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Unit 11: Pharmacology

Drugs affecting the Autonomic Nervous System

Chap 14: Sedative – Hypnotic

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Nervous System

Drugs that affect the nervous system act upon the:

1. Central Nervous System (CNS)

2. Autonomic Nervous System (ANS)

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Autonomic Nervous System

Regulatory and self-governing

Without conscious thought

Maintains internal environment

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Autonomic Nervous System: Divisions

1. Sympathetic System

Fight or flight

under stress

2. Parasympathetic System

Rest and digest

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Innervation

Most organs are innervated by BOTH Sympathetic and Parasympathetic

Keeps a balance of function

For example:

Heart

Eyes

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Sympathetic Nervous System Drugs

1. Adrenergic (Sympathomimetic) Drugs

Mimic the action of sympathetic nervous system

For example, Epinephrine (Adrenalin)

2. Anti-Adrenergic (Sympatholytic) Drugs

Block the action of sympathetic nervous system

Division:

1. Alpha adrenergic blockers

2. Beta blockers

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Parasympathetic Nervous System Drugs

1. Cholinergic (Cholinomimetic) drugs

Stimulate the Parasympathetic Nervous System

2. Anti-Cholinergic (Cholinolytic) drugs

Inhibit the Parasympathetic Nervous System

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Adrenergic (Sympathomimetic)

Mimic the action of the Sympathetic Nervous System

Therapeutic uses and adverse effects targets:

Heart, lungs, and blood vessels

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Adrenergic (Sympathomimetic): Receptors

Receptor Location Stimulation

Alpha blood vessels

vasoconstrictions,

↑ BP,

↓ nasal congestion,

contraction of GIT and urinary bladder sphincter

Beta 1 heart↑ HR

(+) contraction

Beta 2lungs

peripheral blood vessels

bronchodilator

vasodilation

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Adrenergic (Sympathomimetic): Drugs

1. Cathecholamines

Cannot cross Blood Brain Barrier

Endogenous: Epinephrine, NE, Dopamine

Exogenous (synthetic): Dobutamine (post-heart failure) and Isoproterenol (Bronchodilators)

2. Non-Cathecholamines

Cross the Blood Brain Barrier

Ephedrine (Metabolife – diet pills), albuterol (anti-asthma), and phenylephrine (decongestant)

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Adrenergic (Sympathomimetic): Uses

Primarily used for emergency drugs

1. Cardiac arrest – stimulates the heart

2. Hypotension – increase BP

3. CHF – increase force and contraction of heart

4. Asthma – bronchodilator

5. URT Congestion – decongestant

6. Allergic reaction – vasoconstriction and decongestant

7. Hypoglycemia – glycogenolysis

8. Local bleeding – vasoconstriction

9. Obstetrics – uterine relaxant

10. Eye disorder – vasoconstriction

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Adrenergic (Sympathomimetic): Adverse Effects

1. Cathecholamines

Nervousness and restlessness

Angina

Hypertension

Tachycardia

Hyperglycemia

Nausea and vomiting

2. Non-Cathecholamines

Severe anxiety and insonmia

Tachycardia and palpitations

Dysrhythmias

Muscular weakness and cramps

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Adrenergic (Sympathomimetic): Contraindications

Cardiac dysrythmia

Angina

Hypertension

Glaucoma

Pregnant women

Caution with children !!

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Adrenergic (Sympathomimetic): Cathecholamine Drugs

Epinephrine hydrochloride (Adrenalin Chloride)

Drug of choice for Anaphylaxis

Active ingredient in OTC asthma preparation

Effects: (+) Alpha and Beta recepts

↑ BP and ↑ HR

↑ blood flow to brain, heart, and skeletal muscle

Peripheral vasoconstriction

(-) GIT motility

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Adrenergic (Sympathomimetic): Cathecholamine Drugs

Norepinephrine (Levophed)

Strong vasoconstrictor

Used for Hypotension and Cardiac Arrest

Dopamine Hydrochloride (Intropin)

Precursor to NE

Dosage effects:

Low dose – causes renal perfusion

Low to moderate dose – causes increased CO

Higher doses – increased peripheral resistance and BP

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Adrenergic (Sympathomimetic): Cathecholamine Drugs

Dobutamine hydrochloride (Dobutrex)

Synthetic cathecholamine

Acts directly on heart muscle to increase the contraction

Isoproterenol hydrochloride (Isuprel)

Synthetic cathecholamine

Bronchodilator

(+) Beta1 and Beta2 receptors

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Adrenergic (Sympathomimetic): Anti-Cathecholamine Drugs

Ephedrine and Pseudoephedrine (Sudafed)

Less potent but longer acting than epinephrine

Bronchodilator and Nasal decongestant (allergic reaction)

Phenylephrine hydrochloride (Neo-Synephrine)

(+) Alpha receptor

Vasoconstrictor, decongestant, and bronchodilator

Albuterol (Proventil)

Bronchodilator

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Anti-Adrenergic (Sympatholytic)

Block the effect of sympathetic nervous system

Treatment goal is to reduce pathologic response to activity, stress, and other stimuli

Two major types:

1. Alpha-adrenergic blocking agent

2. Beta-adrenergic blocking agent

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Anti-Adrenergic (Alpha-adrenergic): Uses

1. Mild to moderate hypertension

2. Benign prostatic hypertrophy (BPH)

3. Migraine headaches

4. Pheochromocytoma – tumor of the adrenal glands

Increased secretion of Epinephrine and NE

5. CHF with diuretics

6. Peripheral vascular disorders (frostbites)

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Anti-Adrenergic (Alpha-adrenergic): Adverse Effects

Nasal congestion

Nausea

Vomiting

Postural hypotension

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Anti-Adrenergic (Alpha-adrenergic): Contraindications

Hypersensitivity

Sepsis

Vascular disease

Hepatic or renal disease

Atherosclerosis

Hypertension

Anemia

Pregnancy and lactating

Caution to children and elderly

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Anti-Adrenergic (Alpha-adrenergic): Important Drugs

Phentolamine mesylate (Regitine)

Prevents tissue necrosis after extravasation of IV NE

Prevents and controls hypertension caused by Pheochromocytoma

Doxazosin (Cardura), Prozosin (Minipress), and Terazosin (Hytrin)

Acts on the periphery

Treats hypertension or BPH

Sumatriptan (Imitrex)

Vascular headache suppressant to treat migraines

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Anti-Adrenergic (Beta-Adrenergic)

Block the effect of Adrenergic stimulation of Beta1 or Beta2

Competes with NE receptor site

Beta blockers

Decrease in BP, heart contraction, and CO

Beta2 blockers causes vasodilation in skeletal muscles

Treatment for Angina pectoris and decrease BP

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Anti-Adrenergic (Beta-Adrenergic): Uses

Angina – decrease in O2 demand, heart contraction, HR, BP

Dysrhythmias – slow sinus node, prolongs AV conduction

Hypertension – lowers BP

MI – to decrease Cathecholamin-induced dysrhythmias

Glaucoma – decreases IOP

Migraine – unclear

Palpitation and Tremor – unapproved anti-anxiety

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Anti-Adrenergic (Beta-Adrenergic): Adverse Effects

Bradycardia

Shortness of breath

Edema

Reduced tolerance to exercise

Hypoglycemia

CHF

Orthostatic hypotension

Fatigue

Nausea

Vomiting

Bronchospasm

Impotence

Depression

Sleep disorders

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Anti-Adrenergic (Beta-Adrenergic): Contraindication

Diabetes with insulin

Kidney and liver disease (metabolism and excretion)

Alcohol, CNS depressant, and OTC decongestant

Not affective for African-Americas

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Anti-Adrenergic (Beta-Adrenergic): Important Drugs Propranolol hydrochloride (Inderal)

Treats hypertrophic subaortic stenosis, hypertension, angina, dysrythmias, and MI

Metoprolol tartrate (Lopressor)

Treats hypertension and dysrythmias

Atenolol (Tenormin)

Treats hypertension, angina, and MI

Timolol maleate (Timoptic)

Eye drop for treatment of Glaucoma

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Parasympathetic Nervous System

75% of all parasympathetic fiber are in the Vagus Nerve

Functions in Rest and Repair

Found in Digestion, Excretion, Cardiac deceleration, and Anabolism

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Parasympathetic Nervous System

Acetylcholine is the neurotransmitter

Stimulation

Constricted pupils

Contraction of GIT smooth muscle

Bronchoconstrictor

Bradycardia

Increased glandular secretion (except sweat)

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Cholinergic (Parasympathomimetic): Receptors

1. Nicotinic (resembles nicotine)

Tachycardia

Hypertension

Peripheral vasosconstriction

2. Muscarinic

Bradycardia

Hypotension

Increase salivation

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Cholinergic (Direct-acting): Effects

Decreased heart rate

Increased GIT muscle and secretion

Relaxation of sphincters

Increased respiratory secretions

Constriction of pupils

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Cholinergic (Direct-acting): Uses

Glaucoma

Gastric reflux

Prevention of nausea & vomiting

Related to chemotherapy

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Cholinergic (Direct-acting): Adverse Effects

Nausea and Vomiting

Diarrhea

Wheezing & shortness or breath

Bradycardia

Hypotension

Headache

Increased salivation

Increased sweating

Impaired vision

Poor night vision

Anxiety and restlessness

Sleep disturbance

Convulsion

coma

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Cholinergic (Direct-acting): Contraindication

Diabetes mellitus

Coronary artery disease (bradycardia)

MI

Heart block

Intestinal obstruction

Peptic ulcer

Asthma (increased secretion)

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Cholinergic (Direct-acting): Drugs Bethanechol chloride (Urecholine)

Treats urinary retention and glaucoma

Pilocarpine hydrochloride (Pilocar)

Decreases IOP in Glaucoma

Carbachol intraocular (Miostat)

Treats Glaucoma

Metoclopramide hydrochloride (Reglan)

Prevents chemotherapy-induced nausea and vomiting

Treats Acid-reflux disease

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Cholinergic (Indirect-acting):

Inhibit the action of Acetylcholinesterase

Enzyme that breaks down acetylcholine.

Prolongs the effects of Ach

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Cholinergic (Indirect-acting): Uses

Myasthemia gravis – autoimmune

Decreased neuromuscular transmission

muscle weakness

Glaucoma

Bladder emptying

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Cholinergic (Indirect-acting): Adverse Effects

Hypotension

Miosis – constriction of the pupils

Vasodilation

Bradycardia

Intestinal spasm

Increased salivation

diaphoresis

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Cholinergic (Indirect-acting): Contraindications

Diabetes mellitus

Coronary artery disease

Heart block

Urinary tract obstruction

asthma

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Cholinergic (Indirect-acting): Important drugs

Neostigmine bromide (Prostigmin)

Treats urinary retention

Edrophonium chloride (Tensilon)

Diagnoses Myasthenia gravis

Pyridostigmine bromide (mestinon)

Drug of choice for Myasthenia gravis

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Anti-cholinergic (Parasympatholytic):

Sometimes called Muscarinic antagonist (blocker)

Competes with Ach at the receptor site

Depresses the CNS

Targets the skin, eyes, GIT, urinary bladder, bronchi, and heart

X

X

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Anti-cholinergic (Parasympatholytic): Uses

Widespread effects on the body. Thus, limits the use

Treats GIT disorders by increasing motility, secretion, with accompanying pain.

Urinary disorder – antispasm

Respiratory disorder – causes bronchodilation

Cardiac disease – treats bradycardia

Parkinson’s – decreases salivation and tremors

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Anti-cholinergic (Parasympatholytic): Adverse Effects

Dry mouth

Constipation

Difficulty urination

Tachycardia

Intolerance to heat

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Anti-cholinergic (Parasympatholytic): Contraindication

Glaucoma – drugs causes dilatation of pupil

Hypersensitivity to drug

Chronic lung, renal, and liver disease

Myasthenia gravis

Heart disease

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Anti-cholinergic (Parasympatholytic): Drugs

Atropine sulfate

Used to pre-operatively to dry secretions

Treats bradycardia

Belladonna tincture

Treats GIT disorders

Hemoatropine (spectro-homatropine)

Eye drops to produce Mydriasis (pupil dilation) and cycloplegia (paralysis of ciliary muscle)