Endocrine Pharmacology — MCQs

Endocrine Pharmacology Indian Medical PG Practice Questions and MCQs

Question 691: A 30-year-old woman has experienced the loss of her newborn. She is currently producing breast milk leading to discomfort and the risk of developing a breast abscess due to milk stasis and incomplete emptying. Which of the following drugs can be used to prevent this complication?

A. Cabergoline (Correct Answer)
B. Chlorpromazine
C. Metoclopramide
D. Mifepristone

Explanation: ***Cabergoline*** - **Cabergoline** is a dopamine agonist that inhibits prolactin secretion, thereby suppressing lactation and preventing breast engorgement and its complications after childbirth. - It has a longer duration of action compared to bromocriptine, allowing for less frequent dosing and better patient compliance in lactation suppression. *Chlorpromazine* - **Chlorpromazine** is an antipsychotic medication primarily used to treat psychotic disorders; it doesn't suppress lactation. - While it can cause hyperprolactinemia as a side effect due to its antidopaminergic action, it is not used to manage lactation or its complications. *Metoclopramide* - **Metoclopramide** is a dopamine receptor antagonist that *increases* prolactin levels, and is sometimes used to *stimulate* lactation, not suppress it. - It enhances gastrointestinal motility and is primarily used as an antiemetic or for gastric emptying disorders. *Mifepristone* - **Mifepristone** is a progesterone receptor antagonist primarily used for medical abortion and induction of labor. - It is not indicated for the suppression of lactation or the prevention of breast engorgement.

Question 692: A 55-year-old female with a history of diabetes and hypertension is undergoing a hysterectomy. Which medication should be avoided due to its potential to cause hyperglycemia?

A. Dexamethasone (Correct Answer)
B. Lidocaine
C. Fentanyl
D. Midazolam

Explanation: ***Correct: Dexamethasone*** - **Dexamethasone** is a potent **corticosteroid** that significantly increases blood glucose levels through enhanced hepatic gluconeogenesis and peripheral insulin resistance - Particularly problematic in patients with **pre-existing diabetes**, where perioperative use can exacerbate **hyperglycemia** - Increases risk of surgical complications and requires intensive perioperative glucose management - Should be avoided or used with extreme caution in diabetic patients undergoing surgery *Incorrect: Lidocaine* - **Lidocaine** is a local anesthetic that does not affect glucose metabolism - Used for regional anesthesia and pain management with minimal systemic metabolic effects - Safe to use in diabetic patients *Incorrect: Fentanyl* - **Fentanyl** is an opioid analgesic that acts on pain perception pathways - Does not directly cause **hyperglycemia** or affect glucose homeostasis - Main side effects involve respiratory depression and sedation, not metabolic disturbances *Incorrect: Midazolam* - **Midazolam** is a benzodiazepine used for sedation and anxiolysis - Acts by enhancing GABAergic neurotransmission in the CNS - Does not cause **hyperglycemia** or affect glucose metabolism - Safe to use in diabetic patients from a glycemic control perspective

Question 693: A 25-year-old woman presents with hyperthyroidism. Which of the following is the first-line thionamide drug that inhibits thyroid hormone synthesis by blocking thyroid peroxidase?

A. Methimazole (Correct Answer)
B. Levothyroxine (synthetic thyroid hormone)
C. Propranolol (beta-blocker)
D. Propylthiouracil (PTU)

Explanation: ***Methimazole*** - **Methimazole** is the **first-line thionamide** drug that inhibits thyroid hormone synthesis by blocking the enzyme **thyroid peroxidase**. - This action prevents the **oxidation of iodide** and its subsequent organification (incorporation into tyrosine residues on thyroglobulin), thereby reducing the formation of **T3** and **T4**. - It has a **longer half-life** than PTU, allowing for **once-daily dosing**, and has a **better safety profile** (lower risk of hepatotoxicity). - **Preferred for most patients** with hyperthyroidism except in **first trimester of pregnancy** and **thyroid storm**. *Levothyroxine (synthetic thyroid hormone)* - **Levothyroxine** is a synthetic form of **thyroxine (T4)**, used to *replace* thyroid hormones in patients with **hypothyroidism**. - It does not *inhibit* thyroid hormone synthesis; rather, it *supplements* it. *Propranolol (beta-blocker)* - **Propranolol** is a **beta-adrenergic blocker** that primarily alleviates the **symptoms of hyperthyroidism** (e.g., palpitations, tremor, anxiety) by blocking the action of **catecholamines**. - It does not directly inhibit the **synthesis of thyroid hormones** but can block the peripheral conversion of T4 to T3. *Propylthiouracil (PTU)* - Like methimazole, **PTU** is a **thionamide** that inhibits thyroid hormone synthesis by blocking **thyroid peroxidase**. - However, PTU is **not first-line** due to **shorter half-life** (requires multiple daily doses) and **higher risk of hepatotoxicity**. - **Preferred only in specific situations**: **first trimester of pregnancy** (methimazole is teratogenic) and **thyroid storm** (due to additional inhibition of peripheral T4→T3 conversion).

Question 694: A patient with type II diabetes is prescribed a drug that enhances insulin sensitivity by activating AMP-activated protein kinase (AMPK). What is the primary effect of AMPK activation on lipid metabolism?

A. Promotes fatty acid oxidation
B. Stimulates lipid synthesis
C. Inhibits fatty acid synthesis (Correct Answer)
D. Increases fatty acid storage

Explanation: ***Inhibits fatty acid synthesis*** - **AMPK activation** leads to the phosphorylation and **inactivation of acetyl-CoA carboxylase (ACC)**, a key enzyme in fatty acid synthesis. - By inhibiting ACC, AMPK reduces the production of **malonyl-CoA**, which is both a substrate for fatty acid synthesis and an inhibitor of CPT-1, an enzyme crucial for fatty acid oxidation. - This is the **primary and direct action** of AMPK on lipid metabolism. *Promotes fatty acid oxidation* - While AMPK activation does generally promote **fatty acid oxidation**, this is an **indirect effect** resulting from the inhibition of fatty acid synthesis. - The inhibition of ACC relieves the malonyl-CoA-mediated inhibition of CPT-1, allowing fatty acid oxidation to proceed. - This is a secondary consequence, not the primary effect. *Stimulates lipid synthesis* - AMPK is a metabolic sensor that is activated during low energy states, and its primary role is to **conserve ATP**. - Stimulating lipid synthesis would be an **anabolic process** that consumes ATP, which is contrary to the energy-conserving role of AMPK. *Increases fatty acid storage* - Increased fatty acid storage, often in the form of triglycerides, is generally associated with an **excess of energy intake** and an increase in lipid synthesis. - AMPK's actions, by inhibiting fatty acid synthesis and promoting oxidation, would tend to **decrease fatty acid storage**, not increase it.

Question 695: Which antidiabetic drug primarily works by reducing hepatic glucose production through AMPK activation?

A. Sulfonylureas
B. DPP-4 inhibitors
C. Thiazolidinediones
D. Metformin (Correct Answer)

Explanation: ***Metformin*** - **Metformin** is a biguanide that primarily works by **decreasing hepatic glucose production** through activation of **AMP-activated protein kinase (AMPK)**, which inhibits gluconeogenesis. - It also **increases insulin sensitivity** in peripheral tissues like muscle and adipose tissue as a secondary benefit. - First-line agent for type 2 diabetes mellitus due to its efficacy, safety profile, and weight-neutral or weight-loss effects. *Sulfonylureas* - **Sulfonylureas** primarily stimulate **insulin secretion** from pancreatic beta cells by binding to the sulfonylurea receptor (SUR1) and closing ATP-sensitive potassium channels. - They do not reduce hepatic glucose production or significantly increase insulin sensitivity. - Examples: glibenclamide, glipizide, gliclazide. *DPP-4 inhibitors* - **DPP-4 inhibitors** (gliptins) work by preventing the breakdown of **incretin hormones** (GLP-1 and GIP), which enhance glucose-dependent insulin secretion and suppress glucagon secretion. - Their primary mechanism does not involve direct reduction of hepatic glucose production or peripheral insulin sensitization. - Examples: sitagliptin, vildagliptin, linagliptin. *Thiazolidinediones* - **Thiazolidinediones (TZDs)** primarily improve **insulin sensitivity** in peripheral tissues (muscle and adipose) and liver by activating **peroxisome proliferator-activated receptor gamma (PPAR-γ)**. - They reduce hepatic glucose output indirectly through improved insulin sensitivity, but their primary action is peripheral insulin sensitization, not direct suppression of hepatic gluconeogenesis like metformin. - Examples: pioglitazone (rosiglitazone withdrawn in many countries).

Question 696: Which outcome best evaluates the effect of a new antidiabetic medication on patient health?

A. Patient reports of improved well-being
B. Measured decrease in HbA1c levels (Correct Answer)
C. Weight loss
D. Decreased frequency of urination

Explanation: ***Measured decrease in HbA1c levels*** - **HbA1c** provides an average measure of blood glucose control over the past 2-3 months, directly reflecting the medication's effectiveness in managing **hyperglycemia** [1]. - A significant decrease in HbA1c levels indicates improved **long-term glycemic control**, reducing the risk of diabetes-related complications [4]. *Patient reports of improved well-being* - While important, **patient reports of well-being** are subjective and can be influenced by various factors beyond glycemic control, such as the **placebo effect** or concurrent lifestyle changes. - They do not offer a **quantitative, objective measure** of the medication's direct impact on controlling blood sugar. *Weight loss* - **Weight loss** can be a beneficial side effect of some antidiabetic medications, but it is not the primary measure of their effectiveness in controlling **hyperglycemia** [2], [3]. - Many effective antidiabetic medications do not cause weight loss, and some can even cause weight gain, yet they still improve **glycemic control** [3]. *Decreased frequency of urination* - **Decreased frequency of urination** can be a symptom improvement in some diabetic patients, particularly those with severe hyperglycemia causing **polyuria**. - However, it is a **symptomatic outcome** and not a direct, objective measure of the medication's effectiveness in maintaining stable blood glucose levels over time, unlike HbA1c.

Question 697: Which antidiabetic drug is most likely to cause hypoglycemia due to increased insulin secretion from the pancreas?

A. Metformin
B. Glipizide (Correct Answer)
C. Pioglitazone
D. Acarbose

Explanation: ***Glipizide*** - **Glipizide** belongs to the class of **sulfonylureas**, which work by stimulating pancreatic beta cells to release more insulin, regardless of blood glucose levels. - This **insulin secretagogue** action directly increases the circulating insulin, making **hypoglycemia** a common and significant side effect, especially when food intake is delayed or insufficient. *Metformin* - **Metformin** primarily reduces **hepatic glucose production** and improves insulin sensitivity in peripheral tissues, rather than directly stimulating insulin secretion. - It has a very low risk of causing **hypoglycemia** when used as monotherapy because its mechanism does not involve increasing insulin levels beyond physiological needs. *Pioglitazone* - **Pioglitazone** is a **thiazolidinedione** that improves insulin sensitivity in target tissues by activating **PPAR-gamma receptors**. - It does not directly stimulate insulin secretion from the pancreas, so the risk of **hypoglycemia** is minimal when used alone. *Acarbose* - **Acarbose** is an **alpha-glucosidase inhibitor** that delays the absorption of carbohydrates from the gastrointestinal tract. - It does not affect insulin secretion, therefore, it does not cause **hypoglycemia** when used as monotherapy.

Question 698: A patient receives a medication for osteoporosis that selectively binds to bone surfaces and inhibits osteoclast activity. Which drug is used?

A. Raloxifene
B. Calcitonin
C. Alendronate (Correct Answer)
D. Teriparatide

Explanation: ***Alendronate*** - **Alendronate** is a **bisphosphonate** that selectively binds to bone surfaces and inhibits **osteoclast** activity, thereby reducing bone resorption. - Its mechanism of action leads to increased bone mineral density and reduced fracture risk in patients with **osteoporosis**. *Raloxifene* - **Raloxifene** is a **selective estrogen receptor modulator (SERM)** that acts as an estrogen agonist in bone, reducing bone resorption, but does not directly bind to bone surfaces or inhibit osteoclasts. - It also has estrogen antagonist effects in breast and uterine tissue, differentiating it from bisphosphonates. *Calcitonin* - **Calcitonin** is a hormone that directly inhibits **osteoclast** activity, but it does not bind to bone surfaces like bisphosphonates do. - Its primary clinical use in osteoporosis is often for pain relief associated with acute vertebral fractures, and its overall efficacy for fracture prevention is less robust than bisphosphonates. *Teriparatide* - **Teriparatide** is a recombinant form of **parathyroid hormone (PTH)** that, when given intermittently, stimulates **osteoblast** activity and promotes new bone formation. - This is an **anabolic agent**, making it distinct from antiresorptive drugs that inhibit osteoclasts.

Question 699: What is the role of AMP-activated protein kinase (AMPK) in metabolic regulation, and which therapeutic strategy targeting AMPK is most effective for the treatment of type 2 diabetes?

A. AMPK activation increases insulin sensitivity; therefore, metformin is an effective treatment. (Correct Answer)
B. AMPK activation promotes lipid oxidation; therefore, statins are not appropriate.
C. AMPK activation enhances glucose uptake; therefore, sulfonylureas targeting AMPK are preferred.
D. AMPK activation suppresses gluconeogenesis; therefore, DPP-4 inhibitors are the most effective AMPK activators.

Explanation: ***AMPK activation increases insulin sensitivity; therefore, metformin is an effective treatment.*** - **AMPK** is a crucial energy sensor that, when activated, promotes catabolic pathways like **fatty acid oxidation** and **glucose uptake** and inhibits anabolic pathways, thereby improving **insulin sensitivity**. - **Metformin** is a well-established first-line treatment for **type 2 diabetes** that primarily acts by activating AMPK, leading to reduced hepatic glucose production and improved peripheral glucose utilization. *AMPK activation promotes lipid oxidation; therefore, statins are not appropriate.* - While **AMPK activation** does promote lipid oxidation, **statins** are prescribed to lower cholesterol levels by inhibiting HMG-CoA reductase, an unrelated mechanism. - Statins are often beneficial for patients with **type 2 diabetes** due to their increased cardiovascular disease risk, but they do not work through AMPK activation. *AMPK activation enhances glucose uptake; therefore, sulfonylureas targeting AMPK are preferred.* - While **AMPK activation** does enhance glucose uptake, **sulfonylureas** work by closing ATP-sensitive potassium channels in pancreatic beta cells to stimulate insulin secretion, not by activating AMPK. - Sulfonylureas do not target AMPK and are not the most effective strategy for AMPK-based therapy in type 2 diabetes. *AMPK activation suppresses gluconeogenesis; therefore, DPP-4 inhibitors are the most effective AMPK activators.* - While **AMPK activation** does suppress hepatic **gluconeogenesis**, **DPP-4 inhibitors** work by prolonging incretin hormone activity to enhance insulin secretion and suppress glucagon, not primarily through AMPK activation. - **Metformin**, not DPP-4 inhibitors, is the primary therapeutic agent that effectively targets AMPK for diabetes treatment.

Question 700: A 50-year-old male with type 2 diabetes is prescribed a new medication to manage his condition. Which drug reduces postprandial hyperglycemia without increasing insulin levels?

A. Metformin
B. Glibenclamide
C. Voglibose (Correct Answer)
D. Pioglitazone

Explanation: ***Voglibose*** - **Voglibose** is an alpha-glucosidase inhibitor that works by delaying the digestion and absorption of carbohydrates in the small intestine. - This mechanism specifically reduces the postprandial rise in blood glucose without directly affecting insulin secretion or sensitivity. *Metformin* - **Metformin** primarily reduces hepatic glucose production and increases insulin sensitivity in peripheral tissues. - It does not specifically target postprandial hyperglycemia by delaying carbohydrate absorption to the extent that alpha-glucosidase inhibitors do, nor does it increase insulin levels. *Glibenclamide* - **Glibenclamide** is a sulfonylurea that stimulates insulin release from pancreatic beta cells. - This mechanism directly increases insulin levels, which is contrary to the question's premise. *Pioglitazone* - **Pioglitazone** is a thiazolidinedione (TZD) that improves insulin sensitivity in adipose tissue, muscle, and liver. - While it helps manage blood glucose, its primary action is not to reduce postprandial hyperglycemia without altering insulin levels; rather, it improves the body's response to existing insulin.

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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