Endocrine Pharmacology Practice Questions

Q: 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?

Rosiglitazone. **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.

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

Linagliptin. **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.

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

Constipation. **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.

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

Calcitonin. **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.

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

Polycystic ovarian syndrome. **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.

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

Decreased synthesis of vitamin D. 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.

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

They are safe during pregnancy.. ### 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.

Q: Which one of the following statements regarding Centchroman is not true?

It is a synthetic hormone. **Explanation:** Centchroman (Ormeloxifene) is a unique pharmacological agent used in contraception and the management of dysfunctional uterine bleeding. **Why Option C is the correct answer (The False Statement):** Centchroman is **not a hormone**. It is a **Non-Steroidal**, Selective Estrogen Receptor Modulator (SERM). Unlike traditional oral contraceptive pills (OCPs) that contain synthetic estrogen and progesterone, Centchroman is a chemical derivative (benzopyran) that modulates estrogen receptors without the metabolic side effects associated with steroid hormones. **Analysis of other options:** * **Option A (It is estrogenic):** This is technically true in a tissue-specific context. As a SERM, it has **weak estrogenic** effects on the vagina and bones but potent **anti-estrogenic** effects on the uterus and breasts. * **Option B (Acts on the endometrium):** True. Its primary contraceptive mechanism is preventing the normal preparation of the endometrium for implantation. It creates an "asynchrony" between ovulation and endometrial receptivity, making the environment hostile for a fertilized ovum. * **Option D (Developed in India):** True. It was developed by the **Central Drug Research Institute (CDRI), Lucknow**. It is marketed under the brand name **Saheli** and is included in the National Family Planning Program as **Chhaya**. **High-Yield Clinical Pearls for NEET-PG:** * **Dosage Schedule:** 30 mg twice weekly for the first 3 months, followed by once weekly (the "3-month loading dose" rule). * **Side Effects:** The most common side effect is a **delay in the menstrual cycle** (prolonged cycles), which occurs in about 8% of users. * **Contraindications:** Polycystic Ovarian Syndrome (PCOS), cervical dysplasia, and recent history of jaundice or liver disease. * **Benefit:** It does not suppress ovulation in most cycles and has no effect on lactation, making it an excellent choice for postpartum contraception.

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

Nephrogenic diabetes insipidus. **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 1

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?

Accepted Answer

Rosiglitazone

Answer

Repaglinide

Answer

Voglibose

Answer

Exenatide

Question 2

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

Accepted Answer

Linagliptin

Answer

Sitagliptin

Answer

Vildagliptin

Answer

Saxagliptin

Question 3

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

Accepted Answer

Constipation

Answer

Flu-like symptoms

Answer

Osteonecrosis of the jaw

Answer

Dizziness

Question 4

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

Accepted Answer

Calcitonin

Answer

Cholecalciferol

Answer

Teriparatide

Answer

Zoledronate

Question 5

Centchroman is not used in which of the following conditions?

Accepted Answer

Polycystic ovarian syndrome

Answer

Prevention of pregnancy

Answer

Prevention of dysfunctional uterine bleeding

Answer

None of the above

Question 6

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

Accepted Answer

Decreased synthesis of vitamin D

Answer

Decreased absorption of calcium from the gut

Answer

Increased excretion of calcium by the kidney

Answer

Increased demineralization from bone

Question 7

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

Accepted Answer

They are safe during pregnancy.

Answer

They make the gland less vascular.

Answer

They are useful in the treatment of thyrotoxic crisis.

Answer

Clinical benefit is seen within 10-14 days.

Question 8

Which one of the following statements regarding Centchroman is not true?

Accepted Answer

It is a synthetic hormone

Answer

It is estrogenic

Answer

It acts on the endometrium

Answer

It is developed in India

Question 9

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

Accepted Answer

Increased annexin synthesis

Answer

Increased IL-2 production

Answer

Decreased arachidonic acid release

Answer

Decreased CRP levels

Question 10

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

Accepted Answer

Nephrogenic diabetes insipidus

Answer

Neurogenic diabetes insipidus

Answer

Nocturnal enuresis (bed wetting) in children

Answer

Bleeding due to mild hemophilia A

Endocrine Pharmacology — MCQs

Endocrine Pharmacology — MCQs

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