NEET-PG 2018 - Pharmacology Practice Questions

Q: Which antiretroviral drug also has anti-hepatitis activity?

Tenofovir. ***Tenofovir*** - **Tenofovir** is a nucleotide reverse transcriptase inhibitor (NtRTI) that is highly effective against both **HIV** and **Hepatitis B virus (HBV)**. - It is a **first-line agent** for HBV treatment with a **high barrier to resistance**, making it the preferred choice for dual therapy in HIV/HBV coinfection. - It is FDA-approved for both HIV and HBV treatment and is a key component in antiretroviral therapy (ART) regimens for coinfected patients. *Abacavir* - **Abacavir** is a nucleoside reverse transcriptase inhibitor (NRTI) used for HIV treatment. - It does not have significant activity against **Hepatitis B virus (HBV)** or other hepatitis viruses. *Emtricitabine* - **Emtricitabine** is a nucleoside reverse transcriptase inhibitor (NRTI) that has activity against both **HIV** and **HBV**. - While it is FDA-approved for HBV treatment, it has a **lower barrier to resistance** compared to tenofovir and is less preferred as monotherapy for HBV. - It is commonly used in combination with tenofovir (as in Truvada) for enhanced efficacy in HIV/HBV coinfection. - **Tenofovir remains the best answer** due to its superior resistance profile and status as first-line HBV therapy. *Nevirapine* - **Nevirapine** is a non-nucleoside reverse transcriptase inhibitor (NNRTI) used specifically for **HIV infection**. - It does not demonstrate antiviral activity against **Hepatitis B virus (HBV)** or other forms of viral hepatitis.

Q: Anaerobes are resistant intrinsically against which of the following?

Aminoglycosides. ***Aminoglycosides*** - **Aminoglycosides** require an **oxygen-dependent transport system** to enter bacterial cells. [3] - Since **anaerobes** thrive in low-oxygen environments, this transport system is inactive, making them intrinsically resistant to aminoglycosides. [3] *Azithromycin* - **Azithromycin** (a macrolide) inhibits protein synthesis by binding to the 50S ribosomal subunit. - Many anaerobes are susceptible to **azithromycin**, making it an effective treatment for certain anaerobic infections. *Metronidazole* - **Metronidazole** is a potent prodrug that requires reduction by **anaerobic metabolism** to become active. [1], [2] - Its mechanism of action involves creating **cytotoxic free radicals** that damage DNA, making it highly effective against most anaerobes. [2] *Beta lactam antibiotics* - **Beta-lactam antibiotics**, such as **penicillins** and **cephalosporins**, interfere with bacterial cell wall synthesis. - While some anaerobes are susceptible, others have developed resistance mechanisms like producing **beta-lactamase enzymes**, but they are not intrinsically resistant across the board. [4]

Q: Tadalafil should not be given with:

Vasodilators. ***Vasodilators*** - Tadalafil is a **phosphodiesterase-5 (PDE5) inhibitor** that causes **vasodilation** by increasing cGMP levels, leading to smooth muscle relaxation. - Combining tadalafil with other **vasodilators**, particularly **nitrates**, can lead to a severe and potentially life-threatening drop in **blood pressure (hypotension)**. *Antibiotics* - While some antibiotics, particularly macrolides or azoles, can inhibit **CYP3A4** and increase tadalafil levels, this interaction is typically managed by dose adjustments rather than an absolute contraindication. - The primary concern with administering antibiotics and tadalafil concurrently is **pharmacokinetic interactions**, not a direct pharmacodynamic synergy leading to acute, severe adverse effects. *Vasoconstrictors* - Vasoconstrictors have an effect **opposite** to tadalafil, as they narrow blood vessels. - There is generally no contraindication for co-administration, and in fact, tadalafil's **vasodilatory effects** could potentially **counteract** some of the vasoconstriction, although concurrent use is not typically recommended for erectile dysfunction. *Valproate* - **Valproate** is an **anticonvulsant** and mood stabilizer, and there is no significant or clinically relevant drug interaction established with tadalafil. - It does not share common metabolic pathways or pharmacodynamic effects that would lead to dangerous interactions with tadalafil.

Q: Colonoscopy performed on a 25 year old woman with eating disorder showed dark brown to black pigmentary deposit in the lining of the large intestine. Histopathology of biopsy revealed pigment laden macrophages within the lamina propria. On probing, the woman revealed use of laxatives for 9 months to lose weight. What could be the probable laxative agent that could have caused these findings?

Senna. ***Senna*** - Chronic use of **anthraquinone laxatives** like senna [1] leads to **melanosis coli**, characterized by dark brown pigment in the colon. - Histopathology reveals **pigment-laden macrophages** in the lamina propria, confirming melanosis coli. *Castor oil* - **Castor oil** is a stimulant laxative that acts on the small intestine but does not typically cause **melanosis coli**. - Its primary action is to increase fluid secretion and bowel motility, rather than pigment deposition. *Bisacodyl* - **Bisacodyl** is a stimulant laxative that works locally in the colon to increase fluid and electrolyte secretion and stimulate peristalsis. - It works on different pharmacological mechanisms and typically does not cause the characteristic **pigment-laden macrophages** that define melanosis coli. *Sorbitol* - **Sorbitol** is an osmotic laxative that works by drawing water into the colon, softening stools and promoting bowel movements. - It does not induce the characteristic **darkening of the colonic mucosa** or the specific histological changes observed in melanosis coli.

Q: Which drug increases bone formation in osteoporosis?

Teriparatide. ***Correct Option: Teriparatide*** - **Teriparatide** is a recombinant form of **parathyroid hormone (PTH)** that, when administered intermittently, stimulates **osteoblast activity** to increase bone formation. - It is an **anabolic agent** specifically designed to build new bone, making it unique among osteoporosis treatments that primarily inhibit bone resorption. - Administered as a **daily subcutaneous injection** for up to 2 years. *Incorrect Option: Calcitonin* - **Calcitonin** is a hormone that inhibits **osteoclast activity**, thereby reducing bone resorption, but does not directly stimulate bone formation. - It may be used for pain relief in acute vertebral fractures but has a minor role in increasing bone density. *Incorrect Option: Risedronate* - **Risedronate** is a **bisphosphonate** that works by inhibiting **osteoclast-mediated bone resorption**, preventing bone breakdown. - It does not directly promote new bone formation; its primary action is to reduce bone turnover. *Incorrect Option: Denosumab* - **Denosumab** is a **monoclonal antibody** that targets and binds to **RANKL**, thereby inhibiting **osteoclast formation, function, and survival**, leading to decreased bone resorption. - Like bisphosphonates, its main mechanism is anti-resorptive, not anabolic.

Q: Coagulation testing is needed for:

Lepirudin (direct thrombin inhibitor). ***Lepirudin (direct thrombin inhibitor)*** - **Lepirudin**, being a direct thrombin inhibitor, necessitates **coagulation testing** (such as aPTT) to monitor its anticoagulant effect and adjust dosing, especially in patients with renal impairment. - Its narrow therapeutic window and potential for bleeding complications require careful monitoring to ensure patient safety and drug efficacy, as it lacks a specific antidote. *Dabigatran (oral anticoagulant)* - **Dabigatran** is a **direct oral anticoagulant (DOAC)** that typically does not require routine coagulation monitoring due to its predictable pharmacokinetic and pharmacodynamic profiles. - While specific tests can assess its effect in emergencies, they are not part of standard management, distinguishing it from drugs requiring regular monitoring. *Enoxaparin (low molecular weight heparin)* - **Enoxaparin**, a **low molecular weight heparin (LMWH)**, usually does not require routine coagulation monitoring in most patients due to its predictable dose-response relationship. - Monitoring with anti-Xa levels may be considered in specific populations, such as those with renal insufficiency, extremes of weight, or in pediatric and pregnant patients. *Fondaparinux (synthetic pentasaccharide)* - **Fondaparinux** is a synthetic pentasaccharide that **does not require routine coagulation monitoring** as its anticoagulant effect is highly predictable and dose-dependent. - Its action is mediated through selective inhibition of **Factor Xa**, and standard coagulation tests like aPTT or PT are not sensitive to its effects.

Q: Amphotericin B acts on:-

Cell membrane. ***Cell membrane*** Amphotericin B primarily targets the **ergosterol** in the fungal **cell membrane** [1]. It binds to **ergosterol**, forming pores and disrupting the membrane's integrity, leading to leakage of cellular contents and ultimately cell death [1]. *Cytoplasm* The cytoplasm is the internal fluid of the cell where many metabolic processes occur, but it is **not the primary target** of amphotericin B's fungicidal action. While cytoplasmic contents leak out due to membrane damage, the drug does not directly act on cytoplasmic components to exert its effect. *Nucleus* The nucleus contains the genetic material of the fungal cell, but amphotericin B does **not directly interact with nuclear components** or DNA. Damage to the cell membrane is the primary mechanism, with nuclear function only indirectly affected by overall cellular disruption. *Cell wall* Fungal cell walls are composed of **chitin and glucans**, but amphotericin B **does not target these components**. Its action is distinct from drugs that inhibit cell wall synthesis, such as echinocandins.

Q: Drug which lacks intrinsic activity against anaerobes is:-

Aminoglycosides. ***Aminoglycosides*** - Aminoglycosides require an **oxygen-dependent transport system** to enter bacterial cells and exert their effects. - Due to the **anaerobic environment**, this transport system is inactive, rendering aminoglycosides ineffective against anaerobic bacteria. *Beta lactams* - Many beta-lactam antibiotics, especially certain **cephalosporins (e.g., cefoxitin, cefotetan)** and **carbapenems (e.g., imipenem, meropenem)**, have significant activity against anaerobes. - They inhibit **cell wall synthesis** and are a common choice for infections involving anaerobes. *Metronidazole* - **Metronidazole** is a potent and widely used antibiotic specifically effective against a broad spectrum of **anaerobic bacteria** and protozoa. - It acts by forming **cytotoxic reduced products** that disrupt bacterial DNA synthesis in anaerobic conditions. *Chloramphenicol* - **Chloramphenicol** is a broad-spectrum antibiotic that is highly effective against both aerobic and **anaerobic bacteria**. - It works by binding to the **50S ribosomal subunit**, thereby inhibiting bacterial protein synthesis.

Q: All are false about tigecycline, except:-

It is a broad spectrum antimicrobial. ***It is a broad spectrum antimicrobial*** - **Tigecycline** is known for its wide spectrum of activity, effective against a variety of gram-positive, gram-negative, and anaerobic bacteria. - It is particularly useful in treating infections caused by **multidrug-resistant (MDR)** organisms, including MRSA and VRE. *90% pseudomonas strains are sensitive* - Tigecycline generally has **poor activity** against *Pseudomonas aeruginosa*, and its use is specifically cautioned against for such infections. - **Many *Pseudomonas* strains are intrinsically resistant** to tigecycline, making it an unreliable choice for treating these infections. *It is bactericidal drug* - Tigecycline is a **bacteriostatic** antibiotic, meaning it inhibits bacterial growth rather than directly killing bacteria. - It achieves its effect by binding to the **30S ribosomal subunit**, thereby blocking protein synthesis. *Dose reduction is required in renal failure* - **Tigecycline** is primarily eliminated via **biliary and fecal excretion**, with only a small portion excreted renally. - Therefore, **dose adjustments are generally not required** in patients with renal impairment, but caution is usually advised in severe hepatic impairment.

Question 1

Which antiretroviral drug also has anti-hepatitis activity?

Accepted Answer

Tenofovir

Answer

Abacavir

Answer

Nevirapine

Answer

Emtricitabine

Question 2

Anaerobes are resistant intrinsically against which of the following?

Accepted Answer

Aminoglycosides

Answer

Azithromycin

Answer

Metronidazole

Answer

Beta lactam antibiotics

Question 3

Tadalafil should not be given with:

Accepted Answer

Vasodilators

Answer

Antibiotics

Answer

Vasoconstrictors

Answer

Valproate

Question 4

Colonoscopy performed on a 25 year old woman with eating disorder showed dark brown to black pigmentary deposit in the lining of the large intestine. Histopathology of biopsy revealed pigment laden macrophages within the lamina propria. On probing, the woman revealed use of laxatives for 9 months to lose weight. What could be the probable laxative agent that could have caused these findings?

Accepted Answer

Senna

Answer

Castor oil

Answer

Bisacodyl

Answer

Sorbitol

Question 5

Which drug increases bone formation in osteoporosis?

Accepted Answer

Teriparatide

Answer

Calcitonin

Answer

Risedronate

Answer

Denosumab

Question 6

Mechanism of action of d-tubocurarine is:

Accepted Answer

Competitive, nondepolarizing block at the Nm cholinergic receptor

Answer

Noncompetitive, depolarizing block at the Nm cholinergic receptor

Answer

Non-competitive, nondepolarizing block at the Nm cholinergic receptor

Answer

Competitive, depolarizing block at the Nm cholinergic receptor

Question 7

Coagulation testing is needed for:

Accepted Answer

Lepirudin (direct thrombin inhibitor)

Answer

Dabigatran (oral anticoagulant)

Answer

Enoxaparin (low molecular weight heparin)

Answer

Fondaparinux (synthetic pentasaccharide)

Question 8

Amphotericin B acts on:-

Accepted Answer

Cell membrane

Answer

Cytoplasm

Answer

Nucleus

Answer

Cell wall

Question 9

Drug which lacks intrinsic activity against anaerobes is:-

Accepted Answer

Aminoglycosides

Answer

Beta lactams

Answer

Metronidazole

Answer

Chloramphenicol

Question 10

All are false about tigecycline, except:-

Accepted Answer

It is a broad spectrum antimicrobial

Answer

90% pseudomonas strains are sensitive

Answer

It is bactericidal drug

Answer

Dose reduction is required in renal failure

NEET-PG 2018 — Pharmacology