Hypothalamic and Pituitary Pharmacology

Question 1

Preferentially selective agonist for vasopressin V2 receptors:
A) Vasopressin 
B) Desmopressin 
C) Oxytocin
D) Conivaptan
E) Prolactin

Answer 1

B

Question 2

Stimulates milk production in lactation:
A) Vasopressin 
B) Desmopressin 
C) Oxytocin
D) Conivaptan
E) Prolactin

Answer 2

E

Question 3

Also known as antidiuretic hormone (ADH):
A) Vasopressin 
B) Desmopressin 
C) Oxytocin
D) Conivaptan
E) Prolactin

Answer 3

A

Question 4

Primary pharmacological use is for its vasopressor effect:
A) Vasopressin 
B) Desmopressin 
C) Oxytocin
D) Conivaptan
E) Prolactin

Answer 4

A

Question 5

Stimulates milk letdown during lactation:
A) Vasopressin 
B) Desmopressin 
C) Oxytocin
D) Conivaptan
E) Prolactin

Answer 5

C

Question 6

Treatment for central diabetes insipidus:
A) Vasopressin 
B) Desmopressin 
C) Oxytocin
D) Conivaptan
E) Prolactin

Answer 6

B

Question 7

Treatment for SIADH (syndrome of inappropriate secretion of antidiuretic hormone):
A) Vasopressin 
B) Desmopressin 
C) Oxytocin
D) Conivaptan
E) Prolactin

Answer 7

D

Question 8

Which of the following drugs is a growth hormone receptor antagonist?
A. somatropin
B. pegvisomant 
C. mecasermin 
D. octreotide
E. bromocriptine 
F. conivaptan

Answer 8

B

Pegvisomant is a growth hormone (GH) antagonist; it competes with GH for binding to GH

Question 9

Which of the following drugs would be the most appropriate therapy for a 4-year-old boy with
 hypopituitary dwarfism?
A. Mecasermin 
B. Octreotide 
C. Testosterone 
D. Somatropin 
E. Pegvisomant

Answer 9

D
Hypopituitary dwarfism is the result of lack of growth hormone (GH) due to inadequate secretion of GH from the anterior pituitary, which could happen as a result of various problems. Somatropin is recombinant human growth hormone, so this drug provides straightforward
replacement therapy. If the patient had Laron syndrome, the problem would be due to insensitivity to GH (e.g. defective GH receptor), and circulating GH levels would be normal or high, but there would be a failure to produce IGF-1.
A. Mecasermin (recombinant IGF-1) would be
the treatment of the short stature in this case.

Question 10

Which of the following conditions limits the ability of growth hormone to increase height in
 adolescents?
A. Hyperglycemia
B. Initiation of puberty
C. Epiphyseal closure
D. Hepatic IGF-1 formation 
E. Increased muscle mass

Answer 10

C
Longitudinal bone growth can continue until epiphyseal closure occurs. The primary cause of epiphyseal closure is sexual maturity; the initiation of puberty is usually accompanied by growth spurt, but as sex hormones become established at higher levels, the process of epiphyseal closure is initiated.

Question 11

Which of the following happens when pegvisomant binds to growth hormone (GH) receptors?
A) GH secretion is blocked
B) IGF-1 is secreted
C) Nothing
D) IGF-1 receptors are blocked 
E) Somatostatin is secreted.

Answer 11

C
Pegvisomant is a growth hormone antagonist. When it binds to the GH receptor, it keeps GH from binding, but there is no activation of the receptor.

Question 12

Why is it recommended to administer mecasermin just after a snack?
A) To prevent GI distress
B) To be sure there is energy available to support the stimulated growth
C) Because mecasermin increases appetite
D) To prevent hypoglycemia

Answer 12

D
Mecasermin is an IGF-1 analog, and as such it can activate insulin receptors, with the potential to cause hypoglycemia. Hypoglycemia is the most important side (or adverse) effect of mecasermin

Question 13

A 45-year-old man is diagnosed with acromegaly. He is prescribed octreotide. What change would be expected to occur in this man’s IGF-1 levels compared to pretreatment levels?
A) Increase
B) Decrease
C) Remain unchanged

Answer 13

B
Octreotide is a Somatostatin analog used to decrease GH secretion in acromegaly. The resulting decrease in GH levels will most likely be accompanied by a decrease in IGF-1 levels.

Question 14

Is octreotide an agonist or an antagonist at somatostatin receptors?

Answer 14

Agonist
Octreotide is a somatostatin receptor agonist. It binds to the receptor and activates it in a manner analogous to the stimulation caused by somatostatin.

Question 15

hich of the following describes the mechanism most relevant to the observation that antipsychotic drugs can cause galactorrhea?
A) Dopamine D2 antagonists block the prolactin-release inhibiting action of endogenous dopamine on the anterior pituitary
B) Dopamine D2 agonists directly stimulate anterior pituitary prolactin secretion
C) Dopamine D2 antagonists directly block anterior pituitary prolactin secretion
D) Antipsychotic drugs block dopamine production in the nerve terminals innervating the anterior pituitary

Answer 15

A
Galactorrhea is inappropriate lactation in either men or women and most commonly occurs when circulating prolactin levels are abnormally high. Prolactin release from the anterior pituitary is normal under inhibitory control by dopamine acting as an agonist via D2 receptors. Antipsychotic drugs that are dopamine D2 antagonists bind to pituitary D2 receptors, blocking the effects of endogenous dopamine and resulting in increased prolactin secretion.

Question 16

What route of administration of oxytocin should be used for initiation and support of labor?
A) Oral
B) Intranasal
C) Intravenous 
D) Subcutaneous

Answer 16

C
It is important to be able to carefully titrate (control) the exposure of the contracting uterus to oxytocin. Because this peptide hormone has a short circulating half-life, it is relatively easy to regulate the dose in response to monitored uterine contractions if the drug is given IV. It is not possible to achieve this type of regulation with any other route of administration.

Question 17

T or F: Desmopressin is a vasopressin analog that lasts longer in the circulation than native vasopressin, but exhibits the same receptor specificity.

Answer 17

FALSE
Desmopressin is a vasopressin analog that lasts longer in the circulation than native vasopressin, but it is also selective for V2 receptors relative to V1 receptors. Thus, desmopressin is used to elicit the renal actions of vasopressin without causing the vasoconstriction that vasopressin would also cause.

Question 18

T or F: Desmopressin is unlikely to be efficacious in the treatment of nephrogenic diabetes insipidus, because in nephrogenic diabetes insipidus, the primary problem is not a lack of vasopressin.

Answer 18

TRUE
This is a true statement. In central diabetes insipidus, the problem is a lack of production of vasopressin, and so using desmopressin as a replacement drug is effective. In nephrogenic diabetes insipidus, the problem lies in a lack of ability of the V2 receptor to be activated by vasopressin, and so administering a V2 receptor agonist is unlikely to be very effective, although it is occasionally possible to achieve some therapeutic effect in nephrogenic diabetes insipidus with very high doses of desmopressin.

Question 19

Which of the following drugs is a high-affinity vasopressin V2 receptor antagonist?
A) Desmopressin 
B) Octreotide
C) Somatostatin 
D) Mecasermin 
E) Conivaptan

Answer 19

E
Conivaptan is a high affinity antagonist at the vasopressin V2 receptor, where it binds to the receptor but does not activate it.