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Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Chapter 13Drugs Affecting Adrenergic Function
Chapter 13Drugs Affecting Adrenergic Function
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
IntroductionIntroduction
• The nervous system is divided into two main branches:
Central Nervous System
Brain and the Spinal Cord
Peripheral Nervous System.
Somatic Autonomic
Controls voluntary Sympathetic Parasympathetic
movements (Adrenergic) (Cholinergic)
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
The Autonomic Nervous System 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.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Important Point!Important Point!
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Important Point!Important Point!
• To effect an action, the neurotransmitter needs to bind with an appropriate receptor site on the effector organ or tissue
• A neuro-pharmacologic drug works by increasing or decreasing receptor activation in the Autonomic Nervous System
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
SNS and PSNS Effects on the BodySNS and PSNS Effects on the Body
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Adrenergic Receptors SNSAdrenergic Receptors SNS
• Types of adrenergic receptors:
alpha-adrenergic
beta-adrenergic
• dopaminergic (dopamine is the precursor to NE).
• Alpha and beta receptors are located throughout the body.
• Alpha-1 and beta-1 receptors respond to :
epinephrine, norepinephrine, and dopamine.
• Alpha-2 receptors respond to epinephrine and NE.
• Beta-2 receptors respond only to epinephrine.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Pathophysiology Pathophysiology
• The therapeutic uses of sympathetic drugs are related to providing: extra-adrenergic stimulation
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
cells without oxygen and nutrients
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Adrenergic AgonistsAdrenergic Agonists
• Drugs that: mimic the action of the SNS.( sympathomimetic)
exert their effects by direct or indirect stimulation
of adrenergic receptors
Divided into two groups:
catecholamines - ( similar chemical structure)
short duration of action
cannot be given orally
do not cross the blood brain barrier
non-catecholamines- ( do the opposite of above)
Both alpha and beta adrenergic agonists are classified also as
catecholamines or non-catecholamines
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Adrenergic AgonistsAdrenergic Agonists
• Adrenergic agonists ( sympathomimetics) 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.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Epinephrine: Core Drug KnowledgeEpinephrine: Core Drug Knowledge• Pharmacotherapeutics
– Wide variety of indications: asthma, shock
• Pharmacokinetics
– Administered: parenterally, topically, or by inhalation. Metabolism: liver.
– Absorption: into the tissues.
– Excreted: kidneys. Duration: 1-4 hours.
• Pharmacodynamics
– It stimulates all adrenergic receptors
– Profound effects in the cardiovascular system and CNS.
– Acts directly on the postsynaptic adrenergic receptors
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Epinephrine: Core Drug Knowledge Epinephrine: Core Drug Knowledge • Contraindications and precautions:
hypersensitivity, sulfite sensitivity, closed-angle glaucoma
patients with severe cardiac disease
• Adverse effects
Severe: hypertensive crisis, angina, cerebral hemorrhage, and cardiac arrhythmias
Main adverse effects: tremors, palpitations, apprehension
Increase in blood glucose
• Drug interactions
– Tricyclic antidepressants, oxytocics, halogenated anesthetics, and beta blockers.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Epinephrine: Core Patient Variables 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.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Epinephrine: Nursing Diagnoses and Outcomes 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.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Epinephrine: Planning & InterventionsEpinephrine: Planning & 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.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Epinephrine: Teaching, Assessment & EvaluationsEpinephrine: Teaching, Assessment & 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.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
QuestionQuestion
• 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
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Alpha-1 Adrenergic Agonists Alpha-1 Adrenergic Agonists
• The alpha-1 adrenergic agonists are drugs that stimulate the alpha-1 receptor directly.
• Prototype drug: phenylephrine (Neo-Synephrine).
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Phenylephrine: Core Drug Knowledge Phenylephrine: Core Drug Knowledge
• Pharmacotherapeutics
– Used parenterally for vascular failure in shock.
– Used topically for relief of nasal mucosal congestion.
• Pharmacokinetics
– Administered: parenterally or topically.
– Metabolism: liver.
– Excreted: urine. Onset: 15 to 20 minutes. Duration: 1-2 hours.
• Pharmacodynamics
– Is structurally similar to epinephrine and is a powerful alpha-1 adrenergic agonist ( depends on the route )
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Phenylephrine: Core Drug Knowledge 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
• Drug interactions
– Monoamine oxidase inhibitors (MAOIs), tricyclic antidepressants, and oxytocics
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Phenylephrine: Core Patient Variables Phenylephrine: Core Patient Variables
• Health status
– Assess medical history and obtain baseline assessment
• Life span and gender
– Used in pregnancy only if absolutely necessary
• Lifestyle, diet, and habits
– Document the patient’s occupation and activities of daily living
• Environment
– Closely monitor during administration in acute care setting
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Phenylephrine : Nursing Diagnoses and Outcomes 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.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Phenylephrine: Planning & InterventionsPhenylephrine: Planning & Interventions
• Maximizing therapeutic effects
– Corrected any blood losses prior to administration.
– To produce optimal mydriasis, instill the ophthalmic form into the conjunctival cul-de-sac.
• Minimizing adverse effects
– IV administration is through a large vein.
– Avoid driving at night because blurred vision can be hazardous.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Phenylephrine : Teaching, Assessment & EvaluationsPhenylephrine : Teaching, Assessment & Evaluations
• Patient and family education
– Stress the hazards associated with driving and operating heavy machinery.
– Teach the patient about drug interactions.
• Ongoing assessment and evaluation
– Completing a detailed and thorough history and physical examination is essential for any patient anticipating long-term adrenergic drug therapy.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Alpha-Adrenergic Antagonists 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).
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Prazosin: Core Drug Knowledge Prazosin: Core Drug Knowledge • Pharmacotherapeutics
– Used to treat:
– congestive heart failure , hypertension, prostatic outflow obstruction
• Pharmacokinetics
– Administered: oral. Metabolism: liver.
– Excreted: bile, feces, and urine.
– Onset: 1 hour. Duration: 10 hours.
• Pharmacodynamics
– Blocks postsynaptic alpha-1 adrenergic receptors: lowers supine and standing blood pressure.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Prazosin: Core Drug Knowledge Prazosin: Core Drug Knowledge
• Contraindications and precautions
– Hypersensitivity; use caution with angina because hypotension may worsen the condition
• Adverse effects
– Light-headedness, dizziness, headache, drowsiness, weakness, lethargy, nausea, and palpitations
– Serious : “first dose syncope”
• Drug interactions
– Other antihypertensive medications
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Prazosin: Core Patient Variables Prazosin: Core Patient Variables
• Health status
– Past medical history and physical assessment
• Life span and gender
– Pregnancy category C
• Lifestyle, diet, and habits
– Document the occupation and daily activities
• Environment
– Assess environment where drug will be given
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Prazosin: Nursing Diagnoses and Outcomes 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.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Prazosin: Planning & InterventionsPrazosin: Planning & Interventions
• Maximizing therapeutic effects
– Take as prescribed.
– Refraining from OTC medication usage.
• Minimizing adverse effects
– Take the first dose just before bedtime.
– Monitor weight and check for edema.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Prazosin: Teaching, Assessment & EvaluationsPrazosin: Teaching, Assessment & Evaluations
• Patient and family education
– Take drug as prescribed.
– Adverse effects, including symptoms, to report to doctor
• Ongoing assessment and evaluation
– Monitor blood pressure, heart and lung sounds, and edema.
– Identify potential drug interactions.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Beta-Adrenergic Antagonists :Beta Blockers Beta-Adrenergic Antagonists :Beta Blockers
• 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: Propranolol (Inderal).
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Propranolol: Core Drug Knowledge Propranolol: Core Drug Knowledge • Pharmacotherapeutics
– Treatment of hypertension, angina, irregular cardiac rhythms, pheochromocytoma, and migraine.
• Pharmacokinetics
– Administered: parenterally and orally.
– Metabolism: liver.
– Excreted: urine.
– Onset & duration: varies with route of administration.
• Pharmacodynamics
– Decreased cardiac output and blood pressure.
– Slowing of atrioventricular conduction and suppression of automaticity.
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Propranolol: Core Drug Knowledge Propranolol: Core Drug Knowledge
• Contraindications and precautions
– Severe bradycardia, complete heart block, reactive airway disease and use of antidepressant drugs
• Adverse effects
– Cognitive dysfunction, hypoglycemia in patients with type 1 diabetes, diarrhea, and weight gain
• Drug interactions
– Several drug interactions
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Propranolol: Core Patient Variables Propranolol: Core Patient Variables
• Health status
– Past medical and physical assessment
• Life span and gender
– Pregnancy category C
• Lifestyle, diet, and habits
– Document occupation and daily activities
• Environment
– Assess environment where drug will be given
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Propranolol: Nursing Diagnoses and Outcomes Propranolol: Nursing Diagnoses and Outcomes
• Sexual Dysfunction related to decreased libido or erectile dysfunction secondary to beta blockade
– Desired outcome: the patient will adapt to altered sexual functioning.
• 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.
• Activity Intolerance related to lethargy and weakness secondary to beta blockade
– Desired outcome: the patient will maintain a satisfactory activity level.
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Propranolol: Planning & InterventionsPropranolol: Planning & Interventions• Maximizing therapeutic effects
– Do not abruptly stop medication.
• Minimizing adverse effects
– Check the apical and peripheral pulses prior to administration
– Monitor: blood pressure
cardiac rhythm
conduction.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Propranolol: Teaching, Assessment & EvaluationsPropranolol: Teaching, Assessment & Evaluations
• Patient and family education
– Do not abruptly stop medication.
– Adverse effects, including symptoms, to report to doctor.
• Ongoing assessment and evaluation
– 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.