Endocrine Pharmacology Practice Questions

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: Which is the fastest calcium-lowering agent?

Calcitonin. **Explanation:** The management of hypercalcemia depends on the severity of symptoms and the urgency of calcium reduction. **Why Calcitonin is the correct answer:** Calcitonin (specifically Salmon Calcitonin) is the **fastest-acting** calcium-lowering agent. It works within **2 to 4 hours** of administration. Its rapid onset is due to its direct action on osteoclasts, where it inhibits bone resorption, and its secondary effect of increasing renal calcium excretion. However, its use is limited by **tachyphylaxis** (rapidly diminishing response) after 24–48 hours due to the downregulation of calcitonin receptors. **Analysis of Incorrect Options:** * **B. Plicamycin (Mithramycin):** An older cytotoxic antibiotic that inhibits bone resorption. It takes about 24–48 hours to show effects and is rarely used today due to significant toxicity (thrombocytopenia, hepatic and renal toxicity). * **C. Etidronate:** A first-generation bisphosphonate. Like all bisphosphonates, it has a slow onset of action (2–4 days) because it requires incorporation into the bone matrix to inhibit osteoclast activity. * **D. Zoledronate:** A potent, third-generation intravenous bisphosphonate. While it is the **most effective** and preferred drug for long-term management of malignancy-associated hypercalcemia, its peak effect occurs only after **48–72 hours**. **NEET-PG High-Yield Pearls:** * **Drug of Choice (Initial):** Aggressive IV hydration with Normal Saline (0.9% NaCl) is the first step in treating hypercalcemic crisis. * **Most Potent/DOC for Malignancy:** Zoledronate (IV). * **Fastest Acting:** Calcitonin (useful for the "gap" before bisphosphonates kick in). * **Cinacalcet:** A calcimimetic used specifically for secondary hyperparathyroidism in CKD.

Q: Which of the following is NOT a second-generation sulfonylurea drug?

Tolbutamide. Sulfonylureas are insulin secretagogues used in the management of Type 2 Diabetes Mellitus. They are classified into two generations based on their potency and duration of action [1]. **Why Tolbutamide is the correct answer:** **Tolbutamide** belongs to the **First-generation** sulfonylureas [1]. These older agents (including Chlorpropamide, Tolazamide, and Acetohexamide) are characterized by lower potency, requiring higher milligram doses, and a higher risk of drug interactions compared to the newer generation [1], [2]. Tolbutamide specifically has a short duration of action and is primarily metabolized in the liver [3], [4]. **Why the other options are incorrect:** * **Glipizide (Option A):** A potent **Second-generation** sulfonylurea with a short half-life, making it a preferred choice in elderly patients to minimize the risk of prolonged hypoglycemia [1], [3]. * **Gliclazide (Option B):** A **Second-generation** agent known for its additional antioxidant properties and lower risk of hypoglycemia compared to glibenclamide. * **Glibenclamide (Option D):** Also known as Glyburide, this is a classic **Second-generation** drug [1]. It is highly potent but carries a significant risk of prolonged hypoglycemia, especially in patients with renal impairment [3]. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism of Action:** They block ATP-sensitive $K^+$ channels in pancreatic $eta$-cells, leading to depolarization, $Ca^{2+}$ influx, and insulin release [2]. * **Glimepiride:** Often classified as a **Third-generation** sulfonylurea due to its once-daily dosing and rapid onset. * **Side Effects:** Hypoglycemia (most common) and weight gain. * **Disulfiram-like reaction:** Most commonly associated with **Chlorpropamide** (1st Gen). * **Safety in Renal Failure:** **Gliquidone** is the sulfonylurea of choice in renal insufficiency as it is primarily excreted via bile.

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: Which drug causes hypothyroidism?

Lithium. **Explanation:** **Lithium (Option B)** is a mood stabilizer used in bipolar disorder that frequently causes thyroid dysfunction. It induces hypothyroidism through multiple mechanisms: 1. **Inhibition of Iodine Uptake:** It interferes with the trapping of iodine by follicular cells. 2. **Inhibition of Thyroid Hormone Release:** This is the most significant mechanism; lithium inhibits the proteolytic cleavage of thyroglobulin, preventing the release of $T_3$ and $T_4$ (similar to the effect of high-dose iodine). 3. **Interference with Deiodination:** It may inhibit the peripheral conversion of $T_4$ to $T_3$. Up to 10–20% of patients on long-term lithium therapy develop goiter or clinical hypothyroidism. **Incorrect Options:** * **Carbamazepine (A):** While it can lower serum $T_4$ levels by inducing hepatic microsomal enzymes (increasing metabolism), it rarely causes clinical hypothyroidism as $TSH$ usually remains normal. * **Sulfasalazine (C):** Used in inflammatory bowel disease and RA; it does not have a documented inhibitory effect on the thyroid axis. * **Methotrexate (D):** An antimetabolite used in oncology and autoimmune diseases; it is not associated with thyroid dysfunction. **High-Yield NEET-PG Pearls:** * **Amiodarone** is another high-yield drug causing thyroid issues (can cause both hypothyroidism via the Wolff-Chaikoff effect and hyperthyroidism). * **Monitoring:** Patients on Lithium must have their **TSH levels** monitored every 6–12 months. * **Treatment:** Lithium-induced hypothyroidism is treated with Levothyroxine; the drug does not necessarily need to be discontinued if it is effectively managing the psychiatric condition.

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.

Q: Which of the following is an inhalational form of insulin?

Afrezza. **Explanation:** **Afrezza** is the correct answer as it is currently the only FDA-approved **ultra-rapid-acting inhalational insulin**. It consists of a dry powder formulation of recombinant human insulin delivered via a thumb-sized inhaler. Upon inhalation, the powder dissolves in the alveolar fluid and is rapidly absorbed into the systemic circulation, reaching peak concentrations within 12–15 minutes, mimicking the first-phase insulin release. **Analysis of Incorrect Options:** * **A. Lispro:** This is a rapid-acting insulin analogue (modified at the B28 and B29 positions). It is administered via subcutaneous injection or insulin pumps, not inhalation. * **C. Humulin:** This is a brand name for biosynthetic human insulin. It is available as Humulin R (Regular/Short-acting) and Humulin N (NPH/Intermediate-acting), both of which are injectable. * **D. Ultralente:** This is an older, long-acting crystalline zinc insulin suspension. It has largely been replaced by modern long-acting analogues like Glargine and Degludec and is administered subcutaneously. **High-Yield Clinical Pearls for NEET-PG:** * **Contraindications:** Afrezza is strictly contraindicated in patients with chronic lung diseases such as **Asthma or COPD** due to the risk of acute bronchospasm. * **Monitoring:** Baseline **FEV1** (Forced Expiratory Volume) must be measured before starting therapy, at 6 months, and annually thereafter. * **Smoking:** It is not recommended in patients who smoke or have recently quit smoking (<6 months). * **Historical Note:** Exubera was the first inhalational insulin but was withdrawn from the market due to its bulky design and poor sales; Afrezza is the modern, compact alternative.

Q: Which antidiabetic medication is known to cause osteoporosis as an adverse drug reaction?

Pioglitazone. **Explanation:** **Pioglitazone** belongs to the **Thiazolidinedione (TZD)** class of antidiabetic drugs. These agents act as agonists for the **PPAR-γ (Peroxisome Proliferator-Activated Receptor gamma)** receptor. While PPAR-γ activation improves insulin sensitivity, it has a significant impact on bone metabolism. In the bone marrow, mesenchymal stem cells can differentiate into either adipocytes or osteoblasts. PPAR-γ activation shifts this balance toward **adipogenesis** (fat cell formation) while inhibiting **osteoblastogenesis** (bone-forming cell formation). This leads to decreased bone formation, reduced bone mineral density, and an increased risk of fractures, particularly in postmenopausal women. **Analysis of Incorrect Options:** * **Metformin (Biguanide):** Generally considered bone-neutral or potentially bone-protective. Its primary side effects are gastrointestinal (diarrhea, abdominal cramps) and lactic acidosis. * **Glibenclamide (Sulfonylurea):** Works by stimulating insulin secretion from pancreatic beta cells. It is primarily associated with hypoglycemia and weight gain, not osteoporosis. * **Acarbose (Alpha-glucosidase inhibitor):** Acts locally in the intestine to delay carbohydrate absorption. Its side effects are limited to the GI tract (flatulence, bloating). **High-Yield Clinical Pearls for NEET-PG:** * **TZD Side Effects:** Weight gain, **fluid retention/edema** (contraindicated in NYHA Class III/IV heart failure), and increased risk of **bladder cancer** (specifically associated with Pioglitazone). * **Fracture Site:** Fractures associated with TZDs often occur in distal upper or lower limbs (humerus, radius, feet) rather than the typical hip or spine fractures seen in involutional osteoporosis. * **Other drugs causing Osteoporosis:** Glucocorticoids (most common), Heparin (long-term), Phenytoin, and Proton Pump Inhibitors (PPIs).

Question 1

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

Accepted Answer

Rosiglitazone

Answer

Gliclazide

Answer

Glimiperide

Answer

Repaglinide

Question 2

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 3

Which is the fastest calcium-lowering agent?

Accepted Answer

Calcitonin

Answer

Plicamycin

Answer

Etidronate

Answer

Zoledronate

Question 4

Which of the following is NOT a second-generation sulfonylurea drug?

Accepted Answer

Tolbutamide

Answer

Glipizide

Answer

Gliclazide

Answer

Glibenclamide

Question 5

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 6

Which drug causes hypothyroidism?

Accepted Answer

Lithium

Answer

Carbamazepine

Answer

Sulfasalazine

Answer

Methotrexate

Question 7

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.

Question 8

Which of the following is an inhalational form of insulin?

Accepted Answer

Afrezza

Answer

Lispro

Answer

Humulin

Answer

Ultralente

Question 9

A patient receiving insulin and acarbose for diabetes mellitus developed hypoglycemia. Which of the following should be used for the treatment of hypoglycemia in this patient?

Accepted Answer

Glucose

Answer

Sucrose

Answer

Galactose

Answer

Starch

Question 10

Which antidiabetic medication is known to cause osteoporosis as an adverse drug reaction?

Accepted Answer

Pioglitazone

Answer

Metformin

Answer

Glibenclamide

Answer

Acarbose

Endocrine Pharmacology — MCQs

Endocrine Pharmacology — MCQs

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