Endocrine Pharmacology — MCQs

Endocrine Pharmacology Indian Medical PG Practice Questions and MCQs

Question 741: Which of the following antidiabetic drugs is a GLP-1 receptor agonist?

A. Pramlintide
B. Glucomannan
C. Exenatide (Correct Answer)
D. Sitagliptin

Explanation: ***Exenatide*** - **Exenatide** is a synthetic analog of **glucagon-like peptide-1 (GLP-1)**, acting as a GLP-1 receptor agonist [1]. - It works by stimulating **insulin secretion** in a glucose-dependent manner, suppressing glucagon release, slowing gastric emptying, and promoting satiety [2], [3]. - Other GLP-1 agonists include liraglutide, dulaglutide, and semaglutide [1]. *Pramlintide* - **Pramlintide** is an **amylin analog**, not a GLP-1 receptor agonist. - It is used in both type 1 and type 2 diabetes to slow gastric emptying, suppress glucagon secretion, and promote satiety, but it acts via **amylin receptors**. *Glucomannan* - **Glucomannan** is a **dietary fiber** derived from the konjac plant, used as a food additive and supplement for weight loss and constipation. - It does not directly affect GLP-1 receptors or regulate insulin or glucagon secretion as a pharmacological agent. *Sitagliptin* - **Sitagliptin** is a **DPP-4 inhibitor** (dipeptidyl peptidase-4 inhibitor), not a GLP-1 receptor agonist [2]. - While it enhances endogenous GLP-1 activity by preventing its degradation, it does not directly stimulate GLP-1 receptors like exenatide does [4].

Question 742: Which of the following statements about Selective Estrogen Receptor Modulators (SERMs) is correct?

A. Act as agonists on estrogen receptors.
B. Some SERMs can act as both agonists and antagonists on estrogen receptors. (Correct Answer)
C. Used to reduce the risk of hot flushes and thromboembolism.
D. Act as antagonists on estrogen receptors.

Explanation: ***Some SERMs can act as both agonists and antagonists on estrogen receptors.*** - **SERMs** (Selective Estrogen Receptor Modulators) exert tissue-specific effects, meaning they can act as an **estrogen receptor agonist** in some tissues while acting as an **antagonist** in others. - This **selective mechanism** allows them to confer beneficial estrogenic effects where desired (e.g., bone) and anti-estrogenic effects where unwanted (e.g., breast tissue). *Act as agonists on estrogen receptors.* - This statement is incomplete because while some SERMs can act as **agonists** in certain tissues (e.g., affecting bone density), they are not pure agonists across all tissues. - Their defining characteristic is their **selective action**, exhibiting mixed agonist and antagonist effects depending on the tissue. *Used to reduce the risk of hot flushes and thromboembolism.* - SERMs like **tamoxifen** and **raloxifene** can actually **increase the risk** of both hot flushes and thromboembolism. - **Hot flushes** occur due to their **anti-estrogenic effects** on the hypothalamus, which disrupts thermoregulation. - **Thromboembolism** risk is increased due to their **estrogenic (agonist) effects** on hepatic synthesis of coagulation factors. *Act as antagonists on estrogen receptors.* - This statement is also incomplete because, while some SERMs exhibit **antagonist activity** in certain tissues (e.g., the breast), they simultaneously act as **agonists** in other tissues (e.g., bone or endometrium). - A pure antagonist would block estrogen receptors in all tissues, which is not the defining feature of SERMs.

Question 743: Which drug is commonly used to treat hyperprolactinemia in women experiencing infertility?

A. Bromocriptine (Correct Answer)
B. Gonadotropin-Releasing Hormone (GnRH)
C. Testosterone (Androgen)
D. Corticosteroids

Explanation: ***Bromocriptine*** - **Bromocriptine** is a **dopamine agonist** that directly inhibits **prolactin secretion** from the pituitary gland. - By lowering prolactin levels, it helps restore **ovulatory function** and **fertility** in women with hyperprolactinemia. - It is the **first-line treatment** for hyperprolactinemia-induced infertility. *Gonadotropin-Releasing Hormone (GnRH)* - **GnRH** (or its agonists/antagonists) is primarily used to control **gonadotropin release** for conditions like **endometriosis** or **fibroids**, or in **assisted reproductive technologies**. - It does not directly treat hyperprolactinemia by inhibiting prolactin secretion. *Testosterone (Androgen)* - **Testosterone** is an **androgen** and is generally not used in women for infertility, especially not for hyperprolactinemia. - High testosterone levels in women can cause **hirsutism** and **anovulation**, which would worsen infertility. *Corticosteroids* - **Corticosteroids** are potent **anti-inflammatory** and **immunosuppressive** agents. - They are used to treat various autoimmune conditions or inflammation but have no direct role in treating hyperprolactinemia or female infertility in this context.

Question 744: A patient has Cushing syndrome due to an adrenal tumor. Which drug should be given?

A. Ketoconazole (Correct Answer)
B. Spironolactone
C. Hydrocortisone
D. Dexamethasone

Explanation: ***Ketoconazole*** - **Ketoconazole** is an antifungal agent that also inhibits several enzymes involved in **steroidogenesis**, including 17α-hydroxylase and 11β-hydroxylase. - This action helps to reduce the overproduction of **cortisol** in Cushing syndrome caused by an adrenal tumor. *Hydrocortisone* - **Hydrocortisone** is a glucocorticoid itself and would exacerbate the symptoms of **Cushing syndrome** by adding to the already elevated cortisol levels. - It is used for **cortisol replacement therapy** in conditions like Addison's disease, where cortisol levels are low. *Dexamethasone* - **Dexamethasone** is a potent synthetic glucocorticoid used to suppress **ACTH production** in cases of ACTH-dependent Cushing's syndrome (e.g., Cushing's disease) or to diagnose Cushing's syndrome. - In an adrenal tumor, which is **ACTH-independent**, dexamethasone would not reduce cortisol production but could instead worsen the hypercortisolism. *Spironolactone* - **Spironolactone** is an **aldosterone antagonist** and a weak antiandrogen, primarily used for conditions like hyperaldosteronism, heart failure, and hirsutism. - It has no direct effect on the overproduction of **cortisol** from an adrenal tumor in Cushing syndrome.

Question 745: Which of the following is the longest acting glucocorticoid?

A. Prednisone
B. Prednisolone
C. Cortisone
D. Dexamethasone (Correct Answer)

Explanation: ***Correct: Dexamethasone*** - **Dexamethasone** is a long-acting glucocorticoid with a **biological half-life of 36–72 hours**, making it the longest acting among the options provided - Its prolonged action is due to its **high affinity for the glucocorticoid receptor** and relatively slow metabolism - Provides sustained anti-inflammatory and immunosuppressive effects *Incorrect: Prednisone* - **Prednisone** is an intermediate-acting glucocorticoid with a biological half-life of 12-36 hours - Requires metabolism in the liver to its active form, prednisolone - Duration of action is significantly shorter than dexamethasone *Incorrect: Prednisolone* - **Prednisolone** is the active form of prednisone, with a similar intermediate duration of action (12-36 hours) - Primarily used when liver conversion of prednisone is impaired - Does not possess the extended duration of action characteristic of dexamethasone *Incorrect: Cortisone* - **Cortisone** is a short-acting glucocorticoid with a biological half-life of 8-12 hours - It is a prodrug that needs to be converted to **hydrocortisone** (cortisol) in the liver to become active - Has the shortest duration among all options

Question 746: What conditions is Metformin primarily used to treat?

A. Only Type 2 Diabetes
B. Only Polycystic Ovary Syndrome (PCOS)
C. Both Type 2 Diabetes and Polycystic Ovary Syndrome (PCOS) (Correct Answer)
D. Pregnancy Induced Hypertension

Explanation: ***Both Type 2 Diabetes and Polycystic Ovary Syndrome (PCOS)*** - **Metformin** is a first-line treatment for **Type 2 Diabetes** due to its ability to decrease hepatic glucose production and improve insulin sensitivity [1], [2]. - It is also commonly used off-label for **PCOS** to improve insulin resistance, ovulation, and reduce androgen levels. *Only Type 2 Diabetes* - While Metformin is a cornerstone for **Type 2 Diabetes** treatment, stating "only" is incorrect as it has other significant therapeutic uses [2]. - Its benefits extend beyond diabetes management, particularly in conditions involving **insulin resistance**. *Only Polycystic Ovary Syndrome (PCOS)* - Metformin is used in **PCOS**, but it is not the sole condition it treats, and its primary indication remains **Type 2 Diabetes** [2]. - This option incorrectly limits its application to just one condition, overlooking its major role in diabetes. *Pregnancy Induced Hypertension* - **Metformin** is not indicated for the treatment of **pregnancy-induced hypertension** (gestational hypertension). - Treatment for pregnancy-induced hypertension typically involves medications like **labetalol**, **methyldopa**, or **nifedipine**, with delivery being the definitive management for severe cases.

Question 747: Which of the antithyroid drugs inhibits iodine trapping?

A. Radioactive iodine
B. Iodides
C. Thiocyanates (Correct Answer)
D. Methimazole

Explanation: ***Thiocyanates*** - **Thiocyanates** are competitive inhibitors of the **sodium-iodide symporter (NIS)**, which is responsible for actively transporting iodide into thyroid follicular cells (iodine trapping) [1]. - By blocking NIS, thiocyanates prevent the thyroid gland from accumulating iodide, thereby inhibiting thyroid hormone synthesis [1]. *Radioactive iodine* - **Radioactive iodine (RAI)** primarily works by being taken up by thyroid cells and emitting **beta particles**, which destroy the thyroid tissue [3]. - It does not inhibit iodine trapping, but rather uses the trapping mechanism to concentrate in the thyroid and exert its destructive effect [3]. *Iodides* - **Iodides** (e.g., Lugol's solution) paradoxically inhibit organification and hormone release from the thyroid gland, an effect known as the **Wolff-Chaikoff effect** [2]. - They also decrease the vascularity and size of the thyroid gland, making them useful in preparing patients for thyroidectomy, but do not directly inhibit iodine trapping [2]. *Methimazole* - **Methimazole** is a **thionamide** drug that primarily inhibits the enzyme **thyroid peroxidase**. - This prevents the **organification of iodide** (incorporation of iodine into tyrosine residues) and the **coupling of iodotyrosines** (forming T3 and T4), not the initial trapping of iodine.

Question 748: Which medication increases insulin secretion from beta cells?

A. Metformin
B. Repaglinide (Correct Answer)
C. Pioglitazone
D. Pramlintide

Explanation: ***Repaglinide*** - This medication is a **meglitinide analog** that stimulates **insulin release** from pancreatic beta cells by closing ATP-sensitive potassium channels. - Its fast onset and short duration of action make it particularly useful for controlling **postprandial glucose** excursions. *Metformin* - This medication primarily works by **decreasing hepatic glucose production** and improving insulin sensitivity in peripheral tissues. - It does **not directly stimulate insulin secretion** from beta cells; thus, it carries a lower risk of hypoglycemia compared to sulfonylureas or meglitinides. *Pramlintide* - This is an **amylin analog** that works by slowing gastric emptying, suppressing postprandial glucagon secretion, and increasing satiety. - It is an **injectable medication** used as an adjunct to insulin therapy and does not directly enhance insulin secretion from beta cells. *Pioglitazone* - This drug is a **thiazolidinedione** that improves insulin sensitivity in target tissues (e.g., muscle, fat, liver) by activating **peroxisome proliferator-activated receptor-gamma (PPAR-γ)**. - While it improves the body's response to insulin, it does **not directly stimulate insulin secretion** from the beta cells.

Question 749: Which of the following drugs can cause thyroid dysfunction?

A. Amiodarone (Correct Answer)
B. Ampicillin
C. Ibutilide
D. Acyclovir

Explanation: ***Amiodarone*** - **Amiodarone** is known to cause both **hypothyroidism** and **hyperthyroidism** due to its high iodine content and direct toxic effects on the thyroid gland. - Its effects can persist for months after discontinuation due to its **long half-life** and accumulation in tissues. *Ampicillin* - **Ampicillin** is an antibiotic that generally does not directly affect thyroid function. - Its primary mechanism of action involves inhibiting **bacterial cell wall synthesis**, with no known significant endocrine side effects. *Ibutilide* - **Ibutilide** is an antiarrhythmic drug used for recent-onset atrial fibrillation or flutter. - It works by blocking potassium channels and has no recognized association with thyroid dysfunction. *Acyclovir* - **Acyclovir** is an antiviral medication used to treat herpes virus infections. - Its mechanism of action involves inhibiting viral DNA replication and it is not known to impact thyroid hormone synthesis or metabolism.

Question 750: Which of the following statements about sitagliptin is false?

A. Used in type II diabetes mellitus
B. Cannot be used orally (Correct Answer)
C. Used in combination with other oral hypoglycemic agents
D. All of the above statements are true

Explanation: ***Cannot be used orally*** - This statement is **false** because **sitagliptin** is an **oral medication** approved for the treatment of type 2 diabetes mellitus. - As a **DPP-4 inhibitor**, it is designed to be taken by mouth to increase incretin hormone levels. *Used in type II diabetes mellitus* - This statement is **true** as **sitagliptin** is a commonly prescribed **oral antidiabetic drug** for the management of type 2 diabetes. - It works by inhibiting the enzyme **dipeptidyl peptidase-4 (DPP-4)**, which increases levels of **GLP-1** and **GIP** to enhance insulin secretion and reduce glucagon secretion. *Used in combination with other oral hypoglycemic agents* - This statement is **true** as **sitagliptin** is often used as **add-on therapy** with other oral hypoglycemic agents like **metformin** or a **sulfonylurea** when monotherapy is insufficient. - This combination approach helps achieve better glycemic control by targeting different mechanisms of action. *All of the above statements are true* - This statement is **false** because the first statement "Cannot be used orally" is incorrect. - Since sitagliptin is indeed an oral medication, not all the above statements are true, making this option incorrect.

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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