoma?
A single IV dose of phentolamine is given to the hypertensive patient. If the blood pressure declines rapidly, it is highly likely that the patient has a pheochromocytoma.
What are some adverse effects alpha blockers can have on the cardiovascular system?
palpitations, orthostatic hypotension, tachycardia, edema, chest pain
What are some adverse effects alpha blockers can have on the CNS?
dizziness, headache, anxiety, depression, weakness, numbness, fatigue
What are some adverse effects alpha blockers can have on the gastrointestinal system?
nausea, vomiting, diarrhea, constipation, abdominal pain
What are some common alpha blockers?
phenoxybenzamine (Dibenzyline) phentolamine (Regitine) prazosin (Minipress) terazosin (Hytrin) alfuzosin (UroXatral) tamsulosin (Flomax)
What do beta blockers do and how do they do it?
block stimulation of beta receptors in the SNS by competing with norepinephrine and epinephrine.
What are beta blockers called that are selective for beta1-adrenergic receptors that are primarily located in the heart called?
Selective blockers - cardioselective beta blockers or beta1-blocking drugs.
What are beta blockers called that block both beta1 and beta2-adrenergic receptors called
Nonselective blockers
What are the outcomes of cardioselective beta blockers?
- reduced SNS stimulation of the heart
- decrease heart rate
- prolong sinoatrial (SA) node recovery
- slow conduction rate through the AV node
- decrease myocardial contractility, thus reducing myocardial oxygen demant
What are the outcomes of nonselective beta blockers?
- cause same effects on heart as cardioselective beta blockers
- constrict bronchioles, resulting in narrowing of airways and shortness of breath
- produce vasoconstriction of blood vessels
What are beta blockers used for?
- Angina: decreases the demand for myocardial oxygen
- Cardioprotective: inhibits stimulation from circulating catecholamines
- Dysrhythmias
- Migraine headache: lipophilicity allows entry into CNS
- Antihypertensive
- Heart failure
- Glaucoma (topical use)
What is the purpose of the beta blocker metoprolol (Lopressor)?
to inhibit stimulation of the myocardium by circulating catecholamines
Nonselective beta blockers may interfere with normal responses to what?
hypoglycemia - may mask signs and symptoms such as tremor, tachycardia, nervousness.
Why are nonselective beta blockers life threatening in patients with asthma?
they may cause bronchoconstriction
What should a nurse assess a patient for prior to beginning adrenergic-blocking drugs?
allergies and history of COPD, hypotension, cardiac dysrhythmias, bradycardia, heart failure, or other cardiovascular problems.
What conditions might adrenergic blocking drugs precipitate?
- Alpha blockers may precipitate hypotension
- Beta blockers may precipitate bradycardia, hypotension, heart block, heart failure, ad bronchoconstriction
What OTC meds might interact with adrenergic blocking drugs?
Antacids Antimuscarinics/anticholinergics Diruretics and cardiovascular drugs Neuromuscular blocking drugs Oral hypoglycemic drugs
What are some of the therapeutic effects patents taking adrenergic blocking drugs should be monitored for?
- decreased chest pain in patients with angina
- return to normal BP and HR
What should patients who are taking beta blocking drugs report to their physician?
- weight gain of more than 2 pounds in 1 day or 5 pounds in 1 week
- Edema of the feet or ankles
- shortness of breath
- excessive fatigue or weakness
- syncope or dizziness
