Autonomic Nervous System
Sympathetic v. Parasympathetic nervous system branches
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Sympathetic Nervous System (Adrenergic Branch, “Fight or Flight”): tends toregulate the expenditure of energy and is operative when the organism is
confronted with stressful situations. Anti-adrenergic or Adrenergic Blocking medications block or inhibit the system and sympathetic nervous system. One of the major body systems impacted by adrenergic blocking drugs is the heart and vascular system. Some of the drugs are also used to treat hypertension.
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Alpha-adrenergic blocking drugs: produce their greatest effect on thealpha-receptors of the adrenergic nerves that control the vascular system, causing vasodilation and relaxing the
smooth muscle of blood vessels (also used to constrict pupil).
Example: Phentolamin (Regitine)
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Beta-adrenergic blocking drugs (Beta Blockers): blocks β-adrenergicreceptors and their effect
on β receptors, primarily the β receptors of the heart, decreasing heart rate and dilates the
blood vessels.
Examples: Atenolol, Metoprolol (Lopressor, Toprol XL), Propranolol
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α- β adrenergic blocking drugs: blocks both α AND β adrenergic receptors and effects thenerve fibers
Example: Carvedilol (Coreg)
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Anti-adrenergic drugs: prevents the release of neurotransmitternorepinephrine and blocks the adrenergic nerve impulse in both central & peripheral nervous systems
Example: Clonidine (Catapres)
Atenolol
(Tenormin, Tenoretic) ACTION
• β-Adrenergic Blocking Drug (Beta Blocker) • Decreases stimulation of sympathetic
nervous system by:
○ Decreasing excitability of heart ○ Decreasing cardiac workload and
oxygen consumption ○ Provides membrane-stabilizing effects USES • Hypertension • Angina • Acute MI ADVERSE REACTIONS
*Bradycardia, dizziness, fatigue, weakness, hypotension, N/V/D, nervousness
CONTRAINICATIONS
*Patients with sinus bradycardia, second or third degree heart block, heart failure and those with asthma, emphysema or hypotension.
*Used cautiously in patients with diabetes, thyrotoxicosis or peptic ulcer.
* β-Blockers are recommended for pregnant women over other hypertensive drugs because of the risk to the fetus is less with these drugs.
INTERACTIONS Drugs:
Antidepressants (MAOIs, SSRIs) increased effect
of β-blocker, bradycardia
NSAIDs decreased effect of β-blocker Loop diuretics increased risk of hypotension Clonidine increased risk of paradoxical
hypertensive effect
Cimetidine (GI problems) increased serum level of
β-blocker & higher risk of β-blocker toxicity
Lidocaine increased serum level of β-blocker &
higher risk of β-blocker toxicity
*Older adults are at an increased risk for adverse reactions when taking β-blockers. The nurse should monitor older adults closely for confusion, heart failure, worsening of angina, shortness of breath and
peripheral vascular insufficiency (examples: cold extremities, paresthesia of the hands, weak peripheral pulses).
*Beta-blockers may mask tachycardia caused by hyperthyroidism
*Beta-blockers may mask signs/symptoms of hypoglycemia in diabetic patients
*With-hold medication is HR is less than 60 bpm, or
systolic BP less than 90 mm Hg
Propranolol
(Inderal)
ACTION
• β-Adrenergic Blocking Drug (Beta Blocker)
• Decreases stimulation of sympathetic nervous system by:
○ Decreasing excitability of heart ○ Decreasing cardiac workload and
oxygen consumption ○ Provides membrane-stabilizing effects USES • Cardiac arrhythmias • MI, angina • Hypertension • Migraine prophylaxis
• Hypertrophic Sub-aortic stenosis
• Pheochromocytoma
• Essential Tremor
ADVERSE REACTIONS
*Bradycardia, dizziness, hypotension, N/V/D, bronchospasm, hyperglycemia, pulmonary edema
CONTRAINICATIONS
*Patients with sinus bradycardia, second or third degree heart block, heart failure and those with asthma, emphysema or hypotension. *Used cautiously in patients with diabetes, thyrotoxicosis or peptic ulcer.
* β-Blockers are recommended for pregnant
women over
other hypertensive drugs because of the risk to the fetus is
less with these drugs. INTERACTIONS Drugs:
Antidepressants (MAOIs, SSRIs) increased effect
NSAIDs decreased effect of β-blocker Loop diuretics increased risk of hypotension Clonidine increased risk of paradoxical
hypertensive effect
Cimetidine (GI problems) increased serum level of
β-blocker
& higher risk of β-blocker toxicity
Lidocaine increased serum level of β-blocker &
higher risk of β-blocker toxicity
NURSING INTERVENTIONS
*Instruct patient to take drug with food
*Older adults are at an increased risk for adverse reactions
when taking β-blockers. The nurse should monitor older adults closely for confusion, heart failure, worsening of angina,
shortness of breath and peripheral vascular insufficiency (examples: cold extremities, paresthesia of the hands, weak peripheral pulses). *Abrupt withdrawal of drug may cause exacerbation of angina
or MI, discontinue slowly
*Beta-blockers may mask signs/symptoms of hypoglycemia in diabetic patients
*With-hold medication is HR is less than 60
bpm, or systolic BO is less than 90 mm Hg
Metoprolol
(Lopressor, Toprol-XL)
ACTION
• β-Adrenergic Blocking Drug (Beta Blocker)
• Decreases stimulation of sympathetic nervous system by:
○ Decreasing excitability of heart
○ Decreasing cardiac workload and oxygen consumption ○ Provides membrane-
stabilizing effects
USES
• Hypertension • Angina
• MI, Heart Failure
ADVERSE REACTIONS
*Dizziness, hypotension, HF, cardiac arrhythmias, N/V/D
*Patients with sinus bradycardia, second or third degree heart block, heart failure and those with asthma, emphysema or hypotension.
*Used cautiously in patients with diabetes, thyrotoxicosis or peptic ulcer.
* β-Blockers are recommended
for pregnant
women over other hypertensive drugs
because of the risk to the fetus is less with these drugs.
INTERACTIONS Drug:
Antidepressants increased effect of Beta blocker, bradycardia
NSAIDs decreased effect of beta blocker Loop Diuretic increased risk of
hypotension
Clonidine increased risk of paradoxical hypertensive effect
Cimetidine higher risk of B-blocker toxicity
Iidocaine higher risk of B-blocker toxicity
NURSING PRECAUTIONS
*Take apical pulse and BP before administration
*Hold if BP is less than 100/60
OR greater
than 140/90, OR HR less than 60
*Monitor BP, HR and ECG carefully during IV administration
Carvedilol
(Coreg)
ACTION
•
α- β Adrenergic Blocking Drug○
Blocks both α- β receptorsresulting in peripheral vasodilation
USES
• HF
• Left ventricular dysfunction
ADVERSE REACTIONS
*Bradycardia, hypotension, cardiac insufficiency, fatigue, dizziness, diarrhea
CONTRAINIDCATIONS
*Patients with bronchial asthma, decompensated heart failure and severe bradycardia.
*Used cautiously in patient with drug- controlled HF, chronic bronchitis or impaired hepatic or cardiac function, in those with diabetes and during pregnancy or lactation.
INTERACTION Drug:
Antidepressants (tricyclics, SSRIs)
increased risk of tremors
Cimetidine increase effect of the
adrenergic blocker
Halothane increase effect of the
adrenergic blocker
Clonidine increased effect of the clonidine
(big drop in BP)
Digoxin increased levels of digoxin, risk of
toxicity
NURSING INTERVENTIONS
*Monitor patient with heart failure for worsening condition, renal failure or fluid retention; diuretics may need to be increased *If drug must be stopped, do so gradually over 1-2
weeks, if possible
*If patient is jaundice, STOP medication IMMEDIATELY hepatic injury
*Observe patient for dizziness for lightheadedness for
1 hour after giving each new dose *Monitor elderly patients carefully; drug levels are
about 50% higher in elderly patients than in younger patients
*Inform patients who wear contact lenses that their
*Take medication with food, capsules should NOT BE crushed, chewed or divided
Clonidine
(Catapres)
ACTION
• Anti-Adrenergic Drugs (Centrally- acting)
○ Inhibits the release of norepinephrine and acts in the Central Nervous System
Affects the sympathetic nervous system
USES
• Hypertension
• Severe pain in patients with cancer
ADVERSE REACTIONS
*Drowsiness, dizziness, sedation, dry mouth, constipation, syncope, dreams, rash
CONTRAINDICATION
*Patients in active hepatic disease and patients on MAOIs
*Used cautiously in patients with a history of liver disease or renal impairment and during pregnancy and lactation
INTERACTIONS Drug:
Adrenergic drugs increased risk of hypertension
Levodopa decreased effect of levodopa, hypotension
Anesthetic agents increased effect of the anesthetic
β-blockers increased risk of hypertension
Lithiumincreased risk for lithium toxicity Haloperidol increased risk of psychotic behavior
NURSING INTERVENTIONS
*If prescribed for opiate withdrawal: monitor for N/V/D, cramps, insomnia, shivering & dilated pupils
*Monitor I/Os and edema *Give last dose at bedtime
*Discontinuing abruptly may result in anxiety, increased BP, headache, insomnia, increased pulse, tremors, nausea, sweating
*DO NOT use OTC (cough, cold or allergy) medications unless approved by MD *Rise slowly to prevent drop in BP *May cause dry mouth; recommend hard candy or frequent mouth rinsing