Pharmacology Chapter 18 - Adrenergic Agonists and Adrenergic Blockers Flashcards

Opposite

similar

MIMICS

BLOCKS

Adrenergic system

Norepinephrine

Cholinergic system

acetylcholine (ACh)

Drugs that stimulate the sympathetic nervous system because they mimic the neurotransmitters norepinephrine and epinephrine. They act on one or more of the adrenergic receptor sites located in the effector cells. There are 4 main receptors, alpha₁, alpha₂, beta₁, beta₂ (which mediate different responses)

INCREASES force of heart contraction;
vasoconstriction INCREASES BP;
mydriasis (dilation of pupil);
DECREASES secretion in salivary glands;
INCREASES urinary bladder relaxation and sphincter contraction

INHIBITS release of norepinephrine;
DILATES blood vessels;
produces HYPOTENSION;
DECREASES GI motility and tone

INCREASES heart rate AND force of contraction;
INCREASES renin secretion, which INCREASES BP

DILATES bronchioles;
promotes GI and uterine RELAXATION;
promotes INCREASE in blood sugar thru glycogenolysis in liver;
INCREASES blood flow to skeletal muscles

MAO (monamine oxidase) inside the neuron

COMT (catechol-O-methyltransferase) outside the neuron

1- inhibit norepi reuptake, which prolongs the action

2- inhibit the degradation of norepi by enzyme action

Direct Acting sympathomimetics, which directly stimulate the adrenergic receptor (e.g., norepi and epi)

Indirect Acting sympathomimetics, which stimulate the release of norepi from the terminal nerve endings (e.g., amphetamine)

Mixed Acting sympathomimetics (both direct and indirect acting), which stimulate the adrenergic receptor sites and stimulate the release of norepi from the terminal nerve endings (e.g., ephedrine)

Fig 18-3 p. 258

they are the chemical structures of a substance (either endogenous or synthetic) that can produce a sympathomimetic response.

Examples of endogenous catecholamines are:

Epinephrine, Norepinephrine, and dopamine

An endogenous catecholamine that acts on alpha_1, alpha_2, beta_1, and beta_2. In anaphylactic shock, it is useful because it increases blood pressure, heart rate, and airflow through the lungs. It is considered to be NONSELECTIVE because it affects different adrenergic receptors.

Administration: subQ, IV, topically, inhalation, intracardiac, and instillation methods. NOT GIVEN PO. High doses can cause dysrhythmias. It can also cause renal vasoconstriction, decreasing renal perfusion and urinary output.

Tricyclic antidepressants and MAOIs allow the effects to be intensified and prolonged. Administration with digoxin may caus dysrhythmias.

To treat anaphylaxis, asthma, bronchospasm, severe hypotension, cardiac arrest.

Acts on alpha and beta receptors;
promotes CNS & cardiac stimulation and bronchodilation
strengthens cardiac contraction
increases cardiac rate and output
reverses anaphylactic reactions
reduces mucosal congestion by inhibiting histamine release

Anorexia, nausea, vomiting, nervousness, tremors, agitation, sweating, headache, pallor, insomnia, weakness, and dizziness

(think of how a panic attack makes you feel)

palpitations, tachycardia, hypertension, dyspnea

Necrosis and gangrene of IV site upon infiltration

Life threatening: Ventricular fibrillation and pulmonary edema.

For cardiac resuscitation, 1 mg IV; may repeat q3-5 min. Follow each dose with 20 mL of saline flush to ensure proper delivery. It is normally administered 1 mg IV over 1 minute; however, in cardiac arrest, it may be given more rapidly. Monitor IV site frequently for because extravasation can cause tissue necrosis.

A beta₂ adrenergic agonist that is selective for beta₂ adrenergic receptors, so the response is relaxation of bronchial smooth muscle and bronchodilation.

If it is taken with and MAOI, hypertensive crisis can result. Beta blockers may inhibit the action of albuterol.

Check urinary output and bladder for distension because urinary retention can result from high drug dose. Offer food to patient to avoid nausea and vomiting. Evaluate blood glucose levels in diabetic patients because they may increase.

Do not use if solution is discolored or has particles in it. Inject subcutaneously. Apply sufficient pressure to activate epipen while holding device in place for 5-10 seconds. It should be inserted into outer thigh. Massage injection site for 10 seconds to promote absorption and reduce vasoconstriction and tissue irritation.

aka adrenergic antagonists or smpatholytics. They act as antagonists to adrenergic agonists by blocking the alpha and beta receptor sites.

These drugs block or inhibit a response at the alpha adrenergic receptor site. They can cause orthostatic hypotension and reflex tachycardia, so they are not used as frequently as beta blockers.

They promote vasodialation, causing a decrease in BP. They can be used to treat peripheral vascular disease such as Raynaud's disease

They can be selective or nonselective. Use extreme caution with nonselective beta blockers in patients with COPD or asthma.

They decrease the heart rate, and a decrease in BP usually follows. Useful in treating mild to moderate hypertension, angina pectoris, and myocardial infarction

THESE DRUGS COMMONLY END IN -LOL

The first beta blocker prescribed to treat angina, cardiac dysrhythmias, hypertension and heart failure. Also given for migranes. It has many side effects due to its nonselective response in blocking both beta_{1 & 2}

atenolol (Tenormin)

metoprolol tartrate (Lopressor)

A selevtive beta₁ blocker, and it is one of the most frequently prescribed drugs in the US. It decreases sympathetic outflow to the periphery and suppresses the renin angiotension aldosterone system response.

Contraindicated: bradycardia, heart block, cardiogenic shock, pulmonary edema, acute bronchospasm and pregnancy

drowsiness, dizziness, fainting, depression, alopecia, weakness, nausea, vomiting, diarrhea, cool extremities, impotence, decreased libido

bradycardia, hypotension, heart failure, masking of hypoglycemia

Life threatening: bronchospasm, pulmonary edema, dysrhythias, thrombocytopenia

Risk of hypoglycemia is increased when the pt is taking insulin and sulfonylureas.

NSAIDs decrease hypotensive effect.

chest pain related to decreased blood flow to heart

a condition in which you heart suddenly cant pump enough blood to meet your body's needs. most often caused by a severe heart attack

A

The major therapeutic effect of dobutamine is to increase cardiac output. Cardiac output is reflected in the patient’s heart rate, blood pressure, and urine output. An increase in blood pressure is the expected therapeutic effect.

A

Adrenergic agents stimulate the sympathetic nervous system, which increases heart rate (positive chronotropic effect), contractility (positive inotropic effect), and conductivity (positive dromotropic effect). The nurse would be most concerned that the pulses remain weak and heart rate decreased after receiving this drug, as the therapeutic effect is not being achieved.

D

The nurse’s first action is to stop the infusion, followed by infusing phentolamine (Regitine) into the area to counteract vasoconstrictive effects of the dopamine.

D

Nonselective beta blockers are used to treat supraventricular dysrhythmias secondary to their negative chronotropic effects (decreasing heart rate). They may exacerbate heart failure and COPD. The patient could receive a selective beta blocker instead. The nurse should make the health care provider aware of the patient’s history of respiratory disease.

B

At therapeutic dosages, atenolol selectively blocks only the beta₁ receptors in the heart, not the beta₂ receptors located in the lungs. It is not necessary to determine specifically the history of respiratory disease. Although the nurse should assess the patient overall on a regular basis, the assessment should include all body systems, not only the lungs. It is not necessary to notify the health care provider prior to administration of the first dose of the medication.

C

Abrupt withdrawal of a beta blocker can cause rebound hypertension. The nurse should immediately check the patient’s blood pressure and then proceed with teaching and calling the health care provider.

D

Propranolol (Inderal) is nonselective—it blocks both beta₁ and beta₂ receptors at therapeutic doses. The medication is administered to treat hypertension. The patient’s blood pressure is within normal limits, which indicates therapeutic effect.

A

Decreased cardiac output puts the patient at highest risk. Although the other nursing diagnoses are pertinent, they are not the priority.

A

Acebutolol HCl (Sectral), a beta blocker, has negative chronotropic effects and could cause symptomatic bradycardia and/or heart block. The health care provider should be consulted before acebutolol is administered to a patient with bradycardia (heart rate less than 60 beats/min).

ADE

Beta blockers are effective in treating hypertension (secondary to negative inotropic effects) and angina pectoris (decreases cardiac workload when decreasing heart rate and contractility). Beta blockade has also been shown to reduce mortality in patients with CHF.