Endocrine Pharmacology Practice Questions

Q: Which drug commonly causes gynecomastia?

Spironolactone. **Explanation:** **Spironolactone** is a potassium-sparing diuretic and a competitive aldosterone antagonist. It is the most common pharmacological cause of gynecomastia. The underlying mechanism is twofold: 1. **Anti-androgenic effect:** It binds to and blocks androgen receptors. 2. **Hormonal imbalance:** It inhibits testosterone synthesis and increases the peripheral conversion of testosterone to estradiol. This shift in the estrogen-to-androgen ratio leads to the development of glandular breast tissue in males. **Analysis of Incorrect Options:** * **B. Rifampicin:** This is an enzyme inducer (CYP450). While it can alter the metabolism of various hormones, it is not classically associated with gynecomastia. * **C. Penicillin:** This is a beta-lactam antibiotic with no hormonal activity; it does not cause gynecomastia. * **D. Bumetanide:** This is a potent loop diuretic. Unlike spironolactone, loop diuretics do not interfere with steroid hormone receptors. **High-Yield Clinical Pearls for NEET-PG:** * **Eplerenone:** A selective aldosterone antagonist that does **not** cause gynecomastia because it has low affinity for androgen and progesterone receptors. It is the preferred alternative if a patient develops breast tenderness on spironolactone. * **Mnemonic for drugs causing Gynecomastia (DISCO):** **D**igoxin, **I**soniazid, **S**pironolactone, **C**imetidine, **O**estrogens/Ketoconazole. * **Cimetidine:** Another high-yield cause; it acts as a H2 blocker and also has significant anti-androgenic properties.

Q: Which drug class is known to cause osteoporosis on long-term use?

GnRH analogues. ### Explanation **Correct Option: C. GnRH analogues** The correct answer is **GnRH analogues** (e.g., Leuprolide, Goserelin). When administered continuously, these drugs cause down-regulation and desensitization of GnRH receptors in the pituitary gland. This leads to a profound suppression of FSH and LH, resulting in a state of **hypogonadotropic hypogonadism**. Since estrogen and testosterone are essential for maintaining bone mineral density (BMD) by inhibiting osteoclast activity, their chronic suppression leads to accelerated bone resorption and **osteoporosis**. **Analysis of Incorrect Options:** * **A. Estrogen:** Estrogen is actually **bone-protective**. It inhibits RANK-L signaling and induces osteoclast apoptosis. It is used in HRT to prevent postmenopausal osteoporosis. * **B. Progesterone:** Progestins generally have a neutral or slightly protective effect on bone. However, high-dose Medroxyprogesterone acetate (DMPA) can cause transient bone loss, but it is not the classic "textbook" cause compared to GnRH analogues. * **D. Warfarin:** While some studies suggest Warfarin interferes with Vitamin K-dependent bone proteins (like osteocalcin), it is not a primary or high-yield cause of osteoporosis in clinical exams. **Heparin** is the anticoagulant classically associated with osteoporosis. **High-Yield Clinical Pearls for NEET-PG:** * **Other drugs causing osteoporosis:** Glucocorticoids (most common cause), Heparin (long-term), Phenytoin, Proton Pump Inhibitors (PPIs), and Aromatase Inhibitors (e.g., Anastrozole). * **Add-back therapy:** To prevent bone loss during long-term GnRH analogue use (e.g., for endometriosis or fibroids), low-dose estrogen/progestin is often co-administered. * **GnRH Pulsatility:** Remember, **pulsatile** GnRH stimulates ovulation, while **continuous** GnRH suppresses the axis.

Q: Prolactin secretion is decreased by which of the following agents?

All of the above. **Explanation:** Prolactin secretion is primarily under **tonic inhibitory control** by **Dopamine** (acting on D2 receptors) from the tuberoinfundibular pathway. Any agent that increases dopaminergic activity or interferes with stimulatory pathways (like Histamine) will decrease prolactin levels. * **L-dopa:** It is a precursor of dopamine. It crosses the blood-brain barrier and is converted into dopamine, which directly inhibits the lactotrophs in the anterior pituitary, thereby decreasing prolactin secretion. * **Bromocriptine:** It is a potent **D2-receptor agonist**. By directly stimulating dopamine receptors on pituitary lactotrophs, it mimics the natural inhibitory effect of dopamine. It is a first-line treatment for prolactinomas. * **Diphenhydramine:** While dopamine is the primary inhibitor, **Histamine (via H1 receptors)** acts as a physiological stimulator of prolactin release. Diphenhydramine, being an H1-receptor antagonist, blocks this stimulatory effect, leading to a decrease in prolactin levels. **Clinical Pearls for NEET-PG:** 1. **Dopamine Antagonists (Antipsychotics, Metoclopramide):** These are the most common causes of drug-induced **hyperprolactinemia** (leading to galactorrhea and amenorrhea). 2. **TRH Connection:** Primary hypothyroidism can cause hyperprolactinemia because elevated TRH (Thyrotropin-releasing hormone) acts as a prolactin-releasing factor. 3. **Cabergoline:** It is currently preferred over Bromocriptine for prolactinomas due to its higher affinity for D2 receptors and longer half-life (dosed twice weekly). 4. **Somatostatin:** While it primarily inhibits GH and TSH, it also has a minor inhibitory effect on prolactin.

Q: All of the following can cause hypersecretion of prolactin, except?

Cabergoline. **Explanation:** The correct answer is **Cabergoline** because it is a **Dopamine (D2) receptor agonist**. In the body, dopamine acts as the primary "Prolactin Inhibiting Factor" (PIF). By stimulating D2 receptors on the lactotrophs of the anterior pituitary, Cabergoline suppresses the synthesis and release of prolactin. Therefore, it is used to *treat* hyperprolactinemia, not cause it. **Analysis of Incorrect Options:** * **Prolactinoma (A):** This is a benign tumor of the pituitary gland (lactotroph adenoma) that autonomously secretes high levels of prolactin. It is the most common pathological cause of hyperprolactinemia. * **Haloperidol (B):** This is a typical antipsychotic that acts as a **D2 receptor antagonist**. By blocking the inhibitory effect of dopamine on the pituitary, it leads to "disinhibition" and subsequent hyperprolactinemia. * **Hypothyroidism (C):** In primary hypothyroidism, low levels of thyroid hormones lead to a compensatory increase in **Thyrotropin-Releasing Hormone (TRH)**. TRH acts as a potent prolactin-releasing factor, thereby increasing prolactin levels. **NEET-PG High-Yield Pearls:** * **Drug of Choice:** Cabergoline is the preferred drug for prolactinomas due to its higher efficacy and better side-effect profile (longer half-life) compared to Bromocriptine. * **Physiological causes:** Pregnancy, lactation, and stress are common non-pathological causes of elevated prolactin. * **Clinical Presentation:** In females, it presents as the **Amenorrhea-Galactorrhea syndrome**; in males, it causes decreased libido, erectile dysfunction, and gynecomastia. * **Stalk Effect:** Any pituitary mass that compresses the pituitary stalk prevents dopamine from reaching the gland, leading to moderately elevated prolactin levels.

Q: Which antidiabetic drug has an anorectic effect?

Liraglutide. **Explanation:** **Liraglutide** is the correct answer because it is a **GLP-1 (Glucagon-Like Peptide-1) receptor agonist**. These drugs exert an anorectic effect through two primary mechanisms: 1. **Central Action:** They act on the hypothalamus to increase satiety and decrease appetite. 2. **Peripheral Action:** They delay gastric emptying, leading to a prolonged feeling of fullness (postprandial satiety). Due to these effects, Liraglutide is specifically FDA-approved for chronic weight management in addition to Type 2 Diabetes. **Analysis of Incorrect Options:** * **Gliclazide & Chlorpropamide:** These are **Sulfonylureas**. They stimulate insulin release from the pancreas. Since insulin is an anabolic hormone, sulfonylureas are notorious for causing **weight gain**, not weight loss. * **Acarbose:** This is an **Alpha-glucosidase inhibitor**. It works locally in the gut to delay carbohydrate absorption. While it is "weight neutral," it does not possess a direct anorectic (appetite-suppressant) effect. **High-Yield Clinical Pearls for NEET-PG:** * **Weight Loss Drugs:** GLP-1 agonists (Liraglutide, Semaglutide) and SGLT-2 inhibitors (Dapagliflozin) are the preferred antidiabetics for obese patients. * **Weight Gain Drugs:** Sulfonylureas, Meglitinides, Insulin, and Thiazolidinediones (Pioglitazone). * **Black Box Warning:** Liraglutide is contraindicated in patients with a personal or family history of **Medullary Thyroid Carcinoma** or Multiple Endocrine Neoplasia type 2 (MEN 2). * **Side Effects:** The most common side effects are GI-related (nausea/vomiting) and a potential risk of pancreatitis.

Q: Which of the following decreases the effectiveness of insulin?

Thiazide. **Explanation:** **Thiazide diuretics** (e.g., Hydrochlorothiazide) are well-known to cause **hyperglycemia**, thereby antagonizing the effects of insulin. The primary mechanism involves the induction of **hypokalemia**. Low serum potassium levels inhibit the release of insulin from pancreatic beta cells (as insulin secretion is dependent on ATP-sensitive $K^+$ channels) and decrease peripheral insulin sensitivity. Consequently, patients on thiazides may require higher doses of insulin to maintain glycemic control. **Analysis of Incorrect Options:** * **Atropine:** This is a muscarinic antagonist. While the parasympathetic system plays a minor role in insulin secretion, atropine does not have a clinically significant effect on blood glucose levels or insulin effectiveness. * **Beta-blockers:** These are complex. While they can mask the tachycardic symptoms of hypoglycemia and potentially inhibit glycogenolysis, they do not directly decrease insulin's effectiveness. In fact, non-selective beta-blockers can prolong insulin-induced hypoglycemia. * **Acute alcohol ingestion:** Alcohol inhibits gluconeogenesis in the liver. When combined with insulin, it increases the risk of **severe hypoglycemia** rather than decreasing insulin's effect. **High-Yield Clinical Pearls for NEET-PG:** * **Drugs causing Hyperglycemia (Decreasing Insulin Effect):** Thiazides, Loop diuretics, Corticosteroids, Oral contraceptives, Diazoxide, and Phenytoin. * **The "Hypokalemia Connection":** Always remember that any drug causing significant potassium depletion (like Thiazides) can impair insulin secretion. * **Beta-blocker Caution:** In diabetic patients, beta-blockers are used cautiously because they mask the "warning signs" of hypoglycemia (tremors, palpitations), except for sweating (which is mediated by cholinergic sympathetic nerves).

Q: Spironolactone is most useful in which syndrome?

Conn's syndrome. **Explanation:** **Correct Option: B. Conn's syndrome** Spironolactone is a competitive antagonist of the **Mineralocorticoid Receptor (MR)**. Conn’s syndrome, or **Primary Hyperaldosteronism**, is characterized by the autonomous overproduction of aldosterone (usually due to an adrenal adenoma). This leads to the classic triad of hypertension, hypokalemia, and metabolic alkalosis. Spironolactone directly counteracts the effects of excess aldosterone at the distal renal tubules, making it the medical treatment of choice for managing symptoms and stabilizing blood pressure before surgery. **Why other options are incorrect:** * **A. Zollinger-Ellison syndrome:** This is a gastrin-secreting tumor leading to severe peptic ulcers. The treatment of choice is high-dose **Proton Pump Inhibitors (PPIs)** like Omeprazole. * **C. Cushing syndrome:** This involves excess cortisol. While spironolactone has some anti-androgenic effects, it is not the primary treatment. Drugs used here include **Ketoconazole** or **Metyrapone** (to inhibit steroid synthesis) or **Mifepristone** (glucocorticoid receptor antagonist). * **D. Acromegaly:** This is caused by excess Growth Hormone (GH). Treatment involves **Somatostatin analogs** (Octreotide), **Dopamine agonists** (Cabergoline), or **GH receptor antagonists** (Pegvisomant). **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Spironolactone also blocks androgen receptors, which can lead to **gynecomastia** and decreased libido in males (Eplerenone is a more selective MR antagonist with fewer side effects). * **Other Indications:** It is a "potassium-sparing diuretic" used in Congestive Heart Failure (to prevent cardiac remodeling), Hepatic Cirrhosis with ascites, and Polycystic Ovary Syndrome (PCOS) for hirsutism. * **Contraindication:** It should be avoided in patients with **hyperkalemia** or severe renal impairment.

Q: What is the mechanism of action of bromocriptine?

Agonism at D2 receptors. **Bromocriptine** is a semi-synthetic ergot alkaloid that acts as a potent **selective agonist at Dopamine D2 receptors** [1]. In the anterior pituitary, dopamine acts as the primary prolactin-inhibiting hormone. By stimulating D2 receptors on lactotrophs, bromocriptine inhibits the synthesis and release of prolactin. It also acts on D2 receptors in the nigrostriatal pathway, which accounts for its utility in movement disorders. **Analysis of Options:** * **Option A (Correct):** Bromocriptine mimics the action of endogenous dopamine at D2 receptors, making it the drug of choice for hyperprolactinemia. * **Option B & C:** Antagonism at D2 or D1 receptors is the mechanism of **Antipsychotics** (e.g., Haloperidol). D2 antagonism actually *causes* hyperprolactinemia as a side effect. * **Option D:** While some ergot derivatives have complex effects on alpha receptors, bromocriptine’s primary therapeutic effects in endocrine and neurological conditions are mediated via D2 agonism. **Clinical Pearls for NEET-PG:** 1. **Indications:** Hyperprolactinemia (Prolactinoma), Acromegaly (at high doses), Parkinson’s disease, and Type 2 Diabetes Mellitus (Quick-release formulation). 2. **Drug of Choice:** While bromocriptine is classic, **Cabergoline** is now preferred for prolactinomas due to its higher efficacy, longer half-life (twice-weekly dosing), and better tolerability. 3. **Side Effects:** Nausea/vomiting (due to CTZ stimulation), postural hypotension, and digital vasospasm. 4. **Contraindication:** History of psychiatric disorders (may exacerbate psychosis) and valvular heart disease (ergot-related fibrosis).

Question 1

Which drug commonly causes gynecomastia?

Accepted Answer

Spironolactone

Answer

Rifampicin

Answer

Penicillin

Answer

Bumetanide

Question 2

Which drug class is known to cause osteoporosis on long-term use?

Accepted Answer

GnRH analogues

Answer

Estrogen

Answer

Progesterone

Answer

Warfarin

Question 3

Prolactin secretion is decreased by which of the following agents?

Accepted Answer

All of the above

Answer

L-dopa

Answer

Bromocriptine

Answer

Diphenhydramine

Question 4

All of the following can cause hypersecretion of prolactin, except?

Accepted Answer

Cabergoline

Answer

Prolactinoma

Answer

Haloperidol

Answer

Hypothyroidism

Question 5

Propranolol is contraindicated in diabetes mellitus because it:

Accepted Answer

Masks the hypoglycemic symptoms

Answer

Causes hyperglycemia

Answer

Causes seizures

Answer

Causes hypotension

Question 6

Which antidiabetic drug has an anorectic effect?

Accepted Answer

Liraglutide

Answer

Gliclazide

Answer

Acarbose

Answer

Chlorpropamide

Question 7

What are the known side effects of diethylstilbesterol when used in pregnant women?

Accepted Answer

Infertility and development of vaginal carcinoma in female offspring

Answer

Deep vein thrombosis in the pregnant woman

Answer

Feminization of the external genitalia of male offspring

Answer

Virilization of the external genitalia of female offspring

Question 8

Which of the following decreases the effectiveness of insulin?

Accepted Answer

Thiazide

Answer

Atropine

Answer

Beta-blockers

Answer

Acute alcohol ingestion

Question 9

Spironolactone is most useful in which syndrome?

Accepted Answer

Conn's syndrome

Answer

Zollinger-Ellison syndrome

Answer

Cushing syndrome

Answer

Acromegaly

Question 10

What is the mechanism of action of bromocriptine?

Accepted Answer

Agonism at D2 receptors

Answer

Antagonism at D2 receptors

Answer

Antagonism at D1 receptors

Answer

Antagonism at alpha receptors

Endocrine Pharmacology — MCQs

Endocrine Pharmacology — MCQs

On this page

Practice by Chapter

Want unlimited practice?