Ppt chapter 13

Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

Chapter 13

Drugs Affecting Adrenergic Function


Question

• The sympathetic nervous system produces what type of response?

– A. Adrenergic

– B. Antiadrenergic

– C. Cholinergic

– D. Anticholinergic


Answer

• A. Adrenergic

• Rationale: The sympathetic nervous system produces an adrenergic response, and the parasympathetic nervous system produces a cholinergic response.


Chapter Summary

• The nervous system is divided into two main branches, the central nervous system (CNS) and the peripheral nervous system (PNS).

• The efferent division has neurons that carry signals away from the brain and spinal cord to the periphery.

• The afferent division contains neurons that carry impulses from the periphery to the CNS.

• The autonomic nervous system (ANS) is in turn subdivided into the sympathetic nervous system (SNS) and the parasympathetic nervous system (PSNS).


Function of the Autonomic Nervous System

• The ANS has been identified as an involuntary system responsible for the control of smooth muscle.

• The actual connection between neurons and effector organs or tissues relies on neurotransmitters and synaptic transmission.

• The neurotransmitters in the ANS include acetylcholine (ACh), norepinephrine (NE), and epinephrine (Epi).

• Synaptic transmission initially involves the synthesis of neurotransmitters in the nerve terminal.

• In the SNS, preganglionic transmission is mediated by ACh, whereas postganglionic transmission is mediated by NE.


SNS and PSNS Effects on the Body


Adrenergic Receptors

• In the SNS, there are several types of adrenergic receptors, including alpha-adrenergic and beta-adrenergic receptors.

• Another type of receptor, the dopaminergic receptor, is related to adrenergic receptors in that dopamine is the precursor to NE.

• Alpha and beta receptors are located throughtout the body.

• Alpha-1 and beta-1 receptors respond to epinephrine, NE, and dopamine.

• Alpha-2 receptors respond to epinephrine and NE.

• Beta-2 receptors respond only to epinephrine.


Pathophysiology

• The therapeutic uses of sympathetic drugs are related to providing extra-adrenergic stimulation or blockade of normal ANS functioning.

• One of the most frequent indications for adrenergic agonist drugs is shock.

• Shock is the result of inadequate tissue perfusion, leaving the cells without the oxygen and nutrients they need to function normally and survive.


Adrenergic Agonists

• Adrenergic agonists are drugs that mimic the action of the SNS.

• They exert their effects by direct or indirect stimulation of adrenergic receptors.

• These drugs are generally divided into two groups— catecholamines and noncatecholamines.

• Adrenergic agonists are also classified according to their selectivity.

• Nonselective adrenergic agonists stimulate both alpha and beta receptors.

• Prototype drug nonselective adrenergic agonist—epinephrine.


Epinephrine: Core Drug Knowledge

• Pharmacotherapeutics

– Wide variety of indications—asthma, shock, etc.

• Pharmacokinetics

– Administered—parenterally, topically, or by inhalation. Metabolism: liver. Absorption: into the tissues. Excreted: kidneys. Duration: 1 to 4 hours.

• Pharmacodynamics

– It stimulates all adrenergic receptors and causes adverse effects in the cardiovascular system and CNS.


Epinephrine: Core Drug Knowledge • Contraindications and precautions

– Absolute contraindications to epinephrine include hypersensitivity, sulfite sensitivity, closed-angle glaucoma, and its use during labor.

• Adverse effects

– Severe adverse effects include hypertensive crisis, angina, cerebral hemorrhage, and cardiac arrhythmias.

• Drug interactions

– Tricyclic antidepressants, oxytocics, halogenated anesthetics, and beta blockers


Epinephrine: Core Patient Variables

• Health status

– Document preadministration vital signs. Review health history.

• Life span and gender

– Pregnancy risk category C

• Lifestyle, diet, and habits

– Document the patient’s occupation and daily activities.

• Environment

– IV administration only by trained personnel


Epinephrine: Nursing Diagnoses and Outcomes • Imbalanced nutrition: Less Than Body Requirements related to drug-

induced anorexia or nausea

– Desired outcome: The patient will maintain adequate nutrition.

• Disturbed Sleep Pattern, Insomnia, related to CNS excitation

– Desired outcome: The patient will learn about and practice sleep hygiene.

• Disturbed Sensory Perception related to impaired vision

– Desired outcome: The patient will notify the provider if vision changes occur.

• Ineffective Tissue Perfusion (Cardiopulmonary) related to cardiovascular effects of epinephrine

– Desired outcome: The patient will notify the provider if tachycardia, chest pain, or palpitations occur.


Epinephrine: Planning and Interventions

• Maximizing therapeutic effects

– Requires close monitoring of vital signs and careful monitoring for adverse effects.

– Take as prescribed.

• Minimizing adverse effects

– When treating anaphylactic shock, monitor blood pressure.

– Assisting the patient with menu planning may help to promote appetite and counteract the anorectic influence of epinephrine.


Epinephrine: Teaching, Assessment, and Evaluations

• Patient and family education

– Acute illness: Teaching should be brief, simple, and supportive.

– Explain how to administer drug properly.

• Ongoing assessment and evaluation

– Assess the patient for resolution of the presenting problem.

– Important to remember that epinephrine is a nonselective adrenergic agonist.


Question

• Which of the following receptors is (are) stimulated by epinephrine?

– A. Alpha 1

– B. Alpha 2

– C. Beta 1

– D. Beta 2

– E. All of the above


Answer

• E. All of the above

• Rationale: Epinephrine is a nonselective adrenergic agonist. This drug stimulates alpha-1, alpha-2, beta-1, and beta-2 receptors. The only adrenergic receptor subtype it does not stimulate is the dopamine receptor.


Alpha-1 Adrenergic Agonists

• The alpha-1 adrenergic agonists are drugs that stimulate the alpha-1 receptor directly.

• Prototype drug: phenylephrine (Allerest)


Phenylephrine: Core Drug Knowledge • Pharmacotherapeutics

– Used parenterally for vascular failure in shock.

– Used topically for relief of nasal mucosal congestion.


– Administered: parenterally or topically. Metabolism: liver. Excreted: urine. Onset: 15 to 20 minutes. Duration: 1 to 2 hours.


– Is structurally similar to epinephrine and is a powerful alpha-1 adrenergic agonist.


Phenylephrine: Core Drug Knowledge

• Contraindications and precautions

– Hypersensitivity, sulfite sensitivity, severe hypertension, ventricular tachycardia, and closed-angle glaucoma

• Adverse effects

– Headache, restlessness, excitability, and reflex bradycardia


– Monoamine oxidase inhibitors (MAOIs), tricyclic antidepressants, and oxytocics


Phenylephrine: Core Patient Variables

• Health status

– Assess medical history and obtain baseline assessment.


– Used in pregnancy only if absolutely necessary


– Document the patient’s occupation and activities of daily living.

• Environment

– Closely monitor during administration in acute care setting.


Phenylephrine: Nursing Diagnoses and Outcomes • Impaired Gas Exchange related to bronchoconstriction

– Desired outcome: Gas exchange will remain unimpaired.

• Imbalanced nutrition: Less Than Body Requirements related to anorexia or nausea

– Desired outcome: The patient will take sufficient nourishment.

• Disturbed Sleep Pattern, Insomnia, related to CNS excitation secondary to phenylephrine use

– Desired outcome: The patient will maintain normal sleep patterns.


Phenylephrine: Planning and Interventions


– Corrected any blood losses prior to administration.

– To produce optimal mydriasis, instill the ophthalmic form into the conjunctival cul-de-sac.


– IV administration is through a large vein.

– Avoid driving at night because blurred vision can be hazardous.


Phenylephrine: Teaching, Assessment, and Evaluations


– Stress the hazards associated with driving and operating heavy machinery.

– Teach the patient about drug interactions.


– Completing a detailed and thorough history and physical examination is essential for any patient anticipating long-term adrenergic drug therapy.


Alpha-2 and Beta-Adrenergic Agonists

• Alpha-2 adrenergic agonists

– Stimulation of alpha-2 receptors in the CNS decreases sympathetic outflow by inhibiting the release of norepinephrine.

• Beta-adrenergic agonists

– Beta-adrenergic agonists also mimic the action of the SNS.

– Beta-adrenergic agonists are also labeled according to their selectivity.

– Prototype: dopamine (Intropin).


Dopamine: Core Drug Knowledge


– Used to correct the hemodynamic imbalances present in shock.


– Distribution: throughout the tissues. Metabolism: kidney, liver, and plasma. Excreted: kidneys. Onset: 5 minutes. Duration: 10 minutes.


– Stimulates alpha-1 and beta-1 receptors: increased cardiac output


Dopamine: Core Drug Knowledge


– Pheochromocytoma, uncorrected tachyarrhythmias, and ventricular fibrillation

• Adverse effects

– Ectopic beats, nausea and vomiting, tachycardia, angina, palpitation, dyspnea, headache, hypotension, and vasoconstriction


Dopamine: Drug Interactions


Dopamine: Core Patient Variables

• Health status

– Assess medical history (chronic illness & allergies)


– Pregnancy Category C drug

• Environment

– Administered only in acute care settings


Dopamine: Nursing Diagnoses and Outcomes

• Risk for Ineffective Tissue Perfusion to Vital Organs related to drug effect

– Desired outcome: The patient will maintain sufficient perfusion of vital organs to prevent serious damage.

• Risk for Injury related to adverse effects of drug therapy

– Desired outcome: Adverse effects of drug therapy will not occur or will be minimized to prevent injury.


Dopamine: Planning and Interventions


– Administer using an infusion pump to regulate flow.

– Titrate dose to desired effect.


– Follow the manufacturer’s instructions for dilution.

– Monitor IV site.

– Assess for disproportionate rise in diastolic blood pressure.


Dopamine: Teaching, Assessment, and Evaluations


– If administered during a crisis, limited teaching occurs at that time.

– Reassure the patient and family that the patient will be monitored closely during administration of the drug.


– Treatment is effective if blood pressure stabilizes, urinary output returns to normal, and cardiac output returns to normal.


Question

• Dopamine is administered by which of the following routes?

– A. Oral

– B. IM

– C. IV

– D. ET


Answer

• C. IV

• Rationale: Dopamine is given only via the IV route.


Dopaminergic Agonists

• There are five types of dopamine receptors; only dopamine-1 (DA1) and dopamine-2 (DA2) receptors mediate responses in the adrenergic nervous system.

• Stimulation of DA1 and DA2 receptors results in peripheral vasodilation.

• Stimulating both receptors may have either complementary or opposing effects.

• Prototype drug: fenoldopam (Corlopam)


Fenoldopam: Core Drug Knowledge


– Short-term management of severe hypertension.


– Administered: parenterally. Metabolism: by conjugation. Excreted: urine and feces. Steady state: 20 minutes.


– It does not bind with DA2, alpha, or beta receptors. It provides rapid vasodilation to the coronary, renal, mesenteric, and peripheral arteries.


Fenoldopam: Core Drug Knowledge


– Hypersensitivity to sulfites

• Adverse effects

– Symptomatic hypotension, tachycardia, abdominal or back pain, GI effects, sweating, and CNS effects, such as insomnia, dizziness, nervousness, or anxiety


– Beta blockers and diuretics


Fenoldopam: Core Patient Variables

• Health status

– Medical history and pre-administration physical assessment


– Pregnancy Category B drug

• Environment

– Administered only in the acute care hospital setting


Fenoldopam: Nursing Diagnoses and Outcomes

• Risk for Ineffective Tissue Perfusion related to hypotension, tachycardia, or increased intraocular pressure

– Desired outcome: The patient will maintain adequate tissue perfusion throughout therapy.

• Risk for Injury related to hypokalemia

– Desired outcome: The patient will maintain a serum potassium level within normal limits throughout therapy.


Fenoldopam: Planning and Interventions• Maximizing therapeutic effects

– Dilute with 0.9% sodium chloride or 5% dextrose.

– The drug is administered using an infusion pump.

– Titrate dose to effect.


– Visually inspect the drug ampule.

– Start at low doses and titrate up to avoid reflex tachycardia.

– Monitor vital signs during administration.


Fenoldopam : Teaching, Assessment, and Evaluations


– Explain to the patient and family the rationale for the use.

– Reassure the patient that close monitoring will be maintained throughout drug therapy.


– Monitor vital signs throughout infusion.

– Evaluate the efficacy by monitoring blood pressure.


Alpha-Adrenergic Antagonists

• Alpha-adrenergic antagonists block the stimulation of alpha receptors.

• Alpha-1a receptors mediate human prostatic smooth muscle contraction.

• Alpha-1b and alpha-1d receptors are involved in vascular smooth muscle contraction.

• Prototype drug: prazosin (Minipress).


Prazosin: Core Drug Knowledge


– Used to treat congestive heart failure, Raynaud vasospasm, and prostatic outflow obstruction.


– Administered: oral. Metabolism: liver. Excreted: bile, feces, and urine. Onset: 1 hour. Duration: 10 hours.


– Blocks postsynaptic alpha-1 adrenergic receptors: lowers supine and standing blood pressure.


Prazosin: Core Drug Knowledge


– Hypersensitivity; use caution with angina because hypotension may worsen the condition

• Adverse effects

– Light-headedness, dizziness, headache, drowsiness, weakness, lethargy, nausea, and palpitations


– Other antihypertensive medications


Prazosin: Core Patient Variables

• Health status

– Past medical history and physical assessment


– Pregnancy Category C


– Document the occupation and daily activities

• Environment

– Assess environment where drug will be given


Prazosin: Nursing Diagnoses and Outcomes • Ineffective Tissue Perfusion related to prazosin-induced

hypotension

– Desired outcome: The patient will maintain adequate tissue perfusion.

• Imbalanced nutrition: Less Than Body Requirements related to nausea secondary to prazosin use

– Desired outcome: The patient will receive adequate nourishment by practicing appropriate dietary management.

• Risk for Injury related to orthostatic hypotension

– Desired outcome: The patient will remain free of injury.


Prazosin: Planning and Interventions


– Take as prescribed.

– Refraining from OTC medication usage.


– Take the first dose just before bedtime.

– Monitor weight and check for edema.


Prazosin: Teaching, Assessment, and Evaluations


– Take drug as prescribed.

– Adverse effects, including symptoms, to report to doctor.


– Monitor blood pressure, heart and lung sounds, and edema.

– Identify potential drug interactions.


Beta-Adrenergic Antagonists

• Grouped according to their specificity of action at the beta-1 and beta-2 receptors.

• Stimulation of beta-1 only (tachycardia, increased lipolysis, inotropy).

• Stimulation of both beta-1 and beta-2 receptors (vasodilation, decreased peripheral resistance, bronchodilation).

• Prototype drug: metoprolol (Lopressor, Toprol XL).


Metoprolol: Core Drug Knowledge • Pharmacotherapeutics

– Treatment of hypertension, angina, and controlled congestive heart failure.


– Administered: parenterally and orally. Metabolism: liver. Excreted: urine and breast milk. Onset & duration: varies with route of administration.


– Decreased cardiac output and blood pressure.

– Slowing of atrioventricular conduction and suppression of automaticity.


Metoprolol: Core Drug Knowledge


– Severe bradycardia, cardiogenic shock, airway diseases, Raynaud syndrome, and use of antidepressant drugs

• Adverse effects

– Cognitive dysfunction, hypoglycemia, diarrhea, and severe hypertension


– Several drug interactions


Metoprolol: Core Patient Variables

• Health status

– Past medical and physical assessment


– Pregnancy Category C


– Document occupation and daily activities

• Environment

– Assess environment where drug will be given


Metoprolol: Nursing Diagnoses and Outcomes • Risk for Ineffective Tissue Perfusion related to

hypotension, bradycardia, or decreased cardiac output

– Desired outcome: The patient will maintain adequate tissue perfusion throughout therapy.

• Risk for Injury related to dizziness secondary to beta blockade

– Desired outcome: The patient will not sustain injury.

• Disturbed Sleep Pattern, Insomnia and Drowsiness, secondary to beta blockade

– Desired outcome: The patient will sleep normally and awaken rested.


Metoprolol: Nursing Diagnoses and Outcomes (cont.)

• Activity Intolerance related to lethargy and weakness secondary to beta blockade

– Desired outcome: The patient will maintain a satisfactory activity level.

• Risk for Fluid Volume excess related to decreased cardiac output

– Desired outcome: The patient with chronic heart failure will not develop worsening of symptoms while on metoprolol.


Metoprolol: Planning and Interventions


– Take medication as prescribed.

– Do not abruptly stop medication.


– Prior to dose, check the apical and peripheral pulses.

– Monitor blood pressure, pulmonary wedge pressure, and cardiac rhythm and conduction.


Metoprolol: Teaching, Assessment, and Evaluations


– Do not abruptly stop medication.

– Adverse effects, including symptoms, to report to doctor.


– When evaluating the success of nursing management, anticipate the absence of signs and symptoms for the condition being treated.

– Monitor cardiovascular system: BP, heart rate, edema.

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Ppt chapter 13