Endocrine Pharmacology Practice Questions

Q: Which of the following is NOT a mode of action of sulfonamides?

Decreasing glucose absorption from the gut.. **Explanation:** Sulfonylureas (often referred to in this context as sulfonamide derivatives) are insulin secretagogues used in Type 2 Diabetes Mellitus. Their primary mechanism involves stimulating the pancreas, but they also possess significant extrapancreatic effects. **Why Option D is Correct:** **Decreasing glucose absorption from the gut** is the mechanism of action of **Alpha-glucosidase inhibitors** (e.g., Acarbose, Miglitol) and, to a lesser extent, Biguanides (Metformin). Sulfonylureas have no pharmacological effect on intestinal glucose transport or carbohydrate digestion. **Analysis of Incorrect Options:** * **Option A:** This is the **primary pancreatic action**. Sulfonylureas bind to the SUR1 subunit of ATP-sensitive K⁺ channels on beta-cell membranes, causing channel closure, depolarization, calcium influx, and subsequent insulin release. * **Option B:** This is an **extrapancreatic action**. Sulfonylureas reduce hepatic glucose production by inhibiting gluconeogenesis and glycogenolysis, thereby improving fasting plasma glucose. * **Option C:** Sulfonylureas increase **peripheral insulin sensitivity** by enhancing post-receptor signaling and increasing the number/sensitivity of insulin receptors on target tissues like muscle and fat. **High-Yield NEET-PG Pearls:** * **Generations:** First-gen (Tolbutamide - shortest acting) vs. Second-gen (Glimepiride - most potent). * **Side Effects:** Hypoglycemia (most common) and weight gain. * **Disulfiram-like reaction:** Classically associated with **Chlorpropamide**. * **Safety in Renal Failure:** **Gliquidone** is primarily excreted in bile, making it safer in renal impairment. * **K-ATP Channels:** These drugs also affect cardiac K-ATP channels; however, **Glimepiride** is considered more "pancreato-selective."

Q: Prolonged use of steroids may cause which of the following?

Decrease in bone matrix protein. ### Explanation **Correct Answer: A. Decrease in bone matrix protein** Prolonged use of glucocorticoids leads to **Glucocorticoid-Induced Osteoporosis (GIOP)** through several mechanisms. Steroids inhibit **osteoblasts** (bone-forming cells) and stimulate **osteoclasts** (bone-resorbing cells). Crucially, they decrease the synthesis of **Type I collagen** and other bone matrix proteins, leading to a reduction in the organic matrix (osteoid). Additionally, steroids decrease intestinal calcium absorption and increase renal calcium excretion, further weakening the bone. **Why the other options are incorrect:** * **B. Hypoglycemia:** Steroids are "diabetogenic." They stimulate gluconeogenesis and decrease peripheral glucose uptake, leading to **hyperglycemia**, not hypoglycemia. * **C. Hypotension:** Steroids have mineralocorticoid activity (causing sodium and water retention) and sensitize blood vessels to catecholamines. This typically results in **hypertension**. * **D. Early healing of wound:** Steroids **delay wound healing** by inhibiting fibroblast proliferation, reducing collagen synthesis, and suppressing the inflammatory response necessary for tissue repair. **High-Yield Clinical Pearls for NEET-PG:** * **Most common site of steroid-induced fracture:** Vertebrae (followed by the femoral neck). * **Avascular Necrosis (AVN):** A serious complication of long-term steroid use, most commonly affecting the **head of the femur**. * **Prophylaxis:** Patients on long-term steroids should be started on **Calcium, Vitamin D, and Bisphosphonates** (the drug of choice for GIOP). * **Ocular side effects:** Steroids can cause **posterior subcapsular cataracts** and **glaucoma** (due to increased intraocular pressure).

Q: Which of the following conditions is a primary indication for the use of prostaglandins?

Missed abortion. **Explanation:** Prostaglandins (PGs) are potent stimulators of uterine smooth muscle contraction and are essential in obstetric practice for cervical ripening and uterine evacuation. **Why Missed Abortion is the Primary Indication:** In a **missed abortion**, the products of conception are retained despite fetal demise. Prostaglandins, specifically **Misoprostol (PGE1)**, are the drug of choice for medical management. They act by softening and dilating the cervix (cervical ripening) and inducing myometrial contractions to expel the retained tissue, avoiding the need for invasive surgical evacuation in many cases. **Analysis of Incorrect Options:** * **Second-trimester abortion:** While PGs (like Carboprost or Misoprostol) are used, they are often part of a combined regimen with Mifepristone. In the context of "primary" pharmacological management of a non-viable pregnancy, missed abortion is the classic indication. * **Ectopic pregnancy:** This is a **contraindication** for prostaglandin use. The primary medical management for an unruptured ectopic pregnancy is **Methotrexate** (a folate antagonist). * **Postpartum hemorrhage (PPH):** While **Carboprost (PGF2α)** and Misoprostol are used in PPH, they are typically **second-line** agents. **Oxytocin** remains the primary drug of choice for both the prevention and initial treatment of PPH. **High-Yield NEET-PG Pearls:** * **Misoprostol (PGE1):** Orally active, stable at room temperature; used for missed abortion and NSAID-induced peptic ulcers. * **Dinoprostone (PGE2):** Most commonly used for induction of labor (cervical ripening). * **Carboprost (15-methyl PGF2α):** Used for refractory PPH; contraindicated in **Asthma** due to bronchoconstriction. * **Gemeprost (PGE1 analog):** Specifically used for second-trimester abortions via vaginal suppository.

Q: Which is the most common adverse drug reaction of acarbose?

Flatulence. **Acarbose** is an **$\alpha$-glucosidase inhibitor** used in the management of Type 2 Diabetes Mellitus. Its mechanism involves inhibiting the enzyme $\alpha$-glucosidase at the brush border of the small intestine, which delays the digestion and absorption of complex carbohydrates (starch and sucrose) [1]. **Why Flatulence is the correct answer:** Because carbohydrate absorption is delayed, undigested carbohydrates reach the **colon**. Here, they undergo bacterial fermentation, leading to the production of gases (CO₂, H₂, and methane). This results in the most common side effects: **flatulence (seen in >70% of patients)**, abdominal bloating, and osmotic diarrhea [1]. **Analysis of Incorrect Options:** * **B. Hypoglycemia:** Acarbose does not stimulate insulin secretion (it is euglycemic). Therefore, it does not cause hypoglycemia when used as monotherapy [2]. * **C. Periodic Hyperglycemia:** Acarbose specifically targets **post-prandial hyperglycemia** by slowing glucose absorption; it does not cause rebound or periodic hyperglycemia. * **D. Weight gain:** Unlike sulfonylureas or insulin, acarbose is **weight-neutral** or may even cause modest weight loss, making it a preferred choice in obese diabetic patients. **High-Yield Clinical Pearls for NEET-PG:** * **Treatment of Hypoglycemia:** If a patient on acarbose develops hypoglycemia (due to concurrent use of insulin or sulfonylureas), they must be treated with **pure glucose (dextrose)**, not sucrose (cane sugar), because acarbose prevents the breakdown of sucrose into glucose [2]. * **Contraindication:** It should be avoided in patients with **Inflammatory Bowel Disease (IBD)** or chronic intestinal disorders due to gas production.

Q: Insulin release due to closure of K+ channels is seen with which of the following drugs?

Nateglinde. **Explanation:** The correct answer is **Nateglinide**. **Mechanism of Action (Correct Option):** Nateglinide belongs to the **Meglitinide** (Glinide) class of oral hypoglycemics. Like Sulfonylureas, Meglitinides act as **insulin secretagogues**. They bind to a specific site on the **ATP-sensitive K+ channel (SUR1 subunit)** on the pancreatic beta-cell membrane. This binding causes the closure of K+ channels, leading to cell depolarization, opening of voltage-gated Ca2+ channels, and subsequent exocytosis of insulin. While they share the same mechanism as Sulfonylureas, Meglitinides have a quicker onset and shorter duration of action, making them ideal for controlling **post-prandial hyperglycemia**. **Analysis of Incorrect Options:** * **B. Acarbose:** An **alpha-glucosidase inhibitor** that acts in the intestinal brush border to delay the digestion and absorption of carbohydrates. It does not affect insulin secretion directly. * **C. Exenatide:** A **GLP-1 receptor agonist** (Incretin mimetic). It stimulates insulin release in a glucose-dependent manner via cAMP signaling, not by direct closure of K+ channels. * **D. Sitagliptin:** A **DPP-4 inhibitor** that prevents the breakdown of endogenous GLP-1 and GIP, thereby indirectly increasing glucose-dependent insulin secretion. **High-Yield Clinical Pearls for NEET-PG:** * **K+ channel blockers:** Sulfonylureas (e.g., Glimepiride) and Meglitinides (Repaglinide, Nateglinide). * **K+ channel openers:** Diazoxide and Minoxidil (can cause hypoglycemia inhibition/hyperglycemia). * **Nateglinide vs. Repaglinide:** Nateglinide is D-phenylalanine derivative; Repaglinide is a benzoic acid derivative. * **Safety:** Meglitinides are safer in patients with sulfur allergies (unlike Sulfonylureas) and carry a lower risk of prolonged hypoglycemia.

Q: Which one of the following oral hypoglycemic agents is not an insulin secretagogue?

Rosiglitazone. **Explanation:** The classification of oral hypoglycemic agents (OHAs) is based on their mechanism of action. **Insulin secretagogues** are drugs that stimulate the pancreas to release insulin, whereas **insulin sensitizers** improve the body's response to existing insulin. **Why Rosiglitazone is the correct answer:** Rosiglitazone belongs to the **Thiazolidinedione (TZD)** class. It acts as an **insulin sensitizer** rather than a secretagogue. Its primary mechanism involves activating the **PPAR-γ (Peroxisome Proliferator-Activated Receptor gamma)** receptors in adipose tissue, muscle, and liver. This leads to increased transcription of genes involved in glucose uptake (like GLUT-4) and lipid metabolism, thereby reducing insulin resistance. It does not directly stimulate pancreatic beta cells to release insulin. **Analysis of incorrect options:** * **Gliclazide & Glimepiride (Options A & B):** These are **Sulfonylureas** (2nd and 3rd generation respectively). They act by closing the ATP-sensitive K+ channels on the pancreatic beta-cell membrane, leading to depolarization, calcium influx, and subsequent insulin secretion. * **Repaglinide (Option C):** This is a **Meglitinide** analogue. Like sulfonylureas, it is a secretagogue that closes K+ channels, though it binds to a different site and has a shorter duration of action (used for postprandial glucose control). **High-Yield Clinical Pearls for NEET-PG:** * **Side Effects of TZDs:** Weight gain, edema, and increased risk of congestive heart failure (due to fluid retention). Rosiglitazone specifically has been linked to increased cardiovascular risk. * **Secretagogues and Hypoglycemia:** Because they stimulate insulin release regardless of blood glucose levels, Sulfonylureas carry a high risk of hypoglycemia. * **Drug of Choice:** Metformin (a Biguanide) is also an insulin sensitizer (via AMPK activation) and is the first-line treatment for Type 2 Diabetes.

Q: What is an important difference between leuprolide and ganirelix regarding their effect on gonadotropin secretion?

Ganirelix immediately reduces gonadotropin secretion.. ### Explanation The key difference between these two drugs lies in their mechanism of action at the GnRH receptor. **1. Why Option B is Correct:** * **Ganirelix** is a **GnRH Receptor Antagonist**. It works by competitive blockade of the GnRH receptors in the anterior pituitary. This results in an **immediate** and direct inhibition of LH and FSH secretion. * **Leuprolide**, conversely, is a **GnRH Receptor Agonist**. When given continuously, it initially stimulates the receptors (causing a "flare"), and only after 1–2 weeks does it cause downregulation and desensitization of the receptors, leading to a decrease in gonadotropins. **2. Why the Other Options are Incorrect:** * **Option A:** Both leuprolide and ganirelix are peptides; they are degraded by GI enzymes and must be administered **parenterally** (SC/IM). * **Option C:** **Pulsatile** administration is a characteristic of native GnRH (or Gonadorelin) used to *treat* infertility by stimulating FSH/LH. Ganirelix is used to *suppress* the LH surge. * **Option D:** This describes the "flare effect" seen with **Leuprolide** (GnRH agonist). Ganirelix, being an antagonist, does not cause an initial stimulation. ### NEET-PG High-Yield Pearls: * **Clinical Use:** Ganirelix and Cetrorelix are primarily used in **Controlled Ovarian Hyperstimulation (IVF)** to prevent a premature LH surge. * **Advantage of Antagonists:** Unlike agonists (Leuprolide), GnRH antagonists do not require co-administration of anti-androgens (like Flutamide) because there is no initial testosterone surge/flare. * **Degarelix:** Another GnRH antagonist used specifically for advanced prostate cancer to achieve rapid testosterone suppression.

Q: A 75-year-old woman with diabetes is taking oral antidiabetic drugs. She goes without eating for 18 hours, and her serum glucose concentration is 48 mg/dL (hypoglycemic) upon arrival at the emergency department, where she is deemed to be in critical condition. Which of the following drugs most likely aggravated this fasting hypoglycemia?

Glyburide. **Explanation:** The patient is presenting with severe fasting hypoglycemia, a classic side effect of **Sulfonylureas**. **1. Why Glyburide is Correct:** Glyburide is a second-generation sulfonylurea. Its mechanism of action involves binding to the **SUR1 subunit** of the ATP-sensitive $K^+$ channels in pancreatic beta cells. This leads to channel closure, cell depolarization, calcium influx, and the **insulin secretion regardless of blood glucose levels**. Because sulfonylureas act as "insulin secretagogues," they can cause profound and prolonged hypoglycemia, especially in elderly patients or those who skip meals (fasting). Glyburide, in particular, has long-acting metabolites that increase the risk of hypoglycemia in the elderly. **2. Why the Other Options are Incorrect:** * **Acarbose (Alpha-glucosidase inhibitor):** It acts locally in the gut to delay carbohydrate absorption. It does not stimulate insulin secretion and therefore does not cause hypoglycemia when used as monotherapy. * **Metformin (Biguanide):** It primarily decreases hepatic gluconeogenesis and improves peripheral insulin sensitivity. It is classified as an "euglycemic" agent because it does not stimulate insulin release. * **Pioglitazone (Thiazolidinedione):** It acts via PPAR-gamma receptors to increase insulin sensitivity in muscle and adipose tissue. Like metformin, it does not promote insulin secretion and carries a minimal risk of hypoglycemia. **NEET-PG High-Yield Pearls:** * **Sulfonylureas and Meglitinides** are the only oral classes that directly cause hypoglycemia by stimulating insulin release. * **Management:** Severe sulfonylurea-induced hypoglycemia that is refractory to dextrose can be treated with **Octreotide** (a somatostatin analog that inhibits insulin release). * **Renal Caution:** Glyburide should be avoided in patients with renal impairment due to the accumulation of active metabolites; **Glipizide** is preferred in such cases.

Q: Regarding leflunomide in pregnancy, all are true except?

It is used to treat Rheumatoid arthritis in pregnancy.. **Explanation:** Leflunomide is a Disease-Modifying Antirheumatic Drug (DMARD) that acts by inhibiting **dihydroorotate dehydrogenase**, an enzyme essential for **de novo pyrimidine synthesis**. This leads to decreased T-cell proliferation and reduced inflammation. **Why Option D is the correct answer (The "Except" statement):** Leflunomide is strictly **contraindicated in pregnancy** (FDA Category X). It is highly teratogenic and is never used to treat Rheumatoid Arthritis in pregnant women. If a patient becomes pregnant while on the drug, an emergency washout procedure using **cholestyramine** is required to rapidly lower plasma levels. **Analysis of other options:** * **Option A:** Leflunomide is known to cause severe structural defects, including **hydrocephalus**, craniofacial defects, and **skeletal anomalies**, as demonstrated in animal studies and clinical reports. * **Option B:** This is the correct mechanism of action. By inhibiting pyrimidine synthesis, it arrests stimulated lymphocytes in the G1 phase of the cell cycle. * **Option C:** Leflunomide is a prodrug converted to its active metabolite, **teriflunomide (A77 1726)**. This metabolite undergoes extensive enterohepatic circulation and has a very long half-life (approx. 2 weeks). Consequently, it can take **up to 2 years** to reach plasma levels below 0.02 mg/L (the safe threshold for pregnancy) after stopping the drug. **High-Yield Clinical Pearls for NEET-PG:** * **Washout Protocol:** To accelerate elimination, **Cholestyramine** (8g, 3 times daily for 11 days) is used. * **Monitoring:** Periodic Liver Function Tests (LFTs) are mandatory due to the risk of **hepatotoxicity**. * **Pre-conception:** Both men and women should ensure drug levels are below 0.02 mg/L before attempting to conceive.

Question 1

Which of the following is NOT a mode of action of sulfonamides?

Accepted Answer

Decreasing glucose absorption from the gut.

Answer

Activating receptors on beta cells of the pancreas to release insulin.

Answer

Inhibiting gluconeogenesis in the liver.

Answer

Enhancing insulin-mediated post-receptor enzyme reactions.

Question 2

Prolonged use of steroids may cause which of the following?

Accepted Answer

Decrease in bone matrix protein

Answer

Hypoglycemia

Answer

Hypotension

Answer

Early healing of wound

Question 3

Which of the following conditions is a primary indication for the use of prostaglandins?

Accepted Answer

Missed abortion

Answer

Second-trimester abortion

Answer

Ectopic pregnancy

Answer

Postpartum hemorrhage (PPH)

Question 4

Which is the most common adverse drug reaction of acarbose?

Accepted Answer

Flatulence

Answer

Hypoglycemia

Answer

Periodic Hyperglycemia

Answer

Weight gain

Question 5

What is the most common side effect seen with bisphosphonates?

Accepted Answer

Erosive esophagitis

Answer

Cholelithiasis

Answer

Constipation

Answer

Osteonecrosis

Question 6

Insulin release due to closure of K+ channels is seen with which of the following drugs?

Accepted Answer

Nateglinde

Answer

Acarbose

Answer

Exenatide

Answer

Sitagliptin

Question 7

Which one of the following oral hypoglycemic agents is not an insulin secretagogue?

Accepted Answer

Rosiglitazone

Answer

Gliclazide

Answer

Glimiperide

Answer

Repaglinide

Question 8

What is an important difference between leuprolide and ganirelix regarding their effect on gonadotropin secretion?

Accepted Answer

Ganirelix immediately reduces gonadotropin secretion.

Answer

Ganirelix can be given orally.

Answer

Ganirelix must be given in a pulsatile fashion.

Answer

Ganirelix initially stimulates the release of LH and FSH.

Question 9

A 75-year-old woman with diabetes is taking oral antidiabetic drugs. She goes without eating for 18 hours, and her serum glucose concentration is 48 mg/dL (hypoglycemic) upon arrival at the emergency department, where she is deemed to be in critical condition. Which of the following drugs most likely aggravated this fasting hypoglycemia?

Accepted Answer

Glyburide

Answer

Acarbose

Answer

Metformin

Answer

Pioglitazone

Question 10

Regarding leflunomide in pregnancy, all are true except?

Accepted Answer

It is used to treat Rheumatoid arthritis in pregnancy.

Answer

It can cause hydrocephalus and skeletal anomalies in the fetus.

Answer

It is a pyrimidine synthesis inhibitor.

Answer

Its active metabolite can be detected in plasma for up to 2 years after discontinuation.

Endocrine Pharmacology — MCQs

Endocrine Pharmacology — MCQs

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