Pharmacology Study Notes - Adrenergic Drugs

Chapter 17: Adrenergic Drugs (sympathomimetics) •

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Stimulate the sympathetic nervous system Adrenergic receptors = receptor sites for catecholamines (EPI & NE) Divided into α & β receptor sites: Receptor Alpha1 Alpha2 Βeta1 Beta2 Dopaminerg ic

Mechanism of Action Uses Contraindications Adverse Effects Management of Toxicity & Overdose Nursing Implications

Location Post synaptic effector cells (tissue, muscle, organ) Presynaptic nerve terminal Primarily the heart Smooth muscle of bronchioles, arterioles, & visceral organs Renal, mesenteric, coronary, & cerebral arteries

Response ***predominant***

vasoconstriction & CNS stimulation ***predominant*** Smooth muscle relaxation; glycogenolysis; & cardiac stimulation ***predominant*** Dilation (it’s the only substance that can stimulate these receptors)

Bronchodilators, ophthalmic drugs, nasal decongestants, & vasoactive drugs Asthma, bronchitis, nasal decongestants, Known drug allergy, severe hypertension (General)Headache, restlessness, excitement, insomnia, & euphoria. (α) Chest pain, vasoconstriction, hypertension, tachycardia, palpitations, anorexia, dry mouth. (β) mild tremors, nervousness, dizziness, increased HR, sweating, nausea, & muscle cramps ***aimed at managing S/Sx of the CNS & cardiovascular system*** Diazepam (for seizures), rapid-acting sympatholytic drug (to lower BP~>prevention of hemorrhage) Rinse mouth after each inhalation or use of nebulizer.

Bronchodilators • Stimulate β-2 adrenergic receptors (causes bronchi to dilate) • Uses: asthma • Generic names: a) albuterol sulfate b) epinephrine – drug of choice for acute asthma attacks & anaphylaxis. Produces vasoconstriction, increased BP, cardiac stimulation & dilation of the bronchioles (α & β- drug) c) salmeterol – long term maintenance tx of asthma, NOT INDICATED FOR ACUTE EXACERBATIONS Nasal Decongestants • Causes vasoconstriction in the nasal mucosa • Uses: reduces nasal secretions & leads to easier breathing. (CAUTION: OVERUSE MAY LEAD TO REBOUND PHENOMENON ~> GREATER CONGESTION) • Generic name: a) pseudoephedrine Ophthalmic Decongestants • Results in arteriolar vasoconstriction in the eye • Uses: reduces red-eye • Generic names: a) epinephrine b) phenylphrine c) naphazoline d) tetrahydrozoline (Visine) -- ***most widely used*** Vasoactive Adrenergics • Very potent, quick-acting, & injectable. Wide range of effects. • Uses: heart failure, shock, orthostatic hypotension • Generic names: a) dobutamine

b) dopamine – (low-dose)dilate blood vessels & increases blood flow in the brain, heart, kidneys, &

c)

d) e) f) g)

mesentery. (high-dose) improves cardiac contractility and output. Use of the drug is CONTRAINDICATED IN PT’S WHO HAVE A CATECHOLAMINE-SECRETING TUMOR OF THE ADRENAL GLAND (AKA PHEOCHROMOCYTOMA) epinephrine fenoldopam – short-term tx of severe HTN & increase renal blood flow midodrine – primarily indicated for the tx of ORTHOSTATIC HYPOTENSION. requires careful dosing & monitoring (keeping track of BP in a journal) norepinephrine – used primarily in tx of hypotension and shock phenylephrine

Review Questions: The nurse caring for a pt who is rcv’ing β-agonist drug therapy needs to be aware that these drugs cause: increased cardiac contractility. During a teaching session for a pt who is rcv’ing inhaled salmeterol, the nurse emphasizes that the drug is indicated for: prevention of bronchospasm. For a pt rcv’ing a vasoactive drug such as IV dopamine, which of the following actions by the nurse is most appropriate? Assess the IV site hourly to rule out infiltration. When a drug is characterized as having a negative chronotropic effect, the nurse knows to expect: decreased heart rate. A pt is rcv’ing doputamine for a worsening of heart failure. The pt is now complaining of “chest tightness”. Which statement is most appropriate regarding the pt’s symptoms? – the presence of chest pain and the changes in vital signs need to be evaluated immediately by the nurse and physician.