1. Introduction to Clinical Pharmacology Chapter 24 Adrenergic Drugs

2. INTRODUCTION

3. Introduction
The autonomic nervous system is divided into the sympathetic and the parasympathetic branches. 
The sympathetic system is also called the adrenergic branch.
This chapter discusses drugs that mimic the effects of the sympathetic system—the adrenergic drugs which is regulated by the involuntary control. Also this system is also known as the fight, flight, or freeze response which is evident when body is confronted with stressful event. 
The focus of this chapter is on the drugs used in the prevention (responding to allergic reactions) and the treatment of shock. 
• Central nervous system—wakefulness, quick reaction to stimuli, quickened reflexes

4. Introduction
The focus of this chapter is on the drugs used in the prevention (responding to allergic reactions) and the treatment of shock. 
• Central nervous system—wakefulness, quick reaction to stimuli, quickened reflexes
• Autonomic nervous system—relaxation of the smooth muscles of the bronchi, constriction of blood vessels, sphincters of the stomach, dilation of coronary blood vessels, decrease in gastric motility
• Heart—increase in the heart rate
• Metabolism—increased use of glucose (sugar) and liberation of fatty acids from adipose tissue

5. Introduction
Drugs that block or inhibit the system are called antiadrenergic drugs, adrenergic blocking drugs, or sympatholytics. One of the major body systems affected by adrenergic blocking drugs is the heart and vascular system.
The parasympathetic branch helps conserve body energy and is partly responsible for such activities as slowing the heart rate, digesting food, and eliminating bodily wastes.
Parasympathetic nervous system is known as the cholinergic branch. 

6. Introduction
Catecholamine is a term used for the natural neurohormone or neurotransmitter produced when the body is stressed. Norepinephrine (produced in the medulla of the adrenal gland) is the primary naturally produced neurotransmitter. Other neurotransmitters include epinephrine and dopamine.
Norepinephrine is the primary neurotransmitter in the sympathetic branch of the autonomic nervous system and the substance that keeps the nerve message (or impulse) going from the brain to the target organ. Because this system is activated by norepinephrine, which is the precursor of epinephrine (also called adrenalin), another term for the sympathetic pathway is the adrenergic branch. Therefore, the medicines used that work like the adrenergic branch are termed adrenergic drugs.

7. Introduction
In the sympathetic branch of the autonomic nervous system, adrenergic drugs produce activity similar to the neurotransmitter norepinephrine. Another name for these drugs is sympathomimetic (i.e., mimicking the actions of the sympathetic nervous system) drugs. The adrenergic drugs produce pharmacologic effects similar to the effects that occur in the body when the sympathetic nerves (norepinephrine) and the medulla (epinephrine) are stimulated. Because these all have a similar structure, they are called catecholamine to reflect that likeness to each other. The primary effects of these drugs occur on the heart, the blood vessels, and the smooth muscles, such as the bronchi of the lungs. 

8. Adrenergic Drugs: Actions #1
Produce the following responses in varying degrees:
CNS: wakefulness; quick reaction to stimuli; quickened reflexes
Metabolism: increased use of glucose, liberation of fatty acids—adipose tissue
Heart: increase in heart rate, increased blood pressure
Autonomic nervous system: relaxation—smooth muscles of bronchi; constriction of blood vessels; sphincters—stomach; dilation—coronary blood vessels; decrease gastric motility

9. Adrenergic Drugs: Actions #2
Adrenergic nerve receptors:
Organ affected by sympathetic nervous system depends on which postsynaptic nerve receptor sites are activated
Adrenergic nerves: alpha (α) or beta (β) receptors
Drugs that act on receptors are selective or nonselective
Isoproterenol: acts on β receptors; selective drug and will likely cause increased glucose use, decreased gastric motility, and wakefulness
Epinephrine: nonselective drug; acts on both α and β receptors and when used can increase heart rate

10. Adrenergic Drugs: Uses #1
Adrenergic drugs used for treatment of:
Hypovolemic, septic shock; allergic reactions such as anaphylactic reaction; ventricular arrhythmias; respiratory distress
Control of superficial bleeding during surgical and dental procedures of mouth, nose, throat, and skin; nasal congestion; and glaucoma
Cardiac decompensation and arrest; hypotension
Temporary treatment of heart block
Isoproterenol, dopamine, and epinephrine are to treat severe chest pain in patients with myocardial infarction and cardiac failure.

11. Adrenergic Drugs: Uses #2
Used as vasoconstricting adjunct to local anesthetics to prolong anesthetic action in the tissues
Shock: state of inadequate tissue perfusion
Symptoms: supply of arterial blood, oxygen flowing to cells, tissues is inadequate
Counteract symptoms: body initiates physiologic mechanisms

12. Adrenergic Drugs: Uses #3
Untreated: compensatory mechanisms of body fail, irreversible shock occurs, death follows
Types of shock: hypovolemic shock, cardiogenic shock, distributive shock which will include septic shock, anaphylactic shock, and neurogenic shock that come from things like central line infection, spinal cord injury, or allergic drug reactions
Shock results:
Decrease in cardiac output, respiratory distress such as hypoxia, decrease in arterial blood pressure, reabsorption of water by kidneys

13. Adrenergic Drugs: Uses #4
Increase in carbon dioxide in blood, decrease in oxygen in blood
Increased concentration of intravascular fluid
In cardiogenic shock adrenergic drug may be used with a vasodilating drug
Vasodilator: improves myocardial performance; adrenergic drug maintains blood pressure

14. Adrenergic Drugs: Adverse Reactions
Depend on drug used, dose administered; individualized patient response
Adverse reactions include:
Cardiac arrhythmias; headache; nausea; vomiting; increase in blood pressure
Epinephrine: increase tremor, rigidity in older adults with Parkinson disease; systolic blood pressure dropping below 100 mm Hg

15. Adrenergic Drugs: Contraindications and Precautions #1
Contraindicated in patients:
With hypersensitivity
Isoproterenol: tachyarrhythmias, heart block caused by digitalis toxicity, ventricular arrhythmias, angina pectoris
Dopamine: pheochromocytoma, unmanaged arrhythmias, ventricular fibrillation

16. Adrenergic Drugs: Contraindications and Precautions #2
Contraindicated in patients (cont.)
Epinephrine: narrow-angle glaucoma, local anesthetic adjunct in fingers, toes
Norepinephrine: hypotensive—blood volume deficits
Midodrine causes severe hypertension: patients—lying down-supine hypertension

17. Adrenergic Drugs: Contraindications and Precautions #3
Used cautiously in patients with:
Coronary insufficiency
Cardiac arrhythmias, angina pectoris
Hyperthyroidism, diabetes
Occlusive vascular disease
Prostatic hypertrophy
Clients taking digoxin, phenelzine, guanethidine, oxytocin, halothane, or St. John's Wort should not take Ma Huang.

18. Adrenergic Drugs: Interactions
Interactant drug
Effect of interaction
Antidepressants
Increased sympathomimetic
Oxytocin
Increased risk of hypertension
dopamine and phenytoin
Risk of seizures, hypotension, and bradycardia

19. Nursing Process: Assessment #1
Preadministration assessment:
Identify and record blood pressure, pulse rate and quality, respiratory rate and rhythm
With dobutamine need to also assess level of consciousness; when given with a beta-blocker need to assess and monitor for hypertension
Assess the symptoms, problems, or needs before administering drug and record any subjective or objective data in the patient’s chart
Emergencies occur: then nurse must make assessments quickly and accurately
Level of consciousness should be assessed and recorded and continue to monitor

20. Nursing Process: Assessment #2
Ongoing assessment:
Observe for effect of drug, such as improved breathing of patient with asthma, or response of blood pressure with administration of vasopressor
Evaluate, document drug effect, take and document vital signs
Notify primary health care provider of adverse reactions such as occur with dopamine like nausea, vomiting, ectopic beats/cardiac arrhythmias, tachycardia, anginal pain, palpitations, dyspnea, and hypotension

21. Nursing Process: Planning
Nursing Diagnoses
Risk for Allergy Response related to response to substance trigger (insect sting, drug allergy, specific food)
Ineffective Tissue Perfusion related to hypovolemia, blood loss, impaired distribution of fluid, impaired circulation, impaired transport of oxygen across alveolar and capillary bed, other (specify)
Decreased Cardiac Output related to altered heart rate and/or rhythm
Disturbed Sleep Pattern related to adverse reactions (nervousness) to the drug and the environment

22. Nursing Process: Implementation #1
Promoting an optimal response therapy:
Exercise great care in calculation, preparation of drugs as adrenergic drugs are potentially dangerous
Report, document any complaint patient may have while taking adrenergic drugs; report adverse effects such as development of cardiac arrhythmias immediately, anorexia
Client reports a “fluttering” feeling from the heart
Management of shock is aimed at providing basic life support; drugs used: antibiotics, inotropes, hormones

23. Nursing Process: Implementation #2
Monitoring and managing patient needs:
Ineffective tissue perfusion:
Potential problem with tissue perfusion: Adrenergic drug for hypotension, blood pressure becomes too high
Ineffective tissue perfusion: decreased oxygen, inability of body to nourish cells

24. Nursing Process: Implementation #3
Monitoring and managing patient needs (cont.)
Considerations while administering potent vasopressors dopamine, norepinephrine:
Electronic infusion pump: administer drugs
Do not mix dopamine with other drugs
Administer norepinephrine, dopamine only via IV route

25. Nursing Process: Implementation #4
Monitoring and managing patient needs (cont.)
Monitor blood pressure continuously
Adjust rate: blood pressure
Readjustment of rate flow: IV solution necessary
Inspect needle site, surrounding tissues at frequent intervals
With norepinephrine also monitor client’s urinary output

26. Nursing Process: Implementation #5
Monitoring and managing patient needs (cont.)
Never leave patient receiving drugs unattended
Monitoring: shock—vigilance on part of nurse

27. Nursing Process: Implementation #6
Monitoring and managing patient needs (cont.)
Decreased cardiac output:
Heart rate, stroke volume determine cardiac output
Stroke volume: contractile state of heart, amount of blood in ventricle available to be pumped out

28. Nursing Process: Implementation #7
Monitoring and managing patient needs (cont.)
Shock: monitor vital signs; determine severity of shock
Signs and symptoms of shock include cold and clammy skin, sweating, hypotension (not hypertension), tachycardia (not bradycardia), hypoxia, tachypnea, and decreased urinary output
Nurse reports any progressive fall in blood pressure, this is serious, to primary health care provider

29. Nursing Process: Implementation #8
Monitoring and managing patient needs (cont.)
Disturbed sleep pattern:
Critical care setting: daily pattern of activities is usually disrupted
Patients can easily get confused regarding daytime
Causes great deal of stress in patient

30. Nursing Process: Implementation #9
Monitoring and managing patient needs (cont.)
Identify circumstances: nurse taking vital signs during night or turning overhead light on during night
Weigh importance of monitoring status, vital signs, providing comfort interventions
Explain reason for close monitoring of vital signs

31. Nursing Process: Implementation #10
Educating the patient and family:
Epinephrine autoinjector for allergic reactions instruct client to call 911 and then self inject when alone
Educating patient receiving midodrine:
Patients: severe orthostatic hypotension: instruct client if taking midodrine to report parathesia, headaches, dizziness, dysuria, and supine hypertension, bradycardia, pruritus,
Importance of taking drug during daytime hours

32. Nursing Process: Implementation #11
Educating the patient and family (cont.)
The suggested dosing schedule for the administration of midodrine is shortly before arising in the morning, midday, and late afternoon (not after 6:00 p.m.).
Control supine hypertension, potentially fatal adverse reaction: patient need not become fully supine
Explain that patient should sleep with head of bed elevated

33. Nursing Process: Evaluation
The therapeutic effect is achieved such as increased cardiac output
Stimulation of beta-1 receptors leads to an increase in heart rate and an increase in the force of myocardial contraction
Adverse reactions identified; reported to primary health care provider; managed successfully
Patient verbalizes understanding of treatment modalities and drug regimen; importance of continued follow-up care