Introduction: Understanding inhibitors of pituitary hormones is essential for B. Pharm students studying endocrine pharmacology. This topic covers pharmacological classes such as somatostatin analogs, dopamine agonists, GnRH agonists and antagonists, and GH receptor antagonists, plus newer agents like pasireotide. Key concepts include mechanisms of pituitary suppression, receptor selectivity (SSTR2/SSTR5, D2), clinical indications (acromegaly, prolactinoma, Cushing’s disease, assisted reproduction), adverse effects (hyperglycemia, gallstones, valvulopathy), dosing and monitoring (IGF‑1, prolactin, LFTs). Mastery of these areas helps in rational drug selection and patient monitoring. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. What is the primary mechanism by which octreotide reduces growth hormone (GH) secretion?
- Activation of somatostatin receptors inhibiting GH secretion
- Antagonism of GH receptors in the liver
- Stimulation of dopamine D2 receptors on lactotrophs
- Blockade of GnRH receptors in the pituitary
Correct Answer: Activation of somatostatin receptors inhibiting GH secretion
Q2. Which agent is commonly used as first-line therapy for hyperprolactinemia due to prolactinoma?
- Octreotide
- Bromocriptine
- Leuprolide
- Pegvisomant
Correct Answer: Bromocriptine
Q3. What is a major pharmacologic advantage of cabergoline over bromocriptine in treating prolactinomas?
- It is a somatostatin analog with GH inhibition
- Longer half-life and higher D2 selectivity allowing less frequent dosing
- Direct antagonism of prolactin receptors in target tissues
- Potent inhibition of adrenal steroidogenesis
Correct Answer: Longer half-life and higher D2 selectivity allowing less frequent dosing
Q4. Continuous administration of a GnRH agonist (e.g., leuprolide) results in which pituitary response?
- Persistent stimulation of LH/FSH and sustained sex steroid rise
- Initial stimulation followed by receptor downregulation causing decreased LH and FSH
- Direct blockade of pituitary estrogen receptors
- Immediate and permanent pituitary gonadotroph destruction
Correct Answer: Initial stimulation followed by receptor downregulation causing decreased LH and FSH
Q5. Which drug is a direct GnRH receptor antagonist used to prevent premature LH surge in controlled ovarian stimulation?
- Leuprolide
- Cetrorelix
- Goserelin
- Clomiphene
Correct Answer: Cetrorelix
Q6. Pegvisomant treats acromegaly by which mechanism?
- Somatostatin receptor agonism to reduce GH secretion
- Direct GH receptor antagonism reducing IGF‑1 production
- Dopamine D2 agonism to lower pituitary GH release
- Inhibition of hepatic GH synthesis
Correct Answer: Direct GH receptor antagonism reducing IGF‑1 production
Q7. Which adverse effect is classically associated with chronic somatostatin analog therapy?
- Hyperkalemia
- Gallstone formation due to reduced gallbladder motility
- Renal tubular acidosis
- Pulmonary fibrosis
Correct Answer: Gallstone formation due to reduced gallbladder motility
Q8. Common adverse effects of dopamine agonists (e.g., bromocriptine, cabergoline) include:
- Bradycardia and hyperkalemia only
- Nausea, orthostatic hypotension and psychiatric symptoms (e.g., hallucinations)
- Severe hypoglycemia in all patients
- Acute hepatic necrosis as a routine effect
Correct Answer: Nausea, orthostatic hypotension and psychiatric symptoms (e.g., hallucinations)
Q9. What is the preferred biochemical marker to monitor treatment response in acromegaly?
- Random serum growth hormone (GH) alone
- Serum IGF‑1 level
- Plasma prolactin
- Serum cortisol
Correct Answer: Serum IGF‑1 level
Q10. Which somatostatin analogue is notable for suppressing ACTH secretion and is used in Cushing’s disease?
- Octreotide
- Pasireotide
- Bromocriptine
- Leuprolide
Correct Answer: Pasireotide
Q11. How do dopamine agonists reduce prolactin secretion from pituitary lactotrophs?
- Antagonize prolactin receptors in breast tissue
- Activate D2 receptors on lactotrophs, inhibiting prolactin secretion
- Inhibit somatostatin release from the hypothalamus
- Block pituitary TRH receptors
Correct Answer: Activate D2 receptors on lactotrophs, inhibiting prolactin secretion
Q12. Which condition is a relative contraindication to dopamine agonist therapy due to risk of exacerbation?
- Stable hypothyroidism
- Active psychotic disorder
- Mild osteoarthritis
- Controlled asthma
Correct Answer: Active psychotic disorder
Q13. Which laboratory test is essential to monitor during pegvisomant therapy?
- Serum amylase
- Liver function tests (LFTs)
- Serum potassium
- Urine cortisol
Correct Answer: Liver function tests (LFTs)
Q14. Which somatostatin receptor subtypes are most important for GH suppression?
- SSTR1 and SSTR3
- SSTR2 and SSTR5
- SSTR4 exclusively
- SSTR6 only
Correct Answer: SSTR2 and SSTR5
Q15. Continuous GnRH agonists are commonly used therapeutically for which of the following?
- Hypogonadotropic hypogonadism to stimulate fertility
- Prostate cancer, endometriosis, and precocious puberty (when used continuously)
- To increase ovulation in anovulatory infertility
- As first-line therapy for Cushing’s disease
Correct Answer: Prostate cancer, endometriosis, and precocious puberty (when used continuously)
Q16. What acute effect may occur when starting a GnRH agonist before suppression is achieved?
- Immediate ovarian follicle atresia
- Transient initial hormone ‘flare’ of testosterone/estrogen
- Permanent infertility after a single dose
- Rapid increase in prolactin secretion
Correct Answer: Transient initial hormone ‘flare’ of testosterone/estrogen
Q17. Cetrorelix is primarily used in assisted reproduction to:
- Induce ovulation by stimulating LH release
- Prevent premature LH surge during controlled ovarian stimulation
- Increase endometrial receptivity by acting on estrogen receptors
- Directly stimulate follicle growth by activating FSH receptors
Correct Answer: Prevent premature LH surge during controlled ovarian stimulation
Q18. What cardiac risk is associated with long-term high-dose ergot-derived dopamine agonists such as cabergoline?
- Aortic stenosis caused by lipid deposition
- Valvular fibrosis and regurgitation due to 5‑HT2B agonism
- Myocarditis mediated by IgE antibodies
- Hypertrophic cardiomyopathy via beta-receptor stimulation
Correct Answer: Valvular fibrosis and regurgitation due to 5‑HT2B agonism
Q19. Somatostatin analogs commonly affect glucose metabolism by which mechanism?
- Enhancing insulin secretion causing hypoglycemia
- Inhibiting insulin secretion leading to hyperglycemia (more marked with pasireotide)
- Direct stimulation of pancreatic beta‑cell proliferation
- Increasing peripheral glucose uptake directly
Correct Answer: Inhibiting insulin secretion leading to hyperglycemia (more marked with pasireotide)
Q20. Which drug is most effective for tumor shrinkage in prolactin-secreting pituitary adenomas?
- Pasireotide
- Cabergoline
- Pegvisomant
- Ketoconazole
Correct Answer: Cabergoline
Q21. Which of the following drugs does NOT act primarily by inhibiting pituitary hormone secretion?
- Pasireotide
- Bromocriptine
- Ketoconazole
- Cetrorelix
Correct Answer: Ketoconazole
Q22. Mifepristone is used in select patients with Cushing’s syndrome because it:
- Directly suppresses pituitary ACTH secretion
- Blocks glucocorticoid receptors, antagonizing cortisol action
- Inhibits adrenal 11β‑hydroxylase enzyme
- Acts as a somatostatin analog at SSTR5
Correct Answer: Blocks glucocorticoid receptors, antagonizing cortisol action
Q23. Which somatostatin analogue is commonly used acutely to control bleeding from esophageal varices due to portal hypertension?
- Lanreotide
- Octreotide
- Cabergoline
- Leuprolide
Correct Answer: Octreotide
Q24. Which agent directly antagonizes the action of growth hormone at its receptor?
- Octreotide
- Pegvisomant
- Bromocriptine
- Leuprolide
Correct Answer: Pegvisomant
Q25. By lowering prolactin levels, dopamine agonist therapy can have which reproductive effect in women?
- Permanent ovarian failure
- Restoration of ovulation and fertility in hyperprolactinemic patients
- Induction of menopause within weeks
- Directly increasing estrogen receptor density
Correct Answer: Restoration of ovulation and fertility in hyperprolactinemic patients
Q26. Which long‑acting formulations are available for somatostatin analog therapy in acromegaly?
- Octreotide LAR and lanreotide Autogel
- Short‑acting cabergoline infusion only
- Pegvisomant oral tablets daily
- Leuprolide transdermal patch
Correct Answer: Octreotide LAR and lanreotide Autogel
Q27. What is a key clinical advantage of GnRH antagonists over GnRH agonists?
- They cause a longer initial hormone flare than agonists
- No initial sex‑steroid flare and more rapid suppression of LH/FSH
- They stimulate prolactin secretion beneficially
- They permanently ablate pituitary gonadotrophs after a single dose
Correct Answer: No initial sex‑steroid flare and more rapid suppression of LH/FSH
Q28. The most appropriate test to assess response to therapy in a patient with a prolactin‑secreting adenoma is:
- Random serum GH level
- Serum prolactin concentration
- 24‑hour urinary free cortisol
- Thyroid stimulating hormone (TSH)
Correct Answer: Serum prolactin concentration
Q29. Which class of dopamine agonists is most implicated in drug‑induced valvular heart disease?
- Non‑ergot dopamine agonists (e.g., pramipexole)
- Ergot‑derived dopamine agonists (e.g., cabergoline, pergolide)
- Somatostatin analogues
- GnRH antagonists
Correct Answer: Ergot‑derived dopamine agonists (e.g., cabergoline, pergolide)
Q30. Compared to octreotide, pasireotide differs pharmacologically by:
- Being a dopamine D2 agonist rather than a somatostatin analog
- Broader somatostatin receptor affinity (incl. SSTR5), more ACTH suppression but higher hyperglycemia risk
- Acting as a GH receptor antagonist like pegvisomant
- Primarily increasing insulin secretion and lowering glucose
Correct Answer: Broader somatostatin receptor affinity (incl. SSTR5), more ACTH suppression but higher hyperglycemia risk
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
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