Autonomic Nervous System

Chapter 16, 17, 18, 19, 20

Clinical Drug Therapy

Nervous System

Two main divisions Central Nervous System or CNS Peripheral Nervous System or PNS

Central Nervous System or CNS Brain and spinal cord: receives and

processes incoming sensory information and responds by sending out signals that initiate or modify a process.

Peripheral Nervous System or PNS Includes all the neurons and ganglia found

outside the CNS Afferent (sensory): modify motor output Efferent:

Afferent Neurons

Afferent neurons carry sensory input from the periphery to the CNS and modify motor output through the reflex arc.

Efferent Neurons

Efferent neurons carry motor signals from the CNS to the peripheral areas of the body.

ANS / SNS

Autonomic nervous system controls involuntary activities of smooth muscle, secretory glands and the visceral organs of the body such as the heart (involuntary activities of smooth muscle)

Somatic nervous system innervates the skeletal muscles and controls voluntary movement

Autonomic Nervous System

Sympathetic Nervous System Para sympathetic System Enteric System

The Race Horse and the Cow

Sympathetic Nervous System

Sympathetic System

Fight or Flight – stimulated by physical or emotional stress (exercise or work), pain, hemorrhage, intense emotions, temperature extremes

Sympathetic Nervous System

Protective mechanisms designed to help person cope with the stress or get away from it.

Neurotransmitters

Neurotransmitters Acetylcholine: skeletal muscle Norepinepherine: stress response

Norepinephrine and epinephrine Both always present in the blood. Norepinephrine varies according to the

amount of stress present and will cause transient changes in heart rate and systemic arteries and veins.

Epinephrine is a constant in regulating heart rate, vasoconstriction in systemic arteries and veins and vasodilation of muscles and liver.

Dopamine

Adrenergic neurotransmitter – essential for normal brain function. Studies focus on connection between dopamine

malfunction in schizophrenia and Parkinson’s Disease.

Role of dopamine in drug addition to drugs: stimulants and depressants.

Protective Mechanisms

Intensity of response depends on Norepinephrine and epinephrine

Fight or flight

Body Responses

Increase in blood pressure and cardiac output.

Increase blood flow to brain, heart and skeletal muscles.

Decrease blood flow to skin and organs not needed for “flight”.

Increase in glycogen for energy, mental activity, muscle strength, blood coagulation, respiratory rate, pupil dilation to aid vision, and increase in sweating.

Fight of Flight Response

Can be a problem if the body stay in the “fight or flight” mode.

Type A personalities? High stress environment? Medications may be needed reduce the

physiologic body responses.

Parasympathetic Nervous System

Rest and Digest Save energy Decreased heart rate

Adrenergic Receptors

Norepinephrine and epinephrine interact with two adrenergic receptors Alpha and beta

Alpha 1 Alpha 2 Beta 1 Beta 2

Alpha 1

Alpha 1 receptors allows calcium ions to move into the cell and produce muscle contraction.

Alpha 1

Location Blood vessels Kidney Intestinal smooth muscles Genitourinary Eyes = blinking Pregnant uterus =

contractions Male sexual organs =

sexual function

Effects of stimulation Vasoconstriction Release of renin (kidney) Relaxation

Alpha 2

Location Nerve endings Vascular smooth

muscles Pancreatic beta cells Platelets

Effects of stimulation Inhibits release of

Norepinephrine Vasoconstriction Inhibit insulin secretion Aggregation or clotting

Beta 1

Location Heart

Kidneys

Effects of stimulation Increase heart rate,

force of contraction, automaticity and rate of atrial-ventricular function

Increased renin release

Beta 2

Location Bronchioles Blood vessels Gastrointestinal tract Liver Urinary bladder Pregnant uterus

Effects of stimulation Vasodilation Decreased motility and

tone Glycogenolysis Relaxed detrusor

muscle (bladder muscle)

Relaxation of uterus

Dopamine

Location Blood vessels of

kidney, heart, and other viscera

Effects of stimulation Vasodilation

Parasympathetic Nervous SystemFunctions stimulated by PNS: Resting,

reparative, or vegetative function

Body Responses

Dilation of blood vessels in skin Decrease heart rate (bradycardia) Increase secretion of digestive enzymes Constriction of smooth muscle of bronchi Increase in sweat glands Contraction of smooth muscles of urinary

bladder Contraction of smooth muscle of skeletal

system

Neurotransmitter

Acetylcholine Two types of cholinergic receptors

Nicotinic: located in motor nerves and skeletal muscles

Muscarinic: located in internal organs, cardiovascular, respiratory, GI and GU

Autonomic Drugs

Drugs used due to their ability to stimulate or block activity of the sympathetic or parasympathetic nervous system.

Effect of Drugs

Drugs that act of ANS usually affect the entire body.

Effects depend on whether you are trying to stimulate or inhibit function.

Receptor Activity

Drugs are developed to stimulate or inhibit particular subtypes of receptors.

More selective on particular body tissues. Decrease adverse effects on other body

tissues – side effects.

Simulation of SNS

Stimulation of sympathetic nervous system can be divided into drug classifications: Adrenergic Sympathomimetic Alpha and beta adrenergic agonists

Agonist

In pharmacology an agonist is a substance that binds to a specific receptor and triggers a response in the cell.

Blockage of SNS

Drugs that inhibit sympathetic nervous system are classified as Antiadrenergic Sympatholytic anticholinergic

Stimulation of PNS

Parasympathetic nervous system stimulation drug classifications Cholinergic Parasympathomimenic Cholinomimetic

Blocking of PNS

Drugs that inhibit parasympathetic stimulation are classified as: Anticholinergic Parasympatholytic Cholenergic blocking drugs

Classifications: SNS

Sympathetic nervous system drug classifications Adrenergic - stimulating Antiadrenergic - blocking

Classifications: PNS

Parasympathetic nervous system drugs Cholinergic Anticholinergic

Adrenergic Drugs

Chapter 17

Adrenergic Drugs

What do they do? Stimulation of the sympathetic nervous

system.

Mechanism of Action

Three mechanisms: Directly with alpha 1 or beta-adrenergic receptors

on surface membrane. Indirect effects of postsynaptic adrenergic

receptors. Mixed action – combination of action on direct and

indirect receptor.

Heart

Direct stimulation of receptors Alpha 1 - Vasoconstriction of blood vessels which

increases blood pressure – pressor or vasopressor effect.

Beta 2 - increased force of myocardial contraction - Increased speed of electrical conduction in the heart.

Lungs

Asthma and COPD (Chronic Obstructive Pulmonary Disease): Beta 2 drugs or bronchodilators are used to relieve broncho-constriction and broncho-spasm.

Pregnancy

Adrenergic drugs used to relax uterine muscles in preterm labor.

OTC Adrenergic Drugs

Common cold: anti-histamines Allergy: nasal or oral to relieve nasal

congestion

Adrenergic Drugs

Epinephrine Pseudoephedrine – Sudafed Isoproterenol (Isuprel) Phenylephrine (Neo-Synephrine) Clonidine (antihypertensive)

How does one choose a drug? How emergent is the situation PO or IM or IV

Allergic Response

Runny nose, itchy eyes, cough Asthma: Cough with bronchospasms,

difficulty breathing or SOB (shortness of breath)

Anaphylactic shock – edema of airway

Allergy Response

Nasal congestion, itchy eyes, non-productive cough

Seasonal response to environmental causes Commonly mixed with other drugs in cold

medications

Pseudoephedrine

Therapeutic classification: allergy, cold, and cough remedies, nasal drying, and decongestants.

Indications: symptomatic management of nasal congestion associated with acute viral upper respiratory tract infection. Most often used in combination with other drugs.

Action: stimulates Alpha and beta-adrenergic receptors – vasoconstriction in respiratory tract mucosa – possible bronchodilation

Therapeutic effects: reduction of nasal congestion, and swelling of nasal passages.

Forms and Dosage

How supplied: tabs, chew tabs, extended release tabs, liquid or drops

Dosing: 30 to 60 mg / dose q 6-8 hours PO Maximum dose 240 mg/24 hours Sustained release: 120 mg PO q 12 hours

Contraindications

Severe Hypertension Severe CAD / coronary artery disease Use with caution in pregnancy, breast feeding

and renal failure

Use with caution!

Mild or moderate hypertension, hyperglycemia, hyperthyroidism, and cardiac disease.

Side Effects

Dizziness, nervousness, restlessness, insomnia and arrhythmias

Seizures Cardiovascular collapse

Additional Information

OTC used in combination with anti-histamines

Primarily excreted renally – adjust in patients with renal impairment

May cause false-positive for amphetamines – athletes

Currently need to ask pharmacist for Sudafed – OTC has been limited due to abuse

Nursing Implications

Assess for congestion Monitor pulse and blood pressure before

beginning therapy Assess lung sound for signs of bronchial

secretions

Severe Anaphylactic Shock

Usually involving the airways Some thing as simple as food allergy can

trigger it Peanuts, shell fish, legumes, bee sting,

medications Symptoms usually starts with numbness and

tingling of lips and leads to swelling of the glottis or epiglottis – this can result in closure of the airway.

How Do You Treat It?

Epinephrine would be the drug of choice Classification: adrenergic Action: affects both the beta (cardiac) and

beta (pulmonary) receptors – produces bronchodilation – inhibits hypersensitivity reaction of mast cells.

Epinephrine

Therapeutic Effects: Bronchodilation Maintenance of heart rate and blood pressure

Adverse Side Effects: Nervousness, restlessness, tremors, angina,

arrhythmias, hypertension, tachycardia

How it is given?

Sub-Q or IV or inhaled The subcutaneous or intramuscular

administration will help it to get into the blood stream quicker – epi-pen is given to clients with severe allergy reactions

Not given by mouth because drug is inactivated by gastric juices

Can be inhaled in asthma attack

CAUTION!

Check dose, concentration, and route of administration – fatalities have occurred from medication errors – us TB syringe for subcutaneous administration

Inhaled provided as metered dose inhaler 160 to 250 mcg – broncho-constriction is asthma

IV would be 0.1 to 0.25 mg (cardiopulmonary resuscitation)

Precautions with Use

Tachyarrhythmia's (fast irregular heart rate), headache, nausea, and palpitations

Short acting so more definitive treatment needs to be initiated

Need cardio-respiratory monitoring Pulse oximetry Cardiac monitor

Cardiac Arrest

Epinephrine is the best studied and most

widely administered adrenergic agonist used

for the treatment of cardiac arrest.

Used to jump start the heart.

Vasopressor / Inotropic Drugs Used extensively along with Dopamine to

maintain myocardial and cerebral perfusion post cardiac arrest.

Administered in small, consistent amounts intravenous.

Antiadrenergic Drugs

Chapter 18

Clinical Drug Therapy

Antiadrenergic Drugs

Blocks the effects of the sympathetic nerve stimulation, endogenous catecholamine and adrenergic drugs.

Mechanism of Action

Act on alpha or beta receptors Receptors are blocked by adrenergic

antagonists or pre-synaptic alpha 2 receptors are stimulated.

When Used?

To manage hypertension and a number of cardiovascular disorders.

Anti – hypertensive Medication Clonidine: Catapres, Catapres TTS, Dixarit,

Duracion Pharmacologic classification: adrenergic

(centrally acting) Therapeutic classification: antihypertensive

Clonidine

Action: Stimulates the alpha-adrenergic receptors in the CNS which results in decreased sympathetic outflow inhibiting cardioacceleration and vasoconstriction centers. Prevents pain signal transmission to the CNS by stimulating alpha-adrenergic receptors in the spinal cord.

Therapeutic Effects: decreased blood pressure. Decreased pain.

Cholinergic Drugs

Chapter 19

Clinical Drug Therapy

Cholinergic Drugs

Cholinergic drugs stimulate the parasympathetic nervous system.

Mechanism of Action

Direct acting cholinergic drugs are synthetic derivative of choline.

Effects of drug Decrease heart rate, vasodilation, and changes in

BP Increase tone and contractibility of smooth muscle Increase tone and contractibility of bronchial

smooth muscles Increased respiratory secretions

Indications for Use

Urinary retention without obstruction Postoperative abdominal distention due to

paralytic ileus Myasthenia gravis – muscle weakness During surgery to reverse the effects of

muscle relaxants used during surgery

Nursing Assessment: urine retention Urinary retention

Bladder distention Fluid intake Time of last void

How do you know drug is working? Fluid intake equal to urine output Patient has voided within the last 8 hours

Nursing Assessment: paralytic ileus Paralytic ileus

Hypo-peristalsis Decreased bowel sounds No gas or bowel movement

How do you know drug is working? Bowel sounds heart in all four quadrants Client states has passes gas Client states has had a bowel movement

Nursing Assessment: Myasthenia Gravis Signs and symptoms: muscle weakness,

ptosis (droopy eye lid), diplopia (double vision), difficulty chewing and swallowing, decreased activity intolerance.

How do you know medication is working? Increased muscle tone, no droopy eye lid or double vision, increased activity tolerance.

Nursing Assessment: Alzheimer Signs and symptoms: loss of memory,

cognitive function and decreased self-care Signs medication is working: increase

memory and cognitive function and increase interest in activities of daily living

Use in Older Adults

May be used in myasthenia gravis or Alzheimer’s disease

Contraindications

Renal obstruction Liver disease

Anticholinergic Drugs

Chapter 20

Clinical Drug Therapy

Anticholinergic Drugs

Anticholinergics are a class of medications that inhibit parasympathetic nerve impulses by selectively blocking the binding of the neurotransmitter acetylcholine to its receptor in nerve cells.

Mechanism of Action

Drugs act by occupying receptor sites on target organs innervated by parasympathetic nervous system leaving fewer receptor sites free to respond to acetylcholine.

Parasympathetic response is absent or decreased depending on number of receptors blocked.

Effects of Anticholinergic Drugs CNS stimulation followed by depression Decreased cardiovascular response to

parasympathetic (vagal) stimulation that slows heart rate

Bronchodilation and decrease respiratory secretions

Antispasmodic effects in GI system Change in intra-ocular pressure in patients

with glaucoma

Uses

GI disorders – peptic ulcer disease, gastritis, increased gastric acid secretion – relax gastric smooth muscle (replaced by newer drugs)

Genitourinary – anti-spasmodic – urgency Excessive secretions Ophthalmology – relax eye for exam Respiratory disorder – asthma or bronchitis –

inhaled form only Cardiac disorders – bradycardia or heart block Parkinson’s disease

Side Effects

Hyperthermia, hot, dry flushed skin, dry mouth, tachycardia, delirium, paralytic ileus and urinary retention

Atropine

Pharmacological classification: anticholinergic

Therapeutic classification: antiarrhythmic Action: Inhibits the action of acetylcholine at

postganglionic sites located in the smooth muscle, secretory glands, CNS. Low doses decrease: sweating, salivation and respiratory secretions.

Atropine

Therapeutic effects: Increased heart rate Decreased GI and respiratory secretions Reversal of muscarinic effects May have spasmodic action on the biliary and

genitourinary tracts.

Atropine

Side effects: drowsiness, blurred vision, tachycardia, dry mouth, urinary hesitancy.

Atropine

Prototype of anticholineric drugs – atropine sulfate

Therapeutic

Previously used in preoperative patients to reduce secretions – other newer drugs have replaced