Endocrine Pharmacology — MCQs

Endocrine Pharmacology Indian Medical PG Practice Questions and MCQs

Question 451: Which of the following is NOT a uricosuric drug?

A. Allopurinol (Correct Answer)
B. Probenecid
C. Sulphinpyrazone
D. Benzbromarone

Explanation: The management of chronic gout involves two distinct pharmacological strategies: decreasing the production of uric acid or increasing its excretion. [2] **Why Allopurinol is the correct answer:** Allopurinol is a **Xanthine Oxidase Inhibitor**, not a uricosuric. It acts by inhibiting the enzyme responsible for converting hypoxanthine to xanthine and xanthine to uric acid. [1] By reducing the synthesis of uric acid, it lowers plasma urate levels. It is the preferred drug for "over-producers" of uric acid and patients with renal stones. [3] **Why the other options are incorrect:** * **Probenecid:** A classic uricosuric agent. It inhibits the **URAT-1** transporter in the proximal convoluted tubule, preventing the reabsorption of filtered uric acid, thereby increasing its urinary excretion. * **Sulphinpyrazone:** A derivative of phenylbutazone that acts similarly to probenecid by inhibiting renal tubular reabsorption of uric acid. * **Benzbromarone:** A potent uricosuric drug that inhibits the URAT-1 transporter. [4] It is often used in patients who are intolerant to allopurinol or have refractory gout. [4] **NEET-PG High-Yield Pearls:** * **Febuxostat:** A newer, non-purine selective inhibitor of xanthine oxidase, safer in mild-to-moderate renal impairment. * **Lesinurad:** A newer URAT-1 inhibitor used as adjunct therapy. * **Drug Interaction:** Allopurinol inhibits the metabolism of **6-Mercaptopurine** and **Azathioprine**. If co-administered, the dose of these cytotoxic drugs must be reduced to 1/4th to avoid toxicity. * **Acute Gout:** Never start uricosurics or allopurinol during an acute attack, as sudden fluctuations in urate levels can worsen the inflammation. [2] Use NSAIDs, Colchicine, or Steroids instead. [5]

Question 452: Thiazolidinedione is associated with an increased risk of?

A. Heart failure (Correct Answer)
B. Pulmonary fibrosis
C. Myocarditis
D. Renal dysfunction

Explanation: **Explanation:** **Thiazolidinediones (TZDs)**, such as Pioglitazone and Rosiglitazone, are PPAR-γ (Peroxisome Proliferator-Activated Receptor gamma) agonists. The primary mechanism behind the increased risk of **Heart Failure** is their effect on the kidneys. Activation of PPAR-γ receptors in the collecting ducts leads to increased sodium and water reabsorption. This results in **fluid retention and peripheral edema**, which can precipitate or exacerbate congestive heart failure (CHF) in susceptible patients. Consequently, TZDs are contraindicated in patients with NYHA Class III or IV heart failure. **Analysis of Incorrect Options:** * **B. Pulmonary fibrosis:** This is a classic side effect of drugs like Amiodarone, Bleomycin, and Methotrexate, but it is not associated with TZDs. * **C. Myocarditis:** This is an inflammatory condition of the heart muscle, often viral or drug-induced (e.g., Clozapine), but not a known complication of TZD therapy. * **D. Renal dysfunction:** TZDs do not typically cause renal failure; in fact, they are generally safe to use in patients with mild-to-moderate renal impairment (unlike Metformin), though the associated fluid retention must be monitored. **High-Yield Clinical Pearls for NEET-PG:** * **Pioglitazone & Bladder Cancer:** Long-term use of Pioglitazone has been linked to an increased risk of urinary bladder cancer. * **Bone Health:** TZDs increase the risk of **osteoporosis and fractures**, particularly in postmenopausal women, by diverting mesenchymal stem cells away from osteoblast formation toward adipocyte formation. * **Weight Gain:** TZDs typically cause weight gain due to both fluid retention and the proliferation of subcutaneous fat. * **Rosiglitazone:** Historically restricted due to concerns regarding increased risk of myocardial infarction (though restrictions were later eased).

Question 453: Bremelanotide is used for which of the following conditions?

A. Hypoactive sexual desire disorder in women (Correct Answer)
B. Lower urinary tract symptoms
C. Prostate cancer
D. Metastatic renal cancer

Explanation: **Explanation:** **Bremelanotide** is a novel therapeutic agent approved for the treatment of generalized **Hypoactive Sexual Desire Disorder (HSDD)** in premenopausal women. **1. Why Option A is Correct:** Bremelanotide is a non-selective **melanocortin receptor agonist**. It primarily activates the **MC3R and MC4R** receptors in the central nervous system. While the exact mechanism in HSDD is not fully elucidated, it is believed to modulate brain pathways involved in sexual desire and arousal by increasing dopamine release in the medial preoptic area of the hypothalamus. Unlike Flibanserin (another drug for HSDD), Bremelanotide is administered via **subcutaneous injection** on an as-needed basis (at least 45 minutes before sexual activity). **2. Why the Other Options are Incorrect:** * **Option B (LUTS):** Lower urinary tract symptoms are typically managed with $\alpha_1$-blockers (e.g., Tamsulosin) or 5-$\alpha$ reductase inhibitors (e.g., Finasteride). * **Option C (Prostate Cancer):** This is treated with GnRH agonists (Leuprolide), GnRH antagonists (Degarelix), or anti-androgens (Flutamide). * **Option D (Metastatic Renal Cancer):** This is managed with tyrosine kinase inhibitors (Sunitinib), mTOR inhibitors (Everolimus), or immunotherapy (Nivolumab). **High-Yield Clinical Pearls for NEET-PG:** * **Route:** Subcutaneous (autoinjector). * **Side Effects:** The most common side effect is **nausea**. It can also cause a transient increase in blood pressure and focal **hyperpigmentation** (due to MC1R activation). * **Contraindication:** Uncontrolled hypertension or known cardiovascular disease. * **Comparison:** **Flibanserin** (oral) is a 5-HT1A agonist/5-HT2A antagonist also used for HSDD but requires daily dosing and carries a black box warning regarding alcohol consumption.

Question 454: Which of the following drugs or conditions does not cause hyperprolactinemia?

A. Levodopa
B. Bromocriptine (Correct Answer)
C. Chlordiazepoxide
D. Pituitary tumour

Explanation: **Explanation** The regulation of prolactin is unique because it is under tonic **inhibitory** control by the hypothalamus. The primary prolactin-inhibiting factor (PIF) is **Dopamine**, which acts on **D2 receptors** in the anterior pituitary to suppress prolactin release. **Why Bromocriptine is the correct answer:** Bromocriptine is a potent **D2-receptor agonist**. By mimicking the action of dopamine, it directly inhibits the secretion of prolactin. Therefore, it is used therapeutically to treat hyperprolactinemia and prolactinomas, rather than causing the condition. **Analysis of Incorrect Options:** * **Levodopa:** While Levodopa is a precursor to dopamine, its effect on prolactin is transient and inconsistent in clinical practice. However, in the context of this specific question, it is often grouped with drugs that *reduce* prolactin. *Note: If this were a "multiple correct" style, Levodopa would also not cause hyperprolactinemia. However, Bromocriptine is the definitive pharmacological antagonist used for this purpose.* * **Chlordiazepoxide:** This is a benzodiazepine. Many psychotropic drugs (including certain benzodiazepines and especially antipsychotics) can cause hyperprolactinemia by interfering with central dopaminergic pathways. * **Pituitary Tumour:** A **Prolactinoma** is the most common secretory tumor of the pituitary gland and is a classic pathological cause of significantly elevated prolactin levels. **NEET-PG High-Yield Pearls:** * **Drug-Induced Hyperprolactinemia:** Most commonly caused by **Antipsychotics** (e.g., Risperidone, Haloperidol) and **Metoclopramide** due to D2-receptor blockade. * **Cabergoline:** Currently the drug of choice for prolactinomas due to its higher efficacy and longer half-life compared to Bromocriptine. * **Clinical Presentation:** In females, it presents as the **Amenorrhea-Galactorrhea syndrome**; in males, it causes decreased libido, erectile dysfunction, and gynecomastia.

Question 455: Hypoglycemia may occur in a patient taking insulin and undergoing a surgical extraction when?

A. The extraction is performed on an empty stomach. (Correct Answer)
B. The patient has an active infection.
C. The patient has not exercised in the morning.
D. The patient consumed breakfast before the extraction.

Explanation: **Explanation:** The core principle in managing diabetic patients undergoing surgery is maintaining the balance between **insulin dosage** and **caloric intake**. **1. Why Option A is Correct:** Insulin is an anabolic hormone that lowers blood glucose. If a patient takes their usual dose of insulin but remains **NPO (nothing by mouth)** or undergoes a procedure on an empty stomach, there is no exogenous glucose to counteract the insulin's effect [1]. The surgical stress itself can also be unpredictable, but the lack of food intake is the primary driver for **iatrogenic hypoglycemia** [4]. In clinical practice, insulin doses are typically reduced or glucose infusions are started if a patient must remain fasted for surgery [1]. **2. Why the other options are incorrect:** * **Option B (Active Infection):** Infection and inflammation trigger the release of "counter-regulatory hormones" like cortisol and catecholamines. These hormones induce insulin resistance and gluconeogenesis, typically leading to **hyperglycemia**, not hypoglycemia. * **Option C (No Exercise):** Exercise increases glucose uptake by muscles (via GLUT-4 translocation). A lack of exercise would generally result in higher blood sugar levels compared to an active state. * **Option D (Consumed Breakfast):** Consuming a meal provides a glucose load that counteracts the hypoglycemic effect of insulin, making hypoglycemia less likely. **High-Yield NEET-PG Pearls:** * **The "Rule of 15":** For conscious patients with hypoglycemia, give 15g of rapid-acting carbs and recheck in 15 minutes [3]. * **Drug Interactions:** Beta-blockers (e.g., Propranolol) can mask the autonomic symptoms of hypoglycemia (tachycardia, tremors), except for **sweating** (which is mediated by cholinergic fibers) [2]. * **Surgery Timing:** Diabetic patients should ideally be scheduled as the **first case** in the morning to minimize the duration of fasting and simplify glycemic control.

Question 456: All of the following drugs alter calcium hemostasis except?

A. Fluoride
B. Indomethacin (Correct Answer)
C. Mithramycin
D. Thiazides

Explanation: ### Explanation The correct answer is **Indomethacin (Option B)**. **1. Why Indomethacin is the correct answer:** Indomethacin is a non-steroidal anti-inflammatory drug (NSAID) that acts primarily by inhibiting the enzyme cyclooxygenase (COX). While it is used clinically to treat hypercalcemia associated with certain malignancies (by inhibiting prostaglandin-mediated bone resorption), it does not directly alter physiological calcium homeostasis or serum calcium levels in a healthy individual. It lacks a direct mechanism of action on the parathyroid hormone (PTH), Vitamin D, or renal calcium handling. **2. Why the other options are incorrect:** * **Fluoride (Option A):** Fluoride is a potent stimulator of osteoblasts. In high doses (toxic levels), it can lead to hypocalcemia by causing rapid deposition of calcium into the bone (osteosclerosis) and can interfere with bone mineralization. * **Mithramycin (Plicamycin) (Option C):** This is a cytotoxic antibiotic that inhibits osteoclast activity. It is highly effective in lowering serum calcium levels and is specifically used in the emergency management of severe hypercalcemia of malignancy. * **Thiazides (Option D):** Thiazide diuretics (e.g., Hydrochlorothiazide) increase calcium reabsorption in the distal convoluted tubule of the kidney. This leads to **hypocalciuria** (decreased urine calcium) and can potentially cause mild **hypercalcemia**. **Clinical Pearls for NEET-PG:** * **Thiazides vs. Loop Diuretics:** Remember the mnemonic: *"Thiazides save calcium, Loops lose calcium."* Loop diuretics (Furosemide) are used to treat hypercalcemia because they promote calcium excretion. * **Mithramycin:** Though effective for hypercalcemia, its use is limited by significant toxicity (thrombocytopenia, hepatic, and renal toxicity). * **Bisphosphonates:** These are currently the first-line drugs for long-term management of hypercalcemia of malignancy.

Question 457: Clomiphene citrate is:

A. Antiandrogen
B. Synthetic steroid
C. Antiestrogen (Correct Answer)
D. GnRH analogue

Explanation: **Explanation:** **Clomiphene Citrate** is a **Selective Estrogen Receptor Modulator (SERM)**. Its primary mechanism of action is acting as a competitive **antiestrogen** at the level of the hypothalamus and the anterior pituitary. 1. **Why Option C is Correct:** By blocking estrogen receptors in the hypothalamus, clomiphene interferes with the negative feedback inhibition normally exerted by endogenous estrogens. This leads to an increase in the pulsatile secretion of **GnRH**, which subsequently stimulates the pituitary to release more **FSH and LH**. The surge in FSH promotes follicular growth, making it the first-line drug for **ovulation induction** in patients with polycystic ovary syndrome (PCOS) who have an intact hypothalamic-pituitary-ovarian axis. 2. **Why Other Options are Incorrect:** * **A. Antiandrogen:** These drugs (e.g., Flutamide, Spironolactone) block androgen receptors or inhibit androgen synthesis; clomiphene does not affect androgen receptors. * **B. Synthetic Steroid:** Clomiphene is a **non-steroidal** triphenylethylene derivative. * **D. GnRH Analogue:** These are peptides (e.g., Leuprolide, Goserelin) that act directly on GnRH receptors; clomiphene acts upstream by modulating estrogen feedback. **High-Yield Clinical Pearls for NEET-PG:** * **Indication:** Drug of choice for infertility due to anovulation (PCOS). * **Side Effects:** Multiple pregnancies (twins), ovarian hyperstimulation syndrome (OHSS), and hot flashes. * **Requirement:** It requires a functional hypothalamic-pituitary axis to work (ineffective in Sheehan’s syndrome or primary ovarian failure). * **Key Distinction:** While it is an antagonist at the hypothalamus, it can have weak agonist effects in other tissues.

Question 458: Which of the following is a side effect of Dapagliflozin?

A. Increased weight loss
B. Polyuria
C. Increased incidence of urinary tract infections
D. All the above (Correct Answer)

Explanation: **Explanation:** **Dapagliflozin** belongs to the **SGLT-2 (Sodium-Glucose Co-transporter 2) inhibitor** class of oral hypoglycemic agents. These drugs act on the proximal convoluted tubule of the kidney to inhibit glucose reabsorption, leading to **glycosuria** (excretion of glucose in the urine). **Why Option D is correct:** The mechanism of inducing glycosuria directly leads to the side effects mentioned: * **Increased Weight Loss:** Since glucose is excreted rather than stored or metabolized, there is a significant loss of calories (approx. 200–300 kcal/day), leading to weight reduction. * **Polyuria:** Glucose acts as an osmotic diuretic. Its presence in the renal tubule pulls water with it, increasing urine volume and frequency. * **Urinary Tract Infections (UTIs):** High glucose concentration in the urinary tract provides a fertile breeding ground for bacteria and fungi, leading to increased risks of UTIs and genital mycotic infections (candidiasis). **Why other options are considered:** Options A, B, and C are all documented side effects of SGLT-2 inhibitors. Therefore, "All the above" is the most comprehensive and accurate choice. **High-Yield Clinical Pearls for NEET-PG:** 1. **Euglycemic Ketoacidosis:** A rare but serious side effect where the patient has ketoacidosis despite relatively normal blood glucose levels. 2. **Cardio-Renal Protection:** SGLT-2 inhibitors are now preferred in patients with Heart Failure (reduced ejection fraction) and Chronic Kidney Disease (CKD) due to their protective effects. 3. **Fournier’s Gangrene:** A rare, life-threatening necrotizing fasciitis of the perineum associated with this drug class. 4. **Contraindication:** Generally not initiated if eGFR is <30 ml/min/1.73m².

Question 459: Which of the following agents is NOT used in the management of carcinoma of the prostate?

A. Estrogen
B. Progesterone
C. Cyproterone acetate (Correct Answer)
D. Flutamide

Explanation: **Explanation:** The management of prostate carcinoma primarily revolves around **Androgen Deprivation Therapy (ADT)**, as prostate cancer cells are typically androgen-dependent. **Why Cyproterone Acetate is the correct answer (in the context of this specific question):** While Cyproterone acetate is an anti-androgen, it is historically and clinically **not** a standard first-line or preferred agent for prostate carcinoma management in modern practice compared to the other options. However, there is a nuance: in many competitive exams like NEET-PG, this question refers to the fact that while Cyproterone has anti-androgenic properties, its primary indications are hirsutism and precocious puberty. In the context of oncology, non-steroidal anti-androgens (like Flutamide) or GnRH analogues are preferred. *Note: Some clinical texts mention its use, but for MCQ purposes, it is often the "odd one out" compared to established palliative therapies.* **Analysis of Incorrect Options:** * **A. Estrogen:** Historically, Diethylstilbestrol (DES) was used to treat prostate cancer. It acts by suppressing LH secretion via negative feedback on the pituitary, thereby reducing testosterone levels. * **B. Progesterone:** High-dose progestins (like Megestrol acetate) can be used as secondary hormonal therapy. They suppress the hypothalamic-pituitary-gonadal axis and may have direct cytotoxic effects on prostate cells. * **D. Flutamide:** This is a pure non-steroidal anti-androgen that competes with DHT for the androgen receptor. It is a standard treatment, often used to prevent "testosterone flare" when starting GnRH agonists. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** GnRH agonists (e.g., **Leuprolide**, Goserelin) are currently the mainstay of treatment. * **Abiraterone:** A CYP17 inhibitor used in castration-resistant prostate cancer. * **Enzalutamide:** A potent second-generation androgen receptor signaling inhibitor. * **Side Effect:** Flutamide is notorious for causing **hepatotoxicity** and gynecomastia.

Question 460: Which drug inhibits the conversion of T4 to T3?

A. Carbimazole
B. Methimazole
C. Propylthiouracil (Correct Answer)
D. Lugol's iodine

Explanation: **Explanation:** The conversion of Thyroxine (T4) to the more biologically active Triiodothyronine (T3) occurs in peripheral tissues (liver, kidney, and skeletal muscle) via the enzyme **5’-deiodinase**. **Correct Option: C. Propylthiouracil (PTU)** PTU is a thioamide that possesses a dual mechanism of action. Like other antithyroid drugs, it inhibits **Thyroid Peroxidase (TPO)**, preventing the oxidation of iodide and the coupling of iodotyrosines within the thyroid gland. Uniquely, PTU also inhibits the **Type 1 5’-deiodinase** enzyme in the periphery. This makes it particularly effective in managing **Thyroid Storm**, as it rapidly lowers the levels of the more potent T3. **Incorrect Options:** * **A & B (Carbimazole/Methimazole):** These are potent TPO inhibitors that prevent thyroid hormone synthesis. However, they **do not** inhibit the peripheral conversion of T4 to T3. Methimazole is generally preferred over PTU due to its longer half-life and lower risk of hepatotoxicity, except in specific scenarios. * **D (Lugol’s Iodine):** This acts primarily by the **Wolff-Chaikoff effect**, where high concentrations of iodine acutely inhibit the release of thyroid hormones from the colloid and decrease the vascularity of the gland. It does not affect peripheral deiodination. **High-Yield Clinical Pearls for NEET-PG:** * **Drugs inhibiting T4 to T3 conversion:** Remember the mnemonic **"Pro-Pro-Steroid-Iodine"** — **Pro**pylthiouracil, **Pro**pranolol, **Steroids** (Dexamethasone), and **Iodinated** contrast media (e.g., Ipodate). Amiodarone also inhibits this conversion. * **Pregnancy:** PTU is the drug of choice in the **1st trimester** (less teratogenic/lower risk of aplasia cutis); Methimazole is preferred in the 2nd and 3rd trimesters. * **Side Effect:** The most serious side effect of thioamides is **agranulocytosis**.

Practice by Chapter

Hypothalamic and Pituitary Hormones

Practice Questions

Thyroid Drugs and Antithyroid Agents

Practice Questions

Insulin and Oral Hypoglycemic Agents

Practice Questions

Adrenocorticosteroids

Practice Questions

Sex Hormones: Estrogens and Progestins

Practice Questions

Androgens and Anabolic Steroids

Practice Questions

Hormonal Contraceptives

Practice Questions

Drugs Affecting Calcium Metabolism

Practice Questions

Drugs for Osteoporosis

Practice Questions

Pharmacological Management of Obesity

Practice Questions

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