NEET-PG 2013 - Pharmacology Practice Questions

Q: First generation cephalosporins are active against?

Gram positive bacteria. ***Gram positive bacteria*** - First-generation cephalosporins, such as **cefazolin** and **cephalexin**, primarily exhibit excellent activity against many **Gram-positive cocci**, including **staphylococci** and **streptococci**. - They are commonly used for skin and soft tissue infections and surgical prophylaxis due to this Gram-positive coverage. *Gram negative bacteria* - While first-generation cephalosporins have *some* activity against limited Gram-negative bacteria (e.g., *E. coli*, *Klebsiella pneumoniae*, *P. mirabilis*), their spectrum is generally weak and unreliable compared to later generations of cephalosporins. - They are not the drug of choice for serious Gram-negative infections. *Anaerobes* - First-generation cephalosporins have **poor activity** against most **anaerobic bacteria**. - For infections involving anaerobes, other antibiotics like **metronidazole**, **clindamycin**, or later-generation cephalosporins (e.g., cefoxitin, cefotetan) are generally preferred. *Dermatophytes* - Dermatophytes are **fungi** that cause skin, hair, and nail infections. - Cephalosporins are **antibacterial agents** and have **no activity** against fungi. Antifungal medications are required to treat dermatophyte infections.

Q: Which of the following drugs can cause thyroid dysfunction?

Amiodarone. ***Amiodarone*** - **Amiodarone** is known to cause both **hypothyroidism** and **hyperthyroidism** due to its high iodine content and direct toxic effects on the thyroid gland. - Its effects can persist for months after discontinuation due to its **long half-life** and accumulation in tissues. *Ampicillin* - **Ampicillin** is an antibiotic that generally does not directly affect thyroid function. - Its primary mechanism of action involves inhibiting **bacterial cell wall synthesis**, with no known significant endocrine side effects. *Ibutilide* - **Ibutilide** is an antiarrhythmic drug used for recent-onset atrial fibrillation or flutter. - It works by blocking potassium channels and has no recognized association with thyroid dysfunction. *Acyclovir* - **Acyclovir** is an antiviral medication used to treat herpes virus infections. - Its mechanism of action involves inhibiting viral DNA replication and it is not known to impact thyroid hormone synthesis or metabolism.

Q: In which of the following conditions is Verapamil not typically used?

Ventricular tachycardia. ***Ventricular tachycardia*** - Verapamil, a **non-dihydropyridine calcium channel blocker**, can worsen hemodynamics in patients with **ventricular tachycardia (VT)** by causing profound hypotension or precipitating cardiac arrest. - VT often requires prompt treatment with **antiarrhythmics like amiodarone** or **electrical cardioversion**, as it can be life-threatening. - Verapamil is **contraindicated in VT** due to its negative inotropic effects and risk of hemodynamic collapse. *Angina pectoris* - Verapamil is effectively used to treat angina pectoris by **decreasing myocardial oxygen demand** through negative chronotropic and inotropic effects, and by causing **coronary vasodilation**, improving blood flow. - Its effects help to reduce the frequency and severity of anginal episodes, particularly in **stable angina**. *Atrial fibrillation* - Verapamil is commonly used for **rate control in atrial fibrillation** by **slowing conduction through the AV node**, which decreases the ventricular response rate. - It helps to manage symptoms and prevent complications related to rapid heart rates in this arrhythmia. *Hypertension* - Verapamil is used in the treatment of **hypertension** through its vasodilatory effects and reduction in peripheral vascular resistance. - It is particularly useful in patients who cannot tolerate other antihypertensive agents or as part of combination therapy.

Q: Which of the following is a classic tricyclic antidepressant (TCA) commonly used as the prototype for the class?

Amitriptyline. ***Amitriptyline*** - **Amitriptyline** is a classic tricyclic antidepressant (TCA) and is widely recognized for its use in treating depression, neuropathic pain, and migraine prophylaxis. Its characteristic side effect profile, including **anticholinergic effects** and **sedation**, is well-known. - It is one of the **oldest and most frequently prescribed TCAs**, making it a common reference point in pharmacology and clinical practice. *Citalopram* - **Citalopram** is an **SSRI** (selective serotonin reuptake inhibitor), not a TCA. It works by selectively inhibiting the reuptake of serotonin. - It has a different side effect profile compared to TCAs, generally with fewer anticholinergic and cardiovascular effects. *Venlafaxine* - **Venlafaxine** is an **SNRI** (serotonin-norepinephrine reuptake inhibitor), not a TCA. It inhibits the reuptake of both serotonin and norepinephrine. - It has efficacy in treating depression and anxiety disorders, but its mechanism of action is distinct from TCAs. *Nortriptyline* - **Nortriptyline** is indeed a TCA, specifically a **secondary amine TCA**, which is an active metabolite of amitriptyline. - While it is a TCA, amitriptyline is generally more broadly recognized and used as the prototype for the class, with nortriptyline often being highlighted for its slightly better tolerability profile (e.g., less sedation, less orthostatic hypotension) compared to tertiary amine TCAs like amitriptyline.

Q: Which drug is commonly used to treat chronic hepatitis B infection?

Entecavir. ***Entecavir*** - **Entecavir** is an oral **nucleoside analog reverse transcriptase inhibitor** specifically approved and widely used for the treatment of **chronic hepatitis B virus (HBV) infection**. - It works by inhibiting HBV DNA polymerase, thereby reducing **viral replication** and preventing disease progression. *Atazanavir* - **Atazanavir** is a **protease inhibitor** primarily used in the treatment of **HIV infection**. - It is not indicated for the treatment of **hepatitis B virus infection**. *Zanamivir* - **Zanamivir** is a **neuraminidase inhibitor** used in the treatment and prevention of **influenza A and B viruses**. - It has no activity against **hepatitis B virus**. *Abacavir* - **Abacavir** is a **nucleoside reverse transcriptase inhibitor (NRTI)** used to treat **HIV infection**. - While it is an NRTI, it does not have significant efficacy against **hepatitis B virus** and is not used for its treatment.

Q: Drug that binds bile acids in the intestine and prevents their return to liver via the enterohepatic circulation?

Cholestyramine. ***Cholestyramine*** - **Cholestyramine** is a **bile acid-binding resin** that sequesters bile acids in the intestine, preventing their reabsorption. - This interruption of the **enterohepatic circulation** leads to increased synthesis of new bile acids from cholesterol in the liver, thus lowering plasma LDL cholesterol. *Niacin* - **Niacin (nicotinic acid)** reduces the hepatic synthesis and secretion of **VLDL**, which in turn lowers LDL and triglyceride levels. - It works primarily through mechanisms related to fat metabolism in the liver and adipose tissue, not direct bile acid binding in the intestine. *Fenofibrate* - **Fenofibrate** is a **PPAR-α agonist** that primarily reduces triglyceride levels by increasing fatty acid oxidation and lipoprotein lipase activity, and secondarily increases HDL. - Its main action is on lipid metabolism in the liver and peripheral tissues, not by binding bile acids in the gut. *Gugulipid* - **Gugulipid** is a phytosterol derived from the guggul tree, sometimes used in traditional medicine for cholesterol management. - Its purported mechanism involves increasing **bile acid excretion** and inhibiting cholesterol biosynthesis, but it does not directly bind bile acids in the same manner as resins like cholestyramine.

Q: Which of the following drugs inhibits the activation of plasminogen?

Aminocaproic acid. ***Correct Option: Aminocaproic acid*** - **Aminocaproic acid** is an antifibrinolytic drug that acts by competitively inhibiting the activation of **plasminogen** to plasmin. - By preventing the formation of plasmin, it stabilizes blood clots and is used to treat excessive bleeding. *Incorrect Option: Streptokinase* - **Streptokinase** is a **thrombolytic agent** that forms a complex with plasminogen, converting uncomplexed plasminogen into plasmin. - This action promotes the degradation of fibrin clots, making it a **fibrinolytic drug**, not an inhibitor of plasminogen activation. *Incorrect Option: Reteplase* - **Reteplase** is a **recombinant tissue plasminogen activator (tPA)** that directly converts plasminogen to plasmin. - This drug actively promotes **fibrinolysis** and clot breakdown, making it a thrombolytic agent. *Incorrect Option: Clopidogrel* - **Clopidogrel** is an **antiplatelet drug** that inhibits platelet aggregation by irreversibly blocking the P2Y12 adenosine diphosphate (ADP) receptor on platelets. - Its mechanism of action is focused on **platelet function**, not on the plasminogen-plasmin system.

Q: Lithium directly affects which ion ?

Sodium. ***Sodium*** - Lithium directly interferes with **sodium ion transport** across cell membranes, particularly by inhibiting the **Na+/K+-ATPase** pump. - This interference alters intracellular sodium concentrations and affects neural excitability, contributing to its **mood-stabilizing** effects. *Potassium* - While potassium transport is linked to the **Na+/K+-ATPase pump**, lithium primarily acts through its effect on **sodium transport**, rather than directly mimicking or significantly altering potassium. - Changes in potassium levels due to lithium are largely secondary to its primary impact on sodium. *Magnesium* - Lithium has a more direct impact on **sodium channels** and transporters, contrasting with its less direct or significant interaction with magnesium metabolism. - Though magnesium is crucial for numerous cellular processes, it is not the primary ion directly affected by lithium's therapeutic actions. *Calcium* - Lithium does not directly affect **calcium channels** or calcium signaling pathways in the same way it impacts sodium. - While lithium may indirectly influence calcium-dependent processes, its primary direct target for therapeutic effects is not calcium.

Q: Which of the following is a parenteral direct thrombin inhibitor?

Argatroban. ***Argatroban*** - **Argatroban** is a **synthetic direct thrombin inhibitor** administered exclusively via **intravenous infusion**, making it a parenteral drug. - It does not require antithrombin for its action and is primarily used in patients with **heparin-induced thrombocytopenia (HIT)**. *Ximelagatran* - **Ximelagatran** was an **oral direct thrombin inhibitor** but was withdrawn from the market due to concerns about severe **liver toxicity**. - As an oral drug, it is not a parenteral medication. *Dabigatran* - **Dabigatran** is a **direct thrombin inhibitor** that is administered **orally** in capsule form (as dabigatran etexilate, a prodrug). - Therefore, it is not a parenteral medication. *Heparin* - **Heparin** is an **indirect thrombin inhibitor** because it requires binding to **antithrombin** to exert its anticoagulant effect. - Although administered parenterally, its mechanism of action is indirect.

Q: Which of the following is a renin inhibitor?

Remikiren. **Remikiren** - **Remikiren** is a direct **renin inhibitor** that acts by binding to the active site of renin, preventing its interaction with angiotensinogen. - This inhibition reduces the formation of **angiotensin I** and subsequently **angiotensin II**, leading to decreased blood pressure. *Losartan* - **Losartan** is an **Angiotensin II Receptor Blocker (ARB)**, meaning it blocks AT1 receptors, preventing angiotensin II from binding. - It does not inhibit renin activity directly but rather acts downstream in the **renin-angiotensin-aldosterone system (RAAS)**. *Benazepril* - **Benazepril** is an **Angiotensin-Converting Enzyme (ACE) inhibitor**, which blocks the enzyme responsible for converting **angiotensin I** to **angiotensin II**. - It does not directly inhibit renin production or activity. *Imidapril* - **Imidapril** is also an **Angiotensin-Converting Enzyme (ACE) inhibitor**, similar to benazepril. - Its mechanism of action involves inhibiting ACE, thereby reducing **angiotensin II** levels, rather than directly inhibiting renin.

Question 1

First generation cephalosporins are active against?

Accepted Answer

Gram positive bacteria

Answer

Gram negative bacteria

Answer

Anaerobes

Answer

Dermatophytes

Question 2

Which of the following drugs can cause thyroid dysfunction?

Accepted Answer

Amiodarone

Answer

Ampicillin

Answer

Ibutilide

Answer

Acyclovir

Question 3

In which of the following conditions is Verapamil not typically used?

Accepted Answer

Ventricular tachycardia

Answer

Angina pectoris

Answer

Atrial fibrillation

Answer

Hypertension

Question 4

Which of the following is a classic tricyclic antidepressant (TCA) commonly used as the prototype for the class?

Accepted Answer

Amitriptyline

Answer

Citalopram

Answer

Venlafaxine

Answer

Nortriptyline

Question 5

Which drug is commonly used to treat chronic hepatitis B infection?

Accepted Answer

Entecavir

Answer

Zanamivir

Answer

Atazanavir

Answer

Abacavir

Question 6

Drug that binds bile acids in the intestine and prevents their return to liver via the enterohepatic circulation?

Accepted Answer

Cholestyramine

Answer

Niacin

Answer

Fenofibrate

Answer

Gugulipid

Question 7

Which of the following drugs inhibits the activation of plasminogen?

Accepted Answer

Aminocaproic acid

Answer

Streptokinase

Answer

Reteplase

Answer

Clopidogrel

Question 8

Lithium directly affects which ion ?

Accepted Answer

Sodium

Answer

Potassium

Answer

Magnesium

Answer

Calcium

Question 9

Which of the following is a parenteral direct thrombin inhibitor?

Accepted Answer

Argatroban

Answer

Ximelagatran

Answer

Dabigatran

Answer

Heparin

Question 10

Which of the following is a renin inhibitor?

Accepted Answer

Remikiren

Answer

Losartan

Answer

Benazepril

Answer

Imidapril

NEET-PG 2013 — Pharmacology