Endocrine Pharmacology — MCQs

Endocrine Pharmacology Indian Medical PG Practice Questions and MCQs

Question 41: What is the drug of choice for bisphosphonate-resistant osteoporosis?

A. Teriparatide (Correct Answer)
B. Denosumab
C. Anakinra
D. Calcitonin

Explanation: ### **Explanation** **Correct Answer: A. Teriparatide** **Why it is the Drug of Choice:** Bisphosphonates are the first-line treatment for osteoporosis; however, they are **antiresorptive agents** (they inhibit osteoclasts). In cases of "bisphosphonate resistance" or severe osteoporosis where bone mineral density (BMD) continues to decline despite therapy, a switch to an **anabolic agent** is required. **Teriparatide** is a recombinant human parathyroid hormone (PTH 1-34). When administered in **intermittent low doses**, it stimulates osteoblastic activity more than osteoclastic activity, leading to the formation of new bone. This makes it the preferred choice for patients who fail bisphosphonate therapy or have very high fracture risk. **Why the other options are incorrect:** * **B. Denosumab:** This is a monoclonal antibody against **RANKL**. Like bisphosphonates, it is an antiresorptive agent. While potent, it is generally considered an alternative to bisphosphonates rather than the specific treatment for bisphosphonate-resistant cases. * **C. Anakinra:** This is an **IL-1 receptor antagonist** used primarily in Rheumatoid Arthritis and Cryopyrin-associated periodic syndromes (CAPS). It has no role in the standard management of osteoporosis. * **D. Calcitonin:** A weak antiresorptive agent used primarily for the short-term treatment of bone pain in vertebral fractures. It is significantly less efficacious than bisphosphonates or teriparatide. **High-Yield Clinical Pearls for NEET-PG:** * **Black Box Warning:** Teriparatide carries a risk of **Osteosarcoma** (avoid in patients with Paget’s disease, prior radiation, or unexplained elevated alkaline phosphatase). * **Treatment Duration:** Use is limited to a maximum of **2 years** in a lifetime. * **Mechanism:** Intermittent PTH = Anabolic (Bone forming); Continuous PTH = Catabolic (Bone resorbing). * **Sequential Therapy:** After stopping Teriparatide, an antiresorptive (like bisphosphonates) must be started to maintain the newly formed bone.

Question 42: Which of the following patients is most likely to be treated with intravenous glucagon?

A. A young man who took cocaine and has a blood pressure of 190/110 mm Hg
B. A middle-aged man with type II diabetes who has not taken his regular dose of glipizide for the last 4 days
C. An old man with severe bradycardia and hypotension resulting from ingestion of an overdose of atenolol (Correct Answer)
D. An old woman with lactic acidosis as a complication of severe infection and shock

Explanation: **Explanation** The correct answer is **Option C**. Glucagon is the **first-line antidote for Beta-blocker (e.g., Atenolol) overdose**. **1. Why Option C is correct (Mechanism):** In beta-blocker toxicity, the $\beta_1$ receptors in the heart are blocked, leading to decreased cAMP levels, which results in severe bradycardia and hypotension. Glucagon acts by binding to **specific G-protein coupled glucagon receptors** on the myocardium. This bypasses the blocked beta-receptors and directly stimulates **adenylate cyclase**, increasing intracellular **cAMP**. This leads to positive inotropic (increased contractility) and chronotropic (increased heart rate) effects, effectively reversing the cardiotoxicity. **2. Why other options are incorrect:** * **Option A:** Cocaine causes a sympathomimetic surge. Treating hypertension with glucagon would be counterproductive as it increases heart rate. Management involves benzodiazepines and vasodilators (avoiding pure beta-blockers). * **Option B:** Glipizide is a sulfonylurea. Missing doses would lead to hyperglycemia. Glucagon is used to treat *hypoglycemia*, not hyperglycemia. * **Option D:** Lactic acidosis in shock is managed by treating the underlying infection, fluid resuscitation, and vasopressors. Glucagon has no role here and may worsen metabolic derangements. **3. NEET-PG High-Yield Pearls:** * **Glucagon Uses:** Beta-blocker overdose, Calcium channel blocker overdose (second-line), severe hypoglycemia, and relaxing the lower esophageal sphincter for food bolus impaction. * **Side Effects:** Nausea and vomiting are very common side effects of rapid IV glucagon administration. * **Antidote Mnemonic:** For Beta-blockers, think **"Gluca-GONE"** (the block is gone). * **Diagnostic Clue:** If a patient presents with bradycardia, hypotension, and **hypoglycemia**, suspect Beta-blocker overdose (as they inhibit glycogenolysis).

Question 43: Mifepristone is used in which of the following conditions?

A. Medical termination of pregnancy (Correct Answer)
B. Breast carcinoma
C. Prostatic carcinoma
D. Dysfunctional uterine bleeding

Explanation: ### Explanation **Mifepristone (RU-486)** is a potent **progesterone receptor antagonist** (and at higher doses, a glucocorticoid receptor antagonist). Progesterone is essential for maintaining the decidua and the stability of the uterine lining during pregnancy. By blocking these receptors, mifepristone leads to decidual breakdown, cervical softening, and increased uterine sensitivity to prostaglandins, making it the gold standard for **Medical Termination of Pregnancy (MTP)**. #### Why the other options are incorrect: * **Breast Carcinoma:** While mifepristone has been studied for progesterone-receptor-positive breast cancer, it is not a standard treatment. Selective Estrogen Receptor Modulators (SERMs) like Tamoxifen or Aromatase Inhibitors are the mainstays. * **Prostatic Carcinoma:** This is an androgen-dependent malignancy. Treatment involves androgen deprivation therapy (e.g., GnRH agonists like Leuprolide or androgen antagonists like Flutamide), not progesterone antagonists. * **Dysfunctional Uterine Bleeding (DUB):** While mifepristone can reduce menstrual flow in conditions like uterine fibroids, it is not the indicated treatment for DUB. First-line treatments typically include NSAIDs, Tranexamic acid, or combined oral contraceptives. #### High-Yield Clinical Pearls for NEET-PG: * **MTP Protocol:** Mifepristone (200 mg orally) is followed 36–48 hours later by **Misoprostol** (400–800 µg) to induce uterine contractions. It is effective for termination up to **9–10 weeks (63–70 days)** of gestation. * **Other Uses:** Mifepristone is also FDA-approved for controlling hyperglycemia in **Cushing’s Syndrome** (due to its anti-glucocorticoid action) and as an **emergency contraceptive** (10 mg single dose). * **Side Effects:** Significant vaginal bleeding, abdominal cramps, and incomplete abortion.

Question 44: Dinoprost is:

A. PG El
B. PGE2
C. PGF2 alpha (Correct Answer)
D. PGI2

Explanation: **Explanation:** **Dinoprost** is the naturally occurring form of **Prostaglandin F2 alpha (PGF2α)**. In clinical practice, it is primarily used for its potent oxytocic properties. It acts by stimulating the myometrium of the gravid uterus to contract, making it effective for the induction of second-trimester abortions and the management of uterine atony. **Analysis of Options:** * **Option A (PGE1):** Synthetic analogues of PGE1 include **Misoprostol** (used for medical abortion and NSAID-induced ulcers) and **Alprostadil** (used for maintaining ductus arteriosus patency and erectile dysfunction). * **Option B (PGE2):** The synthetic analogue of PGE2 is **Dinoprostone**. It is commonly used for cervical ripening and induction of labor. * **Option C (PGF2α):** This is the **correct** answer. Dinoprost is the pharmaceutical name for PGF2α. Another important PGF2α analogue is **Carboprost** (15-methyl PGF2α), used in refractory postpartum hemorrhage (PPH). * **Option D (PGI2):** Also known as **Prostacyclin**. Its synthetic analogues include **Epoprostenol** and **Iloprost**, which are potent vasodilators used in pulmonary arterial hypertension. **High-Yield Clinical Pearls for NEET-PG:** * **Dinoprost vs. Dinoprostone:** Remember "E" for Dinoproston**e** (PGE2) and "F" for Dinoprost (PGF2α). * **Ophthalmic PGF2α analogues:** Latanoprost, Bimatoprost, and Travoprost are first-line drugs for Open-Angle Glaucoma (they increase uveoscleral outflow). * **Side Effects:** PGF2α analogues can cause bronchoconstriction; therefore, they are generally avoided in patients with bronchial asthma.

Question 45: Which of the following statements about sulfonylureas is FALSE?

A. They block ATP-sensitive K+ channels, increasing insulin release.
B. They have a higher risk of causing hypoglycemia compared to meglitinides.
C. They are primarily used in Type 1 Diabetes Mellitus. (Correct Answer)
D. Chlorpropamide can cause dilutional hyponatremia.

Explanation: **Explanation:** **Why Option C is the Correct (False) Statement:** Sulfonylureas (SUs) act as **insulin secretagogues**. Their mechanism of action requires functional pancreatic beta cells to stimulate insulin release. In **Type 1 Diabetes Mellitus (T1DM)**, there is an absolute deficiency of insulin due to autoimmune destruction of beta cells; therefore, SUs are ineffective. They are primarily used in the management of **Type 2 Diabetes Mellitus (T2DM)**. **Analysis of Other Options:** * **Option A (True):** SUs bind to the **SUR1 subunit** of ATP-sensitive K+ channels in beta cells. This closes the channels, leading to depolarization, calcium influx, and subsequent exocytosis of insulin. * **Option B (True):** SUs have a longer duration of action compared to meglitinides (e.g., Repaglinide). Meglitinides are short-acting "post-prandial" regulators with a lower risk of prolonged fasting hypoglycemia. * **Option D (True):** **Chlorpropamide** (a first-generation SU) can increase the action of ADH on renal tubules, leading to **SIADH-like effects** and dilutional hyponatremia. It also causes a disulfiram-like reaction with alcohol. **High-Yield NEET-PG Pearls:** * **Weight Gain:** SUs commonly cause weight gain, unlike Metformin or GLP-1 agonists. * **Metabolism:** Most SUs are metabolized by the liver and excreted by the kidneys. **Glipizide** is preferred in patients with mild renal impairment as it is primarily metabolized to inactive metabolites. * **Failure:** "Secondary failure" occurs when SUs lose effectiveness over years due to progressive beta-cell exhaustion. * **Antidote:** Octreotide can be used to manage refractory hypoglycemia caused by sulfonylurea overdose.

Question 46: Intranasal calcitonin is indicated for which of the following conditions?

A. Paget's disease
B. Multiple endocrine neoplasia (MEN) syndrome
C. Hypercalcemia
D. Postmenopausal osteoporosis (Correct Answer)

Explanation: **Explanation:** **Calcitonin** is a hormone secreted by the parafollicular C-cells of the thyroid gland. Its primary physiological action is to lower serum calcium levels by inhibiting osteoclast-mediated bone resorption. **1. Why Option D is Correct:** Intranasal calcitonin is specifically FDA-approved for the treatment of **postmenopausal osteoporosis** in women who are at least five years post-menopause. The intranasal route is preferred for long-term outpatient management due to its ease of administration and unique **analgesic effect** on bone pain, which is particularly beneficial in patients with acute osteoporotic vertebral fractures. **2. Why Other Options are Incorrect:** * **A. Paget’s Disease:** While calcitonin is used in Paget’s disease to reduce bone turnover, the **parenteral (SC/IM) route** is required to achieve the higher systemic concentrations necessary to suppress the disease. The intranasal dose is insufficient. * **B. MEN Syndrome:** MEN 2A and 2B are associated with Medullary Thyroid Carcinoma, which causes *excessive* endogenous calcitonin production. Exogenous calcitonin has no therapeutic role here. * **C. Hypercalcemia:** In emergency management of hypercalcemia, calcitonin is used for its rapid onset of action. However, it must be administered **parenterally (SC/IM)** for a quick effect. Intranasal absorption is too slow and erratic for acute metabolic emergencies. **High-Yield Clinical Pearls for NEET-PG:** * **Tachyphylaxis:** Long-term use of calcitonin leads to a decrease in efficacy due to the downregulation of receptors on osteoclasts. * **Salmon Calcitonin:** The preparation used clinically is derived from salmon because it is more potent and has a longer half-life than human calcitonin. * **Side Effects:** The most common side effect of the nasal spray is local irritation (rhinitis/epistaxis). * **Malignancy Risk:** Recent meta-analyses suggest a small increased risk of malignancies with long-term calcitonin use, leading to its decline as a first-line agent.

Question 47: Which substance is primarily responsible for the erection of the penis?

A. Clomipramine
B. Papaverine (Correct Answer)
C. Buspirone
D. Amitriptyline

Explanation: **Explanation:** **Papaverine** is the correct answer because it is a non-selective **phosphodiesterase (PDE) inhibitor** and a direct-acting smooth muscle relaxant. By inhibiting the breakdown of cAMP and cGMP, it promotes the relaxation of the cavernous smooth muscle and the dilation of the pudendal arteries. This increases blood flow into the corpora cavernosa, leading to an erection [1], [3]. Historically, it was one of the first drugs used via intracavernosal injection for the treatment of erectile dysfunction (ED). **Analysis of Incorrect Options:** * **Clomipramine (A):** A Tricyclic Antidepressant (TCA) with significant serotonergic activity. It is actually used to treat **premature ejaculation** because it delays orgasm [2]; however, it is more likely to cause erectile dysfunction as a side effect. * **Buspirone (C):** An azapirone anxiolytic (5-HT1A partial agonist). While it lacks the sexual side effects of SSRIs, it does not have a direct physiological role in inducing erections. * **Amitriptyline (D):** A TCA that possesses strong anticholinergic properties. Anticholinergic drugs typically interfere with the parasympathetic-mediated vasodilation required for an erection, often leading to impotence. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism of Erection:** Primarily mediated by **Nitric Oxide (NO)** [1], [4], which increases **cGMP** [4]. * **Alprostadil (PGE1):** Currently the preferred intracavernosal agent over Papaverine due to a lower risk of priapism and tissue fibrosis. * **Sildenafil:** The first-line oral treatment for ED; it is a selective **PDE-5 inhibitor** [4]. * **Priapism:** A common complication of intracavernosal papaverine; it is treated with alpha-agonists like **phenylephrine**.

Question 48: Which of the following steroids possesses maximum glucocorticoid activity?

A. Prednisolone
B. Cortisol
C. Aldosterone
D. Dexamethasone (Correct Answer)

Explanation: ### Explanation The potency of corticosteroids is determined by their affinity for glucocorticoid receptors (GR) versus mineralocorticoid receptors (MR). **Why Dexamethasone is Correct:** Dexamethasone is a long-acting, synthetic glucocorticoid. It is approximately **25 to 30 times more potent** than cortisol (hydrocortisone) in its anti-inflammatory and glucocorticoid effects. Crucially, it possesses **zero mineralocorticoid activity**, making it the drug of choice when high-dose steroid therapy is required without the risk of sodium and water retention. **Analysis of Incorrect Options:** * **A. Prednisolone:** This is an intermediate-acting steroid. It is about **4 times** more potent than cortisol but still retains some mineralocorticoid activity. * **B. Cortisol (Hydrocortisone):** This is the endogenous reference standard. It has a potency ratio of **1** and possesses significant mineralocorticoid activity (equal to its glucocorticoid activity). * **C. Aldosterone:** This is the primary endogenous **mineralocorticoid**. While it is a steroid, its glucocorticoid (anti-inflammatory) activity is negligible; its primary role is sodium retention and potassium excretion. **High-Yield NEET-PG Pearls:** 1. **Potency Hierarchy:** Dexamethasone = Betamethasone (25–30) > Methylprednisolone = Triamcinolone (5) > Prednisolone (4) > Hydrocortisone (1). 2. **Duration of Action:** Dexamethasone is **long-acting** (t½ > 36 hours), whereas Hydrocortisone is **short-acting** (t½ 8–12 hours). 3. **Clinical Use:** Dexamethasone is preferred in cerebral edema and for the **Dexamethasone Suppression Test (DST)** to diagnose Cushing’s syndrome because it does not interfere with endogenous cortisol assays. 4. **Fetal Lung Maturity:** Betamethasone and Dexamethasone are used in preterm labor because they cross the placenta and have low protein binding.

Question 49: All of the following drugs are oxytocics except?

A. Oxytocin
B. Ergometrine
C. Prostaglandin
D. Orciprenaline (Correct Answer)

Explanation: **Explanation:** The question asks to identify the drug that is **not** an oxytocic. **Oxytocics** (Ecbolics) are drugs that stimulate uterine contractions, primarily used to induce labor or control postpartum hemorrhage (PPH). Conversely, **Tocolytics** are drugs that relax the uterus to delay preterm labor. **1. Why Orciprenaline is the correct answer:** Orciprenaline (Metaproterenol) is a **$\beta_2$-adrenergic agonist**. Activation of $\beta_2$ receptors in the myometrium increases intracellular cAMP, leading to uterine relaxation. Therefore, Orciprenaline is a **tocolytic**, not an oxytocic. It is primarily used to delay preterm labor or in cases of uterine hyperstimulation. **2. Why the other options are incorrect:** * **Oxytocin:** The drug of choice for induction of labor. It acts via G-protein coupled receptors to increase intracellular calcium, causing rhythmic uterine contractions. * **Ergometrine:** An ergot alkaloid that causes sustained (tetanic) uterine contractions. It is used exclusively postpartum to prevent or treat PPH and is contraindicated for induction of labor due to the risk of fetal asphyxia. * **Prostaglandins (e.g., PGE2, PGF2$\alpha$):** Drugs like Dinoprostone and Misoprostol are potent oxytocics used for cervical ripening, induction of labor, and management of PPH. **Clinical Pearls for NEET-PG:** * **Tocolytic Mnemonic (It’s Not My Time):** **I**ndomethacin (NSAID), **N**ifedipine (CCB - Drug of choice), **M**agnesium sulfate, **T**erbutaline/Ritodrine ($\beta_2$ agonists). * **Atosiban:** A specific oxytocin receptor antagonist used as a tocolytic. * **Ergotism:** Chronic poisoning with ergot alkaloids can lead to gangrene due to persistent vasoconstriction.

Question 50: Which of the following drugs is contraindicated in diabetic patients?

A. Mannitol
B. Steroids (Correct Answer)
C. Enalapril
D. Glycerol

Explanation: **Explanation:** **Correct Option: B. Steroids** Glucocorticoids (Steroids) are potent **diabetogenic** drugs. They increase blood glucose levels through multiple mechanisms: 1. **Increased Gluconeogenesis:** They stimulate the liver to produce glucose from non-carbohydrate sources. 2. **Peripheral Insulin Resistance:** They decrease glucose uptake in skeletal muscle and adipose tissue by interfering with GLUT-4 translocation. 3. **Lipolysis:** They promote the breakdown of fats, increasing free fatty acids which further antagonize insulin action. In diabetic patients, steroid use can lead to severe hyperglycemia or even Diabetic Ketoacidosis (DKA). **Incorrect Options:** * **A. Mannitol:** An osmotic diuretic used primarily to reduce intracranial or intraocular pressure. While it is a sugar alcohol, it is not significantly metabolized to glucose and does not worsen glycemic control. * **C. Enalapril:** An ACE inhibitor. These are actually the **drugs of choice** for hypertensive diabetic patients because they provide **nephroprotection** by reducing efferent arteriolar resistance and slowing the progression of diabetic nephropathy. * **D. Glycerol:** Used as an osmotic agent (e.g., in glaucoma). While it can enter metabolic pathways, it does not pose the same systemic hyperglycemic risk as steroids in standard clinical doses. **High-Yield Clinical Pearls for NEET-PG:** * **Other Diabetogenic Drugs:** Thiazide diuretics, Beta-blockers (can mask hypoglycemia symptoms and worsen insulin resistance), Oral Contraceptives, and Phenytoin. * **Steroid-Induced Diabetes:** Typically presents with elevated postprandial glucose levels rather than fasting levels. * **DOC for Diabetes with HTN:** ACE inhibitors or ARBs (due to their ability to prevent/delay microalbuminuria).

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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