NEET-PG 2013 - Pharmacology Practice Questions

Q: Which calcium channel blocker has the shortest duration of action?

Nimodipine. ***Nimodipine*** - Nimodipine is a **dihydropyridine calcium channel blocker** specifically formulated for cerebral vasodilation and used in conditions like **subarachnoid hemorrhage**. - It has a relatively **short half-life** and rapid onset, making its duration of action shorter compared to other commonly used calcium channel blockers. *Amlodipine* - Amlodipine is known for its **long duration of action** and once-daily dosing due to its slow absorption and high bioavailability. - Its prolonged action is beneficial for conditions like **hypertension and angina**, where sustained vasodilation is desired. *Diltiazem* - Diltiazem's duration of action is **intermediate** compared to other calcium channel blockers, often requiring BID to TID dosing for immediate-release formulations. - It's a **non-dihydropyridine calcium channel blocker** with effects on both vascular smooth muscle and cardiac conduction. *Verapamil* - Verapamil also has an **intermediate duration of action**, similar to diltiazem, with immediate-release forms requiring multiple daily doses. - As a **non-dihydropyridine calcium channel blocker**, it has significant effects on myocardial contractility and AV nodal conduction.

Q: Which medication increases insulin secretion from beta cells?

Repaglinide. ***Repaglinide*** - This medication is a **meglitinide analog** that stimulates **insulin release** from pancreatic beta cells by closing ATP-sensitive potassium channels. - Its fast onset and short duration of action make it particularly useful for controlling **postprandial glucose** excursions. *Metformin* - This medication primarily works by **decreasing hepatic glucose production** and improving insulin sensitivity in peripheral tissues. - It does **not directly stimulate insulin secretion** from beta cells; thus, it carries a lower risk of hypoglycemia compared to sulfonylureas or meglitinides. *Pramlintide* - This is an **amylin analog** that works by slowing gastric emptying, suppressing postprandial glucagon secretion, and increasing satiety. - It is an **injectable medication** used as an adjunct to insulin therapy and does not directly enhance insulin secretion from beta cells. *Pioglitazone* - This drug is a **thiazolidinedione** that improves insulin sensitivity in target tissues (e.g., muscle, fat, liver) by activating **peroxisome proliferator-activated receptor-gamma (PPAR-γ)**. - While it improves the body's response to insulin, it does **not directly stimulate insulin secretion** from the beta cells.

Q: Which of the following is a topical sulfonamide ?

Mafenide. ***Mafenide*** - **Mafenide** is a **sulfonamide antibiotic** primarily used **topically** as a cream for preventing and treating **wound infections**, particularly in **burn patients**. - It works by inhibiting bacterial growth and has good penetrative capabilities in **necrotic tissue** and **eschar**. - It is **water-soluble** and can penetrate burn eschar effectively. *Sulfadoxine* - **Sulfadoxine** is a **long-acting oral sulfonamide** frequently used in combination with **pyrimethamine** for conditions like **malaria** and **toxoplasmosis**. - It is administered **systemically**, not topically. *Sulfamethopyrazine* - **Sulfamethopyrazine** (also known as sulfalene) is another **long-acting sulfonamide** primarily used **orally** for conditions such as **malaria** and **urinary tract infections**. - Its clinical application is **systemic**, not topical. *Sulfisoxazole* - **Sulfisoxazole** is a **short-acting oral sulfonamide** used systemically for **urinary tract infections** and other bacterial infections. - It is **rapidly absorbed** and excreted, making it suitable for systemic use, not topical application.

Q: Which of the following statements about clofazimine is incorrect?

Does not interfere with DNA synthesis. ***Does not interfere with DNA synthesis*** - Clofazimine's primary mechanism of action involves **DNA binding** and **interference with bacterial DNA synthesis**. - It also generates **reactive oxygen species** and disrupts membrane function, contributing to its bactericidal effect. - **This statement is INCORRECT** - clofazimine does interfere with DNA synthesis. *Used in lepra reaction* - Clofazimine is a crucial component in the treatment of **leprosy**, particularly effective in managing **Type 2 lepra reactions (erythema nodosum leprosum)** due to its anti-inflammatory effects. - It helps to reduce the severity and duration of these acute inflammatory episodes. *Used in treatment of leprosy* - Clofazimine is a **core component of multidrug therapy (MDT) for leprosy**, particularly in multibacillary leprosy. - It is recommended by the **WHO** as part of the standard treatment regimen for leprosy. *Causes ichthyosis and hyperpigmentation* - Clofazimine commonly causes **hyperpigmentation of the skin, conjunctiva, and bodily fluids**, often appearing reddish-brown to black. - Less commonly, it can also lead to **ichthyosis (dry, scaly skin)** as a side effect.

Q: Which of the following is the longest acting glucocorticoid?

Dexamethasone. ***Correct: Dexamethasone*** - **Dexamethasone** is a long-acting glucocorticoid with a **biological half-life of 36–72 hours**, making it the longest acting among the options provided - Its prolonged action is due to its **high affinity for the glucocorticoid receptor** and relatively slow metabolism - Provides sustained anti-inflammatory and immunosuppressive effects *Incorrect: Prednisone* - **Prednisone** is an intermediate-acting glucocorticoid with a biological half-life of 12-36 hours - Requires metabolism in the liver to its active form, prednisolone - Duration of action is significantly shorter than dexamethasone *Incorrect: Prednisolone* - **Prednisolone** is the active form of prednisone, with a similar intermediate duration of action (12-36 hours) - Primarily used when liver conversion of prednisone is impaired - Does not possess the extended duration of action characteristic of dexamethasone *Incorrect: Cortisone* - **Cortisone** is a short-acting glucocorticoid with a biological half-life of 8-12 hours - It is a prodrug that needs to be converted to **hydrocortisone** (cortisol) in the liver to become active - Has the shortest duration among all options

Q: What is the drug of choice for pheochromocytoma?

Phenoxybenzamine. ***Phenoxybenzamine*** - This is an **irreversible, non-selective alpha-adrenergic blocker**, which is the drug of choice for preparing patients for surgical removal of a pheochromocytoma. - It effectively controls **hypertension** by blocking the effects of catecholamines on blood vessels, preventing a hypertensive crisis during surgery. *Propranolol* - **Beta-blockers** like propranolol should **not be used as monotherapy** in pheochromocytoma because blocking beta-2 receptors without prior alpha blockade can lead to unopposed alpha-adrenergic vasoconstriction and precipitate a **hypertensive crisis**. - It can be added **after adequate alpha-blockade** to control tachycardia. *Prazosin* - Prazosin is a **reversible, selective alpha-1 adrenergic blocker**, which is not preferred over phenoxybenzamine due to its shorter duration of action and reversibility. - While it can lower blood pressure, its efficacy in preventing hypertensive crises during surgery for pheochromocytoma is **less robust** compared to phenoxybenzamine. *Nitroprusside* - Sodium nitroprusside is a **potent vasodilator** often used for **hypertensive emergencies**, but it is not the drug of choice for long-term management or preoperative preparation in pheochromocytoma. - Its use in pheochromocytoma is typically reserved for **acute hypertensive crises** when other agents are insufficient, rather than initial management.

Q: Thiazides act on which part of the nephron?

Distal Convoluted Tubule. ***Distal Convoluted Tubule*** - **Thiazide diuretics** specifically inhibit the **sodium-chloride cotransporter (NCC)** in the apical membrane of cells in the distal convoluted tubule. - This inhibition leads to decreased reabsorption of sodium and chloride, resulting in increased excretion of water, sodium, and chloride. *Proximal Convoluted Tubule* - The proximal convoluted tubule is the primary site for reabsorption of the majority of filtered substances, including sodium, bicarbonate, glucose, and amino acids. - While some diuretics like **acetazolamide** (a carbonic anhydrase inhibitor) act here, thiazides do not. *Glomerulus* - The **glomerulus** is primarily responsible for the **filtration** of blood, forming the initial filtrate. - It is not a site for diuretic action as it does not participate in active reabsorption or secretion of electrolytes. *Descending limb of loop of Henle* - The descending limb is highly permeable to **water** but impermeable to solutes, leading to water reabsorption due to the hyperosmotic medulla. - Diuretics typically do not act on this segment to inhibit solute transport, though osmotic diuretics can affect water movement here.

Q: Pyridoxine is used in treatment of ?

Homocystinuria. ***Homocystinuria*** - **Pyridoxine (vitamin B6)** is a cofactor for the enzyme **cystathionine beta-synthase**, which is deficient in many forms of homocystinuria. - In pyridoxine-responsive homocystinuria, high doses of pyridoxine can help reduce **homocysteine levels** by stimulating residual enzyme activity. *Galactosemia* - This is an inherited disorder affecting the body's ability to metabolize **galactose**, due to deficiency of enzymes like galactose-1-phosphate uridyltransferase. - Treatment primarily involves dietary restriction of **galactose** and lactose, not pyridoxine. *Phenylketonuria* - This metabolic disorder results from a deficiency in **phenylalanine hydroxylase**, leading to a buildup of phenylalanine. - Treatment involves a strict **low-phenylalanine diet** and sometimes sapropterin (BH4). *Propionic acidemia* - This organic acidemia is caused by a deficiency in **propionyl-CoA carboxylase**, an enzyme requiring **biotin** as a cofactor. - Treatment involves dietary protein restriction and often carnitine supplementation, with **biotin** sometimes used, but not pyridoxine.

Q: The best agent for increasing HDL cholesterol is?

Nicotinic acid. ***Nicotinic acid*** - **Nicotinic acid** (niacin) is known to significantly increase **high-density lipoprotein (HDL) cholesterol** levels by reducing its catabolism. - It also has beneficial effects on other lipid parameters, such as lowering **triglycerides** and **LDL cholesterol**. *Statin* - **Statins** (HMG-CoA reductase inhibitors) are highly effective at lowering **LDL cholesterol** and moderately lowering triglycerides. - While they can cause a modest increase in HDL cholesterol, their primary role is not HDL elevation. *Gugulipids* - **Gugulipids**, derived from the gum resin of the _Commiphora mukul_ tree, have been used in traditional medicine to lower cholesterol. - Evidence for their efficacy in significantly increasing HDL cholesterol is weak and not clinically recommended. *Fibrates* - **Fibrates** primarily work to lower **triglyceride levels** and can modestly increase HDL cholesterol. - Their effect on HDL is generally less pronounced compared to nicotinic acid.

Question 1

Which calcium channel blocker has the shortest duration of action?

Accepted Answer

Nimodipine

Answer

Diltiazem

Answer

Amlodipine

Answer

Verapamil

Question 2

Which medication increases insulin secretion from beta cells?

Accepted Answer

Repaglinide

Answer

Metformin

Answer

Pioglitazone

Answer

Pramlintide

Question 3

Which of the following is a topical sulfonamide ?

Accepted Answer

Mafenide

Answer

Sulfadoxine

Answer

Sulfamethopyrazine

Answer

Sulfisoxazole

Question 4

Which of the following statements about clofazimine is incorrect?

Accepted Answer

Does not interfere with DNA synthesis

Answer

Used in lepra reaction

Answer

Used in treatment of leprosy

Answer

Causes ichthyosis and hyperpigmentation

Question 5

Which of the following is the longest acting glucocorticoid?

Accepted Answer

Dexamethasone

Answer

Prednisone

Answer

Prednisolone

Answer

Cortisone

Question 6

What is the drug of choice for pheochromocytoma?

Accepted Answer

Phenoxybenzamine

Answer

Propranolol

Answer

Prazosin

Answer

Nitroprusside

Question 7

Thiazides act on which part of the nephron?

Accepted Answer

Distal Convoluted Tubule

Answer

Proximal Convoluted Tubule

Answer

Descending limb of loop of Henle

Answer

Glomerulus

Question 8

What is the mechanism of action of clofibrate in lipid metabolism?

Accepted Answer

Increases lipoprotein lipase activity through PPAR alpha, leading to enhanced lipolysis of triglycerides.

Answer

Inhibits lipolysis in adipose tissue.

Answer

Inhibits HMG CoA reductase.

Answer

Binds bile acids and bile salts in the small intestine.

Question 9

Pyridoxine is used in treatment of ?

Accepted Answer

Homocystinuria

Answer

Galactosemia

Answer

Phenylketonuria

Answer

Propionic acidemia

Question 10

The best agent for increasing HDL cholesterol is?

Accepted Answer

Nicotinic acid

Answer

Statin

Answer

Gugulipids

Answer

Fibrates

NEET-PG 2013 — Pharmacology