Endocrine Pharmacology — MCQs

Endocrine Pharmacology Indian Medical PG Practice Questions and MCQs

Question 751: What is the drug of choice for pheochromocytoma?

A. Propranolol
B. Phenoxybenzamine (Correct Answer)
C. Prazosin
D. Nitroprusside

Explanation: ***Phenoxybenzamine*** - This is an **irreversible, non-selective alpha-adrenergic blocker**, which is the drug of choice for preparing patients for surgical removal of a pheochromocytoma. - It effectively controls **hypertension** by blocking the effects of catecholamines on blood vessels, preventing a hypertensive crisis during surgery. *Propranolol* - **Beta-blockers** like propranolol should **not be used as monotherapy** in pheochromocytoma because blocking beta-2 receptors without prior alpha blockade can lead to unopposed alpha-adrenergic vasoconstriction and precipitate a **hypertensive crisis**. - It can be added **after adequate alpha-blockade** to control tachycardia. *Prazosin* - Prazosin is a **reversible, selective alpha-1 adrenergic blocker**, which is not preferred over phenoxybenzamine due to its shorter duration of action and reversibility. - While it can lower blood pressure, its efficacy in preventing hypertensive crises during surgery for pheochromocytoma is **less robust** compared to phenoxybenzamine. *Nitroprusside* - Sodium nitroprusside is a **potent vasodilator** often used for **hypertensive emergencies**, but it is not the drug of choice for long-term management or preoperative preparation in pheochromocytoma. - Its use in pheochromocytoma is typically reserved for **acute hypertensive crises** when other agents are insufficient, rather than initial management.

Question 752: Which of the following antidiabetic drugs (other than insulin) is indicated as adjunct therapy for the management of both type I and type II diabetes mellitus?

A. Sulphonylureas
B. Metformin
C. Acarbose
D. Pramlintide (Correct Answer)

Explanation: Pramlintide - Pramlintide is an amylin analog indicated as an adjunct therapy to insulin for both type 1 and type 2 diabetes, helping to regulate post-prandial glucose. - It slows gastric emptying, suppresses postprandial glucagon secretion, and promotes satiety, leading to reduced insulin requirements and improved glycemic control. Sulphonylureas - Sulphonylureas primarily stimulate insulin secretion from pancreatic beta cells, making them effective only in Type 2 diabetes where some beta-cell function is preserved [2]. - They are not indicated for Type 1 diabetes because these patients have absolute insulin deficiency due to beta cell destruction. Metformin - Metformin is a biguanide that primarily reduces hepatic glucose production and improves insulin sensitivity in peripheral tissues. - It is a first-line treatment for Type 2 diabetes but is generally not used for Type 1 diabetes as it does not address the fundamental lack of insulin. Acarbose - Acarbose is an alpha-glucosidase inhibitor that works by delaying carbohydrate absorption from the gastrointestinal tract, thus reducing postprandial glucose spikes [1]. - While it can be used in Type 2 diabetes to manage postprandial hyperglycemia, it is not typically indicated as an adjunct for Type 1 diabetes alongside insulin [3].

Question 753: What is the initial drug of choice for a suspected case of acute adrenal insufficiency?

A. Norepinephrine
B. Hydrocortisone (Correct Answer)
C. Dexamethasone
D. Fludrocortisone

Explanation: ***Hydrocortisone*** - This is the initial drug of choice due to its **combined mineralocorticoid and glucocorticoid activity**, which effectively replaces the deficient hormones in acute adrenal insufficiency. - It also has a **rapid onset of action** crucial for stabilizing patients in an adrenal crisis. *Norepinephrine* - This is a **vasopressor** used to manage **severe hypotension or shock** by increasing peripheral vascular resistance. - While hypotension is a feature of adrenal insufficiency, norepinephrine does not address the underlying hormonal deficiency directly and is not the primary treatment. *Dexamethasone* - Dexamethasone is a **potent glucocorticoid** and can be used in adrenal insufficiency, but it lacks significant **mineralocorticoid activity**. - Its longer half-life might make it less ideal for immediate, titratable replacement compared to hydrocortisone in an acute setting. *Fludrocortisone* - Fludrocortisone is a **pure mineralocorticoid** primarily used for long-term replacement therapy to manage sodium and potassium balance in adrenal insufficiency. - It does not have sufficient glucocorticoid activity to address the immediate, life-threatening aspects of acute adrenal crisis.

Question 754: Which of the following drugs acts directly to induce an erection without the need for sexual stimulation?

A. Sildenafil
B. Tadalafil
C. Alprostadil (Correct Answer)
D. Testosterone

Explanation: ***Alprostadil***- **Alprostadil** is a **prostaglandin E1** analog that can directly induce vasodilation in the penile arteries, leading to an erection without sexual stimulation [1].- It is typically administered via **intracavernosal injection** or as a **urethral suppository**.*Sildenafil*- **Sildenafil** is a **PDE5 inhibitor** that works by enhancing the effects of **nitric oxide**, which is released in response to sexual stimulation [2, 3].- It requires **sexual arousal** to be effective, as it doesn't directly initiate the erectile process [2, 3].*Tadalafil*- Similar to sildenafil, **tadalafil** is also a **PDE5 inhibitor** that works by increasing cGMP levels and promoting smooth muscle relaxation [2, 3].- Its action is dependent on the release of **nitric oxide** triggered by sexual stimulation [2, 3].*Testosterone*- **Testosterone** is a hormone involved in sex drive and overall erectile function over time, but it does not directly or acutely induce an erection.- Its primary role in erectile dysfunction is in cases of **hypogonadism**, and it requires sexual stimulation for its effects on erection.

Question 755: Which of the following is a selective progesterone receptor modulator?

A. Onapristone
B. Ulipristal (Correct Answer)
C. Nomegestrol
D. Toremifene

Explanation: ***Ulipristal*** - **Ulipristal acetate** is a **selective progesterone receptor modulator (SPRM)** that acts as a progesterone receptor agonist/antagonist. - It is primarily used for **emergency contraception** and for the pre-operative treatment of **uterine fibroids**. *Onapristone* - **Onapristone** is an **antiprogestin** and a **progesterone receptor antagonist**, not a selective modulator. - It has been primarily investigated for its potential role in **breast cancer** treatment but is not approved for general clinical use. *Nomegestrol* - **Nomegestrol** is a **synthetic progestin** used in hormonal contraception. - It functions as a **progesterone receptor agonist** and does not exhibit selective modulation properties. *Toremifene* - **Toremifene** is a **selective estrogen receptor modulator (SERM)**, not a progesterone receptor modulator. - It is used in the treatment of **estrogen receptor-positive metastatic breast cancer** in postmenopausal women.

Question 756: Which steroid has the maximum mineralocorticoid activity?

A. Fludrocortisone (Correct Answer)
B. DOCA
C. Prednisolone
D. Triamcinolone

Explanation: ***Fludrocortisone*** - **Fludrocortisone** is a synthetic corticosteroid specifically designed to have potent **mineralocorticoid activity**, with significant sodium-retaining properties. - Its high affinity for **mineralocorticoid receptors** distinguishes it from other steroids and makes it effective in treating conditions like **Addison's disease** and **postural orthostatic tachycardia syndrome (POTS)** due to its ability to retain sodium and water. *DOCA (Deoxycorticosterone acetate)* - While **DOCA** does possess significant **mineralocorticoid activity** and was historically used for this purpose, **fludrocortisone** is generally considered to have a stronger and more sustained effect in clinical practice. - **DOCA's** mineralocorticoid potency is substantial but slightly less than that of **fludrocortisone** when compared on a weight basis for equivalent sodium retention. *Prednisolone* - **Prednisolone** is primarily a **glucocorticoid** with potent anti-inflammatory and immunosuppressive effects. - It has minimal to negligible **mineralocorticoid activity** and is not used for salt retention purposes. *Triamcinolone* - **Triamcinolone** is a potent **glucocorticoid** with a long duration of action and is known for its strong anti-inflammatory properties. - It has virtually no **mineralocorticoid activity**, making it unsuitable for conditions requiring sodium retention.

Question 757: Which of the following has the least glucocorticoid activity?

A. Fludrocortisone
B. Cortisone (Correct Answer)
C. Dexamethasone
D. Betamethasone

Explanation: ***Cortisone*** - **Cortisone has the LEAST glucocorticoid activity** among the options listed. - It is a **prodrug** that must be converted to **hydrocortisone (cortisol)** by 11β-hydroxysteroid dehydrogenase in the liver to become active. - Its glucocorticoid potency is approximately **0.8** relative to hydrocortisone (when hydrocortisone = 1). - Due to variable hepatic conversion, it has **lower and less predictable glucocorticoid effects** compared to other agents. *Fludrocortisone* - Primarily used for its **potent mineralocorticoid activity** (125× that of hydrocortisone). - However, it retains **significant glucocorticoid activity** approximately **10-15 times** that of hydrocortisone. - Despite being marketed as a mineralocorticoid, its glucocorticoid potency is **considerably higher than cortisone**. *Dexamethasone* - **Highly potent synthetic glucocorticoid** with negligible mineralocorticoid activity. - Glucocorticoid potency is approximately **25-30 times** that of hydrocortisone. - Long duration of action (36-72 hours) and excellent CNS penetration. *Betamethasone* - **Highly potent synthetic glucocorticoid**, structurally similar to dexamethasone (differs only in stereochemistry at C-16). - Glucocorticoid potency is approximately **25-30 times** that of hydrocortisone. - Minimal mineralocorticoid activity, with similar clinical applications to dexamethasone.

Question 758: Desmopressin is preferred over vasopressin because it:

A. Is more potent and has little vasoconstrictor activity (Correct Answer)
B. Is more potent than vasopressin
C. Has little vasoconstrictor activity
D. Is more selective for V2 receptors than vasopressin

Explanation: **Is more potent and has little vasoconstrictor activity** - **Desmopressin** is a synthetic analog of **vasopressin** (ADH) that is modified to have much higher selectivity for **V2 receptors** in the renal collecting ducts, leading to potent **antidiuretic effects** [1], [3]. - This selective action results in significantly **reduced vasoconstrictor activity** (mediated by V1 receptors) compared to natural vasopressin, making it safer for clinical use to manage water balance without significant cardiovascular side effects [1], [3]. *Is more potent than vasopressin* - While desmopressin is indeed more potent in its **antidiuretic effect** due to increased affinity for **V2 receptors**, this option alone doesn't specify the critical advantage of *reduced vasoconstrictor activity* [3]. - Its superior potency alone doesn't fully explain its preference over vasopressin, as the **side-effect profile** is a major consideration. *Has little vasoconstrictor activity* - This statement is true and highlights a key advantage of desmopressin, but it omits the fact that **desmopressin is also more potent** in its desired antidiuretic effect compared to natural vasopressin [1]. - Both the **potency** and **reduced vasoconstrictor activity** contribute to its superior clinical profile [3]. *Is more selective for V2 receptors than vasopressin* - **Desmopressin's increased selectivity** for **V2 receptors** is the mechanistic basis for its preferred properties, leading to both greater antidiuretic potency and reduced vasoconstriction [1], [4]. - However, the option "Is more potent and has little vasoconstrictor activity" describes the *clinical consequences* of this selectivity, which are the direct reasons for its preferred use [2].

Question 759: Which of the following is an intermediate-acting insulin?

A. Insulin lispro
B. NPH insulin (Correct Answer)
C. Insulin glargine
D. Regular insulin

Explanation: ***NPH insulin*** - **NPH (Neutral Protamine Hagedorn) insulin** is characterized by its intermediate duration of action, typically peaking in 4-12 hours and lasting up to 24 hours [1]. - This intermediate profile is achieved by combining insulin with **protamine**, which slows its absorption from the subcutaneous injection site [1]. *Insulin lispro* - **Insulin lispro** is a **rapid-acting insulin** analog, designed to act very quickly after injection, typically within 15-30 minutes [1, 2]. - Its quick onset and short duration make it suitable for dosing **immediately before meals** to control post-prandial glucose levels [1]. *Regular insulin* - **Regular insulin** is a **short-acting insulin**, with an onset of action around 30-60 minutes and a peak effect typically within 2-4 hours. - It is often administered **30 minutes before meals** and can also be used intravenously in acute situations like diabetic ketoacidosis. *Insulin glargine* - **Insulin glargine** is a **long-acting insulin** analog, providing a prolonged and relatively peakless effect over 24 hours [1, 2]. - Its primary role is to provide **basal insulin coverage**, mimicking the body's continuous background insulin production [1, 2].

Question 760: Which of the following is a synthetic estrogen?

A. Estrone
B. Estriol
C. Estradiol
D. Diethylstilbestrol (Correct Answer)

Explanation: ***Diethylstilbestrol*** - **Diethylstilbestrol (DES)** is a **synthetic non-steroidal estrogen** that was historically used as a medication, particularly to prevent miscarriage. - Its use was discontinued after being linked to various adverse effects, including **vaginal clear cell adenocarcinoma** in female offspring whose mothers took DES during pregnancy. *Estrone* - **Estrone** is one of the three major **naturally occurring endogenous estrogens** in humans. - It is the primary estrogen during **menopause** and is derived from androstenedione. *Estriol* - **Estriol** is another of the three major **naturally occurring estrogens**, predominantly produced during **pregnancy** by the placenta. - It is often used as a marker for fetal well-being. *Estradiol* - **Estradiol** is the **most potent and abundant naturally occurring estrogen** in women during their reproductive years. - It plays a crucial role in the development and maintenance of female reproductive tissues and secondary sexual characteristics.

Practice by Chapter

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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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