Which of the following is a primary use of Levamisole?
Emtricitabine is classified as which of the following?
Which of the following is not excreted by the kidney?
Which of the following combinations does not show synergistic action?
In patients undergoing INH therapy, which group is least likely to develop neuropathy?
Which of the following drugs is not used for the treatment of H. Pylori?
Which of the following medications is classified as a stool softener?
Which of the following statements about oral iron preparations is correct?
Which of the following conditions is not associated with an increased risk of neuropathy caused by Isoniazid (INH)?
Idoxuridine is used for treatment of?
NEET-PG 2015 - Pharmacology NEET-PG Practice Questions and MCQs
Question 21: Which of the following is a primary use of Levamisole?
- A. Immunostimulant
- B. Antihelminthic (Correct Answer)
- C. None of the options
- D. Immunomodulator
Explanation: ***Antihelminthic*** - Levamisole is **primarily classified as an antihelminthic drug**, used to treat parasitic worm infections. - It acts as a **nicotinic receptor agonist** in nematodes, causing spastic paralysis of the worms, leading to their expulsion. - It was historically used in humans for treating ascariasis and hookworm infections, and is still used in **veterinary medicine** for deworming livestock. - This is its **primary pharmacological classification** in standard medical textbooks. *Immunomodulator* - Levamisole does have **immunomodulatory properties** that were discovered secondary to its antihelminthic use. - It was used as **adjuvant therapy in colon cancer** (with 5-FU) to enhance immune response. - However, this is a **secondary use**, not its primary classification, and has been largely discontinued due to severe side effects like agranulocytosis. *Immunostimulant* - While levamisole can stimulate certain aspects of cell-mediated immunity, this overlaps with its immunomodulatory effects. - This is **not its primary pharmacological classification** - it remains primarily an antihelminthic agent. *None of the options* - This is incorrect because **antihelminthic** is clearly the primary and correct classification of levamisole in pharmacology. - Its antihelminthic action was its original and primary therapeutic application.
Question 22: Emtricitabine is classified as which of the following?
- A. Alkylating agent
- B. Antimetabolite
- C. NRTI (Correct Answer)
- D. Integrase Inhibitor
Explanation: ***NRTI*** - Emtricitabine is a **nucleoside reverse transcriptase inhibitor (NRTI)**, a class of antiretroviral drugs used in the treatment of **HIV infection**. - As an NRTI, it works by inhibiting the enzyme **reverse transcriptase**, which is crucial for the HIV virus to replicate its RNA into DNA. *Alkylating agent* - Alkylating agents are a type of **chemotherapy drug** that kill cancer cells by damaging their DNA. - They are primarily used in **cancer treatment**, not for viral infections like HIV. *Antimetabolite* - Antimetabolites are drugs that interfere with DNA and RNA synthesis, often used in **chemotherapy** to treat cancer or in immunosuppression. - While they can inhibit nucleic acid synthesis, this is a broad category, and emtricitabine's specific mechanism and classification are as an NRTI. *Integrase Inhibitor* - Integrase inhibitors are another class of **antiretroviral drugs** that block the HIV enzyme integrase, preventing the viral DNA from integrating into the host cell's DNA. - While an antiretroviral, emtricitabine has a different mechanism of action and belongs to the NRTI class.
Question 23: Which of the following is not excreted by the kidney?
- A. Ciprofloxacin
- B. Ofloxacin
- C. Moxifloxacin (Correct Answer)
- D. Levofloxacin
Explanation: ***Moxifloxacin*** - Moxifloxacin is primarily metabolized in the **liver** and excreted through bile and feces. - This characteristic makes it a suitable choice for patients with significant **renal impairment** as dose adjustments are generally not required. *Ciprofloxacin* - Ciprofloxacin is predominantly excreted by the **kidneys** through both glomerular filtration and tubular secretion. - Dose adjustments are crucial in patients with **renal dysfunction** to prevent accumulation and toxicity. *Ofloxacin* - Ofloxacin is largely excreted unchanged in the **urine**, making renal excretion its primary elimination pathway. - **Dose reduction** is necessary for patients with impaired renal function. *Levofloxacin* - Levofloxacin is primarily eliminated via **renal excretion**, with a significant portion appearing in the urine as unmetabolized drug. - Patients with **kidney disease** require appropriate dose adjustments.
Question 24: Which of the following combinations does not show synergistic action?
- A. Streptomycin plus penicillin
- B. Rifampicin plus dapsone
- C. Penicillin plus tetracycline (Correct Answer)
- D. Penicillin plus sulfonamide
Explanation: ***Penicillin plus tetracycline*** - This combination is generally **antagonistic** or **indifferent**, not synergistic. Penicillin is a cell wall synthesis inhibitor that works best on actively growing bacteria, while tetracycline is a bacteriostatic protein synthesis inhibitor that can reduce bacterial growth, thereby diminishing penicillin's effect. - The combination is usually avoided as the **bacteriostatic action of tetracycline** can counteract the **bactericidal action of penicillin**, leading to reduced efficacy, especially in infections requiring rapid bacterial clearance. *Penicillin plus sulfonamide* - This combination can show synergism in some contexts, particularly as sulfonamides inhibit **folate synthesis**, while penicillin inhibits **cell wall synthesis**. - While not a classic synergistic pair for all infections, their mechanisms of action are distinct, and they can sometimes be used together, although specific synergistic effects are more limited compared to other pairs. *Streptomycin plus penicillin* - This is a classic example of **synergistic action**, particularly in conditions like **enterococcal endocarditis**. - Penicillin damages the bacterial cell wall, allowing **streptomycin** (an aminoglycoside) to more easily penetrate the cell and act on ribosomal targets, leading to enhanced bactericidal effect. *Rifampicin plus dapsone* - This combination is a cornerstone of **multi-drug therapy for leprosy**, demonstrating clear synergy against *Mycobacterium leprae*. - **Rifampicin** inhibits bacterial RNA synthesis, and **dapsone** inhibits folate synthesis, attacking different essential bacterial pathways which, when combined, are more effective and reduce the development of resistance.
Question 25: In patients undergoing INH therapy, which group is least likely to develop neuropathy?
- A. Having malnutrition
- B. Alcoholics
- C. Fast acetylators (Correct Answer)
- D. Vitamin B complex deficiency
Explanation: ***Fast acetylators*** - **Fast acetylators** metabolize INH more quickly, leading to lower systemic drug levels and thus a reduced risk of adverse effects like neuropathy. - Neuropathy associated with INH is primarily due to **pyridoxine (vitamin B6) depletion**, which is less pronounced if the drug is rapidly cleared. *Having malnutrition* - **Malnutrition** often involves deficiencies in essential vitamins, including vitamin B6, which is crucial for preventing INH-induced neuropathy. - Patients with poor nutritional status are at a **higher risk** of developing neuropathy during INH therapy due to pre-existing vitamin B6 depletion. *Alcoholics* - **Alcoholism** is strongly associated with deficiencies in various B vitamins, particularly **pyridoxine (vitamin B6)**, due to poor diet and impaired absorption. - This pre-existing deficiency makes alcoholics **highly susceptible** to INH-induced neuropathy. *Vitamin B complex deficiency* - A **deficiency in vitamin B complex**, especially pyridoxine (B6), is a known risk factor for INH-induced neuropathy. - Isoniazid interferes with **pyridoxine metabolism**, and those with pre-existing deficiency are more vulnerable to this adverse effect.
Question 26: Which of the following drugs is not used for the treatment of H. Pylori?
- A. Bismuth
- B. Domperidone (Correct Answer)
- C. Clarithromycin
- D. Amoxicillin
Explanation: ***Correct: Domperidone*** - Domperidone is a **prokinetic drug** used to treat nausea, vomiting, and gastric motility disorders, but it has **no direct antibacterial activity** against *H. pylori*. - It works by blocking **dopamine receptors** in the chemoreceptor trigger zone and peripherally. - Therefore, it is **NOT used for *H. pylori* eradication**. *Incorrect: Bismuth* - **Bismuth subsalicylate** is a key component of **quadruple therapy** for *H. pylori* eradication, particularly in cases of antibiotic resistance or treatment failure. - It has **bactericidal effects** against *H. pylori*, disrupts its cell wall, and inhibits its adherence to the gastric mucosa. *Incorrect: Amoxicillin* - **Amoxicillin** is a penicillin-class antibiotic commonly used in various *H. pylori* eradication regimens, including **triple therapy**. - It acts by **inhibiting bacterial cell wall synthesis**, leading to bacterial lysis. *Incorrect: Clarithromycin* - **Clarithromycin** is a macrolide antibiotic frequently included in standard **triple therapy** for *H. pylori* eradication. - It inhibits **bacterial protein synthesis** by binding to the 50S ribosomal subunit.
Question 27: Which of the following medications is classified as a stool softener?
- A. Bran
- B. Senna
- C. Phenolphthalein
- D. Docusates (Correct Answer)
Explanation: **Docusates** - **Docusates** (e.g., docusate sodium, docusate calcium) are **stool softeners** that work by reducing the surface tension of stool, allowing water and lipids to penetrate. - This increases the water content in the stool, making it softer and easier to pass, which is particularly useful in preventing straining after surgery or in conditions like hemorrhoids. *Bran* - **Bran** is a **bulk-forming laxative**, a type of dietary fiber that adds mass to the stool. - It absorbs water in the intestines, which increases stool volume and stimulates bowel movements, but it does not directly soften the stool in the same way docusates do. *Senna* - **Senna** is a **stimulant laxative** that works by irritating the bowel wall to promote peristalsis and bowel evacuation. - While it can help move stool, it does not act primarily by softening it, and prolonged use can lead to dependency or electrolyte imbalances. *Phenolphthalein* - **Phenolphthalein** is a **stimulant laxative** that was historically used to promote bowel movements. - It is no longer widely used due to concerns about potential carcinogenicity and other adverse effects, and it does not function as a stool softener.
Question 28: Which of the following statements about oral iron preparations is correct?
- A. Most commonly used preparation is ferrous gluconate
- B. Ferrous fumarate is most efficient
- C. Ferric preparations are more effective
- D. Different preparations have different bioavailability (Correct Answer)
Explanation: ***Different preparations have different bioavailability*** - The **bioavailability** of oral iron preparations varies depending on the specific salt used, its formulation, and the presence of absorption enhancers or inhibitors. - This difference in absorption impacts the required dose and efficacy in treating **iron deficiency anemia**. *Most commonly used preparation is ferrous gluconate* - **Ferrous sulfate** is the most commonly prescribed and cost-effective oral iron preparation due to its high iron content and good bioavailability. - While ferrous gluconate is used, its iron content is lower than ferrous sulfate, making it less frequently the primary choice. *Ferrous fumarate is most efficient* - While **ferrous fumarate** has a high elemental iron content, its efficiency doesn't necessarily surpass that of ferrous sulfate or other preparations when considering factors like bioavailability and side effect profile. - **Ferrous sulfate** is often considered efficient due to its balance of elemental iron content, bioavailability, and cost-effectiveness. *Ferric preparations are more effective* - **Ferrous (Fe2+)** iron is generally better absorbed than **ferric (Fe3+)** iron, as ferric iron needs to be reduced to its ferrous form before absorption. - Unless specifically formulated for enhanced absorption (e.g., ferric maltol), ferric preparations are typically *less* effective for initial iron repletion.
Question 29: Which of the following conditions is not associated with an increased risk of neuropathy caused by Isoniazid (INH)?
- A. Uremia
- B. Diabetes mellitus
- C. Poor nutrition
- D. Hyperthyroidism (Correct Answer)
Explanation: ***Hyperthyroidism*** - **Hyperthyroidism** is not typically associated with an increased risk of isoniazid-induced neuropathy. The neuropathy due to INH is primarily linked to **pyridoxine (vitamin B6) deficiency**. - While hyperthyroidism can cause its own set of neurological symptoms, it does not directly impair pyridoxine metabolism or exacerbate INH's neurotoxic effects. *Uremia* - **Uremia** (renal failure) can increase the risk of INH-induced neuropathy due to impaired drug excretion, leading to higher plasma concentrations of INH and its metabolites. - Patients with uremia often have compromised nutritional status and may experience vitamin deficiencies, further contributing to pyridoxine depletion. *Diabetes mellitus* - **Diabetes mellitus** is a significant risk factor for INH-induced neuropathy because it is an independent cause of **peripheral neuropathy** itself, making patients more susceptible to additional nerve damage. - Diabetic patients may also have altered pyridoxine metabolism or suboptimal nutritional intake, predisposing them to INH toxicity. *Poor nutrition* - **Poor nutrition**, particularly malabsorption or inadequate dietary intake, directly contributes to **pyridoxine (vitamin B6) deficiency**. - Isoniazid's mechanism of neurotoxicity involves interfering with pyridoxine metabolism, so pre-existing deficiency significantly increases the risk of neuropathy.
Question 30: Idoxuridine is used for treatment of?
- A. Influenza
- B. RSV
- C. HSV (Correct Answer)
- D. HIV
Explanation: ***HSV*** - **Idoxuridine** is a **pyrimidine analog** that inhibits viral DNA synthesis, making it effective against **herpes simplex virus (HSV)** infections, particularly **herpes keratitis** (ophthalmic use). - Its mechanism involves being incorporated into viral DNA, leading to errors in replication and transcription. - It is applied **topically** for ocular HSV infections due to systemic toxicity concerns. *Influenza* - **Idoxuridine** is not active against **influenza viruses**. - **Antiviral drugs** like **oseltamivir** or **zanamivir** are typically used for influenza treatment. *RSV* - **Idoxuridine** is not indicated for the treatment of **respiratory syncytial virus (RSV)**. - **Ribavirin** is the primary antiviral agent used for severe RSV infections, especially in immunocompromised patients. *HIV* - **Idoxuridine** has no significant activity against **human immunodeficiency virus (HIV)**. - **Antiretroviral therapy (ART)**, a combination of drugs targeting various stages of the HIV life cycle, is used for HIV treatment.