Drugs of Autonomic Nervous System

DRUGS AFFECTING THE AUTONOMIC NERVOUS

SYSTEM

1

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Peripheral Nervous System

Somatic: VoluntaryInnervates skeletal musclesControlled through conscious thought

NeurotransmitterAcetylcholine

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Autonomic Nervous SystemAutonomic or visceral division –

not controlled by consciousControls

• Blood pressure• Heart rate• Gastrointestinal activity• Glandular secretions

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SUBDIVISIONS OF THE AUTONOMIC NERVOUS SYSTEM

Sympathetic nervous system Fight or Flight Useful in highly stressful or emergency

situations Parasympathetic nervous system

Maintains homeostasis Works in “opposition” of the Sympathetic

nervous system “Rest and Digest”

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VOCABULARY“SYNONYMOUS” TERMS

SYMPATHETIC AKA ADRENERGIC SYMPATHOMEMETIC

• MIMICS THE SYMPATHETIC SYSTEM

PARASYMPATHETIC AKA CHOLINERGIC PARASYMPATHOMEMETIC

• MIMICS THE PARASYMPATHETIC NERVOUS SYSTEM

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Adrenergic/SympatheticNEUROTRANSMITTERS (neurohormones)CATECHOLAMINES

Epinephrine (prototype) – secreted by Adrenal gland, direct response at nerve ending

Norepinephrine – secreted by Adrenal gland. Stored in the axon, direct response at the nerve ending

RECEPTORS / RECEPTOR SITESALPHA 1ALPHA 2BETA 1BETA 2

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RECEPTOR Responses to Stimulation

ALPHA I (located on the target cells)

Blood vessels Constriction Pupils Dilation Penis Ejaculation Uterus Contraction Sphincters Constriction

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Alpha-1 Adrenergic drugs

Isuprel (isoproterenol) Used for shock

Adrenalin (epinephrine) Cardiac arrest Anaphylactic shock

Nasal decongestants (phenylephrine – Neo-Synephrine) Pseudoephedrine (Sudafed)

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RECEPTOR Responses to Stimulation

ALPHA 2 (located on presynaptic terminal) Control the release of norepinephrine and

provide the negative feedback inhibition.

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ALPHA 2 Adrenergic Drugs

CLONIDINE (Catepres) Decrease blood pressure Management of Opioid withdrawal

METHYLDOPA Decrease blood pressure, especially use din

pregnant lady to decrease BP.

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RECEPTOR Responses to Stimulation

DOPAMINE RECEPTORS

Located in various tissues and organs Cause dilation of renal, mesenteric, coronary

and cerebral arteries

D1, D2, D3, D4

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Adrenergic drugs (Alpha 1) ADVERSE EFFECTS V.

THERAPEUTIC EFFECTS

Increased HR (tachycardia) Increased Blood pressure Decreased Gastric motility…constipation Restlessness, irritability, anxiety, pallor Increased Alertness

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Adrenergic blocking drugs Alpha and BETA blocking drugs

Uses (Beta1 receptors are located primarily on cardiac tissues - cardioselective)

• Cardiac dysrhythmias• Angina• Hypertension• Congestive heart failure• Prostate hypertrophy (alpha blocker)

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Adrenergic (beta-1) blocking drugs

Beta-adrenergic blocking drugs(A-M are selective, From N-Z are non-selective )

Propranolol (Inderal)………B1, B2Nadolol (Corgard)….B1, B2Atenolol (Tenormin)….B1Metoprolol……B1Timolol (Timoptic)….B1, B2Labetalol……….Alpha and Beta

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ADRENERGIC BLOCKING DRUGS

Adverse reactions

Drowsiness, fatigueBradycardiaHypotensionOrthostatic hypotensionDiarrhea

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Adrenergic blocking drugs

Nursing considerationsPatient teaching

• Postural hypotension• Signs and symptoms of Heart

Failure• Monitor blood pressure• Taking their own pulse

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Parasympathetic (Cholinergic)Nervous

System

NEUROTRANSMITTER (neurohormone)

• Acetylcholine – Produced and stored in nerve endings

• Acetylcholine (ACh) binds to Cholinergic receptor sites and causes a response

Stimulation results in “rest and digest’

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Acetylcholinesterase(aka:cholinesterase)

Breaks down Acetylcholine or limits

response

Maintains the balance between

acetylcholine and dopamine

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Uses – only four for cholinergic drugs:Drugs that increase Acetylcholine in

the Synapse

Glaucoma – Reduce intraocular pressure

Myasthenia gravis – Disease caused by the lack of ACh at the synapse

Relief of urinary retention

Increase GI motility

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Indirect acting Cholinergic drugs

Neostigmine (Prostigmine) (anticholinesterase) prototype

• Primarily used to treat Myasthenia Gravis

Pyridostimine (Mestinon) • Myasthenia Gravis

Donepezil (Aricept) • Works in the CNS to inhibit synthesis of

Acetylcholinesterase• Used to treat Alzheimer’s disease

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Cholinergic drugs

Direct acting Cholinergic drugs

Directly stimulates the nerve ending to secrete acetylcholine

Bethanechol (Urecholine)• Used to treat urinary retention

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ADVERSE REACTIONS CHOLINERGIC DRUGS

Bradycardia Hypotension Headache, dizziness Increased secretions Abdominal cramping Increased respiratory secretions and possibly

bronchospasms

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Anticholinergic Medication

Competitive antagonists Compete with ACh Inhibit nerve transmission

Sites of action All systems except musculo-skeletal

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Anticholinergic Medication

EXAMPLES Bentyl (dicyclomine HCL)

• Antispasmotic used to decrease intestinal cramping in IBS

Atropine (Prototype)

• Acetylcholine antagonist• Antidysrhythmic• Antispasmotic• Antisecretory

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Anticholinergic Medication

USES Dry oral secretions Increase heart rate Treat ureteral colic Decrease GI motility Parkinson’s disease Decrease upper respiratory secretions

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Urinary antispasmodics AKA anticholinergics

OXYBUTYNIN (DITROPAN)• Synthetic antimuscarinic

INCREASES BLADDER CAPACITY DECREASES FREQUENCY OF VOIDING

TOLTERODINE (DETROL, DETROL LA)• Synthetic antimuscarinic

DELAYS THE URGE TO VOID INHIBITS BLADDER CONTRACTIONS

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Anticholinergic Medication

Adverse reactions / Side effects Dry mouth Blurred vision Photophobia Urinary retention Constipation Tachycardia Drowsiness

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Nursing Interventions Monitor for signs of anticholinergic crisis Report changes in heart rate, blood pressure,

or development of dysrhythmias Provide comfort measures for dryness of

mucous membranes Minimize exposure to heat or cold or strenuous

exercise Monitor I&O Monitor patient for abdominal distension, and

auscultate for bowel sounds

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Anticholinergic Crisis

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