Download adrenergic drugs

ADRENERGIC DRUGS
The adrenergic drugs produce pharmacologic effects similar to the effects that occur in the body
when the adrenergic nerves and the medulla are stimulated. The primary effects of these drugs
occur on the heart, the blood vessels, and the smooth muscles, such as the bronchi. Adrenergic
drugs mimic the activity of the sympathetic nervous system. These drugs are also called
sympathomimetic drugs.
ACTIONS –
Adrenergic drugs work by binding to adrenergic nerve fibers which have either alpha or beta
receptors. Adrenergic drugs may act on alpha receptors only, beta receptors only or on both
alpha and beta receptors. The alpha and beta receptors can be further divided alpha1 and alpha2adrenergic receptors and beta1 and beta2 –adrenergic receptors. These actions may result in the
following responses. CNS – wakefulness, quickened reflexes. PNS – relaxation of smooth
muscles of the bronchi, constriction of blood vessels, sphincters of the stomach, dilatation of
coronary blood vessels, decrease in gastric motility. Heart – increase in heart rate. Metabolism –
increase use of glucose and liberation of fatty acids from adipose tissue.
Adrenergic Drugs
１、Adrenergic Synapse
SYMPATHETIC RESPONSE –
HEART – increases rate and strength of
contraction.
BRONCHIAL TUBES – dilates.
IRIS OF EYE – dilate (pupil enlarges).
BLOOD VESSELS – constricts (usually).
SWEAT GLANDS – stimulates.
INTESTINE – inhibits motility.
ADRENAL MEDULLA – stimulates secretion of epinephrine and norepinephrine.
SALIVARY GLANDS – stimulates thick secretion.
USES Hypovolemic and septic shock. Moderately severe to severe episodes of hypotension. Control
of superficial bleeding during surgical and dental procedures of the mouth, nose throat, and skin.
Bronchial asthma. Cardiac decompensation and arrest. Allergic reactions. Temporary treatment
of heart block. Ventricular arrhythmias. Nasal congestion. In conjunction with local anesthetics
to prolong anesthetic action medicine and dentistry.
ADVERSE REACTIONS –
The more common adverse reactions include cardiac arrhythmias (bradycardia and tachycardia),
headache, insomnia, nervousness, anorexia, and an increase in blood pressure.
CONTRAINDICATIONS –
Hypersensitivity. Isoproterenol in patients with tachyarrhythmias, tachycardia or heart block.
Dopamine with pheochromocytoma, unmanaged arrhythmias, and ventricular fibrillation.
Ephinephrine with narrow-angle glaucoma, cerebral arteriosclerosis and cardiac insufficiency.
Norepinephrine and ephedrine with hypotension from blood volume deficits. Midodrine with
severe organic heart disease, acute renal disease, pheochromocytoma and supine hypertension.
INTERVENTIONS –
Obtain blood pressure, pulse rate and quality, respiratory rate and rhythm before administering,
for baseline data.
Dopamine and norepinephrine - Use electronic infusion pump. Check with hospital pharmacist
before adding a second drug to an IV solution containing this drug. Administer via IV route. Do
not dilute. Monitor BP Q2min. until desired BP is achieved, then Q5 to Q15min. Adjust rate of
administration according to BP. Inspect site for signs of extravasation. NEVER LEAVE
PATIENT UNATTENDED WHEN RECEIVING THESE DRUGS.
Midodrine – Administer only when patient is out of bed. Monitor heart rate. Have patient void
before administration ( causes dysuria ). Take during daytime hours only. Do not take within 4
hours of bedtime. To control supine hypertension, the patient should not be fully supine. It may
be necessary for the patient to sleep with the head of the bed elevated. Instruct patient to report
any changes in vision, pounding in head when laying down, slow heart rate, or difficulty
urinating.
Report any progressive fall in BP, a fall below 100mmhg, or any fall of 20mmhg or more of
baseline BP.
Weigh patient daily and keep accurate dietary record to manage anorexia.
To manage insomnia and nervousness, inform patient this is an effect of the drug. Plan care with
as few interruptions as possible. Avoid caffeine. Use sleep aids ( warm milk, back rub).
For nasal decongestion – these drugs are contraindicated in those with high blood pressure and
that overuse can increase in nasal congestion.
ADRENERGIC BLOCKING DRUGS
Adrenergic blocking drugs are also called sympathomimetic blocking drugs. They are divided
into four groups.
ALPHA-ADRENERGIC BLOCKING DRUGS
ACTIONS- Stimulation of alpha-adrenergic fibers results in vasoconstriction. If stimulation of
these alpha-adrenergic fibers is interrupted or blocked, the result will be vasodilation.
USES – Phentolamine is used for its vasodilating effect on peripheral blood vessels. It may be
used in the treatment of hypertension caused by pheochromocytoma. It is also used to prevent or
treat tissue damage caused by extravasation of norepinephrine or dopamine.
ADVERSE REACTIONS – Weakness, orthostatic hypotension, cardiac arrhythmias,
hypotension and tachycardia.
CONTRAINDICATIONS - Hypersensitivity and coronary artery disease.
BETA-ADRENERGIC BLOCKING DRUGS
ACTIONS – Decrease the activity of the sympathetic nervous system on certain tissues. Betaadrenergic receptors are found mainly in the heart. Stimulation of Beta receptors of the heart
increase the heart rate. If stimulation of these beta adrenergic fibers is interrupted or blocked, the
heart rate decreases and the vessels dilate.
USES – Hypertension and certain cardiac arrhythmias, such as ventricular arrhythmias or
supraventricular tachycardia. To prevent reinfarction in patients with recent MI. Topically –
ophthalmic eye drops, for the treatment of glaucoma.
ADVERSE REACTIONS - Othostatic hypotension, bradycardia, dizziness, vertigo,
bronchospasm, hyperglycemia, nausea, vomiting, and diarrhea, symptoms of CHF. Topically –
headache, depression, cardiac arrhythmias, and bronchospasm.
CONTRAINDICATIONS - Allergy, sinus bradycardia, second or third degree heart block, heart
failure, asthma, emphysema, and hypotension.
ANTIADRENERGIC DRUGS –
ACTIONS –Peripherally acting antiadrenergic drugs inhibit the release of norepinephrine from
certain adrenergic nerve endings in the peripheral nervous system. Centrally acting
antiadrenergic drugs act on the CNS centers thereby decreasing some of the activity of the
sympathetic nervous system.
USES - Certain cardiac arrhythmias and hypertension.
ADVERSE REACTIONS – Centrally acting - Dry mouth, drowsiness, sedation, anorexia, rash,
malaise, and weakness. Peripherally acting – hypotension, weakness, light-headedness, and
bradycardia.
CONTRAINDICATIONS – Centrally acting - Hypersensitivity, active hepatic disease.
Peripherally acting – Hypersensitivity. Reserpine in patients who have an active peptic ulcer or
ulcerative colitis and depression.
ALPHA/BETA-ADRENERGIC BLOCKING DRUGS
ACTIONS – Block the stimulation of alpha and beta-adrenergic receptors, resulting in peripheral
vasodilation.
USES – Labetalol is used in the treatment of hypertension. Carvedilol is used to treat essential
hypertension and CHF.
ADVERSE REACTIONS – Labetalol - fatigue, drowsiness, insomnia, weakness, hypotension,
diarrhea, dyspnea, and skin rash. Carvedilol – fatigue, hypotension, cardiac insufficiency, chest
pain, bradycardia, dizziness diarrhea, hypotension, and fatigue.
CONTRAINDICATIONS – Hypersensitivity, bronchial asthma, decompensated heart failure,
and severe bradycardia.
INTERVENTIONS –
Establish accurate baseline data before administering for the first time. Patients with
hypertension must have their BP taken on both arms sitting, standing, and supine before therapy
is begun.
Propanol – Take apical pulse rate and BP before giving the drug. If pulse is below 60bpm or if
systolic BP is less than 90mmhg, withhold drug and contact primary health care giver.
Administer propranolol and metoprolol at the same time each day to enhance bioavailability.
Sotalol is given on an empty stomach because food may reduce absorption of the drug.
Cardiac arrhythmias – Monitor for new or worsening ventricular arrhythmias. If angina worsens
contact primary health care provider.
Hypertension – If BP increases, administer dose and notify primary care provider immediately.
Ophthalmic preparation – timolol – insist patient have periodic examination by an
ophthalmologist.
Hypotension – Postural or orthostatic – Instruct patient to rise slowly from sitting or lying
position. Provide assistance, wait 1 minute before changing positions. Remain with patient while
standing as well as during ambulation. Instruct patient to avoid standing in one place for
prolonged periods. Teach patient to avoid hot showers and baths which increase vasodilation.
Hypertension, cardiac arrhythmia, or angina – Do not stop taking drug abruptly. Use caution
while driving or performing hazardous tasks. Report any signs of CHF immediately. Do not use
any OTC drugs with out approval of primary care provider.
Glaucoma – Adherence to instillation schedule is stressed because omitting or discontinuing may
result in a marked increase in intraocular pressure, which can result in blindness. Instruct patient
to report any eye pain, excessive tearing or any change in vision.
CHOLINERGIC DRUGS
Cholinergic drugs mimic the activity of the parasympathetic nervous system. They are also
called parasympathomimetic drugs.
PARASYMPATHETIC RESPONSE –
HEART – decreases rate: no direct effect on strength of contraction.
BRONCHIAL TUBES – constricts.
IRIS OF EYE – constricts (pupil becomes smaller).
BLOOD VESSELS – no innervation ( innervation – the distribution or supply of nerve fibers or
nerve impulses to a body part).
SWEAT GLANDS – no innervation.
INTESTINE – stimulates motility and secretion.
ADRENAL MEDULLA – no effect.
SALIVARY GLANDS – stimulates profuse, watery secretions.
１、Cholinergic
Synapse
ACTIONS – Direct-acting
cholinergics act like the
neurohormone
ACh(acetylcholine). Indirectacting cholinergics prolong the
activity of ACh by inhibiting the
release of
Ache(acetylcholinesterase).
USES – Treament of glaucoma,
myasthenia gravis, and urinary
retention. Glaucoma may be
treated by topical application of
carbachol or pilocarpine. Drugs used to treat myasthenia gravis include ambenonium and
pyridostigmine. Ambenonium, bethanechol chloride or pyridostigmine is used in the treatment of
urinary retention.
ADVERSE REACTIONS – Oral or parenteral route – nausea, diarrhea, abdominal cramping,
salivation, flushing of the skin, cardiac arrhythmias, and muscle weakness. Topical
administration – temporary reduction of visual acuity (sharpness), and headache.
CONTRAINDICATIONS - Hypersensitivity, asthma, peptic ulcer disease, coronary artery
disease, hyperthyroidism. Bethanecol with mechanical obstruction of gastrointestinal or
genitourinary tracts. Patients with secondary glaucoma, iritis, corneal abrasion, or any acute
inflammatory diseases of the eye should not use the ophthalmic cholinergic preparations.
ATROPINE is the antidote for overdose of cholinergic drugs.
INTERVENTIONS –
Take patients blood pressure and pulse rate before administration of cholinergic drug for urinary
retention.
Monitor for symptoms of cholinergic crisis (drug toxicity) which include severe abdominal
cramping, diarrhea, excessive salivating, muscle weakness, rigidity and spasm, clenching of the
jaw. Report these symptoms immediately to primary health care provider. Monitor for signs of
underdosage in myasthenia gravis which include symptoms of the disease itself.
Glaucoma – Assess eye daily for evidence of redness, inflammation, and excessive secretions. If
secretions are present, remove with cotton ball or gauze soaked in normal saline. When instilling
ophthalmic preparation make sure tip of dropper never touches the eye. If pilocarpine ocular
system is used check for placement and area around cheek and eye several times a day. Change
system every 7 days . Report to primary health care provider if the symptoms of glaucoma
increase, if the patient is unable to retain ocular system, or if redness, eye irritation, or excessive
secretions are noted.
Myasthenia gravis - Assess for presence or absence of the symptoms of myasthenia gravis
before each dosage. Depending on patients response to therapy, dosages may have to be
increased or decreased accordingly.
Urinary retention – Measure and record input and output. If amount of each voiding is
insufficient or if patient fails to void, palpate bladder to determine size and notify primary health
care provider.
Monitor closely for the appearance of adverse drug reactions, because cholinergic drugs given
the oral or parenteral route may affect the heart, respiratory, gastrointestinal and central nervous
systems.
Drug induced myopia – Assist patient with ambulation. Remove obstacles that may hinder
ambulation, especially during the night.
Diarrhea – record number, consistency, and frequency of stools. Report excessive diarrhea to
primary health care provider.
CHOLINERGIC BLOCKING DRUGS
These drugs block the action of the neurotransmitter acetylcholine in the parasympathetic
nervous system. Cholinergic blocking drugs are also called anticholinergic or
parasympathomimetic blocking drugs. Examples of cholinergic blocking drugs include atropine,
scopolamine, and propantheline.
ACTIONS – They inhibit the activity of acetylcholine in parasympathetic nerve fibers. When the
activity of acetylcholine is inhibited, nerve impulses traveling along parasympathetic nerve fibers
cannot pass from the nerve fiber to the effector organ or structure.
USES – Treatment of pylorospasm, peptic ulcer, ureteral and biliary colic, vagal induced bradycardia,
parkinsonism, and preoperatively to reduce secretions of the upper respiratory tract before the
administration of a general anesthetic.
ADVERSE REACTIONS – Dryness of the mouth with difficulty swallowing, blurred vision, and
photophobia, constipation, drowsiness. Sometimes drowsiness is a desired effect. When atropine is used
preoperatively to reduce secretions, drowsiness is part of the desired effect. Confusion or excitement may
be seen in elderly patients. CNS – Headache, flushing, nervousness, weakness, insomnia, nasal
congestion, fever. Eyes – blurred vision, mydriasis, cycloplegia increased ocular tension. GI – Nausea,
vomiting, heartburn. URINARY TRACT – urinary hesitancy, retention, and dysuria. CARDIOVASCULAR
SYSTEM – palpitations, bradycardia, tachycardia. OTHER – urticaria, analphylactic shock, skin
manifestations.
CONTRAINDICATIONS – Glaucoma, tachyarrhythmias, myocardial infarction, and congestive heart
failure.
INTERVENTIONS –
Patient with heart block – place on cardiac monitor during and after administration of drug. Monitor for any
changes in pulse rate or rhythm. Report any changes immediately to primary health care provider.
Receiving as preoperative drug – Have patient void before drug is given. Give at exact time prescribed
because the drug must be allowed to produce the greatest effect, before the administration of a general
anesthetic. The anesthesiologist must be notified of drug is given late.
If excitement, agitation, mental confusion, drowsiness or any other adverse effects occur, withhold next
dose and contact primary health care provider.
Monitor patients for any changes in vision. Assist with ambulation if necessary. Keep rooms dimly lit.
Remove any obstacles out of the way. Caution patient against driving or performing other tasks that
require alertness, and good vision.
Mouth dryness may be severe in some cases. Check oral cavity daily for soreness or ulcerations. Give
small sips of water and hard candy, if allowed.
Increase fluids to 2000ml daily, give high fiber diet, and encourage exercise for patients with constipation.
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