Endocrine Pharmacology Practice Questions

Q: Which of the following drugs does not increase insulin secretion?

Rosiglitazone. ### Explanation The correct answer is **Rosiglitazone**. #### 1. Why Rosiglitazone is Correct Rosiglitazone belongs to the **Thiazolidinedione (TZD)** class. Its primary mechanism of action is as a selective agonist for the nuclear receptor **PPAR-γ** (Peroxisome Proliferator-Activated Receptor-gamma). Instead of stimulating insulin secretion from the pancreas, it acts as an **insulin sensitizer**. It increases glucose uptake in peripheral tissues (skeletal muscle and adipose tissue) and decreases hepatic glucose production. Since it does not act on beta cells to release insulin, it is not associated with hypoglycemia when used as monotherapy. #### 2. Why the Other Options are Incorrect * **Repaglinide:** A **Meglitinide** analogue. It acts as an insulin secretagogue by closing ATP-sensitive K⁺ channels in pancreatic beta cells, similar to sulfonylureas but with a faster onset and shorter duration. * **Exenatide:** A **GLP-1 Receptor Agonist** (Incretin mimetic). It stimulates glucose-dependent insulin secretion, suppresses glucagon release, and slows gastric emptying. * **Sitagliptin:** A **DPP-4 Inhibitor**. It prevents the breakdown of endogenous GLP-1 and GIP, thereby increasing insulin secretion in a glucose-dependent manner. #### 3. High-Yield Clinical Pearls for NEET-PG * **Weight Gain:** Both TZDs (Rosiglitazone) and Secretagogues (Repaglinide) cause weight gain, whereas GLP-1 agonists (Exenatide) cause weight loss. * **Side Effects of TZDs:** Fluid retention (edema), congestive heart failure exacerbation, and increased risk of bone fractures. * **Euglycemics:** Drugs like Metformin and TZDs are termed "euglycemics" because they improve glucose utilization without the risk of inducing hypoglycemia. * **Glucose-Dependency:** GLP-1 agonists and DPP-4 inhibitors only increase insulin secretion when blood glucose is high, significantly reducing the risk of hypoglycemia compared to Meglitinides.

Q: Which of the following is a testosterone receptor antagonist?

Flutamide. Explanation: Flutamide is the correct answer because it is a potent, non-steroidal competitive antagonist at the androgen receptor. By blocking the binding of dihydrotestosterone (DHT) and testosterone to their receptors in target tissues, it inhibits the growth-promoting effects of androgens. It is primarily used in the management of metastatic prostate cancer, often in combination with GnRH analogs to prevent the "testosterone flare." Analysis of Incorrect Options: * Mifepristone (RU-486): This is a progesterone and glucocorticoid receptor antagonist. It is clinically used for medical termination of pregnancy and the management of Cushing’s syndrome. * Danazol: This is a synthetic steroid with weak androgenic activity. It acts as a partial agonist at androgen receptors and suppresses the pituitary-ovarian axis by inhibiting mid-cycle LH and FSH surges. It is used in endometriosis and hereditary angioedema. * Nonoxynol-9: This is a spermicide (surfactant) used in topical contraceptives. It works by disrupting the cell membrane of spermatozoa; it has no hormonal receptor activity. High-Yield Clinical Pearls for NEET-PG: * Bicalutamide and Enzalutamide are newer, more potent androgen receptor blockers with better side-effect profiles than Flutamide. * Side Effect: A significant side effect of Flutamide is hepatotoxicity; liver enzymes must be monitored. It also causes gynecomastia due to increased peripheral conversion of accumulated testosterone to estrogen. * Finasteride vs. Flutamide: Do not confuse them. Finasteride is a 5-alpha reductase inhibitor (prevents conversion of T to DHT), whereas Flutamide blocks the receptor itself.

Q: Which of the following is a male contraceptive pill?

Gossypol. **Explanation:** **Gossypol** is the correct answer. It is a polyphenolic compound derived from the seeds of the cotton plant (*Gossypium*). It acts as a male contraceptive by inhibiting sperm production (spermatogenesis) and reducing sperm motility. While effective, its clinical use has been limited due to two major side effects: **irreversible infertility** in approximately 10–20% of users and **hypokalemia**, which can lead to transient muscle paralysis. **Analysis of Incorrect Options:** * **Quinesterol (A):** This is a long-acting synthetic estrogen. It was historically used as a "once-a-month" female oral contraceptive pill, not for males. * **Saheli (C):** This is the brand name for **Centchroman** (Ormeloxifene). It is a non-steroidal Selective Estrogen Receptor Modulator (SERM) developed by CDRI, Lucknow. It is a female contraceptive taken twice weekly for the first three months, then once weekly. * **MALA-N (D):** This is a combined oral contraceptive pill (OCP) provided free of cost by the Government of India. It contains Levonorgestrel (0.15 mg) and Ethinylestradiol (0.03 mg) and is intended for female use. **High-Yield Clinical Pearls for NEET-PG:** * **Gossypol Mechanism:** It inhibits the enzyme lactate dehydrogenase-X in the testes. * **DMPA-G (Male Injectable):** Another male contraceptive under study is RISUG (Reversible Inhibition of Sperm Under Guidance), which is a non-hormonal injectable polymer. * **Centchroman (Saheli):** High-yield because it is non-hormonal and has a unique "Once-a-Week" dosage schedule, making it a favorite for exam questions.

Q: Which is the most salt-retaining glucocorticoid?

Hydrocortisone. ### Explanation The correct answer is **Hydrocortisone**. **1. Why Hydrocortisone is correct:** Glucocorticoids are classified based on their relative anti-inflammatory (glucocorticoid) and salt-retaining (mineralocorticoid) potencies. **Hydrocortisone** (synthetic cortisol) is considered the standard reference with a ratio of **1:1**. Among the options provided, it has the highest mineralocorticoid activity. It acts on the distal renal tubules to promote sodium reabsorption and potassium excretion, making it the drug of choice for replacement therapy in adrenal insufficiency (Addison’s disease) where both mineralocorticoid and glucocorticoid replacement are needed. **2. Why the other options are incorrect:** * **Prednisolone:** This is an intermediate-acting steroid. It has enhanced anti-inflammatory potency (4x) but significantly **reduced** salt-retaining activity (0.8x) compared to hydrocortisone. * **Betamethasone and Dexamethasone:** These are long-acting, highly potent fluorinated steroids. They possess **zero** (negligible) salt-retaining activity. Their anti-inflammatory potency is 25–30 times that of hydrocortisone. They are preferred when fluid retention must be avoided (e.g., cerebral edema). **3. High-Yield Clinical Pearls for NEET-PG:** * **Potency Hierarchy (Salt Retention):** Hydrocortisone > Prednisolone > Dexamethasone/Betamethasone (Zero). * **Potency Hierarchy (Anti-inflammatory):** Dexamethasone > Prednisolone > Hydrocortisone. * **Drug of Choice for Congenital Adrenal Hyperplasia (CAH):** Hydrocortisone (to suppress ACTH while providing physiological replacement). * **Fetal Lung Maturity:** Betamethasone is preferred over dexamethasone because it has lower protein binding, allowing better placental transfer. * **Aldosterone:** The most potent endogenous mineralocorticoid (3000x salt retention compared to hydrocortisone), but it is not used clinically due to poor oral bioavailability.

Q: Which oral hypoglycemic agent is used to treat obesity?

Metformin. **Explanation:** **Metformin (Option D)** is the correct answer. It is a Biguanide and the first-line drug for Type 2 Diabetes Mellitus. Unlike many other antidiabetic agents, Metformin is **weight-neutral or leads to modest weight loss**. Its mechanism involves activating AMP-activated protein kinase (AMPK), which increases insulin sensitivity, decreases hepatic gluconeogenesis, and slows glucose absorption from the gut. It also suppresses appetite by increasing GLP-1 levels and GDF15 (Growth Differentiation Factor 15). Clinically, it is the preferred agent for obese diabetic patients and is used off-label for weight management in Polycystic Ovary Syndrome (PCOS). **Why the other options are incorrect:** * **Tolbutamide (Option A), Glipizide (Option B), and Gliclazide (Option C)** are all **Sulfonylureas**. Sulfonylureas work by stimulating insulin release from pancreatic beta cells (secretagogues). Because insulin is an anabolic hormone, these drugs characteristically cause **weight gain**, making them less ideal as a primary treatment for obese patients. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Metformin is the first-line drug for T2DM and PCOS-related infertility/obesity. * **Side Effects:** The most common side effects are GI-related (diarrhea, abdominal cramps). The most serious (though rare) side effect is **Lactic Acidosis**. * **Contraindication:** It should be avoided in patients with significant renal impairment (eGFR <30 mL/min) due to the risk of lactic acidosis. * **Vitamin Deficiency:** Long-term use of Metformin is associated with **Vitamin B12 deficiency**. * **Other Weight-Loss Antidiabetics:** While Metformin is the classic answer, newer agents like **GLP-1 agonists** (e.g., Liraglutide, Semaglutide) and **SGLT-2 inhibitors** (e.g., Dapagliflozin) also promote significant weight loss.

Q: A 30-year-old male presents with recurrent attacks of sweating and dizziness. Further workup reveals low blood glucose levels with inappropriately elevated insulin and C-peptide levels. Imaging shows a lesion in the pancreas. He is diagnosed with insulinoma and given diazoxide. What is the mechanism of action of diazoxide?

Opening of ATP-sensitive K+ channels. **Explanation:** **Correct Option: A (Opening of ATP-sensitive K+ channels)** In the normal physiology of insulin secretion, glucose enters pancreatic beta cells and increases the ATP/ADP ratio. This causes the **ATP-sensitive K+ channels ($K_{ATP}$)** to close, leading to cell depolarization, calcium influx, and insulin release. **Diazoxide** acts as a **$K_{ATP}$ channel opener**. By keeping these channels open, it allows potassium to exit the cell (hyperpolarization). This prevents the opening of voltage-gated calcium channels, thereby inhibiting the exocytosis of insulin. In patients with insulinoma, diazoxide is used to manage hypoglycemia by suppressing this excessive insulin secretion. **Incorrect Options:** * **B (Closing of ATP-sensitive K+ channels):** This is the mechanism of **Sulfonylureas** (e.g., Glibenclamide). Closing these channels triggers insulin release, which would worsen hypoglycemia in an insulinoma patient. * **C (Increase in GLUT-4 receptors):** This is the mechanism of **Thiazolidinediones** (e.g., Pioglitazone) and is also a secondary effect of exercise and insulin. It increases peripheral glucose uptake but does not address the primary pathology of hyperinsulinism. * **D (Opening of voltage-sensitive Ca+2 channels):** This occurs downstream of $K_{ATP}$ channel closure and directly triggers insulin release. Diazoxide indirectly prevents this step. **NEET-PG High-Yield Pearls:** * **Insulinoma Triad (Whipple’s Triad):** Hypoglycemic symptoms, low plasma glucose (<50 mg/dL), and relief of symptoms after glucose administration. * **C-peptide:** Elevated in insulinoma (endogenous production) but low/absent in exogenous insulin surreptitious use. * **Other uses of Diazoxide:** It was historically used as an IV vasodilator for hypertensive emergencies (though rarely used now due to side effects like sodium retention and hypertrichosis).

Q: A 46-year-old male patient has Cushing's syndrome due to an adrenal tumor. Which of the following drugs would be expected to reduce the signs and symptoms of his disease?

Ketoconazole. ### Explanation **Correct Option: D. Ketoconazole** Cushing’s syndrome is characterized by excessive cortisol production. In this case, the cause is an adrenal tumor. **Ketoconazole** is an antifungal agent that, at higher doses, acts as a potent inhibitor of steroidogenesis. It inhibits several cytochrome P450 enzymes, most notably **11β-hydroxylase** and **17α-hydroxylase (17,20-lyase)**. By blocking these enzymes, it directly reduces the synthesis of cortisol in the adrenal cortex, thereby alleviating the clinical signs and symptoms of hypercortisolism. **Why other options are incorrect:** * **A. Betamethasone:** This is a potent synthetic glucocorticoid. Administering it would worsen the symptoms of Cushing’s syndrome by increasing the total glucocorticoid burden. * **B. Cortisol:** This is the endogenous glucocorticoid already in excess. Adding exogenous cortisol would exacerbate the disease. * **C. Fludrocortisone:** This is a potent mineralocorticoid used primarily for replacement therapy in adrenal insufficiency (Addison’s disease). It does not inhibit cortisol production and may worsen hypertension or hypokalemia associated with Cushing's. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** While Ketoconazole is frequently used, **Metyrapone** (inhibits 11β-hydroxylase) is often preferred for controlling hypercortisolism in pregnant women. * **Mifepristone:** A glucocorticoid receptor antagonist used for hyperglycemia in Cushing’s patients who are not surgical candidates. * **Mitotane:** An adrenolytic agent used specifically for adrenal carcinoma. * **Side Effect Note:** Ketoconazole can cause hepatotoxicity and gynecomastia (due to inhibition of androgen synthesis), which are common "catch" points in exams.

Q: Liothyronine is the drug of choice in the treatment of:

Myxedema coma. **Explanation:** **Liothyronine (T3)** is the synthetic form of the naturally occurring thyroid hormone triiodothyronine. It is the drug of choice for **Myxedema coma** because it is 3 to 4 times more potent than Levothyroxine (T4) and has a significantly faster onset of action. In a life-threatening emergency like Myxedema coma, the immediate metabolic effect provided by T3 is crucial to reverse severe hypothermia and bradycardia. **Analysis of Options:** * **A. Myxedema coma (Correct):** T3 is preferred due to its rapid action and because the peripheral conversion of T4 to T3 is often impaired in critically ill patients. * **B. Cretinism:** Levothyroxine (T4) is the drug of choice. It provides a stable, long-term hormonal level necessary for brain development and growth, with a longer half-life (7 days) allowing for once-daily dosing. * **C. Iodine deficiency goiter:** The primary treatment is iodine supplementation (e.g., iodized salt) or Levothyroxine to suppress TSH levels. * **D. Papillary thyroid carcinoma:** The mainstay of treatment is surgical resection followed by radioactive iodine (I-131) and TSH suppression therapy using Levothyroxine (T4). **High-Yield NEET-PG Pearls:** * **Drug of Choice for Hypothyroidism:** Levothyroxine (T4) is preferred for routine replacement because it is cheaper, has a longer half-life, and is converted to T3 physiologically. * **Pharmacokinetics:** T3 has a shorter half-life (~1 day) and requires multiple daily doses, making it unsuitable for long-term maintenance. * **Monitoring:** TSH levels are used to monitor T4 therapy, but they are less reliable for T3 therapy. * **Cardiac Warning:** Use T3 with extreme caution in elderly patients or those with heart disease due to the risk of precipitating arrhythmias or angina.

Q: Denosumab, a monoclonal antibody against the RANKL receptor, is used in the treatment of which of the following conditions?

Osteoporosis. **Explanation:** **Denosumab** is a human monoclonal antibody that targets and binds to **RANKL** (Receptor Activator of Nuclear Factor kappa-B Ligand). Under normal physiological conditions, RANKL is secreted by osteoblasts and binds to RANK receptors on osteoclast precursors, leading to their maturation and activation. By inhibiting RANKL, Denosumab prevents osteoclast formation and activity, thereby decreasing bone resorption and increasing bone mineral density. * **Why Option B is correct:** Because it effectively inhibits bone resorption, Denosumab is FDA-approved for the treatment of **postmenopausal osteoporosis**, osteoporosis in men, and bone loss induced by hormone ablation therapy (e.g., in prostate or breast cancer). * **Why Options A, C, and D are incorrect:** * **Rheumatoid Arthritis (A) and SLE (D)** are systemic autoimmune inflammatory diseases. While these conditions can lead to secondary osteoporosis, Denosumab does not treat the underlying inflammatory pathology. * **Osteoarthritis (C)** is a degenerative joint disease involving cartilage breakdown, not a primary disorder of systemic bone resorption. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** It mimics the action of **Osteoprotegerin (OPG)**, the body's natural RANKL decoy receptor. * **Administration:** It is administered as a **subcutaneous injection** once every 6 months. * **Adverse Effects:** The most significant side effects include **hypocalcemia** (must check calcium levels before dosing) and, rarely, **Osteonecrosis of the Jaw (ONJ)** or atypical femur fractures. * **Other Use:** In higher doses (Xgeva), it is used for **Giant Cell Tumor of Bone** and bone metastases.

Q: All the following are pharmacologic therapies for androgen excess except?

Fludrocortisone. ### Explanation The management of androgen excess (hyperandrogenism) focuses on either suppressing the production of androgens or blocking their action at the receptor level. **Why Fludrocortisone is the Correct Answer:** **Fludrocortisone** is a potent **mineralocorticoid** analog used primarily as replacement therapy in adrenal insufficiency (Addison’s disease) or salt-wasting forms of Congenital Adrenal Hyperplasia (CAH). It has no anti-androgenic properties; in fact, its role is to maintain fluid and electrolyte balance. It does not inhibit androgen synthesis or block androgen receptors. **Analysis of Incorrect Options:** * **Glucocorticoids (e.g., Dexamethasone):** These are used in cases of androgen excess caused by CAH. By providing negative feedback to the pituitary, they decrease ACTH secretion, which in turn reduces the overproduction of adrenal androgens. * **Spironolactone:** This is a potassium-sparing diuretic that also acts as a **competitive androgen receptor antagonist** and inhibits 17α-hydroxylase. It is a mainstay treatment for hirsutism in Polycystic Ovary Syndrome (PCOS). * **Oral Contraceptive Pills (OCPs):** OCPs treat androgen excess by multiple mechanisms: they suppress LH secretion (reducing ovarian androgen production), and the estrogen component increases **Sex Hormone-Binding Globulin (SHBG)**, which lowers the levels of free, biologically active testosterone. **Clinical Pearls for NEET-PG:** * **Finasteride:** A 5α-reductase inhibitor often used for hirsutism; it prevents the conversion of Testosterone to the more potent Dihydrotestosterone (DHT). * **Cyproterone Acetate:** A progestin with significant anti-androgenic activity, often found in specific OCP formulations (e.g., Diane-35) used for acne and hirsutism. * **Flutamide:** A pure non-steroidal anti-androgen; however, its use is limited by potential hepatotoxicity.

Question 1

Which of the following drugs does not increase insulin secretion?

Accepted Answer

Rosiglitazone

Answer

Repaglinide

Answer

Exenatide

Answer

Sitagliptin

Question 2

Which of the following is a testosterone receptor antagonist?

Accepted Answer

Flutamide

Answer

Mifepristone

Answer

Danazol

Answer

Nonoxynol

Question 3

Which of the following is a male contraceptive pill?

Accepted Answer

Gossypol

Answer

Quinesterol

Answer

Saheli

Answer

MALA-N

Question 4

Which is the most salt-retaining glucocorticoid?

Accepted Answer

Hydrocortisone

Answer

Prednisolone

Answer

Betamethasone

Answer

Dexamethasone

Question 5

Which oral hypoglycemic agent is used to treat obesity?

Accepted Answer

Metformin

Answer

Tolbutamide

Answer

Glipizide

Answer

Gliclazide

Question 6

A 30-year-old male presents with recurrent attacks of sweating and dizziness. Further workup reveals low blood glucose levels with inappropriately elevated insulin and C-peptide levels. Imaging shows a lesion in the pancreas. He is diagnosed with insulinoma and given diazoxide. What is the mechanism of action of diazoxide?

Accepted Answer

Opening of ATP-sensitive K+ channels

Answer

Closing of ATP-sensitive K+ channels

Answer

Increase in the number of GLUT-4 receptors

Answer

Opening of voltage-sensitive Ca+2 channels

Question 7

A 46-year-old male patient has Cushing's syndrome due to an adrenal tumor. Which of the following drugs would be expected to reduce the signs and symptoms of his disease?

Accepted Answer

Ketoconazole

Answer

Betamethasone

Answer

Cortisol

Answer

Fludrocortisone

Question 8

Liothyronine is the drug of choice in the treatment of:

Accepted Answer

Myxedema coma

Answer

Cretinism

Answer

Iodine deficiency goiter

Answer

Non-resectable causes of papillary thyroid carcinoma

Question 9

Denosumab, a monoclonal antibody against the RANKL receptor, is used in the treatment of which of the following conditions?

Accepted Answer

Osteoporosis

Answer

Rheumatoid arthritis

Answer

Osteoarthritis

Answer

Systemic lupus erythematosus (SLE)

Question 10

All the following are pharmacologic therapies for androgen excess except?

Accepted Answer

Fludrocortisone

Answer

Glucocorticoids

Answer

Spironolactone

Answer

Oral contraceptives

Endocrine Pharmacology — MCQs

Endocrine Pharmacology — MCQs

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