chapter13 pharmacology fall 2012

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Chapter 13Drugs Affecting Adrenergic Function

Chapter 13Drugs Affecting Adrenergic Function


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)


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.


Important Point!Important Point!


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


SNS and PSNS Effects on the BodySNS and PSNS Effects on the Body


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.


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


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


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.


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


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.


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.


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.


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.


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.


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


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).


Phenylephrine: Core Drug Knowledge 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: 1-2 hours.


– Is structurally similar to epinephrine and is a powerful alpha-1 adrenergic agonist ( depends on the route )


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


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


Phenylephrine: Core Patient Variables 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 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 & InterventionsPhenylephrine: Planning & 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 & EvaluationsPhenylephrine : Teaching, Assessment & 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-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).


Prazosin: Core Drug Knowledge Prazosin: Core Drug Knowledge • Pharmacotherapeutics

– Used to treat:

– congestive heart failure , hypertension, 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 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

– Serious : “first dose syncope”


– Other antihypertensive medications


Prazosin: Core Patient Variables 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 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 & InterventionsPrazosin: Planning & 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 & EvaluationsPrazosin: Teaching, Assessment & 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 :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).


Propranolol: Core Drug Knowledge Propranolol: Core Drug Knowledge • Pharmacotherapeutics

– Treatment of hypertension, angina, irregular cardiac rhythms, pheochromocytoma, and migraine.


– Administered: parenterally and orally.

– Metabolism: liver.

– Excreted: urine.

– Onset & duration: varies with route of administration.


– Decreased cardiac output and blood pressure.

– Slowing of atrioventricular conduction and suppression of automaticity.


Propranolol: Core Drug Knowledge Propranolol: Core Drug Knowledge


– 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


– Several drug interactions


Propranolol: Core Patient Variables Propranolol: 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


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.


Propranolol: Planning & InterventionsPropranolol: Planning & Interventions• Maximizing therapeutic effects

– Do not abruptly stop medication.


– Check the apical and peripheral pulses prior to administration

– Monitor: blood pressure

cardiac rhythm

conduction.


Propranolol: Teaching, Assessment & EvaluationsPropranolol: Teaching, Assessment & 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.

chapter13 pharmacology fall 2012

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