Endocrine Pharmacology Practice Questions

Q: Which antidiabetic drug acts independently of insulin?

SGLT2 inhibitor. The correct answer is **A. SGLT2 inhibitor** (e.g., Dapagliflozin, Empagliflozin). **Mechanism of Action:** SGLT2 inhibitors act on the proximal convoluted tubule (PCT) of the kidney to inhibit the Sodium-Glucose Co-transporter 2. This prevents the reabsorption of filtered glucose, leading to **glycosuria** (excretion of glucose in the urine). Because this process depends entirely on the renal filtration of glucose and not on pancreatic function or peripheral insulin sensitivity, it is considered **insulin-independent**. This makes them effective even in patients with long-standing Type 2 Diabetes who have significant beta-cell exhaustion. **Why the other options are incorrect:** * **B. DPP4 inhibitors** (e.g., Sitagliptin) and **D. GLP1 agonists** (e.g., Liraglutide) are incretin-based therapies. They work by stimulating the pancreas to release insulin in a glucose-dependent manner [2]. * **C. Meglitinide analogues** (e.g., Repaglinide) are insulin secretagogues [1]. They close ATP-sensitive K+ channels in pancreatic beta cells, directly triggering insulin release [1], [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Weight Loss & BP:** SGLT2 inhibitors promote weight loss (due to calorie loss via glucose) and lower blood pressure (due to osmotic diuresis). * **Cardio-Renal Protection:** They are the drugs of choice for diabetic patients with **Heart Failure** (reduced HFrEF) and **Chronic Kidney Disease (CKD)**. * **Side Effects:** The most characteristic side effects are **Genital Mycotic Infections** (due to high urinary glucose) and a rare risk of **Euglycemic Ketoacidosis**.

Q: Which drug is useful in neuronal diabetes insipidus in both children and adults when given intranasally?

Desmopressin. **Explanation:** **Desmopressin (DDAVP)** is the drug of choice for Central (Neuronal) Diabetes Insipidus (DI). It is a synthetic analog of Arginine Vasopressin (AVP) with two key modifications: deamination of cysteine and substitution of L-arginine with D-arginine. These changes result in a **selective V2 receptor agonist** action with minimal V1 (vasoconstrictor) activity. Its long duration of action (8–20 hours) and availability in an intranasal formulation make it ideal for long-term management in both children and adults. **Analysis of Incorrect Options:** * **Vasopressin (A):** This is the natural hormone. It acts on both V1 and V2 receptors, leading to significant side effects like vasoconstriction, abdominal cramps, and hypertension. It also has a very short half-life (approx. 20 minutes), making it impractical for chronic DI management. * **Lypressin (C):** A synthetic lysine-vasopressin formerly used intranasally. However, it has a shorter duration of action and more pressor (V1) side effects compared to Desmopressin, rendering it obsolete. * **Presselin (D):** This is not a standard pharmacological agent used in the treatment of Diabetes Insipidus. **NEET-PG High-Yield Pearls:** * **V2 Selectivity:** Desmopressin has a V2:V1 selectivity ratio of approximately 4000:1. * **Other Uses of Desmopressin:** Nocturnal enuresis (bedwetting), von Willebrand Disease (Type I), and Hemophilia A (as it releases Factor VIII and vWF from endothelial storage sites). * **Route of Choice:** While intranasal is common, the **oral** route is increasingly preferred for convenience, though it requires a much higher dose due to low bioavailability. * **Side Effect:** The most serious side effect of Desmopressin is **hyponatremia** (water intoxication).

Q: What is the mechanism of action of Rosiglitazone?

Acts as a PPAR gamma agonist. **Explanation:** **Mechanism of Action (Correct Answer: A)** Rosiglitazone belongs to the **Thiazolidinedione (TZD)** class of oral hypoglycemic agents. Its primary mechanism is the activation of **Peroxisome Proliferator-Activated Receptor-gamma (PPAR-γ)**, a nuclear receptor found predominantly in adipose tissue, muscle, and liver. Activation of PPAR-γ leads to the transcription of genes involved in glucose and lipid metabolism. This results in increased expression of **GLUT-4** transporters and decreased release of free fatty acids, thereby **reducing insulin resistance** (insulin sensitizer). **Analysis of Incorrect Options:** * **B. Inhibitor of alpha-glucosidase:** This describes **Acarbose** and **Voglibose**, which act in the intestinal brush border to delay carbohydrate absorption, reducing postprandial glucose spikes. * **C. Amylin analogue:** This refers to **Pramlintide**, a synthetic analogue of amylin that slows gastric emptying and suppresses glucagon secretion. * **D. Dipeptidyl peptidase-4 (DPP-4) inhibitor:** This describes the **"Gliptins"** (e.g., Sitagliptin), which prevent the breakdown of endogenous incretins like GLP-1. **High-Yield Clinical Pearls for NEET-PG:** * **Site of Action:** TZDs are primarily **insulin sensitizers**; they do not increase insulin secretion. * **Side Effects:** Weight gain and **fluid retention/edema** are common. They are strictly **contraindicated in NYHA Class III/IV Heart Failure**. * **Bone Health:** Long-term use is associated with an increased risk of **osteoporotic fractures** (especially in women). * **Metabolic Effect:** Unlike Pioglitazone (which also affects PPAR-α), Rosiglitazone has a less favorable lipid profile (may increase LDL).

Q: Which of the following is NOT useful for acute hypercalcemia?

Furosemide. ### Explanation **Correct Option: C. Furosemide** **Why Furosemide is the correct answer:** Traditionally, loop diuretics like furosemide were used to treat hypercalcemia because they inhibit the Na⁺-K⁺-2Cl⁻ symporter, which abolishes the positive luminal potential required for calcium reabsorption. However, **current clinical guidelines (AHA/Endocrine Society) no longer recommend furosemide** for acute hypercalcemia unless the patient is in fluid overload or heart failure. This is because furosemide can worsen dehydration—the primary complication of hypercalcemia—and may lead to electrolyte imbalances without significantly lowering calcium levels compared to aggressive hydration alone. **Analysis of Incorrect Options:** * **A. Normal Saline:** This is the **first-line treatment**. It restores intravascular volume and promotes "calciuresis" by increasing the glomerular filtration rate and inhibiting proximal tubular sodium/calcium reabsorption. * **B. Calcitonin:** Used for **rapid reduction** of calcium. It works within hours by inhibiting osteoclast activity and increasing renal excretion. However, its effect is short-lived due to tachyphylaxis (receptor downregulation). * **D. Bisphosphonates (e.g., Zoledronate, Pamidronate):** These are the **most effective long-term agents** for hypercalcemia of malignancy. They potentally inhibit osteoclast-mediated bone resorption, though they take 48–72 hours to reach peak effect. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Hypercalcemia Rx:** "Hydrate (Saline), Hibernate (Bisphosphonates), and Hurry (Calcitonin)." * **Glucocorticoids:** Useful specifically for hypercalcemia caused by Vitamin D toxicity, sarcoidosis, or lymphomas. * **Cinacalcet:** A calcimimetic used for secondary hyperparathyroidism in CKD. * **Denosumab:** A RANKL inhibitor used when bisphosphonates are contraindicated (e.g., severe renal impairment).

Q: Which of the following is a long-acting insulin?

Insulin glargine. ### Explanation Insulin preparations are classified based on their onset and duration of action. Understanding these kinetics is crucial for NEET-PG, as it forms the basis of "Basal-Bolus" therapy. **Correct Answer: A. Insulin glargine** Insulin glargine is a **long-acting (basal) insulin analog**. It is designed with a shifted isoelectric point (by substituting asparagine with glycine and adding two arginines), making it soluble at an acidic pH but poorly soluble at the neutral pH of subcutaneous tissue. Upon injection, it forms micro-precipitates that release insulin slowly over 24 hours. It is often called "peakless" insulin because it provides a steady background level of insulin, mimicking physiological basal secretion. **Incorrect Options:** * **B, C, and D (Lispro, Aspart, Glulisine):** These are **Rapid-acting insulin analogs**. They are designed to dissociate rapidly into monomers after subcutaneous injection, leading to a quick onset (15 mins) and short duration (3–5 hours). They are used as "prandial" or "bolus" insulin to control post-prandial glucose spikes. **High-Yield Clinical Pearls for NEET-PG:** * **Ultra-long acting:** Insulin **Degludec** has the longest half-life (>40 hours) due to the formation of multi-hexamers. * **Intermediate-acting:** **NPH (Isophane)** insulin has a "cloudy" appearance and a duration of 12–18 hours. * **Safety:** Glargine should **not** be mixed in the same syringe with other insulins, as its acidic pH (4.0) can cause the other insulins to precipitate. * **Inhaled Insulin:** Afrezza is a rapid-acting dry powder formulation.

Question 1

Which of the following drugs can enhance the action of sulfonylureas?

Accepted Answer

Diazoxide

Answer

Salicylates

Answer

Propranolol

Answer

Cimetidine

Question 2

Which antidiabetic drug acts independently of insulin?

Accepted Answer

SGLT2 inhibitor

Answer

DPP4 inhibitor

Answer

Meglitinide analogues

Answer

GLP1 agonist

Question 3

Which drug is useful in neuronal diabetes insipidus in both children and adults when given intranasally?

Accepted Answer

Desmopressin

Answer

Vasopressin

Answer

Lypressin

Answer

Presselin

Question 4

All of the following may be used to treat hypercalcemia, except:

Accepted Answer

Normal saline with forced diuresis with thiazide

Answer

Plicamycin

Answer

Gallium nitrate

Answer

Mitramycin

Question 5

A 21-year-old student is diagnosed with hyperthyroidism and is being counselled on treatment options, including radioactive iodine and antithyroid medications. Carbimazole acts on which part of the thyroid hormone synthesis pathway?

Accepted Answer

Organification of iodide by thyroid peroxidase, incorporating it into tyrosine to form MIT and DIT

Answer

Cleavage of thyroglobulin by proteolysis

Answer

Coupling of monoiodotyrosine (MIT) and diiodotyrosine (DIT) forming triiodothyronine (T3) and thyroxine (T4)

Answer

Dehalogenation of iodinated tyrosine to recycle iodide

Question 6

Conversion of T4 to T3 is inhibited by all except:

Accepted Answer

Methimazole

Answer

Propranolol

Answer

Propylthiouracil

Answer

Amiodarone

Question 7

What is the mechanism of action of Rosiglitazone?

Accepted Answer

Acts as a PPAR gamma agonist

Answer

Inhibitor of alpha glucosidase

Answer

Acts as an amylin analogue

Answer

Acts as a dipeptidyl peptidase inhibitor

Question 8

What is the effect of adding progesterone to estrogens?

Accepted Answer

Decrease the occurrence of endometrial cancers

Answer

Decrease the estrogen action on the breast

Answer

Increase the effectiveness of the estrogens

Answer

Inhibit bone resorption

Question 9

Which of the following is NOT useful for acute hypercalcemia?

Accepted Answer

Furosemide

Answer

Normal saline

Answer

Calcitonin

Answer

Bisphosphonates

Question 10

Which of the following is a long-acting insulin?

Accepted Answer

Insulin glargine

Answer

Insulin lispro

Answer

Insulin aspart

Answer

Insulin glulisine

Endocrine Pharmacology — MCQs

Endocrine Pharmacology — MCQs

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