Correct Answer: B. Bromocriptine
This patient presents with galactorrhea and a large pituitary tumor on MRI—the clinical picture of a prolactinoma, the most common functional pituitary adenoma in India. The negative pregnancy test rules out physiological lactation. Bromocriptine is a dopamine D2 receptor agonist that directly suppresses prolactin secretion from lactotroph cells. Unlike surgery, which carries risks of hypopituitarism, CSF leak, and meningitis, bromocriptine offers medical management with high efficacy: 80–90% of prolactinomas shrink with dopamine agonist therapy, and galactorrhea resolves within weeks. The drug crosses the blood–brain barrier and acts on the hypothalamic–pituitary axis where dopamine tonically inhibits prolactin release. In Indian clinical practice (per AIIMS/PGIMER guidelines), bromocriptine is first-line for prolactinomas when surgery is declined or contraindicated. Dosing starts at 1.25 mg daily and titrates to 2.5–5 mg BD based on prolactin levels and tumor response on repeat MRI. Cabergoline (another dopamine agonist) is an alternative but bromocriptine remains the most widely available and cost-effective agent in India.
Why the other options are wrong
A. Octreotide — Octreotide is a somatostatin analog that suppresses growth hormone and TSH, not prolactin. It is the drug of choice for acromegaly (GH-secreting adenomas) and TSH-secreting pituitary tumors. In prolactinomas, octreotide is ineffective and will not reduce galactorrhea or tumor size. This is a classic NBE trap pairing somatostatin analogs with all pituitary tumors. C. Clozapine — Clozapine is an atypical antipsychotic that increases prolactin via dopamine D2 blockade in the tuberoinfundibular pathway. It would worsen galactorrhea and potentially enlarge the prolactinoma. Antipsychotics are a cause of secondary hyperprolactinemia, not treatment. This option tests whether students confuse dopamine antagonism with dopamine agonism. D. Promethazine — Promethazine is a first-generation antihistamine and dopamine antagonist used for nausea and allergies. Like clozapine, it blocks dopamine and would increase prolactin secretion, worsening the clinical picture. It has no role in prolactinoma management and is another dopamine-blocking agent that would be counterproductive.
High-Yield Facts
- Prolactinoma is the most common functional pituitary adenoma (40% of all pituitary tumors); presents with galactorrhea, amenorrhea, and erectile dysfunction.
- Bromocriptine (dopamine D2 agonist) is first-line medical therapy for prolactinomas; achieves tumor shrinkage in 80–90% of cases and resolves galactorrhea within 2–4 weeks.
- Dopamine agonists (bromocriptine, cabergoline) suppress prolactin by restoring dopamine's tonic inhibition of lactotroph cells; surgery is reserved for dopamine-resistant tumors or apoplexy.
- Somatostatin analogs (octreotide, lanreotide) treat GH-secreting and TSH-secreting adenomas, NOT prolactinomas.
- Dopamine antagonists (antipsychotics, metoclopramide, promethazine) cause secondary hyperprolactinemia and are contraindicated in prolactinoma patients.
Mnemonics
DOPA for Prolactinoma Dopamine agonists (bromocriptine, cabergoline) → Oppose prolactin → Prolactinoma shrinks → Amelioration of galactorrhea. Use this when you see prolactinoma + need medical therapy. Pituitary Adenoma Drug Match GH-secreting → Octreotide (somatostatin). Prolactin-secreting → Bromocriptine (dopamine). TSH-secreting → Octreotide. ACTH-secreting → Mitotane (adrenolytic). Anchor: dopamine agonists = prolactin only.
NBE Trap
NBE pairs somatostatin analogs (octreotide) with all pituitary tumors to trap students who memorize "somatostatin = pituitary" without distinguishing hormone-specific pharmacology. The correct discriminator is: dopamine agonists suppress prolactin; somatostatin analogs suppress GH and TSH.
Clinical Pearl
In Indian outpatient practice, a woman presenting with galactorrhea + amenorrhea + large pituitary mass on MRI is almost always a prolactinoma. Starting bromocriptine 1.25 mg at night (to minimize nausea) and titrating over 2–3 weeks often avoids surgery entirely; repeat MRI at 3 months confirms tumor shrinkage and guides dose adjustments.
_Reference: Harrison Ch. 375 (Pituitary Disorders); KD Tripathi Ch. 28 (Anterior Pituitary Hormones & Antagonists)_