Arginine Vasopressin (AVP)

Question 1

What are the trade names of Vasopressin?

Answer 1

Pitressin, ADH

Question 2

What formal drug class is Vasopressin in?

Answer 2

Exogenous antidiuretic peptide and vasopressor

Question 3

What are the clinical uses of Vasopressin?

Answer 3

• used in the treatment of diabetes insipidus (non-nephrogenic)
• in the evaluation of the urine-concentrating abilities of the kidneys after administration of fluorinated volatile anesthetics
• in the management of uncontrolled hemorrhage from esophageal varices
• as an alternative to epinephrine in CPR
• as an adjunct vasopressor in hemorrhagic or septic shock

Question 4

What is the MOA of Vasopressin as a vasoconstrictor?

Answer 4

• Acts as a vasopressor by stimulating V1a receptors on vascular smooth muscle, glomerular mesangial cells, and the vasa recta
• it is an extremely potent vasoconstrictor of the glomerular EFFERENT arteriole, while having little effect on the afferent arteriole, maintaining effective glomerular filtration pressure
• It also promotes hemostasis by increasing von Willebrand factor and factor VIII
• In addition, causes peristalsis by directly stimulating GI smooth muscle

Question 5

What is the MOA of Vasopressin as an antidiuretic?

Answer 5

• activates V2 receptors on the basolateral cell membrane of the renal collecting ducts, which induces water reabsorption and urine dilution
• through activation of G-protein-coupled adenyl cyclase, ATP is converted to cyclic adenosine monophosphate (cAMP). This in turn activates a protein kinase that causes preformed vesicles containing aquaporin-2 water channels to fuse with the apical cell membrane to allow reabsorption of water

Question 6

How is Vasopression metabolized?

Answer 6

Metabolism by tissue peptidases, 33% removed by the kidney

Question 7

What is the e 1/2 time of Vasopressin?

Answer 7

10-20min from enzymatic breakdown in tisues, especially in the kidneys

Question 8

What is the onset of action of nasal Vasopressin?

Answer 8

1 hour

Question 9

What is the duration of action for nasal vasopressin?

Answer 9

3-8 hours; IM/SC 2-8hrs

Question 10

Why cant Vasopressin be administered orally?

Answer 10

Rapid inactivation by trypsin

Question 11

What are the Cardiovascular side effects of Vasopressin?

Answer 11

• IV route may cause coronary artery spasm
• Vasoconstriction and increased SBP occur with doses much larger than those administered for DI, which may cause facial pallor
• in small doses, may produce selective coronary artery vasoconstriction, causing angina and myocardial ischemia

Question 12

What are the GI side effects of Vasopressin?

Answer 12

-Stimulation of GI smooth muscle may cause increased peristalsis, N/V, abdominal pain and the uterus may be stimulated as well

Question 13

As a side effect to Vasopressin, what can happen to platelet count? what is the mechanism for this?

Answer 13

a decreased platelet count has been attributed to AVP via V1 receptors

Question 14

What are the dermatological side effects of Vasopressin?

Answer 14

Urticaria
Anaphylaxis
Diaphoresis

Question 15

What are the CNS side effects of Vasopressin?

Answer 15

Pounding of the head
Vertigo
Fever

Question 16

What are the neuromuscular side effects of Vasopressin?

Answer 16

Tremor

Question 17

What are the Respiratory side effects of Vasopressin?

Answer 17

Bronchial Constriction

Question 18

What are the contraindications to Vasopressin?

Answer 18

Hypersensitivity to AVP or any component of the formulation

Question 19

What are the drug interactions between Vasopressin and NSAIDS and Carbamazapine?

Answer 19

Increase AVP effects

Question 20

What is the drug interaction that occurs between Vasopressin and Lithium, Colchicine, and Vinca alkaloids?

Answer 20

Lithium, Colchicine and Vinca Alkaloids decrease AVP effects

Question 21

What happens when Demeclocycline and Vasopressin are administered together?

Answer 21

Demeclocycline counteracts the action of ADH and can be used for hyponatremia caused by excessive AVP

Question 22

What is the dosage of Vasopressin for Diabetes Insipidus?

Answer 22

During surgery, 100-200mU/hr continuous IV

Question 23

What is the dosage of Vasopressin used for GI hemorrhage?

Answer 23

IV: dilute in NS or D5W to 0.1-1unit/mL
Initial: 0.2-0.4 units/min, then titrate dose as needed, if bleeding stops. Continue for 12hr, taper off over 24-48hr

Question 24

What is the dosage of Vasopressin used for Esophageal Varices?

Answer 24

20units IV over 5min

Question 25

What is the dosage of Vasopressin used for refractory Cardiac Arrest?

Answer 25

40units IV push

Question 26

What is the dosage of Vasopressin used for Hemorrhagic and Septic Shock?

Answer 26

IV gtt: 0.01-0.1 units/min
Doses> 0.05units/min may have more cardiovascular side effects
Most cases have used 0.04units/min as a fixed dose

Question 27

What type of endogenous thing is AVP? where is it normally synthesized? What usually causes release in the body?

Answer 27

an Endogenous 9-amino-acid peptide hormone; normally synthesized in the supraoptic and paraventricular nuclei of the anterior hypothalamus. It undergoes neuroaxial transport to the posterior pituitary gland, where it is stored in granules. Neural stimulation of the cell bodies in the hypothalamus from baroreceptor or osmotic receptor stimulation triggers exocytosis of AVP from the terminal vesicles into the circulation