Nursing School Notes: ANS

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Block only the muscarinic receptors in the PNS and cholinergic receptors in the SNS
Act by competing with acetylcholine for the muscarinic acetylcholine receptor sites
Do not block the nicotinic receptors
Actions:

- ↑ HR
- ↓ GI activity
- ↓ urinary bladder tone & function
- dilate pupils

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Indications:

decrease secretions before anesthesia
treat parkinsonism (by blocking the stimulating effects of acetylcholine)
restore cardiac rate & BP s/p vagal stimulation during surgery
relieve brady s/p hyperactive carotid sinus reflex
relieve pylorospasm & hyperactive bowel
prevent S&S of motion sickness & vomiting
relax biliary and ureteral colic
relax bladder detrusor muscles & tighten sphincters
help to control crying or laughing episodes in pt w/ brain injuries
relax uterine hypertonicity
help in the management of peptic ulcer
control rhinorrhea associated with hay fever
antidote for cholinergic drugs and for poisoning by certain mushrooms
ophthalmic agent to cause mydriasis or cycloplegia in acute inflammatory conditions

Contraindications:

glaucoma
stenosing peptic ulcer
intestinal atony, paralytic ileus, GI obstruction
severe ulcerative colitis
toxic megacolon
prostatic hypertrophy, bladder obstruction
cardiac arrhythmias, tachycardia, myocardial ischemia
impaired liver or kidney function
myasthenia gravis (Low doses of atropine sometimes used in MG to block unwanted GI & CV effects of the cholinergic drugs used to treat it)

Caution:

pregnancy & lactation
HTN
spasticity, brain damage

Adverse Reactions:

Weakness, dizziness, insomnia, mental confusion, excitement
blurred vision, pupil dilation (w/ photophobia, cycloplegia, ↑ IOP)
Dry mouth, altered taste perception
possible tachycardia & palpitations
Urinary hesitancy and retention
nausea, heartburn, constipation, bloated feelings, paralytic ileus
↓ sweating & an ↑ predisposition to heat prostration

Interactions:

↑ effects w/ antihistamines, antiparkinsonism drugs, MAOIs, tricyclic antidepressants (all have anticholinergic activity)

Kinetics:

Well absorbed & Widely distributed throughout the body
excreted in the urine
Crosses blood brain barrier

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Drugs:

1. Atropine

Actions:

Depresses salivation and bronchial secretions
Dilates the bronchi
Inhibits vagal responses in the heart
Relaxes the GI & GU tracts
Inhibits GI secretions
Causes mydriasis
Causes cycloplegia (paralysis ciliary muscles)

Indications:

↓ secretions (before surgery)
bradycardia
pylorospasm, ureteral colic, relaxing of bladder
emotional lability with head injuries
antidote for cholinergic drugs
pupil dilation
Parkinsonism

AE:

Blurred vision, Mydriasis (pupil dilation), Cycloplegia (↓ accommodation reflex), Photophobia
Palpitations, bradycardia
Dry mouth, altered taste perception
Urinary hesitancy & retention
↓ sweating (predisposition to heat prostration)

2. Dicyclomine
- relaxes GI tract; Tx hyperactive or irritable bowel

3. Glycopyrrolate (Robinul)
- adjunct therapy in Tx ulcers

4. Propantheline (Pro-Banthine)
- adjunct in Tx ulcers

5. Scopolamine (Transderm Scop)
- dec N/V associated w/ motion sickness

6. Tiotropium (Spiriva)
-Tx bronchospasm/COPD

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Nursing Mgmt

Assess & monitor:
CV & Respiratory
CNS (LOC, orientation, reflexes)
GI (Constipation)
GU (Urinary retention)
Renal
Monitor for dry mouth & difficulty swallowing
elderly & children more susceptible to adverse effect - reduce dose (constipation, urinary retention, heat intolerance, and confusion)
BUT don't use Dicyclomine w/ kids
Teaching:

- void before taking med
- dry lots of fluids
- avoid hot temperatures
- safety precautions for dizziness/blurred vision

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Anticholinergics

React with acetylcholinesterase preventing Ach from breaking down – results in ↑ Ach
May bind reversibly or irreversibly
Irreversible:

- Not used therapeutically
- Being developed to as nerve gas to be used as weapons

- War setting – antidote readily available

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Indications:

Myasthenia gravis (autoimmune disease of progressive muscle weakness / lack of muscle control)
Alzheimer's (there is a progressive loss of ACh-producing neurons & their target neurons)

Contraindications:

Allergy
Bradycardia
Intestinal or urinary tract obstruction
Lactation

Caution:

Any condition that could be exacerbated by cholinergic stimulation
Asthma, CAD, PUD, arrhythmias, epilepsy, or parkinsonism

Adverse Reactions:

Bradycardia, Hypotension
Bronchoconstriction
↑ bladder tone
↑ GI secretions & activity
Relaxation of GI & GU sphincters
Pupil constriction (miosis)

Interactions:

↑ risk GI bleed if used w/ NSAIDs
↓ anticholinesterase effects if taken w/ any cholinergic drugs because these work in opposition to each other
↑ theophylline levels w/ tacrine

Kinetics:

Well absorbed and distributed throughout the body
Metabolized in the liver and excreted in the urine

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Drugs to Treat Myesthenia gravis:

1. Neostigmine (Prostigmine) - works at neuromuscular junction

2. Pyridostigmine (Regonol, Mestinon) - longer duration than neostigmine

3. Ambenonium (Mytelase) - only PO; cannot be used if patient is unable to swallow

4. Edrophonium (Tensilon, Enlon) - diagnostic agent for myasthenia gravis

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Drugs to Treat Alzheimer's:

1. Tacrine (Cognex) - 1st drug out there to treat Alzheimer's

2. Galantamine (Reminyl) - used to stop Alzheimer's progression

3. Rivastigmine (Exelon) - available in solution for swallowing ease

4. Donepezil (Atricept) - once-a-day dosing!

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Nursing Mgmt

if IV administer slowly
Atropine sulfate on-hand in case of crisis (antidote)
Observe for excessive salivation, diarrhea, emesis, excessive urination
should be taken w/ meals
Prevent injury
Teaching

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Nerve Gas – Irreversible Indirect Cholinergic Agonist:

Irreversible acetylcholinesterase inhibitor
Leads to toxic accumulation of ACh at cholinergic receptor sites

Antidotes:

Pralidoxime (Protopam Chloride); works in PNS

IM or IV
frees up acetylcholinesterase to start breaking down ACh
on-hand for MG receiving an IDCA
antidote for irreversible acetylcholinesterase-inhibiting drugs, or nerve gas
Organophosphate pesticide poisoning

Atropine; works in CNS

Block cholinergic activity & active Ach in CNS
Activate Acetylcholinesterase to breakdown Ach

Adverse Effects

Blurred vision, dizziness, diplopia, headache, hyperventilation
Can cause parasympathetic crisis and muscle paralysis

Indirect-Acting Cholinergic Agnoists

Chemicals that act at the same site as the neurotransmitter acetylcholine (ACh)
Similar response as parasympathetic system activation - Effects are widespread
These drugs usually stimulate muscarinic receptors in PNS
used as systemic agents used to:

- ↑ bladder tone, urinary excretion, & GI secretions
- also used as ophthalmic agents to induce miosis to relieve ↑ IOP of glaucoma via pupil constriction (not systemic when used ophthalmically)
- ↓ HR, ↓ myocardial contractility, bronchoconstriction & ↑ bronchial mucous secretion

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Contraindications:

Any condition that would be exacerbated by parasympathetic effects—bradycardia, hypotension, CAD
PUD, intestinal obstruction or recent GI surgery
Asthma
Bladder obstruction
Epilepsy & parkinsonism

Caution:

pregnancy / lactation

Adverse Reactions:

N/V, diarrhea, cramps, involuntary defecation
Bradycardia, heart block, hypotension
Urinary urgency
Flushing, ↑ sweating & salivation, swallowing difficulty

Interactions:

↑ risk of cholinergic effects if these drugs are combined or given with acetylcholinesterase inhibitors

Kinetics:

Well absorbed and have relatively short half-life (1-6 hr)
Metabolized; excretion of these drugs is not known

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Drugs:

1. Bethanechol (Duvoid, Urecholine)

- urinary retention

- urogenic bladder

- esophageal reflux in infants/kids

Mgmt:

Produces muscarinic effects primarily on GI tract & urinary bladder

↑ tone & peristaltic activity of esophagus, stomach, and intestine
contracts detrusor muscle of urinary bladder, usually enough to initiate micturition.
cant help if obstructed

must monitor for effectiveness - i.e are they having problem still w/ urinary retention? (relief should be quick)
if not working, could be structural problem (BUN & Cr will go way up)

2. Carbachol (Miostat)
- induces miosis to ↓ IOP

3. Cevimiline (Exovac)
- Tx dry mouth

4. Pilocarpine (Salagen)
- Tx dry mouth (xerostomia) s/p radiation therapy of head & neck tumor

- glaucoma (constricts pupil & ↓ IOP)

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Nursing Mgmt
Baseline Assessment:

Cardiovascular - HR, BP CAD
GI - Bleeding, ulcer disease, obstruction, dehydration
Respiratory assessment - Asthma
GU - Recent bladder surgery or obstruction
CNS - Parkinson’s and/or epilepsy

Direct-Acting Cholinergic Agonists

Do not usually block beta-2 receptor sites, including sympathetic bronchodilation
Preferred for patients who smoke or have asthma, obstructive pulmonary disease, or seasonal / allergic rhinitis

Indications

HTN
angina
some cardiac arrhythmias
open-angle glaucoma

Contraindications

brady, heart block
shock, CHF, hypotension

Cautions

COPD
DM, thyroid disease

Adverse Effects

CNS: Fatigue, dizziness, sleep disturbances
CV: Bradycardia, heart block, CHF, hypotension
Resp: Sx in resp tract (range from rhinitis to bronchospasm)
GI: N/V, diarrhea
↓ libido and impotence

Kinetics

absorbed from GI
metabolized in liver and are excreted in the urine

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Drugs
Atenolol (Tenormin)

Tx MI, angina
most used drug in its class for HTN

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Drug Interactions

↓ HTN effects w/ clonidine, NSAIDs, rifampin
↑ toxicity IV lidocaine if given w/ these drugs
↑ risk orthostatic hypotension w/ prazosin

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Nursing Mgmt for All A&B Agonists

Check apical pulse before PO admin, esp. in pt receiving digitalis (both drugs slow AV conduction)

If < 60 bpm, withhold dose & consult physician

Monitor apical pulse, BP, respirations, & peripheral circulation throughout dosage adjustment period. Consult physician for acceptable parameters.
Sudden d/c of drug can exacerbate HTN, angina, & precipitate tachycardia or MI in pt w/ CAD, & thyroid storm in pt w/ hyperthyroidism – due to being hypersensitive to catecholamines

Beta-1 Selective Blockers

competitively block beta receptors in SNS
its therapeutic effects caused by beta-block in heart & juxtaglomerular apparatus

(-) inotrope, (-) chronotrope, (-) dromotope
this leads to ↓ arrhythmia, ↓ cardiac workload, ↓ O2 consumption
& dec BP b/c juxtaglomerular cells not stimulated to secrete renin

drugs ending in -olol

Indications

Tx cardiac conditions – HTN, angina, migraine headaches, preventing re-infarction after MI
off label: anxiety/stage fright

Contraindications

brady, heart block, shock, CHF
COPD/asthma (blocks dilation)

Cautions

diabetes (blocks normal S&S of hyper-/hypoglycemia)
thyrotoxicosis (b/c blocking effects on thyroid gland)
hepatic dysfunction

Adverse Effects

brady, heart block, hypotension, arrhythmia, HF
bronchospasm, cough
fatigue, dizziness
sleep disturbance, depression
N/V, diarrhea
↓ labido, dysuria
↓ exercise tolerance / can no longer "get-up-and-go"

Kinetics

Well absorbed from GI tract
Metabolized in the liver

Drugs
1. Propranolol (Inderal)

Patient teaching required:

teach pt to take pulse / take pulse before taking med
teach pt it blocks S&S hypoglycemia
teach about compliance &
teach that abrupt d/c can lead to withdrawal syndrome (tremors, sweating, headache, malaise, palpitation, rebound HTN, MI, life-threatening arrhythmia)
teach about postural hypotension

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2. Sotalol (Betapace)

indicated for life-threatening arrhythmia & maintenance of sinus rhythm w/ AF or a-fib pt

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Drug Interactions

↓ effectiveness w/ NSAIDs
blood glucose changes w/ diabetic meds & insulin
HTN may occur if given w/ clonidine

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Nursing Mgmt for Nonselective Beta Blockers

if used LT, do not stop abruptly! (receptors become hypersensitive to catecholamines) – can cause rapid inc BP → MI / stroke

should taper over 2wks

labs: liver/kidney function, thyroid function, blood glucose

Nonselective Beta Blockers

These work on alpha receptors
vasodilates aka ↓ BP (alpha 1)
& blocks NE feedback control (alpha 2)

Indications

primarily used to prevent cell death/tissue sloughing r/t IV DA or NE extravasation/infiltration (causes local vasodilation & return of blood flow to the area)
can be used for pheochromocytoma Dx or mgmt of severe HTN reactions s/p pheochromocytoma surgery

CAD or MI

Cautions

pregnancy & lactation

Adverse Effects

(orthostatic) hypotension, arrhythmia (tachy), flushing
angina, MI, CVA

Kinetics

Rapidly absorbed after IV or IM injection
Metabolized in the liver and excreted in the urine

Drug

Phentolamine (Regitine)

Drug Interactions

↓ effectiveness ephedrine & epinephrine
↑ hypotension if combined w/ alcohol

Nursing Mgmt

monitor CNS & CV status

Nonselective Alpha Blockers

These are non-selective drugs.
competitively block norepinephrine at alpha & beta receptors
called sympatholytic drugs b/c they lyse or block SNS effects to prevent S&S associated w/ sympathetic stress reaction

↓ HR & ↓ BP
↑ renal perfusion & ↓ renin levels

Indications

primarily used to treat cardiac conditions i.e essential HTN (usually adjunct w/ diuretics)

Contraindications

brady or heart block
shock or CHF
pregnancy & lactation

Cautions

bronchospasm & resp distress

(due to loss of NE bronchodilation effects)

Adverse Effects

arrhythmia, hypotension, CHF
pulm edema, bronchospasm, dyspnea
dizziness, vertigo
insomnia, fatigue
N/V, gastric pain

Kinetics

Well absorbed
Metabolized in the liver and excreted in the urine & feces

Drugs
1. Amiodarone (Cordarone)

antiarrhythmic agent
reserved for emergency use

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2. Carvedilol (Coreg)

indicated for HF, MI, HTN, left ventricle dysfunction

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3. Labetalol (Normodyne)

indicated for HTN
control of BP in pheochromocytoma
used for clonidine withdrawal HTN

Nursing Mgmt for All A&B Agonists

monitor diabetic pt closely: these drugs also mask S&S hypoglycemic & hyperglycemia
priority for diabetic pt is to monitor glucose over pulse; priority for most pt on adrenergic blockers is to monitor pulse
monitor vitals + blood glucose + liver/kidney function
educate pt about AE, re-educate diabetics about glucose monitoring
find out pt herbal drug use:

Ginseng = ↑ anti-HTN effects (risk hypotension, CNS effects)
Xuan shen, nightshade = ↓ HR (risk severe brady, reflex tachy)
Celery, Xuan shen, coriander = ↓ glucose (inc risk hypoglycemia)
Saw palmetto = ↑ risk urinary tract complications

Nonselective Alpha & Beta Blockers

These selective for beta receptors
↑ heart rate (+ chronotropy), ↑ contractility (+ inotropy), ↑ conductivity (+ dromotropy)
bronchodilation
↑ blood flow to skeletal muscles & splanchnic bed
relaxes uterus
(most drugs in this class at beta-2 selective, used to manage asthma, bronchospasm, COPD)
drugs in this class end in -terol (exception: terbutaline)

Indications

asthma, bronchospasm, obstructive pulm conditions
relaxation of uterus

Contraindications

pulm HTN
halogenated anesthesia (sensitize heart to catecholamines)
eclampsia, uterine hemorrhage, intrauterine death, pregnancy or lactation

Cautions

DM, thyroid disease
vasomotor problems
heart disease, stroke, renal disease

Adverse Effects

restlessness, anxiety, fear
tachy, palpitations, angina, MI
difficulty breathing, cough, bronchospasm
N/V, anorexia
may cause pulm edema, sweating, pupil dilation
sweating, pallor

Kinetics

Rapidly absorbed after injection
Metabolized in the liver and excreted in the urine
half-life usually < 1 hr

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Drugs
1. Isoproterenol (Isuprel)

nonspecific beta agonist
usually reserved for emergency use due to numerous AE
given IV or injected

Indications:

Tx shock, cardiac standstill, heart block in transplanted hearts
prevention bronchospasm during anesthesia
Tx bronchospams

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2. Albuterol (Proventil)

Tx & prevention of bronchospasm
inhaled

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Drug Interactions

inc risk AE when combined w/ others meds in the same class

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Nursing Mgmt for Beta Specific Agonists

baseline assessment of VS, ECG, UO
labs: renal & hepatic function, blood glucose
monitor for therapeutic & adverse effects

Nonselective Beta Agonists

These drugs bind to alpha receptors

Adverse Effects

CNS: anxiety, restlessness, depression, blurred vision/light sensitivty (from pupil dilation)
CV: arrhythmia, ECG changes, BP changes
GU: dec UO, difficulty urinating

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Drugs
1. Phenylephrine (Neo-Synephrine)

potent vasoconstrictor – works on alpha-1 receptors
has little to no effect on heart & bronchi

Indications

Parenterally: shock/shock-like state, SVT, prolong local anesthesia, maintain BP during spinal anesthesia use
Topically: ophthalmic; to ↓ IOP associated w/ glaucoma; dilates pupils during eye exam or surgery
Nasal Spray: used topically to treat allergic rhinitis & receive Sx otitis media
Other: Intracavernosal Phenylephedrine is the drug of choice & first line Tx of low-flow priapism b/c it has almost pure alpha effects & minimal beta activity

Caution:

essential HTN
used in many OTC meds, may cause inadvertent OD

AE:

fear, anxiety, restlessness
headache, nausea, pallor
↓ urine formation

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2. Midodrine (ProAmantine)

orthostatic hypotension (non-responsive to normal therapies)
works on alpha-1 receptors

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3. Clonidine (Catapres)

centrally-acting alpha-2 agonists (stimulates A2 CNS receptors)
they are hypotensive agents – ↓ HR, inhibit NE

Indications

indicated for essential HTN
epidural infusion for Tx chronic pain in terminally ill adults
can be used to treat high BP, ADHD, anxiety/panic disorders

Caution:

do not stop suddenly! - taper over 2-4 days
fall risk (monitor BP closely - esp. w/ postural change)

AE:

hallucinations, bad dreams
headache, sedation, fatigue
dry mouth, dec sexual function
N/V, constipation
can cause extreme hypotension, brady, HF

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Nursing Mgmt

Monitor VS, cardiac status, orthostatic hypotension
do not stop abruptly! – can cause rebound HTN, arrhythmia, flushing

must taper over 2-4 days!

avoid extravasation

Nonselective Alpha Agonists

non-selective drugs

They work on the same receptors but not to the same degree - therefore they have different indications

In general, they work to:

- ↑ HR, vasoconstrict, dilate bonchi,
- promote glycogenolysis (breakdown of glycogen)
- dilate pupils, inc sweating

Indications

Tx hypotensive shock (esp dopamine)
bronchospasm & some types of asthma

Contraindications

Pheochromocytoma (adrenal tumor —> inc catecholamine secretion —> major inc HR & BP)
Tachy-arrhythmias or V-Fib
Hypovolemia
Halogenated hydrocarbon general anesthetics

Cautions

PVD – could be exacerbated by systemic vasoconstriction
pregnancy & lactation

Adverse Effects

Arrhythmias, hypertension, palpitations, angina
dyspnea
N/V
Headache, sweating

Kinetics

Rapidly absorbed after injection or passage through mucous membranes
Metabolized in the liver and excreted in the urine

Drugs
1. Dobutamine (Dobutrex)

preference for B1 receptors –> therefore indicated for CHF
it can inc myocardial contractility (+ inotrope) w/o much change to rate; does not inc O2 demand of the heart, while most other sympathomimetics do

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2. Epinephrine (Adrenaline, Sus-Phrine)

indicated for shock, glaucoma, asthma/COPD, anaphylactic reactions
can also prolong effects of local anesthetics

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3. Norepinephrine (Levophed)

indicated for shock
used during cardiac arrest (V-fib) to get sympathetic activity

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4. Metaraminol (Aramine)

synthetic agent similar to norepinephrine

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Big Guns:
1. Dopamine (Intropin)

Tx hypotensive shock
↑ HR, ↑ BP
maintains renal perfusion (maintains UO / ↑ Na & fluid output)

- most vasoconstrictors aren't able to dilate renal arterioles

Nursing Considerations for Dopamine:

monitor BP, HR, peripheral pulses, UO
precise measurement essential for accurate titration of dosage
report the following to physician:

- dec urine flow in absence of hypotension
- ascending tachy, dysrhythmias, disproportionate rising diastolic (marked dec in Pulse Pressure), S&S peripheral ischemia (pallor, cyanosis, coldness, pain, numbness/burning, mottling)

monitor for extravasions

- have phentolamine on hand – antidote

monitor for effectiveness -

- improved VS & signs of good vital organ perfusion:
- (loss of pallor, inc toe tmp, good cap refill, reversal of confusion)

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2. Ephedrine (pretz-D)

Tx seasonal rhinitis, hypotensive episodes, (recreational use)
causes cardiac stimulation, vasoconstriction, bronchodilartion
stimulates Norepinephrine release
crosses blood brain barrier (BBB) –> CNS stimulation –> used for narcolepsy & depression, (used illegally as sports performance enhancer)
form of the drug (Pseudoephedrine) used as nasal decongestant

Nursing Considerations for Ephedrine

find out pt's OTC med use / education about inadvertent overdose
monitor AE:

CNS: anxiety restlessness
CV: tachy, palpitations
GU: difficult/painful urination, acute urinary retention (esp. older men w/ prostatitis)

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Drug Interactions

inc effects Tricyclic antidepressants (TCAs) and MAOI’s

MAOI inhibits monoamine oxidase which is needed to break down Epi & NE

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Nursing Mgmt for All A&B Agonists

Monitor kidney/liver function, serum electrolytes, I&O, VS, ECG
Herbs to avoid: Ma Huang, guarana, caffeine (↑ BP, stroke death)
ask bout OTC cold, allergy, & diet pills use (↑ BP, stroke death)
Avoid extravasation
Aseptic technique when administering ophthalmic & nasal agents
Monitor light exposure to prevent sensitivity to light from pupil dilation
Encourage voiding prior to med admin to prevent urinary retention due to sphincter contraction
Encourage relaxation to alleviate feelings of tension and anxiety
Usually administered systemically for hypovolemic – hypotensive shock in an ICU (esp Dopamine) so pt needs constant monitoring
monitor systemic effect of nose drops due to excessive dosage due to rapid absorption through nasal mucosa

Nonselective Alpha & Beta Agonists

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