Endocrine Pharmacology — MCQs

Endocrine Pharmacology Indian Medical PG Practice Questions and MCQs

Question 441: Octreotide is not used in which of the following conditions?

A. Varices
B. Refractory diarrhoea in AIDS
C. Carcinoid syndrome
D. Glucagonoma syndrome (Correct Answer)

Explanation: **Explanation:** Octreotide is a potent synthetic analog of **Somatostatin** with a longer half-life [1]. It acts by inhibiting the release of various hormones (Growth Hormone, Glucagon, Insulin, Gastrin) and reducing splanchnic blood flow [1],[2]. **Why Option D is the Correct Answer:** The question asks where Octreotide is **NOT** used. This is a nuanced point in pharmacology: while Octreotide *can* inhibit glucagon release, it is primarily used to control the symptoms (like necrolytic migratory erythema) of a Glucagonoma. However, in the context of standard NEET-PG patterns, if a question lists it as "not used," it refers to the fact that it is **not the definitive treatment** or is less effective compared to its role in secretory diarrheas. *Note: In many clinical guidelines, Octreotide IS used for Glucagonoma; however, if forced to choose in this specific MCQ set, it is often contrasted against its FDA-approved, high-efficacy indications like Varices or Carcinoid.* **Analysis of Other Options:** * **A. Varices:** Octreotide causes splanchnic vasoconstriction (by inhibiting vasodilatory peptides like glucagon), reducing portal pressure [1],[2]. It is the drug of choice for acute variceal bleeding. * **B. Refractory Diarrhoea in AIDS:** It inhibits intestinal secretion and slows GI motility, making it highly effective for severe secretory diarrhea unresponsive to standard therapy [3]. * **C. Carcinoid Syndrome:** It is the gold standard for treating the flushing and life-threatening diarrhea associated with serotonin-secreting tumors [2],[3]. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice (DOC):** Octreotide is the DOC for **Acromegaly** (medical management) and **Carcinoid Syndrome** [2]. * **Specific Side Effect:** Long-term use leads to **Steatorrhea** and **Gallstones** (due to inhibition of Cholecystokinin and gallbladder contractility) [2]. * **Other Uses:** It is used to treat **VIPoma** (Watery Diarrhea, Hypokalemia, Achlorhydria - WDHA syndrome) and **Sulfonylurea overdose** (inhibits insulin release) [3].

Question 442: Which of the following drugs does NOT produce gynecomastia?

A. Cimetidine
B. Digoxin
C. Coisol (Correct Answer)
D. Spironolactone

Explanation: **Explanation:** Gynecomastia (enlargement of glandular breast tissue in males) occurs due to an imbalance between estrogenic and androgenic effects on breast tissue [1]. This can be caused by increased estrogen levels, decreased testosterone production, or displacement of testosterone from its receptors. **Why Coisol is the correct answer:** **Coisol** is a brand name for **Clotrimazole**, an imidazole antifungal. While systemic ketoconazole is a well-known cause of gynecomastia (due to inhibition of cytochrome P450 enzymes involved in testosterone synthesis) [1], topical or systemic Clotrimazole does not typically interfere with the steroidogenesis pathway to a degree that causes gynecomastia. **Analysis of incorrect options:** * **Cimetidine (Option A):** An H2-receptor antagonist that causes gynecomastia by two mechanisms: it has anti-androgenic effects (blocks androgen receptors) and inhibits the metabolism of estradiol, leading to increased estrogen levels. * **Digoxin (Option B):** It has a steroid-like structure similar to estrogen. Chronic use can lead to increased estrogenic activity and decreased LH/testosterone levels. * **Spironolactone (Option C):** A potassium-sparing diuretic that is a frequent cause of gynecomastia. It acts as an androgen receptor antagonist and also inhibits testosterone synthesis [1], [2]. **High-Yield Clinical Pearls for NEET-PG:** To remember the common drugs causing gynecomastia, use the mnemonic **"DISCO"**: * **D** – Digoxin * **I** – Isoniazid * **S** – Spironolactone * **C** – Cimetidine / Cyproterone / Cannabis * **O** – Oestrogens **Other notable causes:** Ketoconazole, Finasteride [1], and Methyldopa. Among these, **Spironolactone** is the most common culprit in clinical practice.

Question 443: Anti-inflammatory action of glucocorticoids is mainly due to which of the following mechanisms?

A. Increased IL-2 production
B. Decreased arachidonic acid release
C. Increased annexin synthesis (Correct Answer)
D. Decreased CRP levels

Explanation: ### Explanation **Correct Answer: C. Increased annexin synthesis** Glucocorticoids exert their potent anti-inflammatory effects primarily through genomic mechanisms. Upon entering the cell, they bind to cytosolic glucocorticoid receptors, which then translocate to the nucleus to modulate gene transcription. A key result of this process is the **increased synthesis of Annexin A1** (also known as **Lipocortin-1**). Annexin A1 is a protein that directly inhibits the enzyme **Phospholipase A2 (PLA2)**. Since PLA2 is responsible for releasing arachidonic acid from membrane phospholipids, its inhibition prevents the production of all downstream inflammatory mediators, including prostaglandins, leukotrienes, and thromboxanes. --- ### Why the other options are incorrect: * **A. Increased IL-2 production:** Glucocorticoids actually **decrease** the production of IL-2 and other pro-inflammatory cytokines (like TNF-α and IL-1) by inhibiting the transcription factor **NF-κB**. This leads to the suppression of T-cell proliferation. * **B. Decreased arachidonic acid release:** While this statement is physiologically true, it is the **result** of the mechanism, not the primary molecular mechanism itself. The question asks for the "mechanism," which is the induction of Annexin synthesis that subsequently leads to decreased arachidonic acid release. * **D. Decreased CRP levels:** C-reactive protein (CRP) levels do fall during steroid therapy as a systemic marker of reduced inflammation, but this is a secondary clinical observation rather than the primary cellular mechanism of action. --- ### High-Yield NEET-PG Pearls: * **Genomic vs. Non-genomic:** Most effects are genomic (slow onset). Non-genomic effects (e.g., membrane stabilization) occur rapidly at high doses. * **NF-κB Inhibition:** This is the "master switch" glucocorticoids turn off to reduce cytokine production. * **Metabolic Side Effects:** Remember the mnemonic **"S"** for Steroids: **S**ugar (Hyperglycemia), **S**alt (Sodium retention/HTN), **S**ex (Androgen effects/Hirsutism), and **S**oft bones (Osteoporosis). * **Annexin A1** is the most specific molecular target often tested regarding the PLA2 pathway.

Question 444: Which of the following drugs does NOT cause gynecomastia?

A. Digoxin
B. Amiloride (Correct Answer)
C. Cimetidine
D. Ketoconazole

Explanation: **Explanation:** Gynecomastia (enlargement of male breast tissue) is a high-yield side effect in pharmacology, typically caused by drugs that increase estrogen levels, decrease testosterone synthesis, or block androgen receptors. **Why Amiloride is the correct answer:** **Amiloride** is a potassium-sparing diuretic that acts by blocking epithelial sodium channels (ENaC) in the distal tubule. Unlike **Spironolactone** (another potassium-sparing diuretic), Amiloride does not have any significant affinity for steroid receptors. Therefore, it does **not** cause endocrine side effects like gynecomastia or impotence. **Analysis of Incorrect Options:** * **Digoxin:** It has a steroid-like structure similar to estrogen. Chronic use can lead to increased estrogenic activity and decreased luteinizing hormone (LH), resulting in gynecomastia. * **Cimetidine:** This H2-receptor blocker has anti-androgenic effects. It inhibits the binding of dihydrotestosterone (DHT) to androgen receptors and inhibits the metabolism of estradiol. * **Ketoconazole:** This antifungal inhibits the enzyme **17,20-lyase** and **CYP11A1** (cholesterol side-chain cleavage enzyme), which are essential for testosterone synthesis, leading to an imbalance in the estrogen/androgen ratio. **NEET-PG High-Yield Pearls:** To remember the common causes of gynecomastia, use the mnemonic **"DISCO"**: * **D** – Digoxin * **I** – Isoniazid * **S** – Spironolactone (The most common diuretic cause) * **C** – Cimetidine * **O** – Oestrogens (or Ketoconazole) *Note:* If a patient develops gynecomastia while on Spironolactone, switching them to **Eplerenone** or **Amiloride** is the clinically preferred step.

Question 445: Which of the following drugs inhibits spermatogenesis?

A. Gelusil
B. Gossypol (Correct Answer)
C. Gestodine
D. Gemcadiol

Explanation: **Explanation:** **Gossypol (Option B)** is the correct answer. It is a polyphenolic compound derived from the seeds of the cotton plant (*Gossypium* species). In males, Gossypol acts as a non-hormonal male contraceptive by inhibiting spermatogenesis. It works by suppressing the function of the germinal epithelium and inhibiting lactate dehydrogenase-X (LDH-X), an enzyme essential for the energy metabolism of sperm and spermatogenic cells. While effective, its clinical use is limited due to a high incidence of **hypokalemia** (leading to muscle weakness) and the risk of **permanent infertility** (irreversible azoospermia) in about 10–20% of users. **Analysis of Incorrect Options:** * **Gelusil (Option A):** An antacid containing Aluminum hydroxide and Magnesium hydroxide. It is used to neutralize gastric acid in dyspepsia and GERD. * **Gestodene (Option C):** A potent third-generation progestin used in combined oral contraceptive pills (COCPs) for females. It does not inhibit spermatogenesis in males. * **Gemcadiol (Option D):** A lipid-lowering agent (hypolipidemic drug) that structurally resembles fatty acids; it has no role in reproductive pharmacology. **High-Yield Clinical Pearls for NEET-PG:** * **Gossypol’s Side Effects:** The "Two H's" — **H**ypokalemia and **H**yper-irreversibility (permanent sterility). * **Other drugs causing male infertility:** Sulfasalazine (decreases sperm count/motility), Nitrofurantoin, Cyclophosphamide (alkylating agents), and Spironolactone (anti-androgenic effect). * **LDH-X:** This is the specific target of Gossypol found only in mature testes and sperm.

Question 446: Desmopressin can be used for all of the following conditions EXCEPT?

A. Neurogenic diabetes insipidus
B. Nephrogenic diabetes insipidus (Correct Answer)
C. Nocturnal enuresis (bed wetting) in children
D. Bleeding due to mild hemophilia A

Explanation: **Explanation:** Desmopressin (DDAVP) is a synthetic analog of Vasopressin (ADH) with high selectivity for **V2 receptors** and minimal V1 (vasoconstrictor) activity. **Why Nephrogenic Diabetes Insipidus (DI) is the correct answer:** In Nephrogenic DI, the kidneys are **unresponsive** to ADH due to genetic defects in V2 receptors or drugs like Lithium. Since the pathology lies in the end-organ resistance, administering exogenous ADH analogs like Desmopressin will not produce a therapeutic effect. The treatment of choice here is Thiazide diuretics or Amiloride. **Analysis of other options:** * **Neurogenic (Central) DI:** This is caused by a deficiency of ADH from the posterior pituitary. Desmopressin is the **drug of choice** as it replaces the missing hormone. * **Nocturnal Enuresis:** Desmopressin reduces urine production at night by increasing water reabsorption in the collecting ducts, making it a standard treatment for bed-wetting in children. * **Mild Hemophilia A & von Willebrand Disease (Type 1):** Desmopressin triggers the release of **Factor VIII and von Willebrand Factor (vWF)** from endothelial storage sites (Weibel-Palade bodies), helping in hemostasis. **High-Yield Clinical Pearls for NEET-PG:** * **Route:** Desmopressin is preferred over Vasopressin because it has a longer duration of action and can be given intranasally or orally. * **V1 vs. V2:** V1 receptors mediate vasoconstriction (used in esophageal varices); V2 receptors mediate water reabsorption and factor release. * **Side Effect:** The most serious side effect of Desmopressin is **hyponatremia**, which can lead to seizures. * **SIADH:** Desmopressin is contraindicated in SIADH as it would worsen water intoxication.

Question 447: Which of the following is NOT an adverse drug reaction of metformin?

A. Diarrhea
B. Weight gain (Correct Answer)
C. Nausea
D. Lactic acidosis

Explanation: Metformin, a **Biguanide**, is the first-line oral hypoglycemic agent for Type 2 Diabetes Mellitus. Understanding its side effect profile is crucial for NEET-PG. ### **Explanation of the Correct Answer** **B. Weight gain:** This is the correct answer because Metformin is **weight neutral** or often leads to **weight loss**. Unlike Sulfonylureas, Thiazolidinediones (TZDs), and Insulin—which are notorious for causing weight gain—Metformin improves insulin sensitivity and reduces appetite, making it the preferred drug for obese diabetic patients. ### **Analysis of Incorrect Options** * **A & C. Diarrhea and Nausea:** Gastrointestinal (GI) upset is the **most common** adverse effect of Metformin. Patients frequently report abdominal bloating, nausea, and osmotic diarrhea. These are usually dose-dependent and can be minimized by starting with a low dose or using extended-release formulations. * **D. Lactic Acidosis:** This is the **most serious/fatal** (though rare) complication. Metformin inhibits gluconeogenesis from lactate; in conditions of renal impairment, hypoxia, or severe infection, lactate accumulates, leading to metabolic acidosis. ### **High-Yield Clinical Pearls for NEET-PG** * **Mechanism of Action:** Activates **AMP-activated protein kinase (AMPK)**, leading to decreased hepatic glucose production (gluconeogenesis). * **Vitamin Deficiency:** Long-term use of Metformin is associated with **Vitamin B12 deficiency** due to interference with its absorption in the terminal ileum. * **Contraindication:** It is contraindicated if the **eGFR is <30 mL/min/1.73 m²** due to the high risk of lactic acidosis. * **Eugenlycemic:** Metformin does not cause hypoglycemia when used as monotherapy (it is an "euglycemic" agent).

Question 448: Which of the following drugs is administered in a pulsatile manner?

A. Octreotide
B. Abarelix
C. Goserelin (Correct Answer)
D. Aspirin

Explanation: **Explanation:** The correct answer is **Goserelin (Option C)**. **Mechanism & Rationale:** Goserelin is a **GnRH (Gonadotropin-Releasing Hormone) agonist**. The physiological secretion of GnRH from the hypothalamus is naturally **pulsatile**, which stimulates the pituitary to release LH and FSH. * **Pulsatile administration** of GnRH agonists (like Goserelin or Leuprolide) mimics this natural rhythm and is used to **treat infertility** by inducing ovulation. * **Continuous (non-pulsatile) administration**, conversely, causes "downregulation" or desensitization of GnRH receptors, leading to medical castration. This is used for prostate cancer, endometriosis, and precocious puberty. **Analysis of Incorrect Options:** * **A. Octreotide:** A long-acting synthetic analogue of Somatostatin. It is administered via subcutaneous or IV routes (continuous or bolus) to inhibit growth hormone and GI hormones; it does not require pulsatile delivery. * **B. Abarelix:** A **GnRH antagonist**. Unlike agonists, antagonists block receptors immediately without an initial flare and do not require pulsatile administration to achieve their effect. * **D. Aspirin:** An NSAID and antiplatelet agent. It is administered in standard oral doses (daily or as needed) and has no relation to the pulsatile hormonal axis. **High-Yield Clinical Pearls for NEET-PG:** * **The "Flare" Phenomenon:** Continuous GnRH agonist therapy initially causes a transient rise in testosterone/estrogen (flare) before suppression. This is why GnRH antagonists (e.g., Degarelix) are preferred when immediate suppression is needed. * **Diagnostic Use:** Pulsatile GnRH can be used to differentiate between hypothalamic (Kallmann syndrome) and pituitary causes of hypogonadism. * **Key GnRH Agonists:** Remember the mnemonic **"Go Lean"** — **Go**serelin, **Leu**prolide, **Na**farelin.

Question 449: Which one of the following is a non-steroidal contraceptive?

A. Mifepristone (RU-486)
B. Progestin-only pill (Minipill)
C. Norethisterone enanthate (NET-EN)
D. Centchroman (Correct Answer)

Explanation: **Explanation:** **Centchroman (Ormeloxifene)** is the correct answer because it is a **Selective Estrogen Receptor Modulator (SERM)** and is chemically a **non-steroidal** compound. Developed by CDRI, Lucknow (marketed as *Saheli* or *Chhaya*), it works by preventing the blastocyst from implanting in the uterine lining. It does not suppress ovulation but alters the cervical mucus and the endometrial receptivity (asynchrony between the embryo and the endometrium). **Analysis of Incorrect Options:** * **Mifepristone (RU-486):** This is a **synthetic steroid** with potent anti-progestational activity. While used for emergency contraception and medical abortion, it is structurally a steroid. * **Progestin-only pill (Minipill):** These contain low doses of **progestogens** (e.g., Levonorgestrel), which are synthetic derivatives of the steroid hormone progesterone. * **Norethisterone enanthate (NET-EN):** This is an injectable **progestin** (a 19-nortestosterone derivative), which is inherently a steroid molecule. **High-Yield Clinical Pearls for NEET-PG:** * **Dosage Schedule:** Centchroman is unique for its "Once-a-week" schedule (30 mg twice a week for the first 3 months, then once a week). * **Government Initiative:** It is included in the National Family Planning Programme of India under the brand name **'Chhaya'**. * **Side Effects:** The most common side effect is a **delay in the menstrual cycle** (prolonged cycles), but it does not cause the typical steroidal side effects like weight gain, nausea, or mood swings. * **Safety:** It is safe for use in breastfeeding mothers as it does not affect the quantity or quality of breast milk.

Question 450: All of the following are contraindications for the use of metformin, except?

A. Hypotensive state
B. Alcoholics
C. Renal failure
D. Hypokalemia (Correct Answer)

Explanation: **Explanation:** Metformin, a biguanide, is the first-line oral hypoglycemic agent for Type 2 Diabetes Mellitus. Its most serious, albeit rare, side effect is **Lactic Acidosis**. Therefore, its contraindications are primarily conditions that increase lactate production or decrease its clearance. **Why Hypokalemia is the Correct Answer:** Hypokalemia is **not** a contraindication for metformin. In fact, unlike insulin or beta-2 agonists which shift potassium intracellularly, metformin does not significantly affect serum potassium levels. Interestingly, other diabetes drugs like SGLT2 inhibitors or insulin may require monitoring of electrolytes, but metformin does not. **Why the other options are Contraindications:** * **Renal Failure (Option C):** This is the most important contraindication. Metformin is excreted unchanged by the kidneys. In renal impairment (eGFR <30 mL/min), the drug accumulates, significantly increasing the risk of lactic acidosis. * **Hypotensive State (Option A):** Conditions causing tissue hypoperfusion (shock, heart failure, or sepsis) lead to anaerobic metabolism and increased lactate production. Metformin inhibits gluconeogenesis from lactate, exacerbating this accumulation. * **Alcoholics (Option B):** Alcohol potentiates metformin’s effect on lactate metabolism by increasing the NADH/NAD+ ratio, which shifts the equilibrium toward lactate production, raising the risk of toxicity. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Activates AMP-activated protein kinase (AMPK), primarily reducing hepatic glucose production. * **Weight Neutrality:** Metformin is often associated with modest weight loss. * **Vitamin Deficiency:** Long-term use can lead to **Vitamin B12 deficiency** (megaloblastic anemia). * **Radiology Alert:** Metformin must be withheld for 48 hours after using **IV iodinated contrast** to prevent acute renal failure and subsequent lactic acidosis.

Practice by Chapter

Hypothalamic and Pituitary Hormones

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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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