Endocrine Pharmacology — MCQs

Endocrine Pharmacology Indian Medical PG Practice Questions and MCQs

Question 71: Which of the following drugs decreases hepatic glucose output and improves peripheral insulin utilization?

A. Chlorpropamide
B. Glyburide
C. Miglitol
D. Pioglitazone (Correct Answer)

Explanation: **Explanation:** The correct answer is **Pioglitazone**. **Mechanism of Action:** Pioglitazone belongs to the **Thiazolidinedione (TZD)** class. It acts as a selective agonist for the nuclear receptor **PPAR-γ** (Peroxisome Proliferator-Activated Receptor-gamma). Activation of this receptor leads to the transcription of genes involved in glucose and lipid metabolism. Its primary effects are: 1. **Liver:** It decreases hepatic glucose output (gluconeogenesis). 2. **Peripheral Tissues (Muscle/Adipose):** It increases the expression of glucose transporters (GLUT-4), thereby improving peripheral insulin sensitivity and glucose utilization. **Analysis of Incorrect Options:** * **A & B (Chlorpropamide & Glyburide):** These are **Sulfonylureas**. Their primary mechanism is to stimulate insulin release from pancreatic beta cells by closing ATP-sensitive K+ channels. They do not directly improve peripheral insulin sensitivity. * **C (Miglitol):** This is an **Alpha-glucosidase inhibitor**. It acts locally in the intestine to delay the absorption of carbohydrates by inhibiting the enzyme that breaks down oligosaccharides into monosaccharides. It has no direct effect on hepatic glucose output or peripheral utilization. **High-Yield Clinical Pearls for NEET-PG:** * **Side Effects of TZDs:** Weight gain, **fluid retention/edema** (contraindicated in NYHA Class III/IV heart failure), and increased risk of bone fractures. * **Pioglitazone specific:** It has been associated with a potential risk of **bladder cancer** (avoid in patients with active or past history of bladder cancer). * **Metformin vs. TZDs:** While both are "insulin sensitizers," Metformin primarily acts on the liver (via AMPK activation), whereas TZDs have a more pronounced effect on peripheral adipose and muscle tissue.

Question 72: Which drug is NOT used in the treatment of Pituitary Adenoma?

A. Octreotide
B. Bromocriptine
C. Orlistat (Correct Answer)
D. Letrozole

Explanation: **Explanation:** The correct answer is **Orlistat** because it is a **lipase inhibitor** used for the management of obesity. It works locally in the gastrointestinal tract to prevent the absorption of dietary fats and has no pharmacological role in modulating pituitary hormones or treating intracranial adenomas. **Analysis of Options:** * **Octreotide (Option A):** A long-acting **Somatostatin analogue**. It is the first-line medical therapy for **Acromegaly** (GH-secreting pituitary adenoma) and is also used in TSH-secreting tumors. It inhibits the release of Growth Hormone by binding to SSTR-2 and SSTR-5 receptors. * **Bromocriptine (Option B):** A **Dopamine (D2) agonist**. It is the drug of choice for **Prolactinomas**. Dopamine naturally inhibits prolactin release; thus, bromocriptine effectively reduces both prolactin levels and tumor size. * **Letrozole (Option D):** An **Aromatase inhibitor**. While primarily used in breast cancer, it is used off-label in the management of **Gonadotroph adenomas** and sometimes in macro-prolactinomas that are resistant to dopamine agonists, as it reduces the feedback effects of estrogen on the pituitary. **NEET-PG High-Yield Pearls:** * **Drug of Choice (DOC) for Prolactinoma:** Cabergoline (preferred over Bromocriptine due to higher efficacy and better side-effect profile). * **DOC for Acromegaly:** Surgical resection (Trans-sphenoidal surgery). Octreotide is the medical DOC. * **Pegvisomant:** A Growth Hormone receptor antagonist used for refractory Acromegaly; it blocks the peripheral action of GH rather than inhibiting its secretion from the tumor. * **Pasireotide:** A newer somatostatin analogue with high affinity for SSTR-5, often used in **Cushing’s Disease** (ACTH-secreting adenoma).

Question 73: Which of the following corticosteroids has the least glucocorticoid action?

A. Fludrocortisone
B. Ciclesonide (Correct Answer)
C. Dexamethasone
D. Betamethasone

Explanation: ### Explanation The correct answer is **Ciclesonide**. The question asks for the corticosteroid with the **least systemic glucocorticoid action**. This is determined by the drug’s potency and its delivery mechanism. **Why Ciclesonide is correct:** Ciclesonide is a **prodrug** used primarily as an inhaled corticosteroid (ICS) for asthma. It is activated by esterases specifically in the bronchial epithelium to its active metabolite, des-ciclesonide. It has **minimal systemic bioavailability** (<1%) and high plasma protein binding, which significantly limits systemic glucocorticoid side effects [1]. Among the options provided, it is designed to have negligible systemic glucocorticoid activity compared to systemic steroids. **Why the other options are incorrect:** * **Dexamethasone and Betamethasone:** These are **long-acting, high-potency systemic glucocorticoids**. They have maximal glucocorticoid activity with zero mineralocorticoid activity. They are used when powerful anti-inflammatory effects are required. * **Fludrocortisone:** While primarily known for its very high **mineralocorticoid** potency (used in Addison’s disease), it still possesses significant systemic glucocorticoid activity (about 10–15 times that of cortisol). Compared to a localized prodrug like Ciclesonide, its systemic glucocorticoid impact is much higher. **High-Yield Clinical Pearls for NEET-PG:** * **Potency Ratio:** Dexamethasone/Betamethasone are the most potent systemic glucocorticoids (Potency = 25–30; Dose = 0.75 mg). * **Ciclesonide Advantage:** Because it is activated only in the lungs, it carries a lower risk of **oropharyngeal candidiasis** compared to other inhaled steroids like Budesonide or Fluticasone. * **Mineralocorticoid Potency:** Fludrocortisone is the drug of choice for mineralocorticoid replacement. * **Short-acting steroid:** Hydrocortisone (equal glucocorticoid and mineralocorticoid action).

Question 74: Hyperglycemia is caused by all EXCEPT:

A. Beta blockers
B. Steroids
C. Diuretics
D. Indomethacin (Correct Answer)

Explanation: **Explanation:** The correct answer is **Indomethacin**. Indomethacin is a non-steroidal anti-inflammatory drug (NSAID) that inhibits prostaglandin synthesis. Unlike the other options, it does not typically cause hyperglycemia; in fact, some studies suggest NSAIDs may slightly increase insulin sensitivity or have a neutral effect on blood glucose. **Why the other options are wrong (Causes of Hyperglycemia):** * **Steroids (Glucocorticoids):** These are potent hyperglycemic agents. They increase gluconeogenesis in the liver, decrease peripheral glucose uptake in muscles, and promote lipolysis, leading to "Steroid-induced Diabetes." * **Diuretics:** Specifically **Thiazides** and **Loop diuretics** cause hyperglycemia. They lead to hypokalemia, which inhibits the release of insulin from pancreatic beta cells (as insulin release is a potassium-dependent process). * **Beta-blockers:** Non-selective beta-blockers (like Propranolol) interfere with insulin release (mediated by $\beta_2$ receptors) and decrease peripheral glucose utilization. Crucially, they also mask the autonomic warning symptoms of hypoglycemia (tachycardia, tremors), making them risky for diabetics. **High-Yield Clinical Pearls for NEET-PG:** * **Drugs causing Hyperglycemia:** "S-T-A-N-D": **S**teroids, **T**hiazides, **A**typical antipsychotics (Clozapine/Olanzapine), **N**iacin, **D**iazoxide/Protease Inhibitors. * **Diazoxide:** A K+ channel opener that hyperpolarizes beta cells, inhibiting insulin release; used specifically to treat insulinomas. * **Beta-blocker Exception:** While they cause hyperglycemia, their most dangerous effect in diabetics is **masking hypoglycemia**, except for sweating (which is mediated by cholinergic fibers).

Question 75: Which of the following statements regarding carbimazole is NOT true when compared to propylthiouracil?

A. Carbimazole crosses the placenta less than propylthiouracil. (Correct Answer)
B. Carbimazole is more potent than propylthiouracil.
C. Carbimazole can be used as a single daily dose, whereas propylthiouracil needs to be given thrice daily.
D. Carbimazole does not inhibit the peripheral conversion of T4 to T3.

Explanation: **Explanation** The correct answer is **A**. This statement is false because **Propylthiouracil (PTU) crosses the placenta less than Carbimazole.** PTU is highly protein-bound (approx. 80–90%) and more ionized at physiological pH, which limits its transfer across the placental barrier. In contrast, Carbimazole (a prodrug of Methimazole) has low protein binding and crosses the placenta more readily, potentially leading to rare fetal scalp defects (Aplasia cutis) and Choanal atresia. **Analysis of Incorrect Options:** * **Option B:** Carbimazole is indeed **more potent** than PTU (roughly 10 times more potent). Smaller doses are required to achieve the same antithyroid effect. * **Option C:** Carbimazole has a **longer duration of action** due to its accumulation in the thyroid gland, allowing for once-daily dosing. PTU has a shorter half-life and typically requires dosing 3–4 times daily. * **Option D:** PTU has a unique dual mechanism: it inhibits thyroid peroxidase (TPO) and **inhibits the peripheral conversion of T4 to T3**. Carbimazole only inhibits TPO and has no effect on peripheral conversion. **High-Yield NEET-PG Pearls:** 1. **Drug of Choice (DOC):** PTU is the DOC in the **1st trimester** of pregnancy (due to lower placental transfer) and in **Thyroid Storm** (due to inhibition of peripheral T4 to T3 conversion). 2. **Methimazole/Carbimazole** is the DOC for the 2nd and 3rd trimesters and for general hyperthyroidism due to better compliance and lower hepatotoxicity. 3. **Side Effects:** Both can cause **Agranulocytosis** (most serious) and skin rashes. PTU carries a higher risk of severe **Hepatotoxicity**.

Question 76: Which is a short-acting glucocorticoid?

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

Explanation: **Explanation:** Glucocorticoids are classified based on their duration of action, which is determined by their biological half-life. **1. Why Hydrocortisone is correct:** Hydrocortisone (Cortisol) is the prototype **short-acting** glucocorticoid [1], [2]. It has a biological half-life of **8–12 hours**. It possesses equal glucocorticoid (anti-inflammatory) and mineralocorticoid (salt-retaining) potency (1:1 ratio) [1]. Due to its short duration and balanced activity, it is the drug of choice for replacement therapy in adrenal insufficiency (Addison’s disease). **2. Analysis of Incorrect Options:** * **Fludrocortisone:** This is a potent **mineralocorticoid** with some glucocorticoid activity. While its plasma half-life is short, its biological effect is intermediate. It is primarily used for its salt-retaining properties. * **Dexamethasone:** This is a **long-acting** glucocorticoid with a biological half-life of **36–72 hours** [1]. It is highly potent, has zero mineralocorticoid activity, and is used for cerebral edema and suppression tests [2]. * **Aldosterone:** This is the primary endogenous **mineralocorticoid** produced by the zona glomerulosa [3]. It has negligible glucocorticoid activity and is not used clinically as a drug due to extensive first-pass metabolism [3]. **3. High-Yield NEET-PG Pearls:** * **Classification by Duration:** * **Short-acting (8–12h):** Hydrocortisone, Cortisone. * **Intermediate-acting (12–36h):** Prednisolone, Methylprednisolone, Triamcinolone. * **Long-acting (36–72h):** Dexamethasone, Betamethasone. * **Potency Tip:** Dexamethasone and Betamethasone have the highest anti-inflammatory potency but **zero** salt-retaining (mineralocorticoid) activity. * **Clinical Note:** For fetal lung maturity in preterm labor, **Betamethasone** is preferred over Dexamethasone due to better neurological outcomes, though both cross the placenta.

Question 77: Which of the following conditions is an indication for the use of somatostatin?

A. Zollinger Ellison syndrome
B. Bleeding esophageal varices (Correct Answer)
C. Steatorrhoea
D. Macroprolactinoma

Explanation: **Explanation:** **Somatostatin** is a potent inhibitory peptide produced by the hypothalamus and the delta cells of the pancreas. Its primary clinical utility in **Bleeding Esophageal Varices** (Option B) stems from its ability to cause **splanchnic vasoconstriction**. By reducing portal venous pressure and decreasing blood flow to the collateral variceal vessels, it helps control acute hemorrhage. While the synthetic analog **Octreotide** is more commonly used due to its longer half-life, somatostatin remains a classic pharmacological indication for this condition. **Analysis of Incorrect Options:** * **A. Zollinger-Ellison Syndrome (ZES):** While somatostatin inhibits gastrin, the first-line treatment for ZES is high-dose **Proton Pump Inhibitors (PPIs)** or surgical resection. Somatostatin analogs are rarely the primary choice. * **C. Steatorrhoea:** Somatostatin actually **causes** steatorrhoea as a side effect because it inhibits the secretion of pancreatic enzymes and reduces gallbladder contraction, leading to fat malabsorption. * **D. Macroprolactinoma:** The treatment of choice for prolactinomas is **Dopamine agonists** (e.g., Cabergoline, Bromocriptine). Somatostatin analogs are used for Growth Hormone-secreting tumors (Acromegaly), not prolactinomas. **High-Yield NEET-PG Pearls:** * **Mechanism:** Somatostatin inhibits "everything" (Growth hormone, TSH, Insulin, Glucagon, Gastrin, and Secretin). * **Octreotide vs. Somatostatin:** Octreotide is preferred clinically because it has a longer half-life (1.5 hours) compared to natural somatostatin (1–3 minutes). * **Other Indications:** Acromegaly, Carcinoid syndrome, VIPoma, and persistent diarrhea in AIDS patients. * **Side Effect:** Cholelithiasis (due to inhibition of CCK and gallbladder stasis).

Question 78: Which antidiabetic drug is used for both Type 1 and Type 2 diabetes mellitus?

A. Sulphonylureas
B. Metformin
C. Acarbose
D. Pramlinitide (Correct Answer)

Explanation: **Explanation:** **Pramlintide** is a synthetic analogue of **Amylin**, a hormone co-secreted with insulin from pancreatic beta cells. It works by slowing gastric emptying, suppressing postprandial glucagon secretion, and increasing satiety. Since its mechanism of action is independent of endogenous insulin production and instead focuses on modulating glucose appearance in the blood, it is the only non-insulin antidiabetic drug FDA-approved for use in **both Type 1 and Type 2 Diabetes Mellitus** (as an adjunct to mealtime insulin). **Why the other options are incorrect:** * **Sulphonylureas (e.g., Glipizide):** These are insulin secretagogues that require functional pancreatic beta cells to work. They are ineffective in Type 1 DM where beta cells are destroyed. * **Metformin:** A biguanide that primarily decreases hepatic glucose production. While sometimes used off-label in obese Type 1 patients to reduce insulin resistance, it is officially indicated only for Type 2 DM. * **Acarbose:** An alpha-glucosidase inhibitor that delays carbohydrate absorption. Like Metformin, it is primarily indicated for Type 2 DM and is not standard therapy for Type 1 DM. **High-Yield NEET-PG Pearls:** * **Route of Administration:** Pramlintide must be administered via **subcutaneous injection** before major meals. * **Major Side Effect:** Severe hypoglycemia (when used with insulin) and gastrointestinal upset (nausea). * **Contraindication:** It is contraindicated in patients with **gastroparesis** due to its effect on slowing gastric emptying. * **Weight Effect:** Unlike insulin or sulphonylureas, Pramlintide is associated with **weight loss**.

Question 79: Which of the following is an indication for the use of corticosteroids?

A. Psychosis
B. Herpes simplex
C. Loffler's syndrome (Correct Answer)
D. Subacute thyroiditis

Explanation: **Explanation:** **Loffler’s Syndrome (Correct Answer):** Loffler’s syndrome is a form of pulmonary eosinophilia characterized by transient lung opacities and peripheral blood eosinophilia, often triggered by parasitic infections or drugs. Corticosteroids are the mainstay of treatment because they are potent anti-inflammatory and immunosuppressive agents. They induce eosinophil apoptosis and inhibit the production of cytokines (like IL-5) that promote eosinophil survival, leading to rapid resolution of symptoms and pulmonary infiltrates. **Analysis of Incorrect Options:** * **Psychosis:** Corticosteroids are known to cause "steroid psychosis" (mood swings, agitation, or delirium) as a side effect. They are strictly **contraindicated** in patients with pre-existing psychotic illnesses. * **Herpes Simplex:** Corticosteroids suppress the immune response, which can lead to the dissemination of viral infections. Specifically, topical steroids in dendritic keratitis (Herpes simplex keratitis) can lead to corneal perforation and are contraindicated. * **Subacute Thyroiditis:** While corticosteroids are used in severe cases of subacute (De Quervain's) thyroiditis to reduce pain and inflammation, **Loffler's syndrome** is a more classic, textbook indication for steroid therapy in the context of eosinophilic lung diseases. *(Note: In some clinical contexts, both could be treated with steroids, but Loffler's is the high-yield academic answer for eosinophilic disorders).* **NEET-PG High-Yield Pearls:** * **Mechanism:** Steroids bind to intracellular receptors, translocate to the nucleus, and inhibit **NF-κB**, reducing the expression of pro-inflammatory genes. * **Hematological effects:** Steroids increase Neutrophils (due to demargination) but **decrease** Lymphocytes, Eosinophils, and Monocytes. * **Diagnostic Tip:** Always look for "eosinophilic" conditions (e.g., Tropical Pulmonary Eosinophilia, HES) as classic indications for steroid therapy in exams.

Question 80: The unique property of Selective Estrogen Receptor Modulators (SERMs) is that they:

A. Have both estrogenic and progestational agonistic activity
B. Inhibit the aromatase enzyme that is required for estrogen synthesis
C. Produce an estrogenic effect without binding to estrogen receptors
D. Act as an agonist in some tissues and an antagonist in other tissues (Correct Answer)

Explanation: ### Explanation **1. Why Option D is Correct:** The defining characteristic of **Selective Estrogen Receptor Modulators (SERMs)** is their **tissue-specific activity**. Unlike pure agonists or antagonists, SERMs bind to estrogen receptors (ER) and induce different conformational changes in the receptor depending on the tissue. This leads to the recruitment of either **co-activators** (resulting in agonistic effects) or **co-repressors** (resulting in antagonistic effects). **2. Why Other Options are Incorrect:** * **Option A:** SERMs interact specifically with estrogen receptors; they do not possess progestational (progesterone-like) activity. * **Option B:** This describes the mechanism of **Aromatase Inhibitors** (e.g., Letrozole, Anastrozole), which block the peripheral conversion of androgens to estrogens. SERMs do not inhibit estrogen synthesis; they modulate the receptor. * **Option C:** SERMs must bind to the estrogen receptor to exert their effects. They are competitive ligands for the ER. **3. High-Yield Clinical Pearls for NEET-PG:** * **Tamoxifen:** * *Antagonist:* Breast (used in ER+ breast cancer). * *Agonist:* Bone (prevents osteoporosis) and **Endometrium** (increases risk of endometrial carcinoma). * **Raloxifene:** * *Antagonist:* Breast and **Endometrium** (no risk of endometrial cancer). * *Agonist:* Bone (DOC for postmenopausal osteoporosis). * **Clomiphene:** Acts as an antagonist in the hypothalamus/pituitary, blocking negative feedback and increasing GnRH/FSH/LH, making it a first-line agent for **ovulation induction**. * **Ospemifene:** Specifically used for dyspareunia (vulvovaginal atrophy) in postmenopausal women.

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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