Adrenergic Agents

Question 1

Epinephrine

Answer 1

Direct Sympathomimetic: a1, B1, B2 agonist.

Rx for cardiac arrest, severe hypotension, bronchospasm in asthma, anaphylaxis, wide-angle glaucoma (topical). Injected with local anesthetics to vasoconstrict and keep contained. SE: HTN, arrhythmia, MI, PE, HA, anxiety.

a1: high doses. Vasoconstriction increases BP
B1: low doses. Increased HR and contractility, increases CO and systolic BP.
B2: low doses. Bronchodilation, vasodilation leads to mild diastolic BP decrease.

Question 2

Norepinephrine

Answer 2

Direct Sympathomimetic: potent a1, a2, B1 agonist.

Used as a pressor in emergency treatment of severe hypotension and shock. SE: angina, MI, arrhythmia, low renal blood flow.

a1, a2: vasoconstriction, increasing systolic and diastolic BP.
B1: increases contractility and HR, but reflex bradycardia = no net HR change.

Question 3

Dopamine

Answer 3

Direct Sympathomimetic: a1, B1, D1 agonist.

Used as a pressor in the emergency treatment of severe hypotension and shock. SE: arrhythmia, angina, HTN, nausea.

a1: high doses. Vasoconstriction, increasing systolic and diastolic BP.
B1: low doses. Increased HR and contractility, increasing CO.
D1: very low doses. Increased renal and splanchnic blood flow, promoting renal perfusion.

Question 4

Dobutamine

Answer 4

Direct Sympathomimetic: B1 agonist

Increases CO. Used in treatment of decompensated CHF or cardiogenic shock. SE: tachyarrhythmia, peripheral vasodilation.

Question 5

__ephedrine

Answer 5

Indirect Sympathomimetic

Stimulates EPI/NE release, a and B agonist. Net effect increases syst/dia BP, CO, bronchodilation, stimulates CNS.

Used as nasal decongestant and female stress incontinence. SE: HTN, tremor, anxiety, arrhythmia, insomnia, improved athletics.

Ex: Ephedrine, Pseudoephedrine.

Question 6

Amphetamine

Answer 6

Indirect Sympathomimetic

Stimulates EPI/NE/DA release, leads to aroused state. SE: insomnia, decreased appetite, psychosis, arrhythmia, seizure, death.

Question 7

Methylphenidate

Answer 7

Indirect Sympathomimetic

Stimulates NE/EPI/DA release, derrivative of Amphetamine. Rx for narcolepsy and ADHD.

Question 8

Cocaine

Answer 8

Indirect Sympathomimetic

Blocks Na+/K+ ATPase that runs reuptake of NE, Serotonin, DA, potentiating their actions. DA in limbic system = euphoria, NE leads to vasoconstriction = cardiac ischemia. Blocks Na+ channels = local anesthetic for ENT surgery. SE: HTN, paranoia, MI, arrhythmias, seizures.

Reserpine and Guanethidine: old HTN treatments, significant side effects. Depletes NE/DA/Serotonin b/c can’t store, and inhibits NE release.

Question 9

Phenylephrine

Answer 9

Adrenergic Agonist, a1.

Systemic vasoconstriction and mydriasis, topically applied to nasal mucosa decreases secretions due to VC.

Rx for severe hypotension and shock, nasal congestion, topical for eye exam. SE: arrhythmias, HA.

Question 10

Midodrine

Answer 10

Adrenergic agonist, a1.

Vasoconstriction, used to treat hepatorenal syndrome and orthostatic hypotension due to ANS dysfunction. SE: supine HTN.

Question 11

Clonadine, Methyldopa

Answer 11

Adrenergic Agonist, a2.

Stimulates vasomotor center in medulla, decreasing neurotransmitter release. Decreased central adrenergic activity leads to decreased vasoconstriction, CO, and HR.

Rx of HTN. Clonadine SE: rebound HTN (quick withdrawal), bradycardia, sedation. Methyldopa SE: sedation, dizziness, + Coombs test. Does not reduce renal blood flow, very good in HTN pts with renal disease.

Question 12

Isoproternol

Answer 12

Adrenergic Agonist, B1 B2.

B1: increases HR and contractility, CO, systolic BP slightly.
B2: peripheral vasodilation, decrease arterial and diastolic BP, bronchodilation.

Rx for torsades de pointes with Mg+, cardiac arrest, complete heart block. SE: tachyarrhythmias, anxiety, pulmonary edema.

Question 13

Fenoldopam

Answer 13

Adrenergic Agonist, D1

Splanchnic and renal vasodilation for the treatment of severe HTN.

Question 14

__terol

Answer 14

Adrenergic Agonist, B2

Bronchodilation via smooth muscle relaxation when inhaled. Rx for asthma. Shifts K+ into cell, so high doses Rx for hyperkalemia. SE minimal when inhaled: tachycardia, tremor, anxiety.

Other: Terbutaline and Ritodrine reduce uterine contractions during premature labor, T treats status asthmaticus.

Ex: Albuterol, Pirbuterol, Bitolterol, Salmeterol (long acting, prevents asthma attacks).

Question 15

Phenoxybenzamine

Answer 15

Adrenergic Antagonist, a1 a2. Irreversible.

Decreases vasoconstriction, decreasing BP.

Rx for Pheochromocytoma, given chronically or prior to resection to prevent HTN crisis. SE: orthostatic hypotension, tachycardia, nasal congestion, inhibition of ejaculation.

Phentolamine: short acting, reversible. Diagnose pheo by demonstrating abnormally large decrease in BP when given.

Question 16

__zosin

Answer 16

Adrenergic Antagonist, a1.

Peripheral vascular smooth muscle contraction, decreasing BP. Decreases prostatic and bladder neck contraction, improving urinary flow.

Rx: HTN, BPH. SE: First dose syncope (severe hyoptension), dizziness, nasal congestion.

Ex: Prazosin, Alfuzosin. BPH: Terazosin, Doxazosin, Tamusulosin.

Question 17

__olol (Non-selective)

Answer 17

Adrenergic Antagonist, B1 B2.

B1: decreased HR and contractility, lower CO leads to reflex peripheral vasoconstriction, net decreased BP.
B2: bronchoconstriction. AVOID use in Asthma.

Rx for HTN, CAD, MI prevention, arrhythmias, tachy associated with hyperthyroid, migraines (cerebral vasodilation), wide-angle glaucoma topically. SE: bronchoconstriction, arrhythmias, sexual dysfunction, fasting hypoglycemia (decreased glycogenolysis), hypotension.

Ex: Propranolol, Nadolol, Pindolol (HTN + brady Rx), Timolol (glaucoma). Additional a1 Antagonist: Carvedilol (Rx for CHF), Labetalol (refractory HTN).

Question 18

__olol (Selective)

Answer 18

Adrenergic Antagonist, B1. Cardioselective.

Decreased HR and contractility, lower CO. Rx of HTN, CAD (diabetics especially), wide-angle glaucoma. SE: some bronchoconstriction, bradycardia, impotence, hypotension. Safer in Asthmatics.

Ex: Metoprolol, Esmolol (short, critical Rx for cradiac ischemia, HTN, arrhythmias), Acebutol (some B agonist, so Rx for HTN + bradycardia), Bisoprolol, Betaxolol (glaucoma).