Endocrine Pharmacology — MCQs

Endocrine Pharmacology Indian Medical PG Practice Questions and MCQs

Question 431: Which of the following is not used for the treatment of insulin-induced hypoglycemia?

A. Intravenous glucose
B. Glucagon
C. Adrenaline (Correct Answer)
D. Oral carbohydrates

Explanation: The primary goal in treating insulin-induced hypoglycemia is to rapidly restore blood glucose levels to prevent neuroglycopenia. **Why Adrenaline is the Correct Answer:** While adrenaline (epinephrine) does increase blood glucose via glycogenolysis and gluconeogenesis, it is **not used clinically** to treat insulin-induced hypoglycemia. Its potent cardiovascular effects—such as severe tachycardia, arrhythmias, and hypertension—make it dangerous, especially in diabetic patients who may have underlying coronary artery disease. Furthermore, more effective and safer alternatives exist. **Analysis of Other Options:** * **Intravenous Glucose (Option A):** This is the **treatment of choice** for severe hypoglycemia in an unconscious patient or a hospital setting (typically 25-50% Dextrose). It provides an immediate source of glucose [2]. * **Glucagon (Option B):** Used as a first-line emergency treatment for severe hypoglycemia when IV access is unavailable [2]. It works by mobilizing hepatic glycogen stores [1]. (Note: It is ineffective in starved patients or those with liver disease due to depleted glycogen [1]). * **Oral Carbohydrates (Option C):** This is the preferred treatment for **conscious patients** who can swallow safely (the "15-15 rule": 15g of fast-acting carbs, recheck in 15 minutes) [2]. **NEET-PG High-Yield Pearls:** * **Drug of Choice (Severe Hypoglycemia):** IV Dextrose (25% or 50%) [2]. * **Glucagon Limitation:** It does not work in Type 1 diabetics with prolonged fasting or alcohol-induced hypoglycemia (depleted glycogen) [1]. * **Beta-Blockers Warning:** They can mask the autonomic symptoms of hypoglycemia (tachycardia, tremors) and delay recovery by inhibiting glycogenolysis. Sweating is the only symptom not masked (mediated by cholinergic fibers).

Question 432: Which of the following is a ligand for peroxisome proliferation activating receptor (PPAR), a group of nuclear hormone receptors involved in the regulation of genes related to glucose and lipid metabolism?

A. Repaglinide
B. Voglibose
C. Exenatide
D. Rosiglitazone (Correct Answer)

Explanation: **Explanation:** **Rosiglitazone** belongs to the **Thiazolidinedione (TZD)** class of oral hypoglycemic agents. These drugs act as selective ligands for the **Peroxisome Proliferator-Activated Receptor-gamma (PPAR-γ)**, a nuclear receptor primarily located in adipose tissue, muscle, and liver. Upon activation, PPAR-γ modulates the transcription of genes involved in glucose and lipid metabolism, leading to increased expression of glucose transporters (GLUT-4) and decreased insulin resistance. This "insulin-sensitizing" effect is their hallmark mechanism. **Analysis of Incorrect Options:** * **A. Repaglinide:** A Meglitinide analog that acts as an insulin secretagogue. It works by closing ATP-sensitive K⁺ channels on pancreatic beta cells, similar to Sulfonylureas, but at a different binding site. * **B. Voglibose:** An Alpha-glucosidase inhibitor. It acts locally in the intestine to inhibit the enzyme responsible for breaking down complex carbohydrates, thereby delaying glucose absorption and reducing postprandial hyperglycemia. * **C. Exenatide:** A Glucagon-like peptide-1 (GLP-1) agonist (Incretin mimetic). It enhances glucose-dependent insulin secretion and suppresses glucagon release. **High-Yield Clinical Pearls for NEET-PG:** * **PPAR-α vs. PPAR-γ:** While TZDs (Rosiglitazone, Pioglitazone) act on **PPAR-γ**, Fibrates (e.g., Fenofibrate) act on **PPAR-α** to lower triglycerides. Saroglitazar is a dual PPAR-α/γ agonist. * **Side Effects of TZDs:** Weight gain, **fluid retention/edema** (contraindicated in NYHA Class III/IV heart failure), and increased risk of bone fractures. * **Pioglitazone** has been specifically associated with a potential risk of bladder cancer (though controversial) and improves lipid profiles better than Rosiglitazone.

Question 433: What is the anti-inflammatory action of cortisol due to?

A. Effect on lymphocytes
B. Effect on cytokines
C. Effect on enzymes
D. All of the above (Correct Answer)

Explanation: **Explanation:** Glucocorticoids like cortisol are the most potent anti-inflammatory and immunosuppressive agents because they act at multiple levels of the inflammatory cascade. 1. **Effect on Lymphocytes (Option A):** Cortisol causes a redistribution of lymphocytes from the vascular compartment to lymphoid tissue. It specifically inhibits T-cell proliferation and induces apoptosis in certain lymphocyte subsets, thereby suppressing cell-mediated immunity. 2. **Effect on Cytokines (Option B):** Cortisol inhibits the expression of genes encoding pro-inflammatory cytokines, most notably **IL-1, IL-2, IL-6, and TNF-α**. It also increases the synthesis of anti-inflammatory proteins like Annexin-1 (Lipocortin-1). 3. **Effect on Enzymes (Option C):** Cortisol inhibits **Phospholipase A2** (via Lipocortin), which prevents the release of arachidonic acid, the precursor for prostaglandins and leukotrienes. It also reduces the induction of **COX-2** (Cyclooxygenase-2) and **iNOS** (inducible Nitric Oxide Synthase). Since cortisol acts through all these mechanisms simultaneously, **Option D** is the correct answer. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism of Action:** Cortisol binds to cytoplasmic receptors (GR), translocates to the nucleus, and binds to **Glucocorticoid Response Elements (GRE)** to alter gene transcription. * **Hematological effects:** Cortisol increases RBCs, platelets, and Neutrophils (due to decreased margination), but **decreases** Lymphocytes, Eosinophils, Monocytes, and Basophils (**Mnemonic: "BEML" goes down**). * **Metabolic hallmark:** It promotes gluconeogenesis and has a "permissive action" on catecholamines (e.g., for lipolysis and bronchodilation).

Question 434: Which DPP-IV inhibitor can be used in renal failure?

A. Linagliptin (Correct Answer)
B. Sitagliptin
C. Vildagliptin
D. Saxagliptin

Explanation: **Explanation:** The correct answer is **Linagliptin**. **1. Why Linagliptin is correct:** The primary pharmacological distinction of Linagliptin among DPP-IV inhibitors is its route of elimination. Unlike most other gliptins, Linagliptin is primarily excreted via the **enterohepatic system (bile/feces)** rather than the kidneys. Approximately 90% of the drug is excreted unchanged in the feces. Therefore, it does not require dose adjustment in patients with any degree of renal impairment, making it the "gliptin of choice" for patients with chronic kidney disease (CKD). **2. Why the other options are incorrect:** * **Sitagliptin, Vildagliptin, and Saxagliptin:** These agents are predominantly excreted by the **kidneys**. In patients with renal failure, their clearance is reduced, leading to drug accumulation and increased risk of toxicity. While they *can* be used in renal failure, they require significant **dose reductions** based on the patient's Creatinine Clearance (CrCl). Linagliptin is unique because it is the only one that can be used at its standard dose (5 mg) regardless of renal function. **3. High-Yield Clinical Pearls for NEET-PG:** * **Saxagliptin Warning:** It is associated with an increased risk of hospitalization for **heart failure** (SAVOR-TIMI 53 trial). * **Vildagliptin:** It is the only common gliptin that requires twice-daily dosing and is associated with a risk of hepatotoxicity (monitor LFTs). * **DPP-IV Inhibitors Mechanism:** They inhibit the breakdown of GLP-1 and GIP, are weight-neutral, and carry a very low risk of hypoglycemia. * **Adverse Effect:** Always remember the association between DPP-IV inhibitors and **acute pancreatitis** and nasopharyngitis.

Question 435: Which of the following are inhalational insulins?

A. Afrezza
B. Exubera
C. Both (Correct Answer)
D. None

Explanation: Explanation: Inhalational insulin is a non-invasive alternative to subcutaneous injections, designed for rapid absorption through the extensive surface area of the alveolar-capillary membrane. 1. Exubera: This was the first-ever inhaled insulin (powdered form) approved by the FDA in 2006. It utilized a large inhaler device. However, it was withdrawn from the market in 2007 due to poor sales, its bulky design, and concerns regarding its long-term effect on pulmonary function. 2. Afrezza: Approved in 2014, Afrezza is a newer, technosphere-based dry powder human insulin [1]. It is delivered via a much smaller, palm-sized inhaler. It is a rapid-acting insulin, typically administered at the beginning of a meal [1]. Why "Both" is correct: Both Afrezza and Exubera are pharmacologically classified as inhalational insulins, regardless of their current commercial availability. High-Yield Clinical Pearls for NEET-PG: * Mechanism: Inhaled insulin mimics the rapid "first-phase" insulin release seen in non-diabetics. * Contraindications: It is strictly contraindicated in patients with chronic lung diseases such as COPD or Asthma due to the risk of acute bronchospasm. * Monitoring: Pulmonary Function Tests (PFTs), specifically FEV1, must be performed at baseline, after 6 months of therapy, and annually thereafter. * Smoking: It is not recommended in active smokers or those who have recently quit (less than 6 months).

Question 436: Which of the following is NOT a side effect of Zoledronic acid?

A. Flu-like symptoms
B. Osteonecrosis of the jaw
C. Dizziness
D. Constipation (Correct Answer)

Explanation: **Explanation:** Zoledronic acid is a potent, intravenous third-generation **nitrogen-containing bisphosphonate** used primarily for osteoporosis, Paget’s disease, and malignancy-associated hypercalcemia. **Why Constipation is the Correct Answer:** Zoledronic acid and other bisphosphonates are more commonly associated with **diarrhea** and abdominal pain rather than constipation. Gastrointestinal distress is a known class effect, though it is more pronounced with oral bisphosphonates (like Alendronate) due to direct mucosal irritation. **Analysis of Incorrect Options:** * **Flu-like symptoms (Option A):** This is the most common acute side effect of intravenous Zoledronic acid (occurring in up to 30% of patients). It is characterized by fever, myalgia, and arthralgia, typically occurring within 24–72 hours of the first infusion due to the release of pro-inflammatory cytokines. * **Osteonecrosis of the Jaw (ONJ) (Option B):** This is a rare but high-yield side effect associated with long-term, high-dose bisphosphonate therapy, especially in cancer patients. It involves the exposure of necrotic bone in the maxillofacial region. * **Dizziness (Option C):** Neurological symptoms, including dizziness and headache, are documented side effects following the systemic administration of potent bisphosphonates. **NEET-PG High-Yield Pearls:** 1. **Mechanism of Action:** Bisphosphonates are structural analogs of pyrophosphate. They concentrate in the bone matrix and inhibit **osteoclast-mediated bone resorption** by inhibiting the enzyme **Farnesyl pyrophosphate (FPP) synthase**. 2. **Renal Safety:** Zoledronic acid is contraindicated if **Creatinine Clearance (CrCl) is <35 mL/min** due to the risk of acute renal failure. 3. **Atypical Fractures:** Long-term use is linked to atypical subtrochanteric femur fractures. 4. **Ocular Side Effects:** Can cause uveitis and episcleritis.

Question 437: What is an agent of choice in acute hypercalcemia due to malignancy?

A. Calcitonin (Correct Answer)
B. Cholecalciferol
C. Teriparatide
D. Zoledronate

Explanation: **Explanation:** The management of acute hypercalcemia of malignancy depends on the severity and the speed of onset. **Why Calcitonin is the correct answer:** In the **acute** setting, **Calcitonin** is the agent of choice because it has the **fastest onset of action** (within 2–4 hours). It works by inhibiting osteoclast activity and increasing renal calcium excretion. While its effect is short-lived due to tachyphylaxis (loss of efficacy after 48 hours), it serves as a vital "bridge" until slower-acting agents take effect. **Analysis of Incorrect Options:** * **Cholecalciferol (Vitamin D3):** This is used to treat Vitamin D deficiency and hypocalcemia. Administering it in hypercalcemia would worsen the condition by increasing intestinal calcium absorption. * **Teriparatide:** This is a recombinant PTH analogue used for osteoporosis. It stimulates osteoblastic activity but also increases serum calcium; thus, it is contraindicated in hypercalcemia and bone malignancies. * **Zoledronate (Bisphosphonate):** While Zoledronate is the **most potent** and preferred drug for long-term management of hypercalcemia of malignancy, its onset of action is slow (24–72 hours). It is not the primary choice for immediate "acute" reduction. **NEET-PG High-Yield Pearls:** 1. **First-line management:** The very first step in treating severe hypercalcemia is **aggressive IV hydration** with Normal Saline (0.9% NaCl). 2. **Calcitonin:** Best for rapid reduction in the first 24–48 hours. 3. **Bisphosphonates (Zoledronate/Pamidronate):** Best for sustained control and the "drug of choice" for malignancy-associated hypercalcemia overall, but not for immediate acute action. 4. **Denosumab:** Used in cases refractory to bisphosphonates. 5. **Cinacalcet:** A calcimimetic used specifically for hypercalcemia due to parathyroid carcinoma.

Question 438: Centchroman is not used in which of the following conditions?

A. Prevention of pregnancy
B. Prevention of dysfunctional uterine bleeding
C. Polycystic ovarian syndrome (Correct Answer)
D. None of the above

Explanation: **Explanation:** **Centchroman (Ormeloxifene)** is a unique **Selective Estrogen Receptor Modulator (SERM)** developed in India (CDRI, Lucknow). Its primary mechanism involves antagonizing estrogen receptors in the uterus, which alters the cervical mucus and creates an asynchronous endometrium, making it hostile for implantation. 1. **Why Polycystic Ovarian Syndrome (PCOS) is the correct answer:** Centchroman is **not** used in the management of PCOS. The mainstay of pharmacological treatment for PCOS includes lifestyle modifications, combined oral contraceptives (to regulate cycles), anti-androgens (like Spironolactone), and insulin sensitizers (like Metformin). For infertility in PCOS, the SERM of choice is **Clomiphene citrate**, which acts on the hypothalamus to increase FSH/LH; Centchroman does not serve this purpose. 2. **Why other options are incorrect:** * **Prevention of Pregnancy:** This is the primary use of Centchroman (marketed as *Saheli*). It is a non-steroidal, once-a-week pill that prevents implantation without suppressing ovulation. * **Dysfunctional Uterine Bleeding (DUB):** Due to its potent anti-estrogenic effect on the endometrium, it is highly effective in reducing menstrual blood loss and is an approved treatment for DUB and menorrhagia. **High-Yield Clinical Pearls for NEET-PG:** * **Dosing Schedule:** For contraception, it is taken 30 mg twice weekly for the first 3 months, followed by once weekly. * **Side Effects:** The most common side effect is a **prolonged menstrual cycle** (delayed periods), which occurs in about 8% of users. * **Other Uses:** It is also used in the management of **Mastalgia** (breast pain) and fibroadenoma due to its anti-estrogenic action on breast tissue. * **Safety:** Being non-steroidal, it has no effect on lipid profile, blood pressure, or coagulation factors, making it safer than traditional OCPs.

Question 439: Osteoporosis in steroid-taking patients can be explained by all except which of the following mechanisms?

A. Decreased absorption of calcium from the gut
B. Increased excretion of calcium by the kidney
C. Decreased synthesis of vitamin D (Correct Answer)
D. Increased demineralization from bone

Explanation: Glucocorticoid-induced osteoporosis (GIOP) is the most common cause of secondary osteoporosis. The pathophysiology involves a multi-factorial reduction in bone mineral density, but it **does not involve decreased synthesis of Vitamin D.** ### Why Option C is Correct Glucocorticoids do not inhibit the synthesis of Vitamin D (cholecalciferol) in the skin or its subsequent hydroxylation in the liver and kidneys. Instead, they interfere with the **Vitamin D receptor (VDR) signaling** in the intestine, leading to resistance to Vitamin D's actions rather than a deficiency in its production. ### Why Other Options are Incorrect * **Option A (Decreased absorption):** Steroids directly antagonize Vitamin D-mediated calcium absorption in the gastrointestinal tract by downregulating calcium transport proteins (like Calbindin). * **Option B (Increased excretion):** Steroids inhibit calcium reabsorption in the renal tubules, leading to hypercalciuria. This negative calcium balance triggers a compensatory rise in Parathyroid Hormone (PTH), further accelerating bone loss. * **Option D (Increased demineralization):** Steroids have a dual effect on bone: they inhibit **osteoblasts** (decreasing bone formation) and stimulate **osteoclasts** (increasing bone resorption) by increasing the RANKL/OPG ratio. ### NEET-PG High-Yield Pearls * **First-line treatment for GIOP:** Bisphosphonates (e.g., Alendronate, Risedronate). * **Gold Standard for diagnosis:** DEXA scan (T-score ≤ -2.5). * **Key Mechanism:** Steroids increase the expression of **RANK-Ligand** and decrease **Osteoprotegerin (OPG)**, leading to increased osteoclastogenesis. * **Clinical Note:** Bone loss is most rapid in the first 6–12 months of steroid therapy; prophylaxis with Calcium and Vitamin D should start early.

Question 440: All of the following statements regarding iodides are true, except?

A. They make the gland less vascular.
B. They are useful in the treatment of thyrotoxic crisis.
C. Clinical benefit is seen within 10-14 days.
D. They are safe during pregnancy. (Correct Answer)

Explanation: ### Explanation The correct answer is **D (They are safe during pregnancy)** because iodides (such as Lugol’s iodine or Potassium Iodide) are **contraindicated** in pregnancy. They readily cross the placenta and can cause fetal goiter, which may lead to airway obstruction or hypothyroidism in the newborn. #### Analysis of Options: * **Option A (Less vascular):** Iodides inhibit the release of thyroid hormones and decrease the vascularity and size of the thyroid gland. This makes the gland firm and less prone to bleeding, which is why they are used preoperatively (7–10 days before surgery) for thyroidectomy. * **Option B (Thyrotoxic crisis):** Iodides are a mainstay in managing thyroid storm (thyrotoxic crisis). They provide the fastest onset of action among anti-thyroid drugs by acutely inhibiting the release of preformed thyroid hormones (the **Wolff-Chaikoff effect**). * **Option C (Clinical benefit in 10-14 days):** The maximum effect of iodides is typically seen within 10–14 days. However, their effect is transient; after this period, the gland "escapes" from the inhibition, and hyperthyroidism may worsen. #### High-Yield Clinical Pearls for NEET-PG: * **Wolff-Chaikoff Effect:** The phenomenon where high concentrations of iodine acutely inhibit thyroid hormone synthesis and release. * **Jod-Basedow Phenomenon:** The opposite effect, where iodine administration induces hyperthyroidism in patients with underlying multinodular goiter. * **Pre-operative use:** Iodides are given 10 days before surgery to decrease vascularity (making the gland "shrunken and firm"). * **Order of administration:** In thyroid storm, always give **Propylthiouracil (PTU)** at least 1 hour *before* giving Iodides to prevent the iodine from being used as a substrate for new hormone synthesis.

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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