Endocrine Pharmacology — MCQs

Endocrine Pharmacology Indian Medical PG Practice Questions and MCQs

Question 171: Which of the following insulins is known as a peakless insulin?

A. Isophane
B. Degludec (Correct Answer)
C. Glulisine
D. Lispro

Explanation: ### Explanation **Correct Option: B. Degludec** Insulin **Degludec** is a long-acting, ultra-long-duration basal insulin. It is characterized as "peakless" because it forms multi-hexamers upon subcutaneous injection, resulting in a slow and continuous release into the circulation. This provides a steady-state concentration for over 42 hours, significantly reducing the risk of nocturnal hypoglycemia compared to older basal insulins. **Analysis of Incorrect Options:** * **A. Isophane (NPH):** This is an intermediate-acting insulin. It has a distinct peak of action (usually 4–10 hours after injection), which increases the risk of hypoglycemia during that period. * **C. Glulisine & D. Lispro:** These are **rapid-acting insulin analogues**. They are designed to have a very sharp, early peak (30–90 minutes) to mimic the postprandial (after-meal) insulin surge. They are never peakless. **High-Yield NEET-PG Pearls:** 1. **Peakless Insulins:** Include **Glargine** and **Degludec**. Degludec is considered "more peakless" and has a longer half-life than Glargine. 2. **Mechanism of Degludec:** It achieves its long duration via **multi-hexamer formation** and binding to albumin via a fatty acid side chain. 3. **Clinical Advantage:** The primary benefit of peakless insulins is a **lower incidence of nocturnal hypoglycemia** and less glycemic variability. 4. **Mixing:** Unlike NPH, long-acting analogues like Glargine cannot be mixed in the same syringe with rapid-acting insulins (due to pH differences), though Degludec is available in fixed-dose combinations with Aspart (IDegAsp).

Question 172: Side effects of glucocorticoids are all of the following except:

A. Hypoglycemia (Correct Answer)
B. Cataract
C. Psychoses
D. Osteoporosis

Explanation: **Explanation:** Glucocorticoids (like Prednisolone and Dexamethasone) are catabolic hormones that significantly impact metabolism, electrolyte balance, and various organ systems. **Why Hypoglycemia is the correct answer:** Glucocorticoids **increase** blood glucose levels; they do not cause hypoglycemia. They promote **gluconeogenesis** in the liver and decrease peripheral glucose utilization in muscles and adipose tissue (anti-insulin effect). This leads to **Hyperglycemia**, which can precipitate or worsen Diabetes Mellitus ("Steroid-induced Diabetes"). **Analysis of incorrect options:** * **Cataract:** Long-term use of steroids is a well-known cause of **posterior subcapsular cataracts**. They also increase intraocular pressure, leading to glaucoma. * **Psychoses:** Glucocorticoids affect the CNS, causing a range of psychiatric symptoms from euphoria and insomnia to severe "steroid psychosis," mania, or depression. * **Osteoporosis:** Steroids are a leading cause of drug-induced osteoporosis. They inhibit osteoblast activity, decrease intestinal calcium absorption, and increase renal calcium excretion, leading to bone resorption. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Steroid Side Effects:** "CUSHINGOID" (Cataracts, Ulcers, Skin thinning/Striae, Hypertension/Hirsutism, Immunosuppression, Necrosis of femoral head, Glucose elevation, Osteoporosis, Impaired wound healing, Depression/Psychosis). * **Electrolyte disturbances:** Glucocorticoids cause **Hypokalemia** and **Hypernatremia** (due to mineralocorticoid activity). * **Growth:** They cause growth retardation in children by inhibiting growth hormone axis and bone formation. * **Withdrawal:** Abrupt cessation after chronic use leads to **Acute Adrenal Insufficiency** (Addisonian crisis) due to HPA-axis suppression.

Question 173: Androgenic activity of the 19-nortesterone nucleus is decreased by?

A. Adding an alkyl group at C17
B. Removal of the methyl group at C19 (Correct Answer)
C. Adding a methyl group at C18
D. Substituting a chlorine atom at C21

Explanation: ### Explanation The question focuses on the structure-activity relationship (SAR) of steroid hormones, specifically how modifications to the testosterone nucleus alter its biological effects. **1. Why the Correct Answer is Right:** The term **"19-nortestosterone"** itself implies the **removal of the methyl group at the C19 position** (the carbon atom located between rings A and B). This specific modification significantly shifts the pharmacological profile of the steroid. While testosterone has a high androgenic-to-anabolic ratio, the removal of the C19 methyl group (creating compounds like Nandrolone) **decreases androgenic activity** while maintaining or enhancing **anabolic activity**. This makes 19-nor derivatives useful in clinical scenarios where muscle building is required with fewer virilizing side effects. **2. Analysis of Incorrect Options:** * **Option A (Adding an alkyl group at C17):** This modification (e.g., 17α-alkylation as seen in Methyltestosterone) is primarily done to make the steroid **orally active** by preventing first-pass hepatic metabolism. It does not decrease androgenic activity; rather, it often increases the risk of hepatotoxicity. * **Option C (Adding a methyl group at C18):** C18 is the methyl group attached to C13. Modifications here are less common in standard androgenic pharmacology and do not define the 19-nortestosterone class. * **Option D (Substituting a chlorine at C21):** Halogenation (like adding chlorine or fluorine) is a common modification in **corticosteroids** (to increase potency) or specific progestins, but it is not the defining feature that reduces androgenicity in the 19-nortestosterone nucleus. **3. High-Yield Clinical Pearls for NEET-PG:** * **Nandrolone Decanoate:** The prototype 19-nortestosterone derivative; used for refractory anemias and catabolic states. * **Progestogenic Activity:** 19-nor compounds (like Norethindrone) often possess significant progestogenic activity, which is why they are widely used in **Oral Contraceptive Pills (OCPs)**. * **Anabolic Steroids:** These are designed to maximize the anabolic-to-androgenic ratio. Remember: No steroid is "purely" anabolic; all retain some androgenic potential.

Question 174: Which drug is used in the management of renal osteodystrophy?

A. Vitamin D
B. Calcitriol
C. Calcifediol
D. All of the above (Correct Answer)

Explanation: **Explanation:** Renal osteodystrophy is a complex bone disorder occurring in chronic kidney disease (CKD) due to the kidney's inability to activate Vitamin D and excrete phosphate. The core pathophysiology involves a deficiency of **1-alpha-hydroxylase**, the enzyme responsible for converting Calcifediol into the active form, Calcitriol. **Why "All of the above" is correct:** Management aims to maintain calcium levels and suppress secondary hyperparathyroidism. * **Calcitriol (1,25-dihydroxyvitamin D3):** This is the active form of Vitamin D. Since the failing kidney cannot perform 1-alpha-hydroxylation, providing the active form directly is the most physiological approach to bypass the renal defect. * **Calcifediol (25-hydroxyvitamin D3):** While it requires renal activation, high doses of Calcifediol can still be used in early stages of CKD or to correct underlying nutritional deficiency. * **Vitamin D (Ergocalciferol/Cholecalciferol):** Native Vitamin D is often supplemented to ensure the liver has enough substrate to produce Calcifediol, maintaining overall Vitamin D stores. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Calcitriol is generally preferred in advanced CKD because it does not require renal activation. * **Alfacalcidol:** Another frequently asked prodrug; it is 1-alpha-hydroxyvitamin D3. It requires **hepatic** activation but bypasses the **renal** step, making it highly effective in renal failure. * **Cinacalcet:** A calcimimetic often used alongside Vitamin D analogs to further suppress Parathyroid Hormone (PTH) by increasing the sensitivity of calcium-sensing receptors. * **Phosphate Binders:** (e.g., Sevelamer, Calcium Acetate) are essential adjuncts to prevent hyperphosphatemia, which worsens bone loss.

Question 175: Which of the following agents is NOT used in the treatment of hypercalcemia?

A. Gallium nitrate
B. Plicamycin
C. Etidronate (Correct Answer)
D. Rizol

Explanation: **Explanation:** The management of hypercalcemia focuses on inhibiting bone resorption and increasing renal calcium excretion. **Why Etidronate is the correct answer:** While Etidronate is a first-generation bisphosphonate, it is **not** typically used in the acute management of hypercalcemia. Its primary drawback is that it inhibits bone mineralization (osteoid calcification) alongside resorption, which can lead to osteomalacia with prolonged use. In clinical practice, more potent nitrogen-containing bisphosphonates like **Zoledronate** or **Pamidronate** are preferred because they effectively inhibit osteoclasts without impairing mineralization. **Analysis of other options:** * **Gallium Nitrate (A):** It inhibits bone resorption by reducing the solubility of hydroxyapatite crystals and inhibiting the osteoclast ATP-dependent proton pump. It is highly effective in cancer-related hypercalcemia but is limited by nephrotoxicity. * **Plicamycin (B):** Also known as Mithramycin, this cytotoxic antibiotic inhibits osteoclast RNA synthesis. It is a potent hypocalcemic agent used in refractory cases, though its use is restricted due to liver, kidney, and bone marrow toxicity. * **Rizol (D):** This is a typographical/brand variation often associated with **Risedronate** (a potent third-generation bisphosphonate) or used in some contexts to refer to specific formulations used in bone metabolism. Risedronate is a standard treatment for hypercalcemia of malignancy and Paget’s disease. **NEET-PG High-Yield Pearls:** 1. **Drug of Choice (DOC):** For acute severe hypercalcemia, the initial step is **aggressive IV hydration with Normal Saline**, followed by **IV Loop diuretics** (Furosemide) to promote calciuresis. 2. **Bisphosphonate of Choice:** **Zoledronate** is the most potent and preferred bisphosphonate for hypercalcemia of malignancy. 3. **Calcitonin:** Used for rapid (but short-lived) reduction of calcium; it exhibits tachyphylaxis (rapidly diminishing effect). 4. **Cinacalcet:** A calcimimetic used specifically for hypercalcemia in parathyroid carcinoma or secondary hyperparathyroidism.

Question 176: A 48-year-old woman presents with vulval pruritus. On examination, there is erythema of the external genitalia. She is a known diabetic for 10 years. Her HbA1c level reduced to 6.6% from a previous value of 7.8% four months ago. What medication is most probably responsible for her symptoms?

A. Sitagliptin
B. Canagliflozin (Correct Answer)
C. Acarbose
D. Exenatide

Explanation: ### Explanation **Correct Answer: B. Canagliflozin** **Mechanism and Clinical Correlation:** The patient is presenting with symptoms of **Vulvovaginal Candidiasis** (vulval pruritus and erythema), a classic side effect of **SGLT-2 inhibitors** like Canagliflozin. SGLT-2 inhibitors work by inhibiting glucose reabsorption in the proximal convoluted tubule of the kidney, leading to **therapeutic glucosuria**. While this effectively lowers HbA1c (as seen in this patient), the increased concentration of glucose in the urinary tract provides a rich medium for the growth of fungi and bacteria. This significantly increases the risk of genital mycotic infections (candidiasis) and urinary tract infections (UTIs). **Analysis of Incorrect Options:** * **A. Sitagliptin (DPP-4 Inhibitor):** These drugs are weight-neutral and generally well-tolerated. Their most characteristic side effects include nasopharyngitis and a rare risk of pancreatitis, but they do not cause glucosuria or genital infections. * **C. Acarbose (Alpha-glucosidase Inhibitor):** This drug acts locally in the GI tract to delay carbohydrate absorption. Its primary side effects are gastrointestinal (flatulence, diarrhea, abdominal bloating), not genitourinary. * **D. Exenatide (GLP-1 Agonist):** These injectable drugs cause delayed gastric emptying and weight loss. Common side effects include nausea, vomiting, and a risk of pancreatitis, but not mycotic infections. **High-Yield Clinical Pearls for NEET-PG:** * **SGLT-2 Inhibitors ("-gliflozins"):** Associated with weight loss, blood pressure reduction, and cardio-renal protection. * **Key Side Effects:** Genital mycotic infections (most common), UTIs, osmotic diuresis (hypotension/dehydration), and a rare but serious risk of **Euglycemic Diabetic Ketoacidosis (eDKA)**. * **Fournier’s Gangrene:** A rare, life-threatening necrotizing fasciitis of the perineum associated with SGLT-2 inhibitor use.

Question 177: Which steroid has the least mineralocorticoid activity?

A. Aldosterone
B. Deoxycorticosterone acetate (DOCA)
C. Methylprednisolone (Correct Answer)
D. Hydrocortisone

Explanation: **Explanation:** The correct answer is **Methylprednisolone**. The classification of corticosteroids is based on their relative **glucocorticoid** (anti-inflammatory) and **mineralocorticoid** (salt-retaining) potencies. Glucocorticoids exert their mineralocorticoid effects by binding to aldosterone receptors in the renal distal tubules, leading to sodium retention and potassium excretion. * **Methylprednisolone:** This is a synthetic intermediate-acting glucocorticoid. It has been chemically modified to enhance anti-inflammatory potency while significantly reducing mineralocorticoid activity. Its salt-retaining potency is near zero (0.5 compared to Hydrocortisone's 1), making it the correct choice among the options. **Analysis of Incorrect Options:** * **Aldosterone:** The primary endogenous mineralocorticoid. It has maximal salt-retaining activity and negligible anti-inflammatory effects. * **Deoxycorticosterone acetate (DOCA):** A precursor of aldosterone. It is a pure mineralocorticoid used experimentally to induce hypertension; it lacks glucocorticoid activity. * **Hydrocortisone (Cortisol):** The main endogenous glucocorticoid. It possesses significant mineralocorticoid activity (ratio of 1:1). It is often avoided in patients where fluid retention is a concern (e.g., heart failure or hypertension). **NEET-PG High-Yield Pearls:** * **Dexamethasone & Betamethasone:** These are long-acting steroids with **zero** mineralocorticoid activity. If they were an option, they would be "less" than methylprednisolone. * **Fludrocortisone:** A synthetic steroid with the highest mineralocorticoid-to-glucocorticoid ratio used clinically (primarily for Addison’s disease). * **Mnemonic for Potency (Least to Most):** **C**ortisol < **P**rednisolone < **M**ethylprednisolone < **D**examethasone (**C**an **P**eter **M**ake **D**inner).

Question 178: Which of the following are uses of danazol?

A. Endometriosis
B. Menorrhagia
C. Hereditary angioneurotic edema
D. All of the above (Correct Answer)

Explanation: **Explanation:** **Danazol** is a synthetic ethisterone derivative with a complex pharmacological profile. It acts as a **weak androgen** and a **gonadotropin inhibitor**, creating a "pseudo-menopausal" state by suppressing the pituitary-ovarian axis (inhibiting LH and FSH surges). **Why "All of the Above" is Correct:** 1. **Endometriosis (Option A):** This is the primary clinical use. Danazol causes atrophy of ectopic endometrial tissue by inhibiting steroidogenesis and creating a hypoestrogenic, hyperandrogenic environment. 2. **Menorrhagia (Option B):** By suppressing the endometrial lining and inducing amenorrhea, it is effective in reducing heavy menstrual bleeding, particularly when associated with fibroids or dysfunctional uterine bleeding. 3. **Hereditary Angioneurotic Edema (HANE) (Option C):** This is a high-yield indication. Danazol increases the hepatic synthesis of the **C1 esterase inhibitor** protein, which is deficient in patients with HANE, thereby preventing attacks. **Clinical Pearls for NEET-PG:** * **Mechanism:** It is a "selective pituitary gonadotropin inhibitor" and also directly inhibits several enzymes involved in adrenal and gonadal steroidogenesis. * **Side Effects:** Due to its androgenic nature, it commonly causes **weight gain, acne, hirsutism, deepening of the voice, and decreased breast size.** * **Contraindications:** It should be avoided in pregnancy (teratogenic—causes virilization of female fetuses) and in patients with significant hepatic dysfunction. * **Other Uses:** It is occasionally used in **Fibrocystic Breast Disease** and **Immune Thrombocytopenic Purpura (ITP)**.

Question 179: Paricalcitol is FDA-approved for which of the following conditions?

A. Rickets
B. Osteomalacia
C. Primary hyperparathyroidism
D. Secondary hyperparathyroidism (Correct Answer)

Explanation: ### Explanation **Correct Option: D. Secondary hyperparathyroidism** **Mechanism and Rationale:** Paricalcitol is a **synthetic Vitamin D analog** (specifically a calcitriol analog). Its clinical utility lies in its **selective** action: it effectively suppresses the synthesis and secretion of Parathyroid Hormone (PTH) by binding to Vitamin D receptors (VDR) in the parathyroid gland, but it has significantly **less effect on intestinal calcium and phosphorus absorption** compared to calcitriol. In patients with **Chronic Kidney Disease (CKD)**, phosphate retention and low calcitriol levels lead to **Secondary Hyperparathyroidism**. Paricalcitol is FDA-approved to treat and prevent this condition because it lowers PTH levels without causing the significant hypercalcemia or hyperphosphatemia often seen with non-selective Vitamin D therapy. **Analysis of Incorrect Options:** * **A & B (Rickets and Osteomalacia):** These conditions are typically treated with nutritional Vitamin D (Ergocalciferol/Cholecalciferol) or active Vitamin D (Calcitriol). Paricalcitol is not used here because these conditions require the restoration of calcium/phosphate homeostasis, whereas Paricalcitol is designed to avoid affecting those minerals. * **C (Primary Hyperparathyroidism):** This is usually caused by a parathyroid adenoma or hyperplasia and is primarily managed surgically (parathyroidectomy) or with Calcimimetics (e.g., Cinacalcet). **NEET-PG High-Yield Pearls:** * **Selective VDR Activators (sVDRA):** Paricalcitol and Doxercalciferol are the two main analogs used to target the parathyroid gland while sparing the gut. * **Clinical Advantage:** The "low calcemic potential" makes Paricalcitol ideal for CKD patients who are at risk of vascular calcification from high calcium-phosphate products. * **Other Vitamin D Analogs:** * **Calcipotriene/Calcipotriol:** Used topically for Psoriasis. * **Doxercalciferol:** A prodrug converted to 1,25-dihydroxyvitamin D2, also used for secondary hyperparathyroidism.

Question 180: Which of the following is not a starting criterion for sulfonylurea therapy?

A. Total pancreatectomy (Correct Answer)
B. Non-insulin-dependent diabetes mellitus (NIDDM)
C. Diabetes diagnosed after 60 years of age
D. None of the above

Explanation: ### Explanation **1. Why "Total Pancreatectomy" is the Correct Answer:** Sulfonylureas (e.g., Glibenclamide, Glimepiride) are **insulin secretagogues** [1], [3]. Their primary mechanism of action involves binding to the SUR1 subunit of ATP-sensitive potassium channels on the **pancreatic beta cells** [1], [3]. This leads to cell depolarization, calcium influx, and the subsequent release of pre-formed insulin [3]. In a patient who has undergone a **total pancreatectomy**, there are no functional beta cells remaining. Since sulfonylureas require endogenous insulin stores to function, they are absolutely ineffective and contraindicated in this scenario. These patients have "surgical diabetes" and require lifelong exogenous insulin therapy. **2. Analysis of Incorrect Options:** * **B. Non-insulin-dependent diabetes mellitus (NIDDM):** This is the primary indication for sulfonylureas [1]. In Type 2 DM, beta cells are still functional but often sluggish; sulfonylureas help "kickstart" insulin secretion. * **C. Diabetes diagnosed after 40-60 years of age:** Sulfonylureas are most effective in patients who develop diabetes later in life (maturity-onset). A diagnosis after age 40, a duration of disease less than 5 years, and a daily insulin requirement of less than 40 units are traditional predictors of a good response to sulfonylureas. **3. NEET-PG High-Yield Pearls:** * **Mechanism:** Blocks $K_{ATP}$ channels $\rightarrow$ Depolarization $\rightarrow$ $Ca^{2+}$ influx $\rightarrow$ Insulin release [3]. * **Primary Side Effect:** Hypoglycemia (most common with Glyburide/Glibenclamide due to long half-life) and weight gain [2]. * **Disulfiram-like reaction:** Classically associated with first-generation sulfonylureas like **Chlorpropamide**. * **Failure Criteria:** "Primary failure" occurs if the drug never works; "Secondary failure" occurs when beta-cell function declines over years of treatment, eventually requiring insulin [1].

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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