Hyp-Pit Pharmacology

Question 1

Controversy for usage of GH in children with idiopathic short stature? (2)

Answer 1

1. Response to GH is highly variable

2. Benefit vs huge cost

Question 2

Uses of GH in adult? (4)

Answer 2

1. Tuner’s syndrome
2. Deficiency in adult – pituitary tumor or post-radiation/surgery
3. Wasting or cachexia in AIDS patients
4. Short bowel syndrome

Question 3

Adverse Reaction of GH

Answer 3

1. Insulin resistance => glucose intolerance
2. Increased risk idiopathic intracranial hypertension
3. Misuse in athletes

Question 4

Tesamorelin

Answer 4

• GHRH

* use in HIV pt with lipodystrophy

Question 5

GHRH Pharmacokinetics

Answer 5

1. Effective IV, SC
2. Adverse effect rare
3. Gs-GPCR => increase cAMP and Ca2+

Question 6

GHRH Uses

Answer 6

1. Diagnostic evaluation for GH deficiency

2. Potential use in GH-deficient children

Question 7

Somatostatin

Answer 7

1. Gi/o => decrease cAMP
2. Decrease secretion gastric enzyme and acid
3. Reduces insulin and glucagon release

Question 8

Somatostatin analogs

Answer 8

1. Octreotide
   * given SC every 6-12 hours
   * given IM every 4 wks
2. Lanreotide - long acting
   * given SC every 4 wks

Question 9

Somatostatin clearance

Answer 9

• Kidney

* t1/2 = 3-4 min

Question 10

Medical therapies for acromegaly

Answer 10

1. Somatostatin analog
   * Lanreotide - long acting; PREFERRED!!
2. GH receptor antagonist
   * Pegvisomant - mutated GH extend t1/2; single dose SC
3. Dopamine agonist
   * Cabergoline - not as effective, adjuvant management

Question 11

Somatostatin non-pituitary uses

Answer 11

octreotide - control bleeding from esophageal varices and GI hemorrhage

• direct action on vascular SM
• Fever side effects than vasopressin

Question 12

Adverse Reaction Somatostatin

Answer 12

Hyperglycemia => improve eventually

Question 13

Prolactin Pharmacodynamics

Answer 13

1. Inhibitory = Dopamine D2 receptor
2. Stimulus for release = suckling
3. Stimulate milk production with appropriate
   * insulin
   * estrogen
   * progestin
   * corticosteroid
4. Inhibit FSH/LH

Question 14

Drugs cause hyperprolactinemia

Answer 14

1. Antipsychotic (anti-Dopamine)

2. Anti-emetics

Question 15

Prolactin useage

Answer 15

1. Hypo-prolactinemia => currently NO commercially available

2. Hyper-prolactinemia => D2 agonist

Question 16

Dopamine Agonist agents

Answer 16

1. Cabergoline!!
   * more effective = more selective for D2 receptor
   * better tolerance
2. Bromocriptine
   * Side effects: n/v, postural hypotension
   * Also activate D1 receptor

Question 17

Desmopressin (DDAVP)

Answer 17

ADH analog = more stable, longer t1/2 (1.5-2.5hrs)

Question 18

ADH

Answer 18

• Act on collecting tubules
• Stimulus = !! rising blood osmolality; decrease circulating volume
• Inhibited release = ethanol

Question 19

ADH Pharmacodynamics

Answer 19

1. Renal action
   * V2 receptor = Gs
   * Increase water channels exocytosis => increase Water permeability => decrease water secretion
2. Non-renal
   * release coagulation factor VIII and von Willebrand

Question 20

ADH act on V1 receptor

Answer 20

V1 receptor = Gq (increase Ca++)
=> * vasoconstriction
* Pressor response = only at much higher Cp

Question 21

Central DI treatment

Answer 21

• 1st line = dDAVP (longer t1/2; no vasopressor effect)

* 2nd line = ADH