Respiratory System Drugs Practice Questions

Q: A 42-year-old patient developed an acute attack of asthma. After management of the acute attack, the patient was referred to the OPD for follow-up. Which of the following is not a recommended prophylactic strategy for this patient?

Blockade of histamine receptors. **Explanation:** The management of bronchial asthma focuses on two pillars: **Relievers** (for acute attacks) and **Controllers/Prophylaxis** (to prevent future attacks). **Why Option D is Correct:** **Blockade of histamine receptors (Antihistamines)** is not recommended for the prophylaxis or treatment of asthma. While histamine is released during mast cell degranulation, it is only one of many mediators. In asthma, **Leukotrienes (LTB4, LTC4, LTD4)** and **Prostaglandins** are far more potent bronchoconstrictors than histamine. Clinical trials have shown that H1-antagonists provide no significant benefit in preventing airway hyperreactivity or inflammation in asthmatic patients. **Analysis of Incorrect Options:** * **A. Inhibition of phospholipase A2:** This is the mechanism of **Corticosteroids** (via induction of Lipocortin/Annexin A1). Inhaled corticosteroids (ICS) are the "gold standard" and first-line prophylactic agents as they suppress the underlying airway inflammation. * **B. Blockade of leukotriene receptors:** Drugs like **Montelukast and Zafirlukast** block CysLT1 receptors. They are effective oral prophylactic agents, especially in aspirin-induced or exercise-induced asthma. * **C. Avoidance of antigen exposure:** Non-pharmacological prophylaxis is the first step in management. Identifying and avoiding triggers (dust mites, pollen, animal dander) reduces the frequency of IgE-mediated mast cell activation. **NEET-PG High-Yield Pearls:** * **Drug of Choice (DOC) for Acute Attack:** Inhaled Short-Acting Beta-2 Agonists (SABA) like Salbutamol. * **DOC for Prophylaxis:** Inhaled Corticosteroids (e.g., Fluticasone, Budesonide). * **Aspirin-Exacerbated Respiratory Disease (AERD):** Characterized by asthma, nasal polyps, and aspirin sensitivity; managed effectively with Leukotriene Antagonists. * **Omalizumab:** A monoclonal antibody against IgE used in severe, refractory allergic asthma.

Q: Inhibition of 5-lipoxygenase is useful in which of the following conditions?

Bronchial asthma. **Explanation:** The correct answer is **Bronchial asthma**. **Mechanism and Rationale:** The enzyme **5-lipoxygenase (5-LOX)** is responsible for converting arachidonic acid into **Leukotrienes (LTB4, LTC4, LTD4, and LTE4)**. In the respiratory system, cysteinyl leukotrienes (LTC4, D4, and E4) are potent bronchoconstrictors, increase mucus secretion, and promote airway edema. By inhibiting 5-lipoxygenase, the production of these inflammatory mediators is blocked, leading to bronchodilation and reduced airway inflammation. **Zileuton** is the specific 5-LOX inhibitor used clinically for the prophylaxis and chronic treatment of bronchial asthma. **Analysis of Incorrect Options:** * **Cardiac failure:** Treatment focuses on reducing preload/afterload (ACE inhibitors, diuretics) and improving contractility. Leukotriene inhibition has no established role here. * **Hepatic failure:** This involves liver parenchymal damage. 5-LOX inhibitors are not used; in fact, Zileuton requires monitoring of liver enzymes due to potential hepatotoxicity. * **Arthritis:** While leukotrienes (specifically LTB4) are involved in inflammation, the mainstay of treatment is inhibiting the **Cyclooxygenase (COX)** pathway (NSAIDs) or using DMARDs. 5-LOX inhibitors are not standard therapy for arthritis. **High-Yield Facts for NEET-PG:** * **Zileuton:** The only 5-LOX inhibitor. Key side effect: Elevation of liver enzymes (ALT). * **Leukotriene Receptor Antagonists (LTRAs):** Montelukast and Zafirlukast. They block the **CysLT1 receptor**. * **Aspirin-Exacerbated Respiratory Disease (AERD):** Aspirin blocks COX, shunting arachidonic acid toward the LOX pathway, increasing leukotrienes and causing bronchospasm. LTRAs/5-LOX inhibitors are particularly effective here. * **Churg-Strauss Syndrome:** A rare systemic vasculitis associated with the use of LTRAs (often during steroid tapering).

Q: Which of the following drugs can cause Churg-Strauss syndrome?

Montelukast. **Explanation:** **Montelukast** is a selective Leukotriene Receptor Antagonist (LTRA) used in the management of bronchial asthma. The association between Montelukast and **Churg-Strauss Syndrome (now known as Eosinophilic Granulomatosis with Polyangiitis - EGPA)** is a classic high-yield association. The underlying medical concept is often attributed to a **"masking effect."** EGPA is a systemic vasculitis characterized by asthma, eosinophilia, and necrotizing vasculitis. In many patients, the introduction of Montelukast allows for the tapering or withdrawal of systemic corticosteroids. This reduction in steroids unmasks a pre-existing subclinical vasculitis that was previously suppressed, leading to the clinical manifestation of Churg-Strauss syndrome. **Analysis of Incorrect Options:** * **Omalizumab (A):** A monoclonal antibody against IgE. While there have been rare case reports of EGPA, it is not the classic association tested in exams compared to LTRAs. * **Theophylline (B):** A methylxanthine that acts by inhibiting phosphodiesterase (PDE). Its primary side effects are GI upset, arrhythmias, and seizures due to a narrow therapeutic index. * **Zileuton (D):** A 5-lipoxygenase inhibitor. While it is a leukotriene modifier, Montelukast and Zafirlukast are much more frequently implicated in the literature and exams regarding this specific syndrome. **Clinical Pearls for NEET-PG:** * **EGPA Triad:** Asthma, peripheral eosinophilia, and extravascular granulomas. * **Marker:** p-ANCA (Anti-neutrophil cytoplasmic antibodies) is positive in about 40-50% of cases. * **Drug-Induced EGPA:** Always look for **Montelukast** or **Zafirlukast** in the history of a patient presenting with new-onset purpura or neuropathy after starting asthma prophylaxis.

Q: Which of the following is a second-generation antihistamine used in allergic rhinitis?

Azelastine. **Explanation:** The correct answer is **Azelastine**. Azelastine is a potent, long-acting **second-generation H1-receptor antagonist**. While most second-generation antihistamines are administered orally, Azelastine is unique because it is primarily used as a **topical nasal spray** for allergic rhinitis. It provides a dual mechanism of action: it blocks H1 receptors and also inhibits mast cell degranulation, reducing the release of inflammatory mediators like leukotrienes. **Analysis of Options:** * **B. Fexofenadine & D. Desloratadine:** These are also second-generation antihistamines. However, in the context of standard pharmacology examinations (like NEET-PG), when a question asks to identify a specific drug among similar classes, it often refers to the drug's unique delivery system or primary clinical application. Azelastine is the prototypical topical second-generation antihistamine used specifically for rapid relief in allergic rhinitis. * **C. Chlorpheniramine maleate:** This is a **first-generation antihistamine**. It is highly sedative, has significant anticholinergic side effects, and crosses the blood-brain barrier. **High-Yield Clinical Pearls for NEET-PG:** * **Second-generation characteristics:** They are peripherally selective, have minimal sedation (except Cetirizine/Levocetirizine, which can cause mild drowsiness), and do not possess significant anticholinergic properties. * **Topical Antihistamines:** Azelastine and Olopatadine are the preferred topical agents for allergic rhinitis and conjunctivitis. * **Metabolism:** Fexofenadine is the active metabolite of Terfenadine; Desloratadine is the active metabolite of Loratadine. * **Safety:** Unlike the older agents Terfenadine and Astemizole, modern second-generation antihistamines do not cause QTc prolongation or *Torsades de Pointes*.

Q: Which of the following is a mast cell stabilizer?

Sodium chromoglycate. **Explanation:** **Sodium chromoglycate** is a classic **mast cell stabilizer**. Its primary mechanism of action involves inhibiting the degranulation of sensitized mast cells by blocking the influx of calcium ions across the cell membrane. This prevents the release of inflammatory mediators like histamine, leukotrienes, and prostaglandins, which are responsible for bronchoconstriction and mucosal edema in allergic reactions. **Analysis of Options:** * **Montelukast (Option A):** This is a **Leukotriene Receptor Antagonist (LTRA)**. It specifically blocks the $CysLT_1$ receptor, preventing the action of leukotrienes rather than stabilizing the mast cell itself. * **Cetirizine (Option B):** This is a **second-generation $H_1$ antihistamine**. It works by competitively antagonizing histamine at the receptor level; it does not prevent the release of histamine from mast cells. * **Theophylline (Option D):** This is a **Methylxanthine**. It acts primarily as a non-selective phosphodiesterase (PDE) inhibitor and adenosine receptor antagonist, leading to bronchodilation. **High-Yield Clinical Pearls for NEET-PG:** * **Prophylaxis only:** Mast cell stabilizers are used for the **prophylaxis** of bronchial asthma and allergic rhinitis. They are ineffective during an acute attack because they cannot reverse the effects of mediators already released. * **Route of Administration:** Sodium chromoglycate is poorly absorbed orally; it is administered via inhalation (MDI/nebulization) for asthma or as drops for allergic conjunctivitis. * **Nedocromil:** Another drug in this class, often considered more potent than sodium chromoglycate. * **Side Effects:** Generally safe, but may cause throat irritation, cough, or a metallic taste.

Q: Which of the following is a monoclonal antibody against IL-5?

Mepolizumab. **Explanation:** **Mepolizumab** is a humanized monoclonal antibody that directly binds to and inhibits **Interleukin-5 (IL-5)**. IL-5 is the primary cytokine responsible for the growth, activation, and survival of eosinophils. By neutralizing IL-5, mepolizumab reduces eosinophilic inflammation, making it a key treatment for **severe eosinophilic asthma** and Hypereosinophilic Syndrome. **Analysis of Incorrect Options:** * **A. Omalizumab:** This is a monoclonal antibody against **IgE**. It prevents IgE from binding to mast cells and basophils, used primarily in severe allergic asthma. * **C. Tocilizumab:** This is an **IL-6 receptor antagonist**. It is used in Rheumatoid Arthritis, Giant Cell Arteritis, and was notably used in managing the "cytokine storm" in severe COVID-19. * **D. Alemtuzumab:** This is a monoclonal antibody against **CD52**, found on mature lymphocytes. It is used in the treatment of Chronic Lymphocytic Leukemia (CLL) and Multiple Sclerosis. **High-Yield NEET-PG Pearls:** 1. **IL-5 Inhibitors:** Remember the "mabs" for eosinophilic asthma: **Mepolizumab** and **Reslizumab** (bind to IL-5) and **Benralizumab** (binds to the IL-5 receptor). 2. **Dupilumab:** Often confused with these, it targets the **IL-4 receptor alpha subunit** (inhibiting both IL-4 and IL-13) and is used for atopic dermatitis and asthma. 3. **Suffix Clue:** "-li-" in Mepo**li**zumab stands for "limbic/immune system," while "-tu-" in Toci**tu**zumab (though often shortened) or Rituximab refers to "tumor."

Q: Which of the following drugs has been found to be useful in acute severe asthma?

Magnesium Sulphate. **Explanation:** **Magnesium Sulphate ($MgSO_4$)** is the correct answer because it acts as a potent bronchodilator by inhibiting calcium influx into bronchial smooth muscle cells, leading to relaxation. In clinical practice, intravenous $MgSO_4$ is indicated as an adjunct therapy for **acute severe asthma** (status asthmaticus) when patients do not respond adequately to initial treatment with inhaled $\beta_2$-agonists and systemic corticosteroids. It helps reduce hospitalization rates in severe exacerbations. **Why the other options are incorrect:** * **Anti-leukotrienes (e.g., Montelukast):** These are used for **prophylaxis** and chronic management of asthma, particularly aspirin-induced or exercise-induced asthma. They have a slow onset of action and are not effective in emergency settings. * **Cromolyn Sodium:** This is a mast cell stabilizer used strictly for **prophylaxis**. It prevents the release of inflammatory mediators but has no bronchodilatory properties, making it useless during an acute attack. * **Cyclosporine:** This is an immunosuppressant reserved for **steroid-dependent, difficult-to-treat chronic asthma**. Its toxicity profile and slow onset make it inappropriate for acute management. **High-Yield Clinical Pearls for NEET-PG:** * **Route:** $MgSO_4$ is given **IV** (2g over 20 mins) for acute severe asthma. Nebulized magnesium is currently not the standard of care. * **Drug of Choice (DOC):** For acute asthma, the DOC is **Inhaled Short-Acting $\beta_2$-Agonists (SABA)** like Salbutamol. * **Steroids:** Systemic corticosteroids (Hydrocortisone/Prednisolone) are essential in acute severe asthma but take 4–6 hours to show clinical effect. * **Aminophylline:** Once a mainstay, it is now a second-line agent due to its narrow therapeutic index and risk of arrhythmias.

Q: All the statements are true regarding Selexipag except?

Selective IP receptor antagonist. **Explanation:** **Selexipag** is a novel, orally active drug used in the management of **Pulmonary Arterial Hypertension (PAH)**. The key to answering this question lies in understanding its mechanism of action as a receptor stimulator rather than a blocker. 1. **Why Option A is the correct (False) statement:** Selexipag is a selective **IP receptor agonist**, not an antagonist. It and its active metabolite (ACT-333602) bind to the prostacyclin (IP) receptors located on vascular smooth muscle cells. This binding stimulates adenylate cyclase, increasing intracellular cAMP, which leads to potent **vasodilation** of the pulmonary circulation. 2. **Why Option B is wrong (True statement):** As mentioned, Selexipag acts as a selective agonist at the prostacyclin (IP) receptor. Unlike older analogues like Epoprostenol, it is non-prostanoid in structure but mimics the beneficial effects of PGI2. 3. **Why Option C is wrong (True statement):** It is FDA-approved for the treatment of PAH (WHO Group 1) to delay disease progression and reduce the risk of hospitalization. 4. **Why Option D is wrong (True statement):** Since it activates the same pathways as prostacyclin analogues (like Iloprost or Treprostinil), it shares a similar side-effect profile, including headache, diarrhea, jaw pain, nausea, and flushing. **High-Yield Clinical Pearls for NEET-PG:** * **Route:** Orally bioavailable (unlike Epoprostenol, which requires continuous IV infusion). * **Metabolism:** It is a **prodrug** metabolized by **CYP2C8** to its active form. * **Benefit:** It avoids the rapid desensitization of receptors often seen with continuous prostanoid infusions. * **Other PAH drugs to remember:** Bosentan (Endothelin antagonist), Sildenafil (PDE-5 inhibitor), and Riociguat (Guanylate cyclase stimulator).

Q: Which of the following is NOT a second-generation antihistamine?

Cyclizine. **Explanation:** The core concept tested here is the classification of H1-antihistamines based on their ability to cross the blood-brain barrier (BBB) and their sedative potential. **Why Cyclizine is the correct answer:** **Cyclizine** is a **first-generation antihistamine** belonging to the piperazine group. Unlike second-generation drugs, first-generation antihistamines are highly lipophilic and readily cross the BBB. They act on central H1 receptors, leading to significant sedation. Additionally, they possess potent anticholinergic properties, making Cyclizine particularly useful for motion sickness and post-operative nausea, rather than allergic rhinitis. **Why the other options are incorrect:** * **Loratadine:** A classic second-generation antihistamine. It is long-acting and lacks central sedative effects because it is a substrate for the P-glycoprotein efflux pump, which keeps it out of the brain. * **Acrivastine:** A second-generation antihistamine derived from triprolidine. Although it has a shorter duration of action than others in its class, it does not cross the BBB significantly. * **Terfenadine:** The first second-generation antihistamine introduced. While it is non-sedating, it is largely withdrawn from many markets due to its risk of causing *Torsades de Pointes* (QT prolongation) when metabolized slowly (e.g., in the presence of CYP3A4 inhibitors). **High-Yield Clinical Pearls for NEET-PG:** * **Metabolites:** Fexofenadine is the active metabolite of Terfenadine; Desloratadine is the metabolite of Loratadine; Cetirizine is the metabolite of Hydroxyzine. * **Safety Profile:** Second-generation drugs are preferred for pilots and students because they do not impair psychomotor performance. * **Side Effects:** First-generation H1 blockers (like Cyclizine or Promethazine) cause "dry mouth, blurred vision, and urinary retention" due to their **antimuscarinic** activity.

Question 1

A 42-year-old patient developed an acute attack of asthma. After management of the acute attack, the patient was referred to the OPD for follow-up. Which of the following is not a recommended prophylactic strategy for this patient?

Accepted Answer

Blockade of histamine receptors

Answer

Inhibition of phospholipase A2

Answer

Blockade of leukotriene receptors

Answer

Avoidance of antigen exposure

Question 2

Inhibition of 5-lipoxygenase is useful in which of the following conditions?

Accepted Answer

Bronchial asthma

Answer

Cardiac failure

Answer

Hepatic failure

Answer

Arthritis

Question 3

Which of the following drugs can cause Churg-Strauss syndrome?

Accepted Answer

Montelukast

Answer

Omalizumab

Answer

Theophylline

Answer

Zileuton

Question 4

What is the only FDA-approved application of inhaled nitric oxide?

Accepted Answer

Newborn with persistent pulmonary hypertension

Answer

Primary pulmonary hypertension

Answer

Congestive cardiac failure

Answer

High-altitude pulmonary edema (HAPE)

Question 5

Which of the following is a second-generation antihistamine used in allergic rhinitis?

Accepted Answer

Azelastine

Answer

Fexofenadine

Answer

Chlorpheniramine maleate

Answer

Desloratadine

Question 6

Which of the following is a mast cell stabilizer?

Accepted Answer

Sodium chromoglycate

Answer

Montelukast

Answer

Cetirizine

Answer

Theophylline

Question 7

Which of the following is a monoclonal antibody against IL-5?

Accepted Answer

Mepolizumab

Answer

Omalizumab

Answer

Tocilizumab

Answer

Alemtuzumab

Question 8

Which of the following drugs has been found to be useful in acute severe asthma?

Accepted Answer

Magnesium Sulphate

Answer

Anti-leukotriene

Answer

Cromolyn Sodium

Answer

Cyclosporine

Question 9

All the statements are true regarding Selexipag except?

Accepted Answer

Selective IP receptor antagonist

Answer

Prostacyclin receptor agonist

Answer

Used in Pulmonary Hypertension

Answer

Adverse effects of Selexipag are similar to those of PGI2 analogues

Question 10

Which of the following is NOT a second-generation antihistamine?

Accepted Answer

Cyclizine

Answer

Loratadine

Answer

Acrivastine

Answer

Terfenadine

Respiratory System Drugs — MCQs

Respiratory System Drugs — MCQs

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