Pharmacology: Chapter 18 Adrenergic agonists

Where are Beta 2 receptors normally found?

Smooth muscle of the bronchioles, arterioles, and visceral organs

Dopaminergic receptors

Stimulated by dopamine Response: dilation of renal, mesenteric, coronary, and cerebral blood vessels.

Norepinephrine (levophea)

Stimulates alpha-adrenergic receptors Causes vasoconstriction Direct-stimulating beta-adrenergic effects on the heart (beta1-adrenergic receptors) No stimulation to beta2-adrenergic receptors of the lung Treatment of hypotension and shock Administered by continuous infusion

Catecholamines

Substances that can produce a sympathomimetic response. They are either endogenous catecholamines (such as epinephrine, norepinephrine, and dopamine) or synthetic catecholamine drugs (such as dobutamine).

What can happen if you administer 2 adrenergic drugs together?

May precipitate severe cardiovascular effects such as tachycardia or hypertension

Adrenergic Receptors

-Located throughout the body -Are receptors for the sympathetic neurotransmitters -Alpha-adrenergic, Beter-adrenergic, and dopaminergic receptors

Alpha-adrenergic agonist responses

-Vasoconstriction -CNS stimulation

Pheochromocytoma

A vascular adrenal gland tumor that is usually benign but secretes epinephrine and norepinephrine, this often causes CNS stimulation and substantial BP elevation

A patient is experiencing bronchospasms after running half a mile. He has several inhalers with him. Which one would be appropriate for treatment at this time? A. albuterol B. salmeterol C. fluticasone D. salmeterol and fluticasone combination (Advair Diskus)

A) albuterol Rationale: Albuterol is a beta2 agonist that is used for acute bronchospasms

A patient has two inhalers that are due to be taken at the same time. One is a bronchodilator; the other is a corticosteroid. Which inhaler should the patient take first? A. The bronchodilator B. The corticosteroid C. it does not matter which one is taken first.

A. The bronchodilator

Drugs that stimulate the sympahetic nervous system are known as

Adrenergic agonists Sympathomimetrics

Which condition is contraindicated for administration of albuterol?

Albuterol is contraindicated for patients taking MAOI therapy.

Beta-Adrenergic Receptors

All are located on POSTsynaptic effector cells

Temporary relief of conjunctival conjections

Alpha adrenergic receptors Examples: epinephrine, naphazoline, phenylephrine, tetrahydrozoline

Treatment of nasal congestion

Alpha1 adrenergic receptors intranasal (topical) application causes constriction of dilated arterioles and reduction of nasal blood flow, thus decreasing congestion examples: ephedrine, naphazoline, oxymetazoline, phenylephrine, and tetrahydrozoline

Vasoactive adrenergics

Also called cardioselective sympathomimetics Used to support the heart during cardiac failure or shock; various alpha and beta receptors affected

What are the interactions?

Anesthetic drugs, tricyclic antidepressants, MAOLs, antihistamines, thyroid preparations, adrenergic antagonists

A patient on a dobutamine drip starts to complain that her intravenous line "hurts." The nurse checks the insertion site and sees that the area is swollen and cool. What will the nurse do first? A. Slow the intravenous infusion. B. Stop the intravenous infusion. C. Inject the area with phentolamine. D. Notify the physician health care provider.

B) Stop the intravenous infusion Rationale: Infiltration of an intravenous solution containing an adrenergic drug may lead to tissue necrosis from excessive vasoconstriction around the IV site.

A 10-year-old child is brought to the emergency department while having an asthma attack. She is given a nebulizer treatment with albuterol. The nurse's immediate assessment priority would be to A. determine the time of the child's last meal. B. monitor Spo2 with a pulse oximeter. C. monitor the child's temperature. D. provide education on asthma management.

B. monitor Spo2 with a pulse oximeter. Rationale: During administration of albuterol, a fast-acting beta2 agonist, the nurse should monitor the patient's respiratory status including SpO2 (with a pulse oximeter), respiratory rate, and breath sounds to ensure that the medication is having a therapeutic effect. The other items can be handled after her respiratory status is stable

Dobutamine (Dobutrex)

Beta1-selective vasoactive adrenergic drug that is structurally similar to the naturally occurring catecholamine dopamine Stimulates beta1 receptors on heart muscle (myocardium); increases cardiac output by increasing contractility (positive inotropy), which increases the stroke volume, especially in patients with heart failure. Intravenous drug; given by continuous infusion

Direct-acting sympathomimetic

Binds directly to the receptor and causes a physiologic response

What's the response of Beta-adrenergic drugs?

Bronchial, gastrointestinal, and uterine smooth muscle RELAXATION Glycogenolysis Cardiac STIMULATION

Drug effects of stimulation of beta2 adrenergic receptors on the airways results in

Bronchodilation Uterine relaxation, glycogenolysis in liver, increased renin secretion in kidneys, relaxation of GI smooth muscle (decreased motility)

Treatment of asthma and bronchitis

Bronchodilators that stimulate beta2 adrenergic receptors of bronchial smooth muscles causing relaxation resulting in bronchodilation examples: albuterol, ephedrine, epinephrine, formoterol, levarbuterol, metaproterenol, pirbuterol, salmeterol, and terbutaline

Which is true about the effect epinephrine has on cardiac output?

Epinephrine increases cardiac output by stimulating muscle contractions in the cardiovascular system.

A patient on a dobutamine drip starts to complain that he feels a "tightness" in his chest that he had not felt before. What will the nurse do first? A. Check the infusion site for possible extravasation. B. Increase the infusion rate. C. Check the patient's vital signs. D. Order an electrocardiogram.

C. Check the patient's vital signs.

What are the adverse effects for beta adrenergic drugs?

CNS - MIld tremors, headaches, nervousness, dizziness CARDIOVASCULAR -Increased heart rate, palpitations (dysrhythmias), fluctuations in blood pressure OTHER -Sweating, nausea, vomiting, and muscle cramps

What are the adverse effects for alpoha adrenergic drugs?

CNS -Headache, restlessness, excitement, insomnia, euphoria CARDIOVASCULAR -Palpitations (dysrhythmias), tachycardia, vasoconstriction, hypertension OTHER -Loss of apeptite,dry mouth, nausea, vomiting, taste changes

Indirect-acting sympathomimetic

Causes release of catecholamine from storage sites (vesicles) in nerve endings catecholamine then binds to receptors and causes a physiologic response

Intravenous (IV) administration

Check IV site often for infiltration use clear IV solutions Use an infusion pump Infuse drug slowly to avoid dangerous cardiovascular effects monitor cardiac rhythm

Mixed-acting sympathomimetic

Directly stimulates the receptors by binding to it and indirectly stimulates the receptor by causing the release of stored neurotransmitters from vesicles in nerve endings

Epinephrine (adrenalin)

Endogenous vasoactive catecholamine Acts directly on both the alpha- and beta-adrenergic receptors of tissues innervated by the SNS Prototypical nonselective adrenergic agonist Administered in emergency situations One of the primary vasoactive drugs used in many advanced cardiac life support protocols

When administering an alpha blocker for the first time , it is important for the nurse to assess the patient for the development of

Hypotenstion

Drug effects of stimulation of beta1 adrenergic receptors on the myocardium, atrioventricular node, and sinoatrial node results in

Increased force of contraction (positive inotropic effect) Increased heart rate (positive chronotropic effect) Increased conduction through AV node (positive dromotropic effect)

Which lab values should be documented with the administration of epinephrine?

Liver and Renal function

Alpha 1 adrenergic receptors

Located on POSTsynaptic cells (the cell, muscle, or organ that the nerve stimulates)

Alpha 2 adrenergic receptors

Located on PREsynaptic nerve terminals (nerve that stimulates the effector cells) Controls the release of neurotransmitters

Dopamine (intropin)

Naturally occurring catecholamine neurotransmitter Potent dopaminergic as well as beta1- and alpha1-adrenergic receptor activity Low dosages: can dilate blood vessels in the brain, heart, kidneys, and mesentery, which increases blood flow to these areas (dopaminergic receptor activity). Higher infusion rates: improve cardiac contractility and output (beta1-adrenergic receptor activity). Highest doses: vasoconstriction (alpha1-adrenergic receptor activity).

first dose phenomenon

Severe and sudden drop in BP after the administration of the first dose of an alpha adrenergic blocker

True or False: Salmeterol is indicated for prevention of bronchospasms, not management of acute symptoms

TRUE

Where are Beta 1 receptors normally found?

The heart

Drug effects of stimulation of alpha adrenergic receptors on smooth muscle results in

Vasoconstriction of blood vessels Relaxation of GI smooth muscles (decreased motility) Constriction of bladder sphincter Contraction of uterus Male ejaculation Contraction of pupillary muscles of the eye (dilated pupils)

Phenylephrine (Neo-synephrine)

Works almost exclusively on the alpha adrenergic receptors used primarily for short term treatment to raise blood pressure in patients in shock Control of supraventricular tachycardia vasoconstriction in regional anesthesia Topical opthalamic drug Nasal decongestant

Examples of vasoactive adrenergics

dobutamine dopamine ephedrine epinephrine fenoldopam phenylephrine midodrine norepinephrine