Respiratory System Drugs — MCQs

Respiratory System Drugs Indian Medical PG Practice Questions and MCQs

Question 21: Which of the following drugs can reduce inflammation in the airways?

A. Fluticasone and Budesonide (Correct Answer)
B. Budesonide and Theophylline
C. Fluticasone and Theophylline
D. Fluticasone and Salbutamol

Explanation: **Explanation:** The primary goal in managing chronic airway diseases like bronchial asthma is to address the underlying **chronic inflammation**. **1. Why Option A is Correct:** **Fluticasone and Budesonide** are potent **Inhaled Corticosteroids (ICS)**. They are the most effective anti-inflammatory agents for airway diseases. They work by binding to intracellular glucocorticoid receptors, leading to: * **Decreased synthesis of inflammatory mediators** (cytokines, leukotrienes, and prostaglandins) by inhibiting the enzyme Phospholipase A2. * **Reduced recruitment and activation** of inflammatory cells like eosinophils, T-lymphocytes, and mast cells. * **Upregulation of β2-receptors**, which helps prevent/reverse β-receptor desensitization. **2. Why Other Options are Incorrect:** * **Theophylline (Options B & C):** This is a Methylxanthine. While it has weak anti-inflammatory effects at high doses, its primary role is as a **bronchodilator** (via non-selective PDE inhibition and adenosine receptor antagonism). It is not classified as a primary anti-inflammatory agent for the airways. * **Salbutamol (Option D):** This is a **Short-Acting β2-Agonist (SABA)**. It acts exclusively as a bronchodilator by relaxing airway smooth muscle. It has **no anti-inflammatory properties** and does not treat the underlying disease progression. **3. NEET-PG High-Yield Pearls:** * **Drug of Choice:** ICS (like Fluticasone) are the first-line maintenance therapy for persistent asthma. * **Side Effects:** The most common local side effects of ICS are **Oropharyngeal Candidiasis (Thrush)** and **Hoarseness (Dysphonia)**. Patients are advised to "rinse and spit" after use. * **Ciclesonide:** A "prodrug" corticosteroid activated only in the lungs by esterases, minimizing systemic side effects and local thrush.

Question 22: All of the following statements regarding theophylline are true EXCEPT:

A. Increases cAMP
B. Inhibits phosphodiesterase
C. Increased dose is required in smokers
D. Increased dose is required in cardiopulmonary disease (Correct Answer)

Explanation: **Explanation:** Theophylline is a methylxanthine derivative used in the management of asthma and COPD. It has a **narrow therapeutic index** (10–20 µg/ml), meaning its dosage must be meticulously adjusted based on factors that influence its metabolism, primarily via the Cytochrome P450 (CYP1A2) system. **Why Option D is the Correct Answer (The False Statement):** In patients with **cardiopulmonary diseases** (such as Congestive Heart Failure or Cor Pulmonale) and **liver cirrhosis**, the hepatic metabolism of theophylline is significantly **decreased**. This leads to reduced clearance and an increased risk of toxicity. Therefore, a **decreased dose** (not increased) is required in these patients. **Analysis of Other Options:** * **Options A & B:** Theophylline acts by **inhibiting the enzyme Phosphodiesterase (PDE)**, specifically PDE3 and PDE4. This inhibition prevents the breakdown of cAMP, leading to **increased intracellular cAMP** levels, which results in bronchodilation and anti-inflammatory effects. It also acts as an Adenosine receptor antagonist. * **Option C:** Cigarette smoking induces the CYP1A2 enzyme. This accelerates the metabolism of theophylline, necessitating an **increased dose** to maintain therapeutic levels in smokers. **High-Yield Clinical Pearls for NEET-PG:** * **Drug Interactions:** Enzyme inhibitors like **Cimetidine, Erythromycin, and Ciprofloxacin** increase theophylline levels (risk of toxicity). Enzyme inducers like **Phenytoin and Rifampicin** decrease its levels. * **Toxicity Profile:** Early signs include GI upset and restlessness; severe toxicity leads to **cardiac arrhythmias** and **seizures** (refractory to anticonvulsants). * **Mechanism:** Apart from PDE inhibition, it also enhances **histone deacetylation**, which helps in reversing corticosteroid resistance in COPD.

Question 23: What is the primary use of a leukotriene antagonist?

A. Anti-neoplastic
B. Anti-asthmatic (Correct Answer)
C. Anti-inflammatory
D. Tocolytic

Explanation: **Explanation:** Leukotriene antagonists (e.g., **Montelukast, Zafirlukast**) are primarily used as **anti-asthmatic** agents. In the pathogenesis of asthma, Cysteinyl Leukotrienes (LTC4, LTD4, and LTE4) are potent inflammatory mediators released from mast cells and eosinophils. They bind to **CysLT1 receptors**, causing intense bronchoconstriction, increased mucus secretion, and airway edema. Leukotriene receptor antagonists (LTRAs) block these receptors, effectively preventing bronchospasm and reducing airway inflammation. **Analysis of Options:** * **B (Correct):** They are used for the prophylactic management of chronic asthma and are particularly effective in **aspirin-induced asthma** and **exercise-induced bronchospasm**. * **A (Incorrect):** Anti-neoplastic drugs inhibit cancer cell proliferation (e.g., Methotrexate). LTRAs have no established role in chemotherapy. * **C (Incorrect):** While they have local anti-inflammatory effects in the lungs, they are not classified as general anti-inflammatory drugs (like NSAIDs or Corticosteroids) because they do not inhibit systemic inflammatory pathways or COX enzymes. * **D (Incorrect):** Tocolytics (e.g., Ritodrine, Nifedipine) are used to suppress premature labor by relaxing uterine smooth muscle. **High-Yield Clinical Pearls for NEET-PG:** * **Zileuton:** A 5-Lipoxygenase (5-LOX) inhibitor; it prevents the *synthesis* of leukotrienes rather than blocking the receptor. * **Aspirin-Exacerbated Respiratory Disease (AERD):** LTRAs are the drug of choice for patients who develop asthma/urticaria after taking NSAIDs. * **Churg-Strauss Syndrome:** A rare side effect (systemic vasculitis) associated with the use of Montelukast/Zafirlukast. * **Administration:** Montelukast is typically given **at night** because asthma symptoms often worsen in the early morning.

Question 24: Use of tiotropium is contraindicated in which of the following conditions?

A. Bronchial asthma
B. Hypertension
C. Urinary retention (Correct Answer)
D. Peptic ulcer disease

Explanation: **Explanation:** **1. Why Urinary Retention is the Correct Answer:** Tiotropium is a **Long-Acting Muscarinic Antagonist (LAMA)**. It works by blocking $M_3$ receptors in the bronchial smooth muscles, leading to bronchodilation. However, $M_3$ receptors are also located in the **detrusor muscle** of the bladder. Blocking these receptors prevents the detrusor from contracting and relaxes the internal sphincter, which significantly hinders the ability to void urine [3]. Therefore, in patients with pre-existing urinary retention or **Benign Prostatic Hyperplasia (BPH)**, tiotropium can exacerbate the condition and lead to acute urinary obstruction [2]. **2. Analysis of Incorrect Options:** * **A. Bronchial Asthma:** Tiotropium is actually an *indication* for asthma. It is used as an add-on therapy (Step 4 or 5) in patients not well-controlled with ICS/LABA combinations [1]. * **B. Hypertension:** Anticholinergics do not have a significant contraindication in hypertension. While they may cause minor tachycardia, they are generally safe for hypertensive patients. * **D. Peptic Ulcer Disease:** Anticholinergics actually reduce gastric acid secretion (via $M_1$ blockade). While not a primary treatment, they are certainly not contraindicated. **3. NEET-PG High-Yield Pearls:** * **Mechanism:** Tiotropium provides "kinetic selectivity" for $M_3$ receptors due to its slow dissociation rate, allowing for once-daily dosing [4]. * **Drug of Choice:** Tiotropium is a first-line maintenance treatment for **COPD** [3]. * **Side Effects:** The most common side effect is **dry mouth** (xerostomia) [3]. * **Cautions:** Use with caution in patients with **narrow-angle glaucoma** (can increase intraocular pressure) and prostatic hypertrophy [2].

Question 25: Inhibition of 5-lipoxygenase is useful in which of the following conditions?

A. Cardiac failure
B. Bronchial asthma (Correct Answer)
C. Hepatic failure
D. Arthritis

Explanation: **Explanation:** **1. Why Bronchial Asthma is Correct:** The pathophysiology of bronchial asthma involves the production of **cysteinyl leukotrienes (LTC4, LTD4, and LTE4)** via the **5-lipoxygenase (5-LOX)** pathway of arachidonic acid metabolism. These leukotrienes are potent bronchoconstrictors, increase mucus secretion, and promote airway edema. **Zileuton** is a specific drug that inhibits the 5-LOX enzyme, thereby preventing the synthesis of these leukotrienes. By blocking this pathway, it reduces airway inflammation and bronchospasm, making it an effective prophylactic treatment for chronic asthma (especially aspirin-induced asthma). **2. Why Other Options are Incorrect:** * **Cardiac Failure:** Management focuses on reducing preload/afterload (ACE inhibitors, diuretics) and improving contractility. 5-LOX inhibitors have no established role in cardiac remodeling or hemodynamics. * **Hepatic Failure:** Treatment involves managing ammonia levels and portal hypertension. In fact, Zileuton is known for potential **hepatotoxicity**, making it contraindicated or used with extreme caution in liver disease. * **Arthritis:** While inflammation is central to arthritis, it is primarily mediated by **Cyclooxygenase (COX)** products (prostaglandins). Therefore, NSAIDs (COX inhibitors) are the mainstay, not 5-LOX inhibitors. **3. NEET-PG High-Yield Pearls:** * **Zileuton:** The only 5-LOX inhibitor; requires frequent monitoring of Liver Function Tests (LFTs). * **Leukotriene Receptor Antagonists (LTRAs):** Montelukast and Zafirlukast block the **CysLT1 receptor**. * **Aspirin-Exacerbated Respiratory Disease (AERD):** Aspirin blocks COX, shunting arachidonic acid toward the 5-LOX pathway, increasing leukotrienes. 5-LOX inhibitors are particularly useful here. * **Churg-Strauss Syndrome:** A rare association noted with the use of LTRAs.

Question 26: Doxapram is which of the following types of drug?

A. Respiratory stimulant (Correct Answer)
B. Antiepileptic
C. Sedative
D. Antidiabetic

Explanation: **Explanation:** **Doxapram** is a potent **analeptic (respiratory stimulant)**. It works by stimulating the peripheral chemoreceptors in the carotid bodies, which in turn increases the rate and depth of respiration (tidal volume). At higher doses, it also directly stimulates the respiratory centers in the medulla oblongata. * **Why Option A is correct:** Doxapram is specifically used to treat acute respiratory insufficiency. Its primary clinical application is in the management of post-anesthetic respiratory depression or acute respiratory failure in patients with COPD, where it provides a temporary boost to ventilation. * **Why Options B, C, and D are incorrect:** * **Antiepileptics** (e.g., Phenytoin, Valproate) are used to control seizures; Doxapram, conversely, can lower the seizure threshold at high doses. * **Sedatives** (e.g., Benzodiazepines) depress the CNS; Doxapram is a CNS stimulant. * **Antidiabetics** (e.g., Metformin, Insulin) regulate blood glucose; Doxapram has no effect on glycemic control. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Stimulates carotid chemoreceptors (low dose) → Medullary centers (high dose). * **Route:** Administered via intravenous infusion because it has a very short duration of action. * **Contraindications:** It should be avoided in patients with hypertension, coronary artery disease, or epilepsy, as it can cause tachycardia and convulsions. * **Comparison:** Unlike Methylxanthines (Theophylline), which are used for chronic management, Doxapram is reserved for acute, emergency stimulation of breathing.

Question 27: Reflex bronchoconstriction is most likely to occur with which of the following forms of inhaled antiasthma medication?

A. Metered dose inhaler spray of drug in solution
B. Dry powder inhaler (rotacap) (Correct Answer)
C. Nebulizer
D. Nebulizer with a spacer

Explanation: **Explanation** The correct answer is **B. Dry powder inhaler (rotacap)**. **Why it is correct:** Dry powder inhalers (DPIs) require a **high inspiratory flow rate** to aerosolize the medication effectively. The inhalation of dry, fine particulate matter, combined with the high-velocity airflow required for delivery, can act as a mechanical and chemical irritant to the hyperreactive bronchial mucosa. This irritation frequently triggers **reflex bronchoconstriction** (cough or wheezing) immediately after inhalation. This is a classic side effect particularly noted in patients with severe asthma or highly sensitive airways. **Why other options are incorrect:** * **A. Metered Dose Inhaler (MDI):** These deliver medication in a fine mist (solution or suspension). While the propellant (CFCs/HFAs) can occasionally cause irritation, the particle impact is generally less irritating than dry powder. * **C. Nebulizer:** These deliver medication as a continuous, humidified mist over several minutes. Because the mist is moist and requires only tidal breathing, it is the least likely to cause mechanical irritation or reflex spasm. * **D. Nebulizer with a spacer:** This is a distractor; spacers are used with MDIs, not nebulizers. Spacers actually *reduce* the risk of irritation by slowing down particle velocity and reducing oropharyngeal deposition. **High-Yield Clinical Pearls for NEET-PG:** * **DPI Requirement:** Patients must be able to generate an inspiratory flow of **>30–60 L/min** for DPIs to be effective; hence, they are not suitable for children <5 years or patients in acute severe asthma. * **MDI + Spacer:** This combination is considered as effective as a nebulizer for treating acute exacerbations in most settings and reduces the "cold Freon effect" (reflex bronchospasm caused by cold propellant). * **Drug of Choice:** For immediate relief of bronchoconstriction, SABA (Salbutamol) remains the gold standard.

Question 28: 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?

A. Inhibition of phospholipase A2
B. Blockade of leukotriene receptors
C. Avoidance of antigen exposure
D. Blockade of histamine receptors (Correct Answer)

Explanation: **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.

Question 29: Inhibition of 5-lipoxygenase is useful in which of the following conditions?

A. Cardiac failure
B. Bronchial asthma (Correct Answer)
C. Hepatic failure
D. Arthritis

Explanation: **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).

Question 30: Which of the following drugs can cause Churg-Strauss syndrome?

A. Omalizumab
B. Theophylline
C. Montelukast (Correct Answer)
D. Zileuton

Explanation: **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.

Practice by Chapter

Bronchodilators

Practice Questions

Corticosteroids in Respiratory Disorders

Practice Questions

Anti-inflammatory Respiratory Agents

Practice Questions

Mast Cell Stabilizers

Practice Questions

Leukotriene Modifiers

Practice Questions

Antitussives and Expectorants

Practice Questions

Nasal Decongestants

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Pulmonary Surfactants

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Drugs for Pulmonary Hypertension

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Oxygen Therapy

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