Autonomic Nervous System

Question 1

What drugs fall under the sympathomimetic/ adrenergic agonist class?

Answer 1

Dopamine, Dobutamine, and Epinephrine

Question 2

What drugs fall under the sympatholytic/ adrenergic antagonist class?

Answer 2

Phentolamine, Labetalol

Question 3

What is the difference between alpha and beta receptors?

Answer 3

Alpha receptors are found on the smooth muscle of blood vessels, eyes, and other organs. Beta receptors are found in the heart, lungs, bladder, uterus, and vascular smooth muscle.

Question 4

What is the difference between muscarinic and nicotinic receptors?

Answer 4

Muscarinic receptors are located in visceral effector organs, sweat glands, and some vascular smooth muscle. Nicotinic receptors are found between pre- and post-ganglionic nerves and neuromuscular junctions.

Question 5

What is the main neurotransmitter for the PNS?

Answer 5

Acetylcholine

Question 6

What is the main neurotransmitter for the SNS?

Answer 6

Norepinephrine/ Epinephrine

Question 7

What is the main indication for Dopamine?

Answer 7

Tx of shock

Question 8

What is the main indication for epinephrine?

Answer 8

Tx of hypotension resulting from shock; prophylaxis

Question 9

What is the main indication for dobutamine?

Answer 9

Tx of HF

Question 10

What are some contraindications for adrenergic agonists?

Answer 10

1. Hypersensitivity
2. Pheochromocytoma
3. Tachyarrhythmias or ventricular fibrillation
4. Hypovolemia
5. Halogenated hydrocarbon general anesthetics
6. Peripheral vascular disease
7. Pregnancy and lactation

Question 11

What are some drug interactions for adrenergic agonists?

Answer 11

1. Increased effects of TCAs and MAOIs bc of the increased norepinephrine
2. Increased risk of hypertension if given with other drugs that have a risk of HTN
3. Halogenated hydrocarbon general anesthetics

Question 12

What adverse effects are associated with adrenergic agonists?

Question 12

What is pheochromocytoma?

Answer 12

A tumor of the adrenal medulla that periodically releases large amounts of norepinephrine and epinephrine with resultant severe HTN and tachycardia.

Question 13

What is the mechanism of action for labetalol?

Answer 13

It blocks alpha and beta receptor sites in the SNS, causing a decrease in blood pressure without reflex tachycardia and decreased renin levels.

Question 14

What is the therapeutic use for labetalol?

Answer 14

Tx of HTN. Used to treat HTN associated with pheochromocytoma and clonidine withdrawal.

Question 15

What drug class does labetalol belong to?

Answer 15

It is a non-selective adrenergic blocking agent

Question 16

What are some drug interactions for labetalol and other non-selective adrenergic antagonists?

Answer 16

1, May increase the effectiveness of some diabetic agents and lead to hypoglycemia
2. Increases risk of hypotension if combined with volatile liquid general anesthetics
3. Co-admin of amiodarone and other antiarrhythmic may prolong QT interval and increase the risk of torsade de pointes.

Question 17

What are some contraindications for labetalol and other non-selective adrenergic antagonists?

Answer 17

1. Hypersensitivity
2. Bradycardia or heart blocks (can be worsened by slowed HR and conduction)
3. Shock of HR requiring inotropic support
4. Lactating
5. Caution in diabetes, bronchospasm or asthma, pregnancy

Question 18

What is the therapeutic use for phentolamine?

Answer 18

1. prevention/control of hypertensive episodes associated with pheochromocytoma
2. Prevention and treatment of dermal necrosis and sloughing associated with extravasation of norepinephrine/dopamine.

Question 19

What drug class does phentolamine belong to?

Answer 19

Nonselective alpha adrenergic antagonists

Question 20

What are some contraindications for phentolamine?

Answer 20

1. Allergy, Hypersensitivity
2. Coronary artery disease or MI
3. Caution in pregnancy and/or lactation

Question 21

What are some nursing considerations for phentolamine?

Answer 21

1. Ephedrine and epinephrine may have decreased hypotensive and vasoconstriction effects if taken with Phentolamine
2. Increased hypertension may occur if the drug is combined with alcohol.

Question 22

What is the mechanism of action for bethanechol? What drug class does it belong to?

Answer 22

It acts directly on cholinergic receptors to mimic the effects of ACh. This drug belongs to the Direct-acting cholinergic agonist class.

Question 23

What are some contraindications for bethanechol and other direct-acting cholinergic agonists?

Answer 23

1. Hypersensitivity
2. Presence of any condition that parasympathetic effects may exacerbate
3. Epilepsy and Parkinsonism
4. Caution in pregnancy and/or lactation

Question 24

Drug interactions for bethanechol?

Answer 24

Increased risk of cholinergic effects if combined with acetylcholinesterase inhibitors (i.e., neostigmine)

Question 25

What is the therapeutic use for bethanechol?

Answer 25

Tx of nonobstructive postoperative and postpartum urinary retention, neurogenic bladder atony

Question 26

What adverse effects may be related to bethanechol and other direct-acting cholinergic agonists?