HPA/Thyroid drugs

Question 1

Vasopressin (ADH)

Answer 1

MOA: Causes vasoconstriction and free water retention by stimulating the V1 (Gq) and V2 (Gs) receptors
Dosing considerations: Short half life, IV only
Special indications: Used in hypotensive crisis along with epi/norepi

Question 2

Desmopressin (DDAVP)

Answer 2

MOA: V2 receptor agonist and acts in the collecting duct to add aquaporin channels (similar to vasopressin)
Dosing considerations: longer half life, multiple formulations (IV, SQ, PO, IN)
Indications: favorable treatment for diabetes insipidus

Question 3

Tolvaptan

Answer 3

MOA: V2 antagonist
Dosing considerations: PO only
Indications: favorable for treatment of SIADH

Question 4

Conivaptan

Answer 4

MOA: V1 and V2 antagonist
Dosing considerations: IV only

Question 5

Oxytocin

Answer 5

MOA: Causes uterine contraction and lactation (Gq)
Dosing considerations: rapid delivery
Indications: post-partum hemorrhage

Question 6

Prolactin

Answer 6

MOA: Stimulates lactation and mammary cell proliferation by RTK dimers and activation of JAK kinases (release is inhibited by dopamine)

Question 7

What can happen if a patient is on prednisone for several months?

Answer 7

• The adrenal glands can shrink due to lower ACTH levels from negative feedback which can cause some patients to not be ale to make enough cortisol
• Treatment: Stress dose corticosteroids (hydrocortisone 100 mg IV)