Endocrine Pharmacology Practice Questions

Q: A 57-year-old lady presents with type II diabetes mellitus with symptoms like polyuria, excessive thirst, fatigue, and blurred vision. Further investigation reveals insulin resistance. Which one of the following drugs is most appropriate for initiating treatment along with diet and exercise?

Metformin. **Explanation:** **Why Metformin is the Correct Choice:** Metformin, a Biguanide, is the **first-line drug of choice** for Type 2 Diabetes Mellitus (T2DM) according to ADA and EASD guidelines [1]. Its primary mechanism of action is the activation of **AMP-activated protein kinase (AMPK)**, which leads to decreased hepatic gluconeogenesis and improved peripheral insulin sensitivity [2]. It is preferred for initiation because it is weight-neutral (or promotes slight weight loss), does not cause hypoglycemia, has a proven cardiovascular safety profile, and is cost-effective [1]. **Why Other Options are Incorrect:** * **Pioglitazone (Thiazolidinedione):** While it effectively reduces insulin resistance via PPAR-̳ activation [2], it is generally a second-line agent due to side effects like weight gain, edema, and risks of heart failure and osteoporosis [2]. * **Glimepiride (Sulfonylurea):** These are "insulin secretagogues." They carry a high risk of hypoglycemia and weight gain, making them less ideal than Metformin for initial monotherapy [1]. * **Repaglinide (Meglitinide):** Also a secretagogue with a short duration of action used primarily for postprandial hyperglycemia [3]. It requires multiple daily dosing and is not the standard first-line agent. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Metformin SE:** **M**etallic taste, **M**egaloblastic anemia (Vitamin B12 deficiency), and **M**ost serious side effect: Lactic Acidosis [2]. * **Contraindication:** Metformin should be avoided if eGFR < 30 mL/min due to the risk of lactic acidosis [2]. * **Efficacy:** Metformin typically reduces HbA1c by 1.0% to 1.5% [2]. * **Pleiotropic effect:** It is also used in Polycystic Ovary Syndrome (PCOS) to improve insulin sensitivity and ovulation.

Q: Which of the following characteristics makes metformin a preferred biguanide compared to phenformin?

It is less liable to cause lactic acidosis. **Explanation:** **1. Why Option B is Correct:** The primary reason metformin replaced phenformin in clinical practice is its significantly lower risk of **lactic acidosis**. Phenformin was withdrawn globally in the 1970s because it has a high affinity for mitochondrial membranes, where it strongly inhibits the mitochondrial respiratory chain (Complex I). This leads to excessive anaerobic glycolysis and a massive buildup of lactate. Metformin, being less lipophilic, has a much weaker effect on mitochondrial respiration at therapeutic doses, making it a safer profile for glycemic control. **2. Why Other Options are Incorrect:** * **Option A:** Phenformin is actually **more potent** than metformin on a milligram-to-milligram basis, but its higher potency is associated with its increased toxicity. * **Option C:** Both metformin and phenformin can interfere with **Vitamin B12 absorption** in the terminal ileum. Long-term metformin use is a well-known cause of B12 deficiency, requiring periodic monitoring. * **Option D:** Metformin is primarily excreted unchanged by the kidneys. Therefore, it is **contraindicated** in patients with significant renal impairment (typically eGFR <30 mL/min) due to the increased risk of accumulation and subsequent lactic acidosis. **3. Clinical Pearls for NEET-PG:** * **Mechanism of Action:** Metformin activates **AMP-activated protein kinase (AMPK)**, leading to decreased hepatic gluconeogenesis and improved peripheral insulin sensitivity. * **Weight Neutrality:** Unlike sulfonylureas or insulin, metformin does not cause weight gain; it is often weight-neutral or promotes modest weight loss. * **First-line Status:** It is the drug of choice for Type 2 Diabetes Mellitus, especially in obese patients. * **Side Effects:** The most common side effects are GI-related (diarrhea, abdominal cramps). The most serious (though rare) is lactic acidosis.

Q: Which drug's action requires the presence of insulin to produce its therapeutic effect?

Pioglitazone. **Explanation:** The correct answer is **Pioglitazone**. **1. Why Pioglitazone is correct:** Pioglitazone belongs to the **Thiazolidinedione (TZD)** class. Its primary mechanism of action is as a selective agonist for the nuclear receptor **PPAR-γ** (Peroxisome Proliferator-Activated Receptor gamma). Activation of this receptor increases the transcription of genes involved in glucose and lipid metabolism, effectively acting as an **insulin sensitizer**. Because Pioglitazone works by enhancing the body's response to insulin (reducing insulin resistance in muscle, fat, and liver), it is physiologically dependent on the presence of either endogenous or exogenous insulin to exert its glucose-lowering effect. **2. Analysis of Incorrect Options:** * **A. Glibenclamide (Sulfonylurea):** These are insulin secretagogues. They work by closing ATP-sensitive K+ channels in pancreatic beta cells, causing depolarization and insulin release. They require functional beta cells, but not the presence of insulin itself, to act. * **B. Nateglinide (Meglitinide):** Similar to sulfonylureas, these are short-acting secretagogues that stimulate the release of insulin from the pancreas. * **C. Empagliflozin (SGLT-2 Inhibitor):** This drug acts on the proximal convoluted tubule of the kidney to inhibit glucose reabsorption. Its mechanism is entirely **insulin-independent**, making it effective even in states of absolute insulin deficiency. **3. NEET-PG High-Yield Pearls:** * **TZDs and Weight:** Unlike many other antidiabetics, TZDs can cause weight gain (due to fluid retention and adipocyte differentiation). * **Contraindication:** Avoid TZDs in patients with NYHA Class III/IV Heart Failure due to the risk of fluid overload. * **Metformin vs. Pioglitazone:** Both are sensitizers, but Metformin primarily acts on the liver (AMPK activation), while TZDs primarily act on peripheral tissues (PPAR-γ).

Q: Which of the following drugs does not increase insulin secretion?

Rosiglitazone. ### Explanation The correct answer is **Rosiglitazone**. #### 1. Why Rosiglitazone is Correct Rosiglitazone belongs to the **Thiazolidinedione (TZD)** class. Its primary mechanism of action is as a selective agonist for the nuclear receptor **PPAR-γ** (Peroxisome Proliferator-Activated Receptor-gamma). Instead of stimulating insulin secretion from the pancreas, it acts as an **insulin sensitizer**. It increases glucose uptake in peripheral tissues (skeletal muscle and adipose tissue) and decreases hepatic glucose production. Since it does not act on beta cells to release insulin, it is not associated with hypoglycemia when used as monotherapy. #### 2. Why the Other Options are Incorrect * **Repaglinide:** A **Meglitinide** analogue. It acts as an insulin secretagogue by closing ATP-sensitive K⁺ channels in pancreatic beta cells, similar to sulfonylureas but with a faster onset and shorter duration. * **Exenatide:** A **GLP-1 Receptor Agonist** (Incretin mimetic). It stimulates glucose-dependent insulin secretion, suppresses glucagon release, and slows gastric emptying. * **Sitagliptin:** A **DPP-4 Inhibitor**. It prevents the breakdown of endogenous GLP-1 and GIP, thereby increasing insulin secretion in a glucose-dependent manner. #### 3. High-Yield Clinical Pearls for NEET-PG * **Weight Gain:** Both TZDs (Rosiglitazone) and Secretagogues (Repaglinide) cause weight gain, whereas GLP-1 agonists (Exenatide) cause weight loss. * **Side Effects of TZDs:** Fluid retention (edema), congestive heart failure exacerbation, and increased risk of bone fractures. * **Euglycemics:** Drugs like Metformin and TZDs are termed "euglycemics" because they improve glucose utilization without the risk of inducing hypoglycemia. * **Glucose-Dependency:** GLP-1 agonists and DPP-4 inhibitors only increase insulin secretion when blood glucose is high, significantly reducing the risk of hypoglycemia compared to Meglitinides.

Q: In terms of birth defect potential, which of the following drugs is the safest?

Progesterone. **Explanation:** The correct answer is **Progesterone**. In pharmacological terms, drugs are classified based on their teratogenic potential. Progesterone is a naturally occurring hormone essential for maintaining pregnancy and is generally considered safe when used appropriately (e.g., for luteal phase support or prevention of preterm labor). Unlike the other options, it does not have a proven association with structural birth defects in humans. **Why the other options are incorrect:** * **Alcohol:** A potent teratogen and the leading cause of preventable intellectual disability. It causes **Fetal Alcohol Syndrome (FAS)**, characterized by craniofacial abnormalities (short palpebral fissures, thin upper lip), growth retardation, and CNS dysfunction. * **Isotretinoin:** A Vitamin A derivative used for acne, it is highly teratogenic (Category X). It causes **Retinoic Acid Embryopathy**, involving severe craniofacial, cardiac, and CNS defects (e.g., microtia, hydrocephalus). * **Tetracyclines:** These are contraindicated in pregnancy because they cross the placenta and chelate calcium. This leads to **permanent discoloration of deciduous teeth** and inhibition of bone growth in the fetus. **High-Yield Clinical Pearls for NEET-PG:** * **Thalidomide:** Causes Phocomelia (seal-like limbs). * **Valproate:** Highest risk of Neural Tube Defects (NTDs). * **Warfarin:** Causes Fetal Warfarin Syndrome (stippled epiphyses and nasal hypoplasia). * **Phenytoin:** Causes Fetal Hydantoin Syndrome (cleft lip/palate and digital hypoplasia). * **ACE Inhibitors:** Cause renal dysgenesis and oligohydramnios in the 2nd/3rd trimesters.

Q: By binding RANKL with high affinity, which of the following drugs reduces bone resorption?

Denosumab. **Explanation:** **Denosumab** is the correct answer because it is a human monoclonal antibody that specifically targets and binds to **RANKL** (Receptor Activator of Nuclear Factor kappa-B Ligand). Under normal physiological conditions, RANKL is secreted by osteoblasts and binds to RANK receptors on osteoclast precursors, leading to their maturation and activation. By inhibiting RANKL, Denosumab prevents osteoclast formation, thereby decreasing bone resorption and increasing bone mineral density. **Analysis of Incorrect Options:** * **Alemtuzumab (A):** A monoclonal antibody against **CD52**, primarily used in B-cell chronic lymphocytic leukemia (CLL) and Multiple Sclerosis. * **Palivizumab (B):** Targets the **F protein** of Respiratory Syncytial Virus (RSV); used for prophylaxis in high-risk infants. * **Daclizumab (C):** An antibody against the **IL-2 receptor (CD25)**; formerly used in Multiple Sclerosis (now largely withdrawn due to toxicity). **High-Yield Clinical Pearls for NEET-PG:** * **Indications:** Denosumab is used for Postmenopausal Osteoporosis and Giant Cell Tumor of Bone. * **Administration:** It is administered **subcutaneously** every 6 months. * **Adverse Effects:** It may cause hypocalcemia (ensure Vitamin D/Calcium supplementation) and, rarely, Osteonecrosis of the Jaw (ONJ). * **Comparison:** Unlike Bisphosphonates, Denosumab can be used in patients with **renal impairment** as it is not cleared by the kidneys. * **OPG Connection:** Denosumab mimics the natural action of **Osteoprotegerin (OPG)**, the body's endogenous RANKL decoy receptor.

Question 1

A patient with nephrotic syndrome on longstanding corticosteroid therapy may develop all the following except?

Accepted Answer

Hypertrophy of muscle

Answer

Hyperglycemia

Answer

Neuropsychiatric symptoms

Answer

Suppression of Hypothalamic pituitary adrenal axis

Question 2

A 57-year-old lady presents with type II diabetes mellitus with symptoms like polyuria, excessive thirst, fatigue, and blurred vision. Further investigation reveals insulin resistance. Which one of the following drugs is most appropriate for initiating treatment along with diet and exercise?

Accepted Answer

Metformin

Answer

Pioglitazone

Answer

Glimepiride

Answer

Repaglinide

Question 3

Which of the following group of antidiabetic drugs are contraindicated in patients with Multiple Endocrine Neoplasia (MEN) syndrome?

Accepted Answer

GLP-1 analogues

Answer

Biguanides

Answer

Alpha-glucosidase inhibitors

Answer

Meglitinides

Question 4

Which of the following characteristics makes metformin a preferred biguanide compared to phenformin?

Accepted Answer

It is less liable to cause lactic acidosis

Answer

It is more potent

Answer

It does not interfere with vitamin B12 absorption

Answer

It is not contraindicated in patients with kidney disease

Question 5

Which drug's action requires the presence of insulin to produce its therapeutic effect?

Accepted Answer

Pioglitazone

Answer

Glibenclamide

Answer

Nateglinide

Answer

Empagliflozin

Question 6

A patient diagnosed with a brain tumor is to be treated with steroids to decrease cerebral edema. Which type of steroid is preferred and why?

Accepted Answer

The preferred steroids cause less sodium and water retention.

Answer

The preferred steroids are more potent.

Answer

The preferred steroids can be administered intravenously.

Answer

The preferred steroids inhibit brain tumors directly.

Question 7

Which of the following drugs does not increase insulin secretion?

Accepted Answer

Rosiglitazone

Answer

Repaglinide

Answer

Exenatide

Answer

Sitagliptin

Question 8

In terms of birth defect potential, which of the following drugs is the safest?

Accepted Answer

Progesterone

Answer

Alcohol

Answer

Isotretinoin (Accutane)

Answer

Tetracyclines

Question 9

By binding RANKL with high affinity, which of the following drugs reduces bone resorption?

Accepted Answer

Denosumab

Answer

Alemtuzumab

Answer

Palivizumab

Answer

Daclizumab

Question 10

Parathormone is useful in which of the following conditions?

Accepted Answer

Hyperparathyroidism

Answer

Paget's disease

Answer

Osteoporosis

Answer

Osteomalacia

Endocrine Pharmacology — MCQs

Endocrine Pharmacology — MCQs

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