Endocrine Pharmacology — MCQs

Endocrine Pharmacology Indian Medical PG Practice Questions and MCQs

Question 301: 100 mg of hydrocortisone is equivalent to how much methylprednisolone?

A. 20 mg methylprednisolone (Correct Answer)
B. 20 mg cortisone acetate
C. 10 mg dexamethasone
D. 10 mg prednisone

Explanation: ### Explanation The core concept tested here is **Glucocorticoid Equipotency**. Hydrocortisone (cortisol) is used as the standard reference with a potency of 1. To determine the equivalent dose of other steroids, we use their relative anti-inflammatory potencies. **Why Option A is Correct:** Methylprednisolone is approximately **5 times more potent** than hydrocortisone. * **Calculation:** 100 mg (Hydrocortisone) ÷ 5 = **20 mg (Methylprednisolone)**. * Prednisone and Prednisolone also share a similar potency ratio (4:1 or 5:1), making 20–25 mg of these drugs equivalent to 100 mg of hydrocortisone. **Why the Other Options are Incorrect:** * **B. 20 mg Cortisone acetate:** Cortisone is *less* potent than hydrocortisone (0.8:1). 100 mg of hydrocortisone is equivalent to **125 mg** of cortisone acetate. * **C. 10 mg Dexamethasone:** Dexamethasone is a long-acting, highly potent steroid (25–30 times more potent than hydrocortisone). 100 mg of hydrocortisone is equivalent to only **~3.3 to 4 mg** of dexamethasone. * **D. 10 mg Prednisone:** As noted above, prednisone is 4 times more potent than hydrocortisone. Therefore, 100 mg of hydrocortisone equals **25 mg** of prednisone. --- ### High-Yield NEET-PG Clinical Pearls 1. **Potency Mnemonic:** Remember the relative potencies (Short to Long acting): * **Hydrocortisone:** 1 (Short-acting, 8–12h) * **Prednisolone/Methylprednisolone:** 4–5 (Intermediate-acting, 12–36h) * **Dexamethasone/Betamethasone:** 25–30 (Long-acting, 36–72h) 2. **Mineralocorticoid Activity:** Hydrocortisone has significant salt-retaining (mineralocorticoid) activity (1:1 ratio). Dexamethasone and Betamethasone have **zero** mineralocorticoid activity, making them safer for patients with hypertension or heart failure. 3. **Pregnancy:** If the fetus needs steroids (e.g., for lung maturity), use **Betamethasone** or **Dexamethasone** (they cross the placenta). If the mother needs steroids but the fetus must be protected, use **Prednisolone** (inactivated by placental 11β-HSD2).

Question 302: Which of the following is not an anti-androgenic drug?

A. Flutamide
B. Spironolactone (Correct Answer)
C. Finasteride
D. Cyproterone acetate

Explanation: **Explanation:** The question asks to identify the drug that is **not** primarily classified as an anti-androgen. While **Spironolactone** has significant anti-androgenic side effects (often used off-label for hirsutism and acne), its primary pharmacological classification is a **Mineralocorticoid Receptor Antagonist (Potassium-sparing diuretic)**. In the context of competitive exams, it is categorized by its primary action on the renal tubules rather than as a dedicated anti-androgenic agent. **Analysis of Options:** * **A. Flutamide:** A pure, non-steroidal **Androgen Receptor Antagonist**. It competes with testosterone and DHT for the receptor. It is primarily used in the management of prostate cancer. * **C. Finasteride:** A **5-alpha reductase inhibitor**. It prevents the conversion of Testosterone to the more potent Dihydrotestosterone (DHT). It is a standard treatment for Benign Prostatic Hyperplasia (BPH) and male pattern baldness. * **D. Cyproterone Acetate:** A steroidal **Androgen Receptor Antagonist** with progestogenic activity. It also inhibits gonadotropin secretion, making it a potent anti-androgen used in precocious puberty and severe hirsutism. **High-Yield Clinical Pearls for NEET-PG:** * **Spironolactone Mechanism:** It inhibits the binding of dihydrotestosterone (DHT) to cytosolic receptors and inhibits 17α-hydroxylase, leading to decreased testosterone synthesis. * **Side Effect:** Gynecomastia in males is a classic side effect of Spironolactone due to its anti-androgenic properties. * **Bicalutamide:** A newer androgen receptor antagonist preferred over Flutamide for prostate cancer due to lower hepatotoxicity. * **Dutasteride:** Unlike Finasteride (Type II selective), Dutasteride inhibits both Type I and Type II 5-alpha reductase isoenzymes.

Question 303: All of the following decrease bone resorption in osteoporosis except?

A. Alendronate
B. Etidronate
C. Strontium
D. Teriparatide (Correct Answer)

Explanation: ### Explanation The management of osteoporosis involves two main classes of drugs: **Antiresorptive agents** (which inhibit osteoclast activity) and **Anabolic agents** (which stimulate osteoblast activity to form new bone). **Why Teriparatide is the correct answer:** Teriparatide is a recombinant form of human **Parathyroid Hormone (PTH)**. While continuous high levels of PTH (as seen in hyperparathyroidism) cause bone resorption, **intermittent (once-daily) administration** of Teriparatide stimulates osteoblastic activity more than osteoclastic activity. Therefore, it is classified as an **Anabolic agent** (bone-forming) rather than an antiresorptive agent. **Analysis of incorrect options:** * **Alendronate & Etidronate (Options A & B):** These are **Bisphosphonates**. They work by concentrating at sites of active bone remodeling and inhibiting osteoclast-mediated bone resorption. Alendronate is a potent nitrogen-containing bisphosphonate, while Etidronate is a first-generation non-nitrogenous bisphosphonate. * **Strontium Ranelate (Option C):** This drug has a **dual mechanism of action**. It both inhibits bone resorption (by inhibiting osteoclast differentiation) and stimulates bone formation (by promoting osteoblast proliferation). Since it does decrease resorption, it does not fit the "except" criteria. **High-Yield Clinical Pearls for NEET-PG:** * **Teriparatide Side Effects:** Hypercalcemia, hyperuricemia, and a theoretical risk of **Osteosarcoma** (avoid in patients with Paget’s disease or prior radiation). * **Bisphosphonates:** Must be taken on an empty stomach with a full glass of water, and the patient must remain upright for 30 minutes to prevent **erosive esophagitis**. * **Denosumab:** A monoclonal antibody against **RANKL**; it is a potent antiresorptive agent. * **Raloxifene:** A SERM that acts as an estrogen agonist in bone (antiresorptive) but an antagonist in the breast and uterus.

Question 304: Glipizide, an oral hypoglycaemic drug, acts by which mechanism?

A. Improving insulin resistance
B. Inhibiting brush border enzymes
C. Stimulating insulin secretion (Correct Answer)
D. Increasing glucose uptake by fat cells

Explanation: **Explanation:** **Mechanism of Action (Correct Answer):** Glipizide is a **second-generation Sulfonylurea**. These drugs act as **insulin secretagogues** by stimulating the release of insulin from pancreatic beta cells. The specific molecular mechanism involves: 1. Binding to the **Sulfonylurea Receptor 1 (SUR1)** on the ATP-sensitive potassium ($K_{ATP}$) channels. 2. Closing these channels, leading to cell depolarization. 3. Opening of voltage-gated calcium channels, causing an influx of $Ca^{2+}$. 4. Triggering the exocytosis of insulin granules. **Analysis of Incorrect Options:** * **Option A (Improving insulin resistance):** This is the mechanism of **Biguanides (Metformin)** and **Thiazolidinediones (Pioglitazone)**, which act as insulin sensitizers. * **Option B (Inhibiting brush border enzymes):** This describes **Alpha-glucosidase inhibitors (Acarbose, Voglibose)**, which delay carbohydrate absorption in the gut. * **Option D (Increasing glucose uptake by fat cells):** While a secondary effect of insulin itself, this is the primary mechanism of **Thiazolidinediones (TZDs)** via PPAR-gamma activation, which increases GLUT-4 translocation. **High-Yield Clinical Pearls for NEET-PG:** * **Side Effects:** The most common side effect of Glipizide is **hypoglycemia** and **weight gain**. * **Pharmacokinetics:** Glipizide is preferred in patients with mild renal impairment because it is primarily metabolized by the liver and has a shorter half-life, reducing the risk of prolonged hypoglycemia compared to Glibenclamide. * **Failure of Therapy:** Sulfonylureas require functional beta cells; therefore, they are ineffective in Type 1 Diabetes Mellitus. * **Disulfiram-like reaction:** This is more commonly associated with first-generation sulfonylureas (Chlorpropamide) than second-generation agents like Glipizide.

Question 305: Which of the following is NOT a sulfonylurea compound?

A. Tolbutamide
B. Chlorpropamide
C. Metformin (Correct Answer)
D. Glibenclamide

Explanation: **Explanation:** The correct answer is **C. Metformin**. **1. Why Metformin is the correct answer:** Metformin belongs to the **Biguanide** class [3] of oral hypoglycemic agents, not the Sulfonylureas. Chemically, it consists of two linked guanidine rings. Its primary mechanism of action is the activation of **AMP-activated protein kinase (AMPK)**, which leads to decreased hepatic gluconeogenesis and improved peripheral insulin sensitivity. Unlike sulfonylureas, metformin does not stimulate insulin secretion and is therefore considered an "euglycemic" agent with a low risk of hypoglycemia. **2. Why the other options are incorrect:** * **A. Tolbutamide:** This is a **First-generation Sulfonylurea** [1]. It is short-acting and primarily metabolized in the liver [2]. * **B. Chlorpropamide:** This is also a **First-generation Sulfonylurea**. It is long-acting and notorious for causing a disulfiram-like reaction with alcohol and SIADH (dilutional hyponatremia). * **C. Glibenclamide (Glyburide):** This is a **Second-generation Sulfonylurea**. It is much more potent than first-generation drugs [2] and works by closing ATP-sensitive K+ channels in pancreatic beta cells, triggering insulin release [1]. **3. High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Metformin is the first-line drug for Type 2 Diabetes Mellitus, especially in obese patients. * **Side Effects:** The most common side effects of Metformin are GI upset (diarrhea, abdominal cramps). The most serious, though rare, is **Lactic Acidosis**. * **Contraindication:** Metformin should be avoided in patients with significant renal impairment (eGFR <30 mL/min) due to the risk of lactic acid accumulation. * **Sulfonylurea Receptor:** Sulfonylureas bind to the **SUR1** subunit of the K+ATP channel [1].

Question 306: Newer progestational contraceptives primarily act by:

A. Altering oviductal motility
B. Modifying the uterine endometrium
C. Changing cervical mucus properties
D. Inhibiting ovulation (Correct Answer)

Explanation: **Explanation:** The primary mechanism of action for hormonal contraceptives depends on the dose and type of progestin used. **Why Option D is Correct:** While older, low-dose "mini-pills" (Progestin-Only Pills or POPs) primarily worked by altering cervical mucus, **newer progestational contraceptives** (such as Desogestrel, Drospirenone, and long-acting injectables/implants like DMPA) contain more potent progestins or higher systemic doses. These newer agents consistently achieve blood levels high enough to suppress the hypothalamic-pituitary-ovarian axis. They inhibit the mid-cycle **LH surge**, thereby **inhibiting ovulation**, which is the most reliable method of preventing pregnancy. **Why Other Options are Incorrect:** * **Options A, B, and C:** These represent "peripheral" mechanisms. While progestins do make the cervical mucus thick and hostile to sperm (Option C), render the endometrium out of sync for implantation (Option B), and alter tubal motility (Option A), these are considered **secondary or backup mechanisms** for newer-generation progestins. In older POPs (e.g., Norethindrone), Option C was the primary mechanism because they did not consistently suppress ovulation. **NEET-PG High-Yield Pearls:** * **Combined Oral Contraceptive Pills (COCPs):** Always act primarily by inhibiting ovulation (Estrogen inhibits FSH; Progestin inhibits LH). * **DMPA (Depot Medroxyprogesterone Acetate):** A highly effective injectable that acts primarily by suppressing ovulation for 3 months. * **Centchroman (Saheli):** A non-steroidal SERM (Selective Estrogen Receptor Modulator) that acts by preventing implantation (making the uterus "unfriendly"). * **Emergency Contraceptive (Levonorgestrel 1.5mg):** Primarily acts by delaying or inhibiting ovulation if taken before the LH surge.

Question 307: Which of the following is an antiandrogenic drug?

A. Fluconazole
B. Itraconazole
C. Ketoconazole (Correct Answer)
D. Terbinafine

Explanation: **Explanation:** **Ketoconazole** is the correct answer because it is a potent inhibitor of steroidogenesis. While primarily used as an antifungal, it inhibits the enzyme **17,20-desmolase** (and to a lesser extent, CYP11A1/side-chain cleavage enzyme), which is essential for the conversion of cholesterol into adrenal and gonadal androgens. By blocking this pathway, it significantly reduces testosterone levels. Clinically, this "side effect" is utilized in the management of advanced prostate cancer and Cushing’s syndrome. **Analysis of Incorrect Options:** * **Fluconazole & Itraconazole (Options A & B):** These are triazole antifungals. Unlike the imidazole ketoconazole, triazoles are highly selective for fungal CYP450 (lanosterol 14α-demethylase) and have negligible effects on human steroid hormone synthesis. Therefore, they do not possess antiandrogenic properties. * **Terbinafine (Option D):** This is an allylamine that inhibits **squalene epoxidase**. Its mechanism is entirely different from the azoles and does not involve the cytochrome P450 system or steroid hormone pathways. **High-Yield Clinical Pearls for NEET-PG:** * **Adverse Effect:** Due to its antiandrogenic activity, ketoconazole frequently causes **gynecomastia**, loss of libido, and erectile dysfunction in males. * **Drug Interactions:** Ketoconazole is a potent **CYP3A4 inhibitor**, leading to numerous drug-drug interactions (e.g., increasing levels of statins or warfarin). * **Hepatotoxicity:** It carries a black box warning for severe liver injury; hence, it is rarely used as a first-line antifungal today. * **Other Antiandrogens to Remember:** Finasteride (5α-reductase inhibitor), Flutamide (Androgen receptor antagonist), and Spironolactone (Aldosterone antagonist with antiandrogenic effects).

Question 308: Octreotide is used in all except which of the following conditions?

A. Glucagonoma
B. Insulinoma
C. Carcinoid syndrome
D. Glioma (Correct Answer)

Explanation: **Explanation:** **Octreotide** is a potent, long-acting synthetic analog of **Somatostatin**. It acts as a universal inhibitor of secretory hormones by binding to somatostatin receptors (SSTR-2 and SSTR-5). **Why Glioma is the correct answer:** Gliomas are primary tumors of the glial cells in the brain. Unlike neuroendocrine tumors, gliomas do not typically express the specific somatostatin receptors targeted by octreotide, nor is their growth primarily driven by hormones that octreotide inhibits. Therefore, octreotide has no established therapeutic role in the management of **Glioma**. **Analysis of incorrect options:** * **Glucagonoma:** This is an alpha-cell tumor of the pancreas. Octreotide effectively inhibits the release of glucagon, helping to resolve the characteristic skin rash (necrolytic migratory erythema). * **Insulinoma:** Octreotide can be used to inhibit insulin secretion in these beta-cell tumors, although its efficacy varies depending on the receptor subtype expression of the specific tumor. * **Carcinoid Syndrome:** Octreotide is the **gold standard** treatment for managing the secretory diarrhea and flushing associated with carcinoid tumors by inhibiting the release of serotonin and other peptides. **Clinical Pearls for NEET-PG:** * **Other Uses:** Acromegaly (inhibits GH), secretory diarrhea in VIPoma, and acute management of bleeding esophageal varices (causes splanchnic vasoconstriction). * **Side Effects:** The most high-yield side effect is the formation of **gallstones (cholelithiasis)** due to the inhibition of cholecystokinin (CCK) and subsequent gallbladder stasis. * **Mechanism:** It is significantly more potent and has a longer half-life (approx. 1.5 hours) compared to natural somatostatin (approx. 2 minutes).

Question 309: Which of the following synthetic steroids shows predominantly mineralocorticoid action?

A. Hydrocortisone
B. Spironolactone
C. Dexamethasone
D. Fludrocortisone (Correct Answer)

Explanation: The correct answer is **Fludrocortisone**. **1. Why Fludrocortisone is correct:** Fludrocortisone is a potent synthetic corticosteroid. While it possesses both glucocorticoid and mineralocorticoid activities, its **mineralocorticoid potency is significantly higher** (approximately 250 times that of hydrocortisone). In clinical practice, it is used almost exclusively for its mineralocorticoid effects—promoting sodium retention and potassium excretion—making it the drug of choice for replacement therapy in primary adrenal insufficiency (Addison’s disease). **2. Why the other options are incorrect:** * **Hydrocortisone:** This is the synthetic form of cortisol. It has a 1:1 ratio of glucocorticoid to mineralocorticoid activity. While it has mineralocorticoid action, it is not "predominantly" mineralocorticoid compared to fludrocortisone. [1] * **Spironolactone:** This is a **mineralocorticoid receptor antagonist** (potassium-sparing diuretic). It blocks the action of aldosterone rather than mimicking it. * **Dexamethasone:** This is a highly potent **pure glucocorticoid**. It has maximal anti-inflammatory activity with virtually zero mineralocorticoid (salt-retaining) properties. [1, 2] **3. High-Yield NEET-PG Pearls:** * **Relative Potency Table:** * *Dexamethasone/Betamethasone:* Highest Glucocorticoid potency; Zero Mineralocorticoid potency. [1, 2] * *Fludrocortisone:* Highest Mineralocorticoid potency. * *Aldosterone:* Natural mineralocorticoid (not used clinically due to high first-pass metabolism). [1] * **Clinical Use:** Fludrocortisone is used in **Addison’s disease** and **Congenital Adrenal Hyperplasia (CAH)** to prevent salt wasting. * **Side Effects:** Excessive doses lead to hypertension, edema, and hypokalemia.

Question 310: Which sulfonylurea drug has the highest insulinotropic potency?

A. Glyburide (Correct Answer)
B. Glipizide
C. Glimepiride
D. Gliclazide

Explanation: **Explanation:** **1. Why Glyburide is correct:** Sulfonylureas act by binding to the **SUR1 subunit** of the ATP-sensitive potassium ($K_{ATP}$) channel on pancreatic beta cells, leading to channel closure, depolarization, and insulin release. **Glyburide (Glibenclamide)** is considered the most potent sulfonylurea on a milligram-per-milligram basis. It has an exceptionally high binding affinity for the SUR1 receptor and a prolonged duration of action. Because of this high insulinotropic potency and long half-life, it carries the **highest risk of severe, prolonged hypoglycemia** among all oral hypoglycemic agents. **2. Analysis of Incorrect Options:** * **Glipizide:** While potent, it has a shorter half-life and lower binding affinity compared to Glyburide. It is preferred in patients with mild renal impairment due to its shorter duration of action. * **Glimepiride:** Often referred to as a "third-generation" sulfonylurea, it is very potent but technically has a lower absolute insulinotropic potency than Glyburide. It is noted for having some extra-pancreatic effects (improving insulin sensitivity). * **Gliclazide:** This drug is known for its antioxidant properties and lower risk of hypoglycemia compared to Glyburide, indicating a lower relative potency in stimulating insulin secretion. **3. NEET-PG High-Yield Pearls:** * **Drug of Choice:** Sulfonylureas are generally avoided in the elderly; however, if used, **Glipizide** is preferred over Glyburide due to a lower risk of hypoglycemia. * **Excretion:** Glyburide has active metabolites excreted by the kidneys; therefore, it is strictly **contraindicated in renal failure**. * **Disulfiram-like reaction:** Most commonly associated with first-generation sulfonylureas (Chlorpropamide), but can rarely occur with others. * **Weight Gain:** A common side effect of all sulfonylureas due to increased insulin levels.

Practice by Chapter

Hypothalamic and Pituitary Hormones

Practice Questions

Thyroid Drugs and Antithyroid Agents

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Insulin and Oral Hypoglycemic Agents

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Adrenocorticosteroids

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Sex Hormones: Estrogens and Progestins

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Androgens and Anabolic Steroids

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Hormonal Contraceptives

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Drugs Affecting Calcium Metabolism

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Drugs for Osteoporosis

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Pharmacological Management of Obesity

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