Pharmacology
10 questionsWhich of the following statements about clofazimine is incorrect?
First generation cephalosporins are active against?
Which drug is commonly used to treat chronic hepatitis B infection?
What is the most serious side effect associated with Raltegravir?
Mode of excretion of cyclophosphamide is?
Which drug is primarily used in the treatment of breast cancer?
Which of the following antiretroviral drugs is not associated with peripheral neuropathy?
Which of the following is a topical sulfonamide ?
Tetracycline injection causes palsy of which nerve?
What is the primary indication for the use of Erlotinib?
NEET-PG 2013 - Pharmacology NEET-PG Practice Questions and MCQs
Question 711: Which of the following statements about clofazimine is incorrect?
- A. Does not interfere with DNA synthesis (Correct Answer)
- B. Used in lepra reaction
- C. Used in treatment of leprosy
- D. Causes ichthyosis and hyperpigmentation
Explanation: ***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.
Question 712: First generation cephalosporins are active against?
- A. Gram negative bacteria
- B. Gram positive bacteria (Correct Answer)
- C. Anaerobes
- D. Dermatophytes
Explanation: ***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.
Question 713: Which drug is commonly used to treat chronic hepatitis B infection?
- A. Zanamivir
- B. Atazanavir
- C. Abacavir
- D. Entecavir (Correct Answer)
Explanation: ***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.
Question 714: What is the most serious side effect associated with Raltegravir?
- A. Hyperglycemia
- B. Hypertension
- C. Headache
- D. Rhabdomyolysis (Correct Answer)
Explanation: ***Rhabdomyolysis*** - Raltegravir, an **integrase strand transfer inhibitor (INSTI)**, can cause muscle-related side effects, including **rhabdomyolysis** and **myopathy**. [2] - Patients may present with muscle pain, weakness, and elevated **creatine kinase (CK)** levels. *Headache* - While headache can be a general side effect of many medications, it is not a **distinguishing or severe adverse effect commonly associated with Raltegravir** that would require specific monitoring. - Other more prominent side effects are typically prioritized in counseling and monitoring for this drug. *Hyperglycemia* - **Hyperglycemia** is not a commonly reported or significant side effect of Raltegravir. - While some antiretrovirals, particularly certain **protease inhibitors (PIs)** and **nucleoside reverse transcriptase inhibitors (NRTIs)**, are associated with altered glucose metabolism, INSTIs like Raltegravir generally have a more favorable metabolic profile. [1] *Hypertension* - Hypertension is generally **not a recognized or common side effect** of Raltegravir. - Cardiovascular events and hypertension are more frequently associated with other classes of antiretroviral drugs or as comorbidities in HIV-positive patients, rather than directly with INSTIs.
Question 715: Mode of excretion of cyclophosphamide is?
- A. Lung
- B. Liver
- C. Kidney (Correct Answer)
- D. Skin
Explanation: ***Kidney*** - Cyclophosphamide is a **prodrug** that undergoes metabolism in the liver to its active forms. However, both the parent drug and its active metabolites are primarily **excreted renally**. [1] - Renal excretion means that patients with **renal impairment** may require dose adjustments to prevent drug accumulation and increased toxicity. [3] *Lung* - The lungs are primarily involved in **gas exchange** and the elimination of volatile substances, not non-volatile drugs like cyclophosphamide. - While some drugs can be excreted to a minor extent via the lungs, it is not the primary route for **cyclophosphamide**. *Liver* - The liver is the primary site of **metabolism** for cyclophosphamide, where it is converted into active cytotoxic metabolites. [1], [2] - While metabolites are formed here, the liver is not the main organ for the final **elimination** (excretion) of the drug or its metabolites from the body. *Skin* - The skin's role in drug excretion is generally minimal, mainly involving substances excreted in **sweat**, and is not a significant route for cyclophosphamide. - Excretion via the skin is typically very limited for most drugs and does not play a major role in the elimination of **chemotherapeutic agents** like cyclophosphamide.
Question 716: Which drug is primarily used in the treatment of breast cancer?
- A. Tamoxifen (Correct Answer)
- B. Cyproterone
- C. Testosterone
- D. Chlorambucil
Explanation: ***Tamoxifen*** - **Tamoxifen** is a **selective estrogen receptor modulator (SERM)** primarily used to treat and prevent **estrogen receptor (ER)-positive breast cancer**. - It works by blocking estrogen from binding to receptors in breast cancer cells, thereby inhibiting their growth. *Cyproterone* - **Cyproterone** is an **anti-androgen** and **progestogen** primarily used to treat conditions like **prostate cancer**, **acne**, and **hirsutism** in women. - Its main mechanism involves blocking androgen receptors and reducing androgen production, which is not the primary pathway for breast cancer. *Testosterone* - **Testosterone** is an **androgen** (male sex hormone) and is **not used** in the primary treatment of breast cancer. - In certain rare cases of severe metastatic breast cancer, androgens like high-dose testosterone have been historically used for palliation, but this is not standard therapy. *Chlorambucil* - **Chlorambucil** is an **alkylating agent** used primarily in the treatment of **chronic lymphocytic leukemia (CLL)** and certain **lymphomas**. - It works by interfering with DNA replication and transcription, but it is not a first-line or primary agent for breast cancer.
Question 717: Which of the following antiretroviral drugs is not associated with peripheral neuropathy?
- A. Stavudine
- B. Zalcitabine
- C. Didanosine
- D. Indinavir (Correct Answer)
Explanation: ***Indinavir*** - **Indinavir** is a **protease inhibitor** that can cause side effects such as **nephrolithiasis** (kidney stones) and **hyperbilirubinemia**, but it is generally *not associated with peripheral neuropathy*. - It works by blocking the viral protease enzyme, preventing the cleavage of viral polyproteins into functional proteins, which disrupts viral replication. *Stavudine* - **Stavudine** is a **nucleoside reverse transcriptase inhibitor (NRTI)** notorious for causing dose-dependent **peripheral neuropathy**. - This toxicity is due to its interference with **mitochondrial DNA synthesis**, leading to nerve damage. *Zalcitabine* - **Zalcitabine** (ddC) is another **NRTI** strongly associated with a high incidence of **peripheral neuropathy**. - Its mechanism of action and side effect profile are similar to those of stavudine in causing **mitochondrial toxicity**. *Didanosine* - **Didanosine** (ddI) is an **NRTI** known to cause several adverse effects, including **peripheral neuropathy**, particularly at higher doses. - Like other dideoxynucleoside analogs, its toxicity is linked to **mitochondrial dysfunction**.
Question 718: Which of the following is a topical sulfonamide ?
- A. Sulfadoxine
- B. Sulfamethopyrazine
- C. Sulfisoxazole
- D. Mafenide (Correct Answer)
Explanation: ***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.
Question 719: Tetracycline injection causes palsy of which nerve?
- A. Radial (Correct Answer)
- B. Median
- C. Ulnar
- D. Superficial peroneal
Explanation: ***Radial*** - Tetracycline injections, especially when given in the deltoid region, can inadvertently injure the **radial nerve** due to its superficial course. - Damage to the radial nerve typically results in **wrist drop** and sensory deficits over the dorsum of the hand. *Ulnar* - The **ulnar nerve** is commonly injured at the elbow (cubital tunnel syndrome) or wrist (Guyon's canal). - Injury typically results in weakness of intrinsic hand muscles and sensory loss in the little finger and ulnar half of the ring finger, which is not characteristic of an injection injury in the deltoid region. *Median* - The **median nerve** is more frequently injured at the wrist (carpal tunnel syndrome) or elbow. - Injury causes difficulty with thumb opposition and sensation in the first three and a half digits on the palmar side. *Superficial peroneal* - The **superficial peroneal nerve** is found in the lower leg and foot, innervating the lateral compartment muscles and providing sensation to the dorsum of the foot. - It would not be affected by an injection in the upper arm or shoulder region.
Question 720: What is the primary indication for the use of Erlotinib?
- A. Colon cancer
- B. Gall bladder cancer
- C. Pancreatic cancer
- D. NSCLC (Correct Answer)
Explanation: ***NSCLC (Non-Small Cell Lung Cancer)*** - **Erlotinib** is primarily indicated for patients with advanced **non-small cell lung cancer (NSCLC)**, particularly those with activating mutations in the **epidermal growth factor receptor (EGFR)**. - It functions as an **EGFR tyrosine kinase inhibitor**, blocking the signaling pathways essential for cancer cell growth and survival. - This is the **FDA-approved primary indication** and where Erlotinib shows the most significant clinical benefit. *Pancreatic cancer* - While Erlotinib has been used in combination with gemcitabine for **locally advanced, unresectable or metastatic pancreatic cancer**, it is not its primary or most prominent indication. - Its efficacy in pancreatic cancer is generally modest and overshadowed by its dramatic impact in EGFR-mutated NSCLC. *Colon cancer* - **Erlotinib** is **not a primary treatment** for **colon cancer**. - Other targeted therapies (such as anti-EGFR monoclonal antibodies like cetuximab) or chemotherapy regimens are typically used for colorectal cancer. *Gall bladder cancer* - **Erlotinib** is generally **not indicated** for the treatment of **gallbladder cancer**. - Treatment often involves surgery, chemotherapy, or radiation, with targeted therapies being less established for this malignancy.