Adrenergic-Blocking Drugs Flashcards
Adrenergic Blockers
Bind to adrenergic receptors but inhibit or block stimulation of the sympathetic nervous system (SNS)
Have the opposite effect of adrenergic drugs
Inhibit (lyse) sympathetic stimulation
A1 receptors effects: 2
constrict BVs and visceral organ sphincters
dilate pupils
A2 receptors effects: 2
inhibit NE release from adrenergic terminals
inhibit insulin secretion
B1 receptors effects: 3
increase HR
inctease FOC
stimulate kidneys to release renin
B2 receptors effects: 3
relaxes uterus
dilate BVs and bronchioles
relaxes smooth muscle walls of GI and urinary visceral organs
Adrenergic blockers also known as:
Adrenergic antagonists
Sympatholytics
α-blockers, β-blockers, and α-β–blockers
Classified by the type of adrenergic receptor they block
α1- and α2-receptors
β1- and β2-receptors
Drug Effects and Indications: α-Blockers
Cause both arterial and venous dilation, reducing peripheral vascular resistance and blood pressure (BP)
Used to treat hypertension
Effect on receptors on prostate gland and bladder decreases resistance to urinary outflow, thus reducing urinary obstruction and relieving the effects of benign prostatic hyperplasia (BPH).
Drug Effects and Indications: α-Blockers
Used to control and prevent hypertension in patients with pheochromocytoma
Raynaud’s disease, acrocyanosis, and frostbite
*Phentolamine
Quickly reverses the potent vasoconstrictive effects of extravasated vasopressors such as norepinephrine or epinephrine
Restores blood flow and prevents tissue necrosis
α-Blockers: Adverse Effects
Body system/adverse effects
Cardiovascular: Palpitations, orthostatichypotension, tachycardia, edema, chest pain
Central nervous system: Dizziness, headache, anxiety, depression, weakness, numbness, fatigue
Gastrointestinal: Nausea, vomiting, diarrhea, constipation, abdominal pain
Other: Incontinence, dry mouth, pharyngitis
Common α-Blockers
phentolamine mesylate (Rogitine®)
tamsulosin (Flomax®)
**phentolamine (Rogitine®)
what receptor does it block?
what does it reduce?
establish a diagnosis of?
Most commonly used to treat the extravasation of?
α-Blocker that reduces systemic vascular resistance and is sometimes used to treat hypertension
Establish a diagnosis of pheochromocytoma
Most commonly used to treat the extravasation of vasoconstricting drugs such as norepinephrine, epinephrine, and dopamine
Contraindicated in known hypersensitivity, myocardial infarction (MI), and coronary artery disease
tamsulosin (Flomax®)
α-Blocker used primarily to treat BPH; exclusively indicated for male patients
Contraindications: known drug allergy and concurrent use of erectile dysfunction drugs such as sildenafil
Adverse effects: headache, abnormal ejaculation, rhinitis, and others
β-Blockers
Block stimulation of β-receptors in the SNS
Compete with norepinephrine and epinephrine
Can be selective or nonselective
-Cardioselective β-blockers or β1-blocking drugs
-Nonselective β-blockers block both β1-receptors and β2-receptors.
β2-Receptors are located primarily on the smooth muscles of the bronchioles and blood vessels.
*carvedilol, labetalol
which receptor does it block?
α-Receptor–blocking activity, especially at higher dosages
acebutolol, pindolol
Not only block β-adrenergic receptors but also partially stimulate them
β1-Receptors
Located primarily on the?
β-Blockers selective for these receptors are called ______ β-blockers.
Located primarily on the heart
β-Blockers selective for these receptors are called cardioselective β-blockers.
B1: increase HR, FOC, and renin release
β2-Receptors
Located primarily on?
Located primarily on smooth muscle of bronchioles and blood vessels
B2: dilates BVs and bronchioles, relaxes smooth muscle walls of GI and GU visceral organs, relaxes uterus
Cardioselective β-blockers (β1)
drug effects; HR, SA node, AV node
decrease_____ thus reducing______
Reduce SNS stimulation of the heart
Decrease heart rate
Prolong sinoatrial node recovery
Slow conduction rate through the atrioventricular (AV) node
Decrease myocardial contractility, thus reducing myocardial oxygen demand
Nonselective β-blockers (β1 and β2)
drug effects on heart and respiratory system
Cause same effects on heart as do cardioselective ß-blockers
Constrict bronchioles, resulting in narrowing of airways and shortness of breath
Produce vasoconstriction of blood vessels
β-Receptors: Indications
Angina, MI, hypertension
-Decrease demand for myocardial oxygen
Cardioprotective
-Inhibit stimulation from circulating catecholamines
Dysrhythmias
Glaucoma (topical use)
Migraine headache
-Lipophilicity allows entry into central nervous system.
β-Blockers: Adverse Effects
Nonselective β-blockers may interfere with normal responses to hypoglycemia (tremor, tachycardia, nervousness).
May mask signs and symptoms of hypoglycemia
Use with caution in patients with diabetes mellitus.
*Atenolol (Tenormin®)
Commonly used to
Management of ______ to help block the symptoms of excessive thyroid activity
Cardioselective β-blocker
Commonly used to prevent future heart attacks in patients who have had one attack
Hypertension and angina
Management of thyrotoxicosis to help block the symptoms of excessive thyroid activity
Available for oral use
*Carvedilol
class?
action
Nonselective β-blocker, an α1-blocker, a calcium channel blocker, and possibly an antioxidant
Uses: heart failure, hypertension, and angina
Slows progression of heart failure and decreases the frequency of hospitalization in patients with mild to moderate (class II or III) heart failure
Most commonly added to digoxin, furosemide, and angiotensin-converting enzyme inhibitors when used to treat heart failure
