Sympatholytics

Question 1

Types of cholinergic receptors and sites of action

Answer 1

1) Nicotinic: ganglia and skeletal muscle
2) Muscarinic: glands (lacrimal, salivary, gastric), smooth muscle (bronchial, GI, bladder, and vessels), and heart (SA and AV node)

Question 2

All preganglionic neurons release what neurotransmitters? Is it excitatory or inhibitory?

Answer 2

Acetylcholine. Excitatory.

Question 3

What is the rate-limiting step in the synthesis of epi and norepi in the adrenal medulla?

Answer 3

tyrosine hydoxylase

Question 4

Ratio of Epi/norepi synthesis in the adrenal medulla

Answer 4

80/20

Question 5

What neurotransmitter precedes the synthesis of norepinephrine?

Answer 5

dopamine

Question 6

Metabolism of norepi and epi

Answer 6

Metabolic degradation by MOA and COMT. However, 80% is reuptake.

Question 7

Beta-1 selective antagonists

Answer 7

atenolol, esmolol, and metoprolol

Question 8

Beta-blockers with alpha effects

Answer 8

labetalol and carvedilol

Question 9

Phentolamine MOA and SE

Answer 9

nonselective reversible IV alpha-blocker. Produces vasodilation. Produces baroceptor-mediated increases in CO and HR. May cause dysrhythmias and angina, as well as hyperperistalsis, abdominal pain, and diarrhea due to the predominance of parasympathetic activity.

Question 10

Clinical uses for phentolamine

Answer 10

Intraop management of pheochromocytoma, autonomic dysreflexia (SCI), and extravasation of IV sympathomimetic.

Question 11

Phenoxybenzamine MOA and SE

Answer 11

nonselective IRREVERSIBLE alpha-blocker. Profound hypotension in the presence of hypovolemia, blood loss, vasodilators, and inhalation agents. Noncardiac effects include miosis, nasal stuffiness, and sedation.

Question 12

Phenoxybenzamine clinical uses

Answer 12

Preoperative management of pheochromocytoma, inoperable adrenal tumors, Raynaud’s diseases (more effective in cutaneous vasoconstriction rather than skeletal muscle flow)

Question 13

Preoperative management of pheochromocytoma with phenoxybenzamine

Answer 13

0.5-1 mg/kg PO beginning two weeks prior to surgery. Make sure intravascular volume is adequate. Prazosin as an alternative.

Question 14

Yohimbine MOA

Answer 14

Selective presynaptic alpha-2 antagonist. Enhances the release of norepinephrine.

Question 15

Yohimbine clinical uses

Answer 15

idiopathic orthostatic hypotension, former treatment for impotence.

Question 16

Prazosin MOA

Answer 16

selective post-synaptic alpha-1 antagonist. Dilates both arterioles and veins. Reflex tachycardia less common because drug has no inhibitory effect on alpha-2 receptors.

Question 17

Prazosin clinical uses

Answer 17

HTN, Raynaud’s, BPH

Question 18

Vasodilators are often combined with which drug and why?

Answer 18

beta-blockers to minimize baroreceptor mediated increases in heart rate and cardiac output.

Question 19

beta-blockers for the management of CHF

Answer 19

metoprolol, carvedilol, and bisoprolol

Question 20

Which beta-blocker increases the risk of amide local anesthetic toxicity and why?

Answer 20

Propranolol. Propranolol induced decreases in hepatic metabolism decrease the clearance of amide LA.

Question 21

Most selective beta-blocker

Answer 21

Atenolol

Question 22

Which type of beta-blocker is preferred in diabetics? Why?

Answer 22

Selective beta-blockers, because they do not potentiate insulin-induced hypoglycemia seen with nonselective beta-blockers (think beta-2 effects).

Question 23

How is esmolol metabolized?

Answer 23

rapid hydrolysis by plasma esterases. Ultra-short acting. Elimination half-life 9 minutes. Return of HR to predrug levels within 10-30 minutes.

Question 24

DOC for treating massive beta-adrenergic antagonist overdose

Answer 24

glucagon

Question 25

Percentage of B1 and B2 receptors in the heart

Answer 25

75% beta-1 and 20% beta-2

Question 26

Which beta-blocker is highly protein-bound?

Answer 26

Propranolol

Question 27

What drug decreases the pulmonary first-pass uptake of fentanyl?

Answer 27

Chronic administration of propranolol results in 2-4 times as much fentanyl being injected into the systemic circulation. Both are basic lipophilic amines.

Question 28

Nonselective beta-blockers should not be used in what type of patients?

Answer 28

Patients with reactive airway disease, peripheral vascular disease, and those who are prone to hypoglycemia.

Question 29

Useful in the management of perioperative thyrotoxicosis, pregnancy-induced HTN, and epinephrine or cocaine-induced cardiotoxicity.

Answer 29

Esmolol because of its rapid onset and it is short-acting.

Question 30

Beta-blockers can affect the serum concentration of what electrolyte?

Answer 30

Potassium, serum concentrations are increased due to the inhibition of insulin release.

Question 31

What receptors does labetalol work on?

Answer 31

alpha 1, beta 1, beta 2. Decreases SVR (alpha 1 blockade) with attenuation of reflex tachycardia by simultaneous beta-blockade.

Question 32

Which common beta-blocker depends on the kidneys as its primary route of elimination?

Answer 32

Atenolol

Question 33

Common beta-blocker with intrinsic sympathomimetic activity

Answer 33

Labetalol

Question 34

alpha 1 receptor stimulation effects

Answer 34

mydriasis, bronchoconstriction, vasoconstriction, uterine contracture, contraction of sphincters of GI/GU tract

Question 35

alpha 2 receptor stimulation effects

Answer 35

Decreased NE release, decreased sympathetic outflow resulting in peripheral vasodilation and decreased BP, sedation, inhibition of insulin release, platelet aggregation

Question 36

Beta 1 receptor stimulation

Answer 36

positive chronotropic, dromotropic, and inotropic effects

Question 37

Beta 2 receptor stimulation

Answer 37

Smooth muscle relaxation (bronchodilation, vasodilation, uterus/bladder/gut), glycogenolysis, lipolysis, gluconeogenesis, insulin secretion, activation of Na/K pump (K goes intracellular, can produce hypokalemia and dysrhythmia)

Question 38

contraindications to beta-blockade

Answer 38

sinus or AV node dysfunction, heart block, hypotension, decompensated heart failure, severe reactive airway disease.

Question 39

Clinical uses for esmolol

Answer 39

HTN & tachycardia in response to intraop noxious stimulation & intubation, ECT, pheo, thyrotoxicosis, PIH, epi or cocaine-induced cardiac toxicity.

Question 40

Which beta-blocker does not cross the BBB/placenta?

Answer 40

esmolol due to its poor lipid solubility

Question 41

Most common SE of labetalol

Answer 41

orthostatic hypotension