Endocrine Pharmacology Practice Questions

Q: What are the contents of Lugol's Iodine?

5% iodine and 10% potassium iodide. **Explanation:** Lugol’s Iodine (Strong Iodine Solution) is a classic pharmacological agent used in endocrine surgery. The correct composition is **5% elemental iodine and 10% potassium iodide (KI)** in distilled water. The potassium iodide acts as a solubilizing agent, allowing the elemental iodine to dissolve in water by forming polyiodide ions ($I_3^-$). **Why Option A is Correct:** The standard pharmaceutical preparation of Lugol's solution is defined by its 1:2 ratio of iodine to potassium iodide, specifically 5g of Iodine and 10g of Potassium Iodide per 100ml of solution. **Why Other Options are Incorrect:** Options B, C, and D provide incorrect concentrations and ratios. Deviating from the 5%/10% standard would either result in a solution that is too dilute to be clinically effective or too concentrated, increasing the risk of iodine toxicity and local irritation of the gastrointestinal mucosa. **Clinical Pearls for NEET-PG:** * **Mechanism of Action:** It works via the **Wolff-Chaikoff effect**, where high levels of plasma iodide acutely inhibit the organification of iodine, thereby decreasing the synthesis and release of thyroid hormones ($T_3$ and $T_4$). * **Surgical Utility:** In Graves' disease, it is administered 7–10 days preoperatively to **decrease the vascularity** and increase the firmness of the thyroid gland, making the surgery technically easier and safer. * **Limitation:** It should not be used long-term because of the "escape phenomenon," where the thyroid resumes hormone production after 10–14 days. * **Contraindication:** It should be avoided in patients with toxic multinodular goiter to prevent the **Jod-Basedow effect** (iodine-induced hyperthyroidism).

Q: The lymphocytopenia seen a few hours after administration of a large dose of prednisone to a patient with lymphocytic leukemia is due to?

massive lymphocytic apoptosis. **Explanation** The correct answer is **A. massive lymphocytic apoptosis.** **Mechanism of Action:** Glucocorticoids like prednisone exert potent lymphotoxic effects. When administered in pharmacological doses, they bind to intracellular glucocorticoid receptors, leading to the modulation of gene transcription. In lymphoid cells (specifically T-cells and neoplastic B-cells), this triggers a cascade of endonucleases that cause DNA fragmentation, resulting in **programmed cell death (apoptosis)**. This effect is rapid, occurring within a few hours, and is the primary reason steroids are used in the induction protocols for acute lymphoblastic leukemia (ALL) and chronic lymphocytic leukemia (CLL). **Why other options are incorrect:** * **B. Bone marrow depression:** While steroids can suppress certain cell lines over long-term use, the acute drop in peripheral lymphocytes seen within hours is due to the destruction and redistribution of existing cells, not a failure of production in the marrow. * **C & D. Activation of cytotoxic/NK cells:** Glucocorticoids are actually **immunosuppressive**. They inhibit the function of cytotoxic T-lymphocytes and natural killer (NK) cells by suppressing cytokine production (like IL-2). They do not activate these cells to kill leukemic cells. **High-Yield NEET-PG Pearls:** * **Redistribution vs. Destruction:** Steroids cause lymphocytopenia, monocytopenia, and eosinopenia (due to redistribution to lymphoid tissue and apoptosis). Conversely, they cause **neutrophilia** (by decreasing the margination of neutrophils). * **Steroid-induced Psychosis:** A common side effect of high-dose prednisone that frequently appears in exams. * **Drug of Choice:** Dexamethasone is often preferred over prednisone for CNS involvement in leukemia due to its superior CNS penetration.

Q: Which of the following drugs acts by stimulating osteoblasts?

Teriparatide. ### Explanation The correct answer is **Teriparatide**. **1. Why Teriparatide is correct:** Teriparatide is a recombinant form of human **Parathyroid Hormone (PTH 1-34)**. While continuous high levels of PTH (as seen in hyperparathyroidism) cause bone resorption, **intermittent (pulsatile) administration** of Teriparatide has a paradoxical **anabolic effect**. It directly stimulates **osteoblasts** to form new bone, increases bone mineral density, and improves bone architecture. It is currently the only class of drugs (along with Abaloparatide) that primarily builds bone rather than just preventing its breakdown. **2. Why the other options are incorrect:** * **Raloxifene:** A Selective Estrogen Receptor Modulator (SERM). It acts as an estrogen agonist in bone, inhibiting **osteoclast** activity. It does not stimulate osteoblasts. * **Risedronate:** A Bisphosphonate. These drugs bind to hydroxyapatite crystals and are taken up by **osteoclasts**, inducing their apoptosis and inhibiting bone resorption. * **Denosumab:** A monoclonal antibody against **RANKL** (Receptor Activator of Nuclear Factor kappa-B Ligand). By inhibiting RANKL, it prevents the maturation and activation of **osteoclasts**. **3. NEET-PG High-Yield Pearls:** * **Mechanism:** Teriparatide increases the number and function of osteoblasts by activating the PTH1 receptor (a G-protein coupled receptor). * **Clinical Use:** Severe osteoporosis or patients who fail bisphosphonate therapy. * **Black Box Warning:** Risk of **Osteosarcoma** (observed in rat studies); hence, treatment is generally limited to a maximum of 2 years. * **Contraindications:** Paget’s disease of bone, prior radiation to the skeleton, or unexplained elevation of alkaline phosphatase.

Q: Which of the following statements regarding bromocriptine is true?

It acts as an agonist to dopamine receptors.. **Bromocriptine** is a semi-synthetic ergot alkaloid that acts as a potent **D2 receptor agonist** and a partial D1 antagonist [3, 2]. 1. **Why Option A is Correct:** Bromocriptine directly stimulates dopamine receptors in the tuberoinfundibular pathway (inhibiting prolactin release from the anterior pituitary) and the nigrostriatal pathway (improving motor control) [2]. This makes it a primary treatment for hyperprolactinemia, prolactinomas, and Parkinson’s disease [1, 2]. 2. **Why Other Options are Incorrect:** * **Option B:** Bromocriptine is **contraindicated** in patients with active peptic ulceration because it can increase the risk of gastrointestinal bleeding. * **Option C:** Postural (orthostatic) hypotension is a **common side effect** of bromocriptine, especially during the initiation of therapy (the "first-dose phenomenon"). Patients are often advised to take the first dose at bedtime. * **Option D:** Unlike newer non-ergot agonists like **Pramipexole** or **Ropinirole**, bromocriptine does not have proven neuroprotective effects. **High-Yield NEET-PG Pearls:** * **Drug of Choice (DOC):** While bromocriptine was traditionally used, **Cabergoline** is now the DOC for prolactinomas due to its higher efficacy, longer half-life (twice-weekly dosing), and better side-effect profile [1]. * **Specific Use:** Bromocriptine is specifically preferred over cabergoline when **pregnancy** is desired, as it has a longer track record of safety data in pregnancy. * **Other Indications:** It is also FDA-approved for the treatment of **Type 2 Diabetes Mellitus** (Quickrelease formulation) and Acromegaly [1]. * **Key Side Effects:** Nausea/vomiting (due to CTZ stimulation), digital vasospasm, and erythromelalgia [2].

Q: Which of the following drugs can cause osteonecrosis when administered intravenously?

Zolendronate. **Explanation:** **Zoledronate** (a potent intravenous bisphosphonate) is the correct answer. The underlying medical concept is **Medication-Related Osteonecrosis of the Jaw (MRONJ)**. Bisphosphonates inhibit osteoclast activity to prevent bone resorption. However, high-potency nitrogen-containing bisphosphonates like Zoledronate, especially when administered intravenously for bone metastases or Paget’s disease, can lead to impaired bone remodeling and decreased angiogenesis. This results in necrotic bone exposure in the maxillofacial region, typically following local trauma or dental surgery. **Analysis of Incorrect Options:** * **Dalteparin:** A Low Molecular Weight Heparin (LMWH) used as an anticoagulant. While long-term heparin use is associated with **osteoporosis**, it does not cause osteonecrosis. * **Calcitriol:** The active form of Vitamin D. It promotes calcium absorption and is used to treat hypocalcemia and metabolic bone disease; it is not associated with bone necrosis. * **Zidovudine:** A Nucleoside Reverse Transcriptase Inhibitor (NRTI) used in HIV. Its primary dose-limiting toxicity is **bone marrow suppression** (anemia/neutropenia) and myopathy, not osteonecrosis. **Clinical Pearls for NEET-PG:** * **MRONJ Risk Factors:** IV route (highest risk), long duration of therapy, and invasive dental procedures. * **Other Drugs:** Denosumab (RANKL inhibitor) and Anti-angiogenic agents (e.g., Bevacizumab) can also cause MRONJ. * **Management:** Patients should undergo a thorough dental examination and complete any necessary extractions *before* starting IV bisphosphonates. * **Zoledronate vs. Alendronate:** Zoledronate is given once yearly (IV) for osteoporosis, whereas Alendronate is given weekly (oral).

Q: Which bisphosphonate is approved for the treatment of osteoporosis and is administered on a yearly basis?

Zoledronate. **Explanation:** **Zoledronate (Zoledronic acid)** is the correct answer because it is the most potent bisphosphonate available. Due to its high affinity for mineralized bone and slow release from the bone matrix, it has a very long duration of action. For the treatment of postmenopausal osteoporosis, it is administered as a **5 mg intravenous infusion once yearly**. **Analysis of Incorrect Options:** * **Alendronate:** A first-line oral bisphosphonate typically administered **once weekly** (70 mg) or daily (10 mg). It must be taken on an empty stomach with a full glass of water to avoid esophageal irritation. * **Risedronate:** Another oral bisphosphonate administered either **daily, weekly, or monthly**. * **Ibandronate:** This can be administered **monthly (oral)** or **every three months (intravenous)**. It is not approved for yearly administration. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism of Action:** Bisphosphonates are pyrophosphate analogs that inhibit **osteoclast-mediated bone resorption** by inducing osteoclast apoptosis and inhibiting the mevalonate pathway (specifically the enzyme farnesyl pyrophosphate synthase). * **Adverse Effects:** * **Oral:** Erosive esophagitis (patients must remain upright for 30 minutes). * **IV (Zoledronate):** Acute phase reaction (flu-like symptoms) and potential nephrotoxicity. * **Class-wide:** Osteonecrosis of the jaw (ONJ) and atypical subtrochanteric fractures. * **Contraindication:** Avoid in patients with severe renal impairment (Creatinine Clearance <35 mL/min).

Q: Which of the following agents is not used in the treatment of erectile dysfunction?

Phenylephrine. **Explanation:** The correct answer is **Phenylephrine** because it is a potent **$\alpha_1$-selective adrenergic agonist**. [4] In the context of erectile physiology, sympathetic stimulation (via $\alpha_1$ receptors) causes vasoconstriction of the penile arteries and contraction of the trabecular smooth muscle, leading to detumescence (loss of erection). [1] Therefore, Phenylephrine is actually used to **treat priapism** (a prolonged, painful erection), not erectile dysfunction (ED). **Analysis of Incorrect Options:** * **Apomorphine (Option A):** A dopamine (D2) receptor agonist that acts centrally on the hypothalamus to initiate the erectile response. [3] It is used as a sublingual treatment for ED. * **Vardenafil (Option B):** A potent **PDE-5 inhibitor** (similar to Sildenafil). [2] It prevents the breakdown of cGMP in the corpus cavernosum, maintaining smooth muscle relaxation and enhancing blood flow. * **Alprostadil (Option D):** A synthetic **Prostaglandin E1 (PGE1)** analogue. It increases cAMP levels, leading to smooth muscle relaxation. It is administered via intracavernosal injection or intraurethral pellets. **Clinical Pearls for NEET-PG:** * **First-line treatment for ED:** Oral PDE-5 inhibitors (Sildenafil, Tadalafil, Vardenafil). * **Priapism Management:** Phenylephrine is the drug of choice (administered via intracavernosal injection). * **Contraindication:** PDE-5 inhibitors must never be used with **Nitrates**, as they can cause synergistic peripheral vasodilation leading to severe, life-threatening hypotension. [2] * **Alprostadil** is also used to maintain the patency of the **Ductus Arteriosus** in neonates with cyanotic heart disease.

Q: A vasopressin analogue does not produce a therapeutic effect through the vasopressin V-2 receptor in which of the following conditions?

Bleeding esophageal varices. **Explanation:** The therapeutic effect of vasopressin analogues depends on which receptor subtype is targeted: **V1 receptors** (located on vascular smooth muscle, causing vasoconstriction) or **V2 receptors** (located in the renal collecting ducts for water reabsorption and on vascular endothelium to trigger factor release) [1]. **Why Option B is correct:** In **Bleeding Esophageal Varices**, the goal is to reduce portal venous pressure. Vasopressin analogues (specifically **Terlipressin**) act via **V1 receptors** to cause splanchnic vasoconstriction, thereby reducing blood flow into the portal system. This effect is independent of the V2 receptor. **Why the other options are incorrect:** * **Central Diabetes Insipidus (A):** Desmopressin (a selective V2 agonist) is the drug of choice. it acts on **V2 receptors** in the renal collecting ducts to increase water permeability via aquaporin-2 channels [1]. * **Type 1 von Willebrand’s Disease (C):** Desmopressin acts on **V2 receptors** on vascular endothelial cells to stimulate the release of stored von Willebrand factor (vWF) and Factor VIII. * **Primary Nocturnal Enuresis (D):** Desmopressin is used to decrease urine production overnight by activating renal **V2 receptors**, helping children who have a nocturnal deficiency of ADH. **High-Yield NEET-PG Pearls:** * **Desmopressin (dDAVP):** Highly selective for **V2**; preferred for DI and bleeding disorders because it lacks the pressor (V1) side effects. * **Terlipressin:** Selective for **V1**; drug of choice for Hepatorenal Syndrome and Variceal bleeding. * **V3 Receptors:** Located in the anterior pituitary; they mediate the release of ACTH [1]. * **Side Effect:** Hyponatremia is a critical risk when using V2 agonists like Desmopressin.

Question 1

What are the contents of Lugol's Iodine?

Accepted Answer

5% iodine and 10% potassium iodide

Answer

10% iodine and 20% potassium iodide

Answer

10% iodine and 15% potassium iodide

Answer

5% iodine and 15% potassium iodide

Question 2

The lymphocytopenia seen a few hours after administration of a large dose of prednisone to a patient with lymphocytic leukemia is due to?

Accepted Answer

massive lymphocytic apoptosis

Answer

bone marrow depression

Answer

activation of cytotoxic cells

Answer

stimulation of natural killer cell activity

Question 3

Which of the following drugs acts by stimulating osteoblasts?

Accepted Answer

Teriparatide

Answer

Raloxifene

Answer

Risedronate

Answer

Denosumab

Question 4

Which of the following statements regarding bromocriptine is true?

Accepted Answer

It acts as an agonist to dopamine receptors.

Answer

It can be used in active peptic ulceration.

Answer

It does not cause postural hypotension.

Answer

It has possible neuroprotective effects.

Question 5

A 35-year-old woman with active lupus nephritis experiences a fall onto her left hand, resulting in immediate pain and crepitus at the wrist on examination. Radiographs reveal radial and navicular fractures along with marked osteopenia. Which of the following medications most likely contributed to the fracture?

Accepted Answer

Hydrocortisone

Answer

Ibuprofen

Answer

Lisinopril

Answer

Losartan

Question 6

Which of the following drugs can cause osteonecrosis when administered intravenously?

Accepted Answer

Zolendronate

Answer

Dalteparin

Answer

Calcitriol

Answer

Zidovudine

Question 7

Which bisphosphonate is approved for the treatment of osteoporosis and is administered on a yearly basis?

Accepted Answer

Zoledronate

Answer

Alendronate

Answer

Risedronate

Answer

Ibandronate

Question 8

Which of the following agents is not used in the treatment of erectile dysfunction?

Accepted Answer

Phenylephrine

Answer

Apomorphine

Answer

Vardenafil

Answer

Alprostadil

Question 9

A vasopressin analogue does not produce a therapeutic effect through the vasopressin V-2 receptor in which of the following conditions?

Accepted Answer

Bleeding esophageal varices

Answer

Central diabetes insipidus

Answer

Type 1 von Willebrand's disease

Answer

Primary nocturnal enuresis

Question 10

True about lispro-insulin is:

Accepted Answer

Action is faster and of longer duration than regular insulin.

Answer

Action is faster and short in duration than regular insulin.

Answer

It is given 15 minutes prior to a meal.

Answer

Source is lamb.

Endocrine Pharmacology — MCQs

Endocrine Pharmacology — MCQs

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