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 Cont Co ntra rain indi dica cati tion ons s Advers Adv erse e Effe Effects cts
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 vasoconstriction 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 Know n drug drug aller allergy gy,, sever severe e hyper hyperte tens nsio ion n (Gener (Ge neral) al)Hea Headac dache, he, res restle tlessn ssness ess,, exci excitem tement ent,, insom insomnia nia,, & eup euphor horia. ia. (α) Che Chest st pai pain, n, 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 •
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Nasal Decongestants Causes vasoconstriction in the nasal mucosa • Uses: reduces nasal secretions secretions & leads to easier breathing. breathing. (CAUTION: OVERUSE MAY LEAD 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) epi epineph ephrine b) phen phenyl ylph phri rine ne c) naph aphazoli zolin ne tetrahydrozoline (Visine) -- ***most widely used*** d) tetrahydrozoline • • •
Vasoactive Adrenergics Very potent, quick-acting, & injectable. Wide range of effects. Uses: heart failure, shock, orthostatic hypotension Generic names: a) dobu obutami amine • • •
(low-dose)dilate blood vessels & increases blood flow in the brain, heart, kidneys, & b) dopamine – (low-dose)dilate mesentery. (high-dose) improves cardiac contractility contractility and output. Use of the drug is CONTRAINDICATED IN PT’S WHO HAVE A CATECHOLAMINE-SECRETING TUMOR OF THE ADRENAL GLAND (AKA PHEOCHROMOCYTOMA) c) epi epineph ephrine fenoldopam – short-term tx of severe HTN & increase renal blood flow d) fenoldopam e) midodrine – primarily indicated for the tx of ORTHOSTATIC HYPOTENSION. requires careful dosing & monitoring (keeping track of BP in a journal) f) norepinephrine – used primarily in tx of hypotension and shock g) phenylephrine Review Questions: The nurse caring for a pt who is r cv’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 broncho bro nchospas spasm m. 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 r ate. 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 immediately by the nurse and physician.
