Which medication is commonly used in heart failure that also has aldosterone antagonistic properties?
Which of the following drugs acts directly to induce an erection without the need for sexual stimulation?
Extrapyramidal syndrome-like side effects are seen in which of the following medications?
Which of the following is a selective progesterone receptor modulator?
Finasteride is classified as a:
Low molecular weight heparin mainly inhibits which factor?
What is the recommended dose of oseltamivir for a child aged 9 months?
Which of the following statements about vinca alkaloids is true?
Which of the following antineoplastic drugs SHOULD NOT be given by rapid IV infusion?
Which of the following substances is known to cause predominantly sensory neuropathy?
NEET-PG 2012 - Pharmacology NEET-PG Practice Questions and MCQs
Question 61: Which medication is commonly used in heart failure that also has aldosterone antagonistic properties?
- A. Carvedilol
- B. Spironolactone (Correct Answer)
- C. Abiraterone
- D. Sacubitril/Valsartan
Explanation: ***Spironolactone*** - **Spironolactone** is a **potassium-sparing diuretic** that acts as a **competitive antagonist of aldosterone** receptors, primarily in the collecting ducts of the kidneys. - This action leads to increased excretion of sodium and water, and retention of potassium, which is beneficial in **heart failure** by reducing fluid overload and mitigating the detrimental effects of aldosterone on cardiac remodeling. *Carvedilol* - **Carvedilol** is a **beta-blocker** with additional **alpha-1 blocking** properties, commonly used in heart failure to reduce heart rate, blood pressure, and myocardial oxygen demand. - It does not possess significant aldosterone antagonistic properties. *Sacubitril/Valsartan* - **Sacubitril/Valsartan** is an **angiotensin receptor-neprilysin inhibitor (ARNI)**. Valsartan is an **angiotensin receptor blocker (ARB)**, and sacubitril inhibits neprilysin, an enzyme that degrades natriuretic peptides. - While it modulates the **renin-angiotensin-aldosterone system (RAAS)** and is highly effective in heart failure, it does not directly antagonize aldosterone receptors. *Abiraterone* - **Abiraterone** is an **androgen-biosynthesis inhibitor** used in the treatment of **prostate cancer**. - Its primary mechanism involves inhibiting **CYP17**, an enzyme critical for androgen production, and it has no role in the management of heart failure or aldosterone antagonism.
Question 62: Which of the following drugs acts directly to induce an erection without the need for sexual stimulation?
- A. Sildenafil
- B. Tadalafil
- C. Alprostadil (Correct Answer)
- D. Testosterone
Explanation: ***Alprostadil***- **Alprostadil** is a **prostaglandin E1** analog that can directly induce vasodilation in the penile arteries, leading to an erection without sexual stimulation [1].- It is typically administered via **intracavernosal injection** or as a **urethral suppository**.*Sildenafil*- **Sildenafil** is a **PDE5 inhibitor** that works by enhancing the effects of **nitric oxide**, which is released in response to sexual stimulation [2, 3].- It requires **sexual arousal** to be effective, as it doesn't directly initiate the erectile process [2, 3].*Tadalafil*- Similar to sildenafil, **tadalafil** is also a **PDE5 inhibitor** that works by increasing cGMP levels and promoting smooth muscle relaxation [2, 3].- Its action is dependent on the release of **nitric oxide** triggered by sexual stimulation [2, 3].*Testosterone*- **Testosterone** is a hormone involved in sex drive and overall erectile function over time, but it does not directly or acutely induce an erection.- Its primary role in erectile dysfunction is in cases of **hypogonadism**, and it requires sexual stimulation for its effects on erection.
Question 63: Extrapyramidal syndrome-like side effects are seen in which of the following medications?
- A. Haloperidol (Correct Answer)
- B. Clozapine
- C. Tetracycline
- D. Ketoconazole
Explanation: ***Haloperidol*** - **Haloperidol** is a **typical antipsychotic** known for its potent **dopamine D2 receptor blockade**. - This strong blockade in the **nigrostriatal pathway** often leads to **extrapyramidal symptoms (EPS)** such as dystonia, akathisia, and parkinsonism. *Clozapine* - **Clozapine** is an **atypical antipsychotic** that has a lower propensity for causing **extrapyramidal symptoms (EPS)** due to its weaker D2 receptor antagonism and potent serotonin 5-HT2A receptor blockade. - While it can cause other severe side effects, such as **agranulocytosis** and **myocarditis**, EPS are less common compared to typical antipsychotics. *Tetracycline* - **Tetracycline** is an **antibiotic** primarily used to treat bacterial infections. - Its mechanism of action involves inhibiting bacterial protein synthesis, and it is not associated with **neurological side effects** like **extrapyramidal symptoms**. *Ketoconazole* - **Ketoconazole** is an **antifungal medication** that works by inhibiting ergosterol synthesis in fungi. - It is known for potential **hepatotoxicity** and **endocrine dysfunction**, but not for causing **extrapyramidal symptoms**.
Question 64: Which of the following is a selective progesterone receptor modulator?
- A. Onapristone
- B. Ulipristal (Correct Answer)
- C. Nomegestrol
- D. Toremifene
Explanation: ***Ulipristal*** - **Ulipristal acetate** is a **selective progesterone receptor modulator (SPRM)** that acts as a progesterone receptor agonist/antagonist. - It is primarily used for **emergency contraception** and for the pre-operative treatment of **uterine fibroids**. *Onapristone* - **Onapristone** is an **antiprogestin** and a **progesterone receptor antagonist**, not a selective modulator. - It has been primarily investigated for its potential role in **breast cancer** treatment but is not approved for general clinical use. *Nomegestrol* - **Nomegestrol** is a **synthetic progestin** used in hormonal contraception. - It functions as a **progesterone receptor agonist** and does not exhibit selective modulation properties. *Toremifene* - **Toremifene** is a **selective estrogen receptor modulator (SERM)**, not a progesterone receptor modulator. - It is used in the treatment of **estrogen receptor-positive metastatic breast cancer** in postmenopausal women.
Question 65: Finasteride is classified as a:
- A. 5-alpha reductase inhibitor (Correct Answer)
- B. Phosphodiesterase inhibitor
- C. Alpha-1 blocker
- D. Androgen receptor antagonist
Explanation: ### ***5-alpha reductase inhibitor*** - **Finasteride** specifically inhibits the enzyme **5-alpha reductase**, preventing the conversion of **testosterone** to **dihydrotestosterone (DHT)** [2], [4]. - This reduction in DHT is clinically useful for treating conditions like **benign prostatic hyperplasia (BPH)** and **androgenetic alopecia** [4]. ### *Phosphodiesterase inhibitor* - **Phosphodiesterase inhibitors** (e.g., sildenafil) typically work by increasing levels of **cyclic GMP**, leading to **vasodilation** and are used for **erectile dysfunction** [3]. - Their mechanism of action is distinct from finasteride's effect on **hormone metabolism**. ### *Alpha-1 blocker* - **Alpha-1 blockers** (e.g., tamsulosin) primarily relax **smooth muscle** in the prostate and bladder neck, improving **urine flow** in BPH [3], [5]. - They act on **adrenergic receptors** and do not affect **hormone synthesis** or **metabolism** [3]. ### *Androgen receptor antagonist* - **Androgen receptor antagonists** (e.g., flutamide) directly block the binding of **androgens** (like testosterone and DHT) to their receptors [1], [4]. - While they also affect androgen action, their mechanism is different from finasteride's **enzyme inhibition** [4].
Question 66: Low molecular weight heparin mainly inhibits which factor?
- A. Factor VIIIa
- B. Factor Xa (Correct Answer)
- C. Factor XIIa
- D. Factor IIa
Explanation: ***Factor Xa*** - Low molecular weight heparin (LMWH) primarily exerts its anticoagulant effect by binding to **antithrombin III** and increasing its inhibitory activity against **Factor Xa**. - This selective inhibition of Factor Xa, rather than Factor IIa (thrombin), accounts for its more predictable anticoagulant response and lower risk of bleeding compared to unfractionated heparin. *Factor VIIIa* - **Factor VIIIa** is a cofactor in the intrinsic pathway, crucial for activating Factor X, but it is not directly inhibited by LMWH. - Its inhibition is more characteristic of **activated protein C**, not LMWH. *Factor XIIa* - **Factor XIIa** is involved in the initiation of the intrinsic coagulation pathway and the kallikrein-kinin system. - LMWH has no significant inhibitory effect on Factor XIIa. *Factor IIa* - While unfractionated heparin inhibits **Factor IIa (thrombin)** relatively equally to Factor Xa, LMWH has a much weaker inhibitory effect on Factor IIa due to its shorter chain length. - The anti-Factor IIa activity of LMWH is generally considered to be negligible compared to its **anti-Factor Xa activity**.
Question 67: What is the recommended dose of oseltamivir for a child aged 9 months?
- A. 2 mg/kg twice daily for 5 days
- B. 2.5 mg/kg twice daily for 5 days
- C. 3 mg/kg twice daily for 5 days (Correct Answer)
- D. 3.5 mg/kg twice daily for 5 days
Explanation: ***3 mg/kg twice daily for 5 days*** - For children aged **less than 1 year**, and weighing less than 15 kg, the recommended oseltamivir dose is **3 mg/kg** administered **twice daily** for 5 days. - This dosage regimen is effective in treating influenza and is based on studies of its **pharmacokinetics** and **efficacy** in this age group. *2 mg/kg twice daily for 5 days* - This dosage is **lower than recommended** for children under 1 year of age and may not achieve adequate therapeutic drug levels. - Subtherapeutic dosing could lead to **reduced antiviral efficacy** and potentially poorer clinical outcomes. *2.5 mg/kg twice daily for 5 days* - Similar to the 2 mg/kg dose, this is **below the standard recommendation** for infants and young children in this age bracket. - Inadequate dosing increases the risk of **treatment failure** and the development of **antiviral resistance**. *3.5 mg/kg twice daily for 5 days* - This dosage might be considered **higher than necessary** for a 9-month-old child and could potentially increase the risk of **adverse effects**. - While exact toxicities are rare within a reasonable range, adherence to recommended guidelines optimizes the **benefit-risk profile**.
Question 68: Which of the following statements about vinca alkaloids is true?
- A. Inhibits mitotic spindle (Correct Answer)
- B. Enhances polymerization of tubulin
- C. Inhibits topoisomerase I
- D. Inhibits topoisomerase II
Explanation: ***Inhibits mitotic spindle*** - **Vinca alkaloids** (e.g., vincristine, vinblastine) exert their cytotoxic effects by binding to **tubulin**, thereby inhibiting its polymerization into microtubules. - This disruption prevents the formation of the **mitotic spindle**, arresting cells in metaphase and leading to apoptosis. *Enhances polymerization of tubulin* - This statement describes the mechanism of action of **taxanes** (e.g., paclitaxel), which stabilize microtubules and prevent their depolymerization. - Vinca alkaloids, in contrast, **inhibit** tubulin polymerization, preventing microtubule assembly. *Inhibits topoisomerase I* - Inhibition of **topoisomerase I** is the mechanism of action for drugs like **irinotecan** and **topotecan**. - These agents cause single-strand breaks in DNA, which is distinct from the microtubule disruption caused by vinca alkaloids. *Inhibits topoisomerase II* - Drugs like **etoposide** and **teniposide** work by inhibiting **topoisomerase II**, leading to double-strand DNA breaks. - This mechanism is different from the disruption of microtubule dynamics seen with vinca alkaloids.
Question 69: Which of the following antineoplastic drugs SHOULD NOT be given by rapid IV infusion?
- A. Cyclophosphamide
- B. Cytosine arabinoside
- C. Cisplatin (Correct Answer)
- D. Bleomycin
Explanation: ***Cisplatin*** - **Cisplatin** is highly nephrotoxic and emetogenic; rapid IV infusion can exacerbate these adverse effects, leading to severe renal damage and intractable nausea/vomiting. - It typically requires **prolonged infusion times** (e.g., 6-8 hours) with extensive pre- and post-hydration to reduce kidney toxicity and ensure patient tolerance. *Cyclophosphamide* - While cyclophosphamide can cause **hemorrhagic cystitis**, this is managed by adequate hydration and mesna, and its infusion rate is generally not as critically prolonged as cisplatin's. - It is often administered as a **relatively quick IV infusion** over 30-60 minutes, emphasizing hydration. *Bleomycin* - **Bleomycin** is known for pulmonary toxicity and hypersensitivity reactions, but these are not primarily linked to its infusion rate. - It is commonly given via **slow IV push or short infusion**, sometimes with a test dose to assess for hypersensitivity. *Cytosine arabinoside* - **Cytosine arabinoside** can cause myelosuppression and cerebellar toxicity, but these toxicities are not typically exacerbated by a rapid infusion rate. - It is often administered via a **continuous infusion** over several days or as a rapid IV bolus.
Question 70: Which of the following substances is known to cause predominantly sensory neuropathy?
- A. Pyridoxine excess
- B. Suramin
- C. Cisplatin (Correct Answer)
- D. Vincristine
Explanation: ***Cisplatin*** - **Cisplatin** is a platinum-based chemotherapy drug well-known for causing **dose-dependent peripheral neuropathy**, primarily affecting sensory neurons. - Patients often present with **numbness**, **tingling**, and **loss of proprioception** in a glove-and-stocking distribution. - This is the **most characteristic** drug for **predominantly sensory neuropathy** among chemotherapeutic agents. *Pyridoxine excess* - While **pyridoxine (vitamin B6) excess** can cause sensory neuropathy, it is less commonly observed as a primary cause compared to cisplatin in the context of drug-induced neuropathies. - High doses of pyridoxine can lead to **dorsal root ganglionopathy**, affecting sensory nerve fibers. *Suramin* - **Suramin** is an anthelmintic agent primarily used for treating sleeping sickness, and it is known to cause a variety of side effects, including **renal toxicity** and **neurological symptoms**. - While neurological side effects can occur, they are not typically characterized as a **predominantly sensory neuropathy** in the same way as cisplatin. *Vincristine* - **Vincristine** is a vinca alkaloid chemotherapy agent that causes peripheral neuropathy. - However, vincristine typically causes **mixed motor and sensory neuropathy** with prominent motor involvement (foot drop, wrist drop). - This differs from cisplatin's **predominantly sensory** presentation.