Endocrine Pharmacology Practice Questions

Q: Continuous GnRH administration is useful in all the following conditions EXCEPT:

Male infertility. To answer this question, one must understand the "GnRH Paradox": the physiological effect of GnRH depends entirely on its mode of administration [1, 2]. ### 1. Why "Male Infertility" is the Correct Answer In male infertility (specifically hypogonadotropic hypogonadism), the goal is to stimulate the pituitary to release LH and FSH to induce spermatogenesis. This requires **pulsatile administration** of GnRH (mimicking physiological secretion) [1, 2]. **Continuous administration** of GnRH (or long-acting GnRH analogs like Leuprolide) causes **down-regulation and desensitization** of GnRH receptors on pituitary gonadotropes [1, 2]. This leads to a state of "medical castration" (suppression of LH/FSH and testosterone), which would worsen infertility. ### 2. Why the Other Options are Incorrect Continuous GnRH administration is used to suppress the Pituitary-Gonadal axis in hormone-dependent conditions: * **Precocious Puberty:** Suppression of premature LH/FSH release prevents early bone maturation and development of secondary sexual characteristics [2]. * **Prostate Cancer:** By suppressing LH, testosterone levels drop to castrate levels, inhibiting the growth of testosterone-dependent prostatic tumors [1]. * **Endometriosis:** Suppression of the axis leads to a hypoestrogenic state, which causes atrophy of ectopic endometrial tissue and provides symptomatic relief [1, 2]. ### 3. High-Yield Clinical Pearls for NEET-PG * **Pulsatile GnRH:** Used for **Infertility** (Male/Female) and Delayed Puberty [1, 2]. * **Continuous GnRH:** Used for **Prostate Cancer, Endometriosis, Precocious Puberty, and Uterine Fibroids [1, 2].** * **Flare Phenomenon:** Initial continuous administration causes a transient rise in LH/T before suppression occurs [1, 2]. To prevent this in prostate cancer, **Flutamide** (an androgen antagonist) is co-administered. * **Drugs:** Leuprolide, Goserelin, Nafarelin, and Buserelin are common GnRH analogs [1, 2].

Q: Which of the following is NOT a pharmacological property of Repaglinide?

Reduces insulin resistance. **Explanation:** **Repaglinide** belongs to the **Meglitinide (Glinide)** class of oral hypoglycemic agents. The correct answer is **B** because Repaglinide does not reduce insulin resistance; its primary action is to stimulate insulin secretion. 1. **Why Option B is correct:** Reducing insulin resistance is a characteristic of **Insulin Sensitizers** like Biguanides (Metformin) and Thiazolidinediones (Pioglitazone). Repaglinide has no direct effect on insulin receptors or glucose transporters in peripheral tissues. 2. **Why Option A is incorrect:** Repaglinide is an **Insulin Secretagogue**. Like sulfonylureas, it closes ATP-sensitive $K^+$ channels in pancreatic $\beta$-cells, leading to depolarization, $Ca^{2+}$ influx, and subsequent insulin release. 3. **Why Option C is incorrect:** Repaglinide has a very short half-life and a rapid onset/offset of action. Because its effect is transient and glucose-dependent, it causes **less incidence of late-fasting hypoglycemia** compared to long-acting sulfonylureas (e.g., Glibenclamide). 4. **Why Option D is incorrect:** Due to its rapid onset, it is specifically used as a **"Prandial Glucose Regulator."** It is taken just before meals to effectively control postprandial glycemic spikes. **High-Yield NEET-PG Pearls:** * **Mechanism:** Binds to a distinct site on the SUR1 receptor (different from the sulfonylurea binding site). * **Safe in Renal Impairment:** Repaglinide is primarily excreted via bile/feces, making it a preferred secretagogue in patients with **chronic kidney disease (CKD)**. * **Skip a Meal, Skip a Dose:** Patients are advised to omit the dose if they skip a meal to avoid hypoglycemia.

Q: Which of the following drugs used in osteoporosis acts by decreasing the resorption of bone as well as inducing new bone formation?

Strontium ranelate. **Explanation** The correct answer is **Strontium ranelate**. This drug is unique in its pharmacological profile because it possesses a **dual mechanism of action**, often referred to as a "dual-acting bone agent" (DABA). 1. **Mechanism of Correct Option:** Strontium ranelate acts by: * **Increasing bone formation:** It stimulates the proliferation of osteoblast precursors and increases collagen synthesis. * **Decreasing bone resorption:** It inhibits osteoclast differentiation and activity (by increasing Osteoprotegerin and decreasing RANKL expression). This "uncoupling" of bone remodeling—where formation is promoted while resorption is suppressed—distinguishes it from other agents. 2. **Analysis of Incorrect Options:** * **Teriparatide (A):** A recombinant PTH analog. It is primarily an **anabolic agent** (induces new bone formation) but does not decrease resorption; in fact, long-term use can slightly increase resorption markers. * **Ibandronate (B):** A Bisphosphonate. These are purely **antiresorptive agents**. they inhibit osteoclast-mediated bone resorption but do not induce new bone formation. * **Calcitonin (D):** A hormone that directly inhibits osteoclasts. It is a weak **antiresorptive agent** and has no anabolic (bone-forming) properties. **NEET-PG High-Yield Pearls:** * **Strontium ranelate Side Effects:** It is associated with an increased risk of **cardiovascular events** (MI) and **Venous Thromboembolism (VTE)**. It is now generally reserved for patients with severe osteoporosis who cannot use other treatments. * **DRESS Syndrome:** Strontium ranelate is a known cause of Drug Reaction with Eosinophilia and Systemic Symptoms. * **Teriparatide Limit:** Due to the theoretical risk of **Osteosarcoma**, its use is typically limited to a maximum of 24 months.

Q: Which of the following statements about romosozumab is FALSE?

Romosozumab is a monoclonal antibody against sclerostin.. **Explanation:** Romosozumab is a novel agent used in the management of severe osteoporosis. The correct answer is **A** because it accurately describes the drug's mechanism of action: it is a humanized monoclonal antibody that binds to and inhibits **sclerostin**. Sclerostin is a protein produced by osteocytes that normally inhibits bone formation (by antagonizing the Wnt signaling pathway) and increases bone resorption. By blocking sclerostin, Romosozumab exerts a unique **"dual effect"**: 1. **Anabolic effect:** It stimulates osteoblast activity, leading to new bone formation (Option C is true). 2. **Antiresorptive effect:** It decreases osteoclast activity and differentiation (Option B is true). **Analysis of Options:** * **Option A (Correct):** This is the defining characteristic of the drug. * **Option B & C (Incorrect as False statements):** These are true statements regarding its dual mechanism. Unlike traditional agents which are either purely antiresorptive (Bisphosphonates) or purely anabolic (Teriparatide), Romosozumab does both. * **Option D (Incorrect as False statement):** It is indeed FDA-approved for the treatment of **postmenopausal osteoporosis** in women at high risk of fracture. **High-Yield Clinical Pearls for NEET-PG:** * **Black Box Warning:** Romosozumab carries a warning for increased risk of **myocardial infarction, stroke, and cardiovascular death**. It should not be initiated in patients who have had an MI or stroke within the preceding year. * **Administration:** It is administered as a subcutaneous injection once a month for a limited duration of **12 months** (due to waning anabolic effects over time). * **Sequence:** After 12 months of Romosozumab, therapy should transition to an antiresorptive agent (like Alendronate) to maintain the bone density gains.

Q: All of the following statements regarding Octreotide are true, EXCEPT:

An absorbent. **Explanation:** **Octreotide** is a synthetic long-acting octapeptide analogue of **Somatostatin** (Growth Hormone Inhibiting Hormone). It mimics the natural hormone but has a much longer half-life (approx. 1.5 hours vs. 2 minutes). **Why Option D is the Correct Answer (The False Statement):** Octreotide is **not an absorbent**. Absorbents (like Kaolin or Pectin) work locally in the gut lumen to bind toxins or water. Octreotide is a systemic pharmacological agent administered parenterally (SC/IV) that acts via specific somatostatin receptors (SSTR-2, 3, and 5) to inhibit the secretion of various hormones and intestinal fluids. **Analysis of Other Options:** * **Option A (True):** It is the most commonly used somatostatin analogue. It is preferred over natural somatostatin because it is more potent and has a longer duration of action. * **Option B (True):** It is highly effective in treating refractory **secretory diarrhea** associated with AIDS and chemotherapy because it decreases intestinal secretion and slows GI motility. * **Option C (True):** It is the drug of choice for symptomatic relief in **Carcinoid syndrome** (flushing and diarrhea) by inhibiting the release of serotonin and other peptides from the tumor. **NEET-PG High-Yield Pearls:** * **Clinical Uses:** Acromegaly (inhibits GH), Esophageal varices (causes splanchnic vasoconstriction), and VIPomas. * **Adverse Effects:** Most common side effect is **steatorrhea** (due to inhibition of pancreatic enzymes). Long-term use carries a high risk of **cholelithiasis** (gallstones) due to inhibition of gallbladder contractility and bile secretion. * **Diagnostic Use:** Radiolabeled octreotide (OctreoScan) is used for localizing neuroendocrine tumors.

Q: Conversion of T4 to T3 inhibition is associated with which of the following drugs?

Propylthiouracil. ### Explanation **Correct Option: A (Propylthiouracil)** The synthesis of thyroid hormones involves multiple steps. While both **Propylthiouracil (PTU)** and Carbimazole/Methimazole inhibit the enzyme **thyroid peroxidase**, preventing the iodination of tyrosine residues and the coupling of iodotyrosines, PTU has a unique additional mechanism. It inhibits the enzyme **5’-deiodinase** (Type 1) in peripheral tissues. This enzyme is responsible for converting the less active prohormone **T4 (Thyroxine)** into the more potent **T3 (Triiodothyronine)**. This dual action makes PTU particularly useful in managing severe thyrotoxicosis. **Analysis of Incorrect Options:** * **B. Ampicillin:** An antibiotic that inhibits cell wall synthesis; it has no known effect on thyroid hormone metabolism. * **C. Lithium:** Used in bipolar disorder, Lithium inhibits the **release** of preformed thyroid hormones from the colloid by interfering with thyroglobulin proteolysis. It does not inhibit peripheral conversion. * **D. Carbimazole:** A prodrug converted to Methimazole. While it is more potent than PTU in inhibiting thyroid peroxidase, it **does not** inhibit the peripheral conversion of T4 to T3. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice in Thyroid Storm:** PTU is preferred over Methimazole because it rapidly lowers T3 levels by blocking peripheral conversion. * **Pregnancy:** PTU is the drug of choice in the **1st trimester** (due to lower teratogenic risk/aplasia cutis associated with Methimazole). Methimazole is preferred in the 2nd and 3rd trimesters to avoid PTU-induced hepatotoxicity. * **Other drugs inhibiting T4 to T3 conversion:** Propranolol (high doses), Glucocorticoids (e.g., Dexamethasone), Amiodarone, and Oral Cholecystographic agents (Ipodate).

Q: Which of the following has the least mineralocorticoid activity?

Dexamethasone. **Explanation:** The correct answer is **Dexamethasone**. In pharmacology, corticosteroids are classified based on their relative **glucocorticoid** (anti-inflammatory/metabolic) and **mineralocorticoid** (salt-retaining) potencies. **Dexamethasone** is a long-acting, highly potent synthetic glucocorticoid. It is specifically designed to have maximal anti-inflammatory effects with **zero to negligible mineralocorticoid activity**. This makes it the drug of choice in conditions where fluid retention must be avoided, such as cerebral edema. **Analysis of Incorrect Options:** * **Aldosterone (A):** The primary endogenous mineralocorticoid. It has maximal salt-retaining activity and negligible glucocorticoid effects. * **Cortisol (B):** The primary endogenous glucocorticoid. While it acts on glucocorticoid receptors, it also has significant mineralocorticoid activity (Ratio 1:1). In high concentrations, it can cause significant sodium retention and potassium loss. * **Fludrocortisone (D):** A synthetic steroid with very high mineralocorticoid potency. It is the drug of choice for replacement therapy in Addison’s disease to provide the necessary salt-retaining effect. **NEET-PG High-Yield Pearls:** 1. **Potency Comparison:** Dexamethasone is ~25–30 times more potent than Hydrocortisone (Cortisol) as an anti-inflammatory agent but has **0** mineralocorticoid potency. 2. **Drug of Choice:** For **Congenital Adrenal Hyperplasia (CAH)** in utero, Dexamethasone is used because it is not inactivated by placental 11β-HSD2, allowing it to reach the fetus. 3. **Topical/Inhaled:** Beclomethasone and Budesonide also have negligible systemic mineralocorticoid effects due to high first-pass metabolism or local action. 4. **Shortest Acting:** Hydrocortisone; **Longest Acting:** Dexamethasone/Betamethasone.

Q: True about sulfonylureas?

The most common side effect is hypoglycemia.. **Explanation:** **1. Why Option B is Correct:** Sulfonylureas (SUs) are "insulin secretagogues." They work by binding to the **SUR1 subunit** of the ATP-sensitive K⁺ channels on pancreatic beta cells. This leads to channel closure, cell depolarization, calcium influx, and the subsequent release of pre-formed insulin. Because this insulin release is **independent of blood glucose levels**, it can persist even when glucose is low, making **hypoglycemia** the most common and clinically significant side effect. **2. Why the Other Options are Incorrect:** * **Option A:** Chlorpropamide, along with Tolbutamide, belongs to the **First-generation** sulfonylureas. Second-generation agents include Glibenclamide (Glyburide), Glipizide, and Gliclazide. * **Option C:** Sulfonylureas require **functional pancreatic beta cells** to work. Since their mechanism involves stimulating the pancreas to release insulin, they are completely ineffective in patients who have undergone a pancreatectomy or those with Type 1 Diabetes. * **Option D:** Sulfonylureas are generally **avoided in pregnancy** as they can cross the placenta and cause fetal hyperinsulinemia and neonatal hypoglycemia. **Insulin** remains the drug of choice for gestational diabetes (though Metformin and Glibenclamide are sometimes used in specific guidelines, they are not the "standard" for safety). **High-Yield Clinical Pearls for NEET-PG:** * **Disulfiram-like reaction:** Most commonly associated with **Chlorpropamide** when taken with alcohol. * **SIADH:** Chlorpropamide can cause water retention and hyponatremia. * **Weight Gain:** A common side effect of SUs (unlike Metformin). * **Glimepiride:** Often classified as a third-generation SU; it has the lowest risk of hypoglycemia among this class.

Q: A 26-year-old man with a 10-month history of ileal Crohn's disease, treated with several drugs, now presents with muscle weakness, centripetal obesity, and a plethoric face. These side effects are most likely associated with the long-term use of which of the following medications?

Prednisone. ### Explanation **Correct Option: D. Prednisone** The patient is presenting with classic features of **Iatrogenic Cushing’s Syndrome** (centripetal obesity, plethoric face, and muscle weakness/proximal myopathy) [1], [2], [3]. Prednisone is a potent glucocorticoid frequently used to induce remission in moderate-to-severe Crohn’s disease [3]. Long-term use leads to: * **Fat Redistribution:** Centripetal obesity, "moon face" (plethora), and "buffalo hump" [1], [3]. * **Protein Catabolism:** Leading to muscle wasting (weakness) and skin thinning [1], [2]. * **Metabolic Effects:** Hyperglycemia and osteoporosis [1]. **Analysis of Incorrect Options:** * **A. Azathioprine:** An immunosuppressant (thiopurine) used for maintaining remission in Crohn’s. Its primary side effects are **bone marrow suppression** (leukopenia) and pancreatitis, not cushingoid features. * **B. Cyclosporine:** A calcineurin inhibitor. While it can cause gingival hyperplasia and hirsutism, it typically presents with **nephrotoxicity, hypertension, and tremors** rather than centripetal obesity. * **C. Olsalazine:** A 5-aminosalicylate (5-ASA) prodrug. It acts locally in the colon and is mainly associated with **secretory diarrhea** and hypersensitivity reactions; it lacks systemic endocrine side effects. **NEET-PG High-Yield Pearls:** * **Steroid-Induced Myopathy:** Characterized by proximal muscle weakness; it is a "painless" myopathy, unlike inflammatory myositis [1], [2]. * **Withdrawal Caution:** Long-term prednisone causes HPA-axis suppression. Abrupt withdrawal can lead to life-threatening **Acute Adrenal Insufficiency** [3]. * **Drug of Choice:** For Crohn’s limited to the ileum/right colon with fewer systemic effects, **Budesonide** is preferred due to high first-pass metabolism.

Question 1

Continuous GnRH administration is useful in all the following conditions EXCEPT:

Accepted Answer

Male infertility

Answer

Precocious puberty

Answer

Prostate cancer

Answer

Endometriosis

Question 2

Which of the following is NOT a pharmacological property of Repaglinide?

Accepted Answer

Reduces insulin resistance

Answer

Insulin Secretagogues

Answer

Causes less hypoglycemia than sulfonylureas

Answer

Effectively reduced postprandial hyperglycemia

Question 3

Which of the following drugs used in osteoporosis acts by decreasing the resorption of bone as well as inducing new bone formation?

Accepted Answer

Strontium ranelate

Answer

Teriparatide

Answer

Ibandronate

Answer

Calcitonin

Question 4

Which of the following statements about romosozumab is FALSE?

Accepted Answer

Romosozumab is a monoclonal antibody against sclerostin.

Answer

It acts by inhibiting osteoclast differentiation and activity.

Answer

It acts by stimulating osteoblast formation and activity.

Answer

It is indicated in postmenopausal osteoporosis.

Question 5

Indications for the use of newer insulins include all of the following EXCEPT:

Accepted Answer

Diabetic kidney disease

Answer

Insulin resistance

Answer

Lipodystrophy

Answer

Pregnancy

Question 6

All of the following statements regarding Octreotide are true, EXCEPT:

Accepted Answer

An absorbent

Answer

It is a somatostatin analogue

Answer

Used in secretory diarrhea in AIDS

Answer

Used in carcinoid

Question 7

Conversion of T4 to T3 inhibition is associated with which of the following drugs?

Accepted Answer

Propylthiouracil

Answer

Ampicillin

Answer

Lithium

Answer

Carbimazole

Question 8

Which of the following has the least mineralocorticoid activity?

Accepted Answer

Dexamethasone

Answer

Aldosterone

Answer

Cortisol

Answer

Fludrocortisone

Question 9

True about sulfonylureas?

Accepted Answer

The most common side effect is hypoglycemia.

Answer

Chlorpropamide is a second-generation agent.

Answer

Effective even after pancreatectomy.

Answer

Safe in pregnancy.

Question 10

A 26-year-old man with a 10-month history of ileal Crohn's disease, treated with several drugs, now presents with muscle weakness, centripetal obesity, and a plethoric face. These side effects are most likely associated with the long-term use of which of the following medications?

Accepted Answer

Prednisone

Answer

Azathioprine

Answer

Cyclosporine

Answer

Olsalazine

Endocrine Pharmacology — MCQs

Endocrine Pharmacology — MCQs

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