Adrenergic Antagonist

Adrenergic Antagonist: 

Adrenergic Blocker Drugs: 

  • Inhibit or block stimulation of the SNS 

    • Meaning they have the opposite effect that adrenergic drugs do  

    • Sympatholytic "blockers" 

  • Classified by type of adrenergic receptors they block  

    • Either A1 A2 B1 or B2 

Alpha Blockers: 

  • Mechanism of action and effects 

    • They interrupt or inhibit the stimulation of A1 receptors 

      • Causes dilation of arteries and veins  

        • Decreases peripheral vascular resistance 

        • Decreases blood pressure  

  • Indications  

    • Hypertension  

    • Benign prostatic hyperplasia BPH  

    • Urinary outflow obstruction  

    • Raynaud's disease, acrocyanosis and frostbite  

    • Reverses the potent vasoconstrictive effects of extravasated vasopressors  

  • Contraindications  

    • Hypersensitivity (allergy) 

    • PVD 

    • CAD 

    • Renal or hepatic disease/dysfunction  

    • PUD 

    • Sepsis  

  • Adverse Effects 

    • First Dose Phenomenon 

      • Causes severe and sudden BP drop 

        • Leads to falls and syncope 

      • Because of this, Alpha blockers are usually administered during the night when patients are sleeping anyways  

    • Cardiovascular  

      • Palpitations 

      • Ortho hypotension  

      • Tachycardia  

      • Edema  

        • Caused by vasodilation that adrenergic antagonists cause  

      • Angina (chest pain) 

    • CNS 

      • Dizziness 

      • Headache 

      • Anxiety, depression  

      • Weakness, numbness  

      • Fatigue  

    • GI 

      • Nausea, vomiting, diarrhea, constipation  

      • Abdominal pain  

  • Toxicity and Management of Overdose 

    • Supportive measures 

      • Vasopressors 

      • Fluids 

        • Both of the above counteract the hypotension  

      • Anticonvulsants  

  • Interactions 

    • Adrenergic blocking drugs can cause a synergy reaction (too much) 

    • Adrenergic drugs 

      • Can counteract agonist drugs  

    • Warfarin  

    • Antihypertensives  

    • ED drugs 

    • Alcohol  

  • Drugs: 

    • Phentolamine  

      • Reduces peripheral vascular resistance 

      • Used to treat hypertension  

      • MOST COMMONLY USED to treat extravasation of vasoconstricting drugs  

        • Such as with dopamine extravasation  

    • Tamsulosin  

      • Used PRIMARILY to treat BPH (benign prostate hyperplasia)  

        • Exclusively male patients  

      • Contraindications  

        • Concurrent use of erectile dysfunction drugs 

          • Could lead to synergy effect that may lead to cardio collapse  

      • Adverse effects 

        • Abnormal ejaculation  

Beta Blockers: 

  • Block the stimulation of beta receptors  

  • Can be selective or nonselective  

    • Cardioselective  

      • B1 blocking drugs  

    • Nonselective will effect both B1 and B2 receptors (heart and lungs) 

  • Mechanism of Action and Effects 

    • Cardioselective B1 

      • Reduces SNS stimulation of the heart  

        • Decreases heart rate  

      • Prolongs SA node recovery  

      • Slows conduction rate through AV node 

      • Decreases myocardial contractility  

        • Reduces myocardial oxygen demand  

    • Nonselective B1 and B2 

      • Same as selective PLUS 

        • Constricts bronchioles 

          • Narrows airways and can cause SOB 

        • Produces vasoconstriction or dilation of blood vessels  

      • Do not use for COPD or asthma pts  

    • Both create -ino, -chrono, - dromo 

  • Indications: 

    • Angina 

      • Decreases demand for myocardial oxygen  

      • Usually given for angina with no known cause (you don’t know if they have heart failure yet) 

    • Cardioprotective effects 

      • Inhibits stimulation from circulating catecholamines 

    • Dysrhythmias  

    • Migraines/headaches 

    • Hypertension 

    • Heart failure 

    • Glaucoma is a topical use (eye drops)  

  • Contraindications  

    • Hypersensitivity  

    • Uncompensated heart failure 

      • Decreasing the ino will cause more damage  

    • Cardiogenic shock  

      • Bronchoconstriction is very bad for these patients  

    • Heart block  

    • Bradycardia 

    • Pregnancy  

    • Pulmonary disease 

    • Raynaud's disease  

      • Vessels are already constricted  

  • Adverse Effects 

    • Blood 

      • Agranulocytosis (decrease in platelets)  

      • Thrombocytopenia  

    • Cardiovascular  

      • AV block 

      • Bradycardia 

      • Heart failure 

    • Respiratory  

      • Wheezing and bronchospasm  

    • CNS 

      • Dizziness and drowsiness  

      • Depression  

      • Unusual dreams  

    • GI 

      • Nausea and vomiting  

      • Constipation  

      • Diarrhea  

    • Others 

      • Impotence, alopecia and dry mouth  

    • Beta Blockers may interfere with normal responses to hypoglycemia  

      • Tremors, tachycardia, and nervousness  

        • May mask these signs of hypoglycemia 

        • Should be used with caution for patients with diabetes mellitus  

  • Toxicity and Management of Overdose  

    • Supportive care 

    • Atropine for bradycardia  

    • Vasopressor  

    • Pacemakers  

    • Hemodialysis  

  • Interactions 

    • Adrenergic blockers can cause synergy reactions 

    • Adrenergic drugs can counteract  

    • Hypoglycemic drugs  

  • Drugs: 

    • Atenolol, Metoprolol 

      • Cardioselective  

        • Only affect B1 

      • Indications 

        • Secondary prevention of Myocardial Infarction  

        • Used to treat hypertension and angina  

        • Used to manage thyrotoxicosis  

          • Blocks the symptoms of excessive thyroid activity  

      • Atenolol is usually oral use 

      • Metoprolol is oral or IV use  

    • Carvedilol 

      • Nonselective  

        • Effects B1 and B2 (heart and lungs) 

      • It is a calcium channel blocker, and possibly an antioxidant 

      • Uses: 

        • Heart failure 

          • Slows progression of 

          • Decreases the frequency of hospitalizations for these patients  

        • Hypertension  

        • Angina  

    • Propranolol  

      • Nonselective 

        • Affects B1 and B2 (heart and lungs) 

      • Indications: 

        • Same for selective beta blockers 

          • Also can be used for digitalis toxicity, pheochromocytoma, migraine, essential tremor 

        • Used a lot to help with anxiety  

      • Caution: 

        • Chronic lung disease patients 

        • Bronchospasm  

      • Route: 

        • Oral or IV use  

  • The Nursing Process  

    • Assess 

      • Careful consideration of medical history  

        • COPD and asthma  

        • Hypotension  

        • Dysrhythmias and bradycardia  

        • Heart failure and cardiovascular problems in general  

      • Assess if preexisting conditions may be exacerbated by the use of these drugs  

        • May be a contraindication for use 

      • Medications history must be assessed for drug drug interactions and solution compatibility  

        • Anticholinergics, diuretics, cardiovascular drugs, neuromuscular blocking drugs and oral hypoglycemic drugs  

      • A baseline physical assessment  

        • Apical pulse and BP 

    • Diagnosis 

      • Tissue perfusion and gas exchange/oxygenation  

      • Blood glucose 

      • Safety and compliance  

    • Planning 

      • Outcomes should focus on improving or stabilizing 

        • Gas exchange/oxygenation  

        • BP and heart rate/rhythm 

        • Perfusion  

        • Safety and understanding/adherence   

    • Implementation 

      • Before intervention/drug admin you should heck 

        • Apical pulse and BP 

          • Hold if pulse is less than 60 or the BP is less than 100/60 

          • Notify provider  

        • You should have no abrupt cessation of drugs  

        • Safety 

          • Watch for orthostatic hypotension  

        • Make sure pt has enough fluids, nutrition and oral care  

    • Patient Education  

      • Emphasize that pts should change positions slowly  

      • Avoid extremes of temperature  

        • Hot showers or hot outside can dilate vessels and cause syncope since adrenergic antagonists already widen vessels  

      • Avoid caffeine and alcohol  

      • Avoid hazardous activities until blood levels become stable  

      • Notify provider of  

        • Palpitations  

        • Dyspnea, edema, SOB 

        • Fatigue and weakness syncope and dizziness  

        • Nausea and vomiting  

        • Weight gain of more than 2 pounds in 1 day or 5 pounds in 1 week 

      • Avoid OTC medications or consult providers/pharm 

      • Take medications as prescribed and do not abruptly stop taking them  

    • Evaluation: 

      • Monitor patient for adverse effects  

        • Bradycardia, hypotension, arrhythmia  

        • Nausea and vomiting  

        • Weight gain and CNS depression  

          • Depression for 6-8 weeks usually  

      • Monitor for therapeutic effects  

        • Decreased angina  

        • Return to normal BP and HR 

        • For BPH patients, evaluate if urinary symptoms have improved