Respiratory System Drugs — MCQs

An agitated and nervous 24-year-old woman has had severe wheezing and shortness of breath for 2 days. After receiving oxygen, steroids, and salbutamol (Ventolin) in the emergency room, her breathing improves. She is still wheezing and now feels tremulous and anxious with a pulse of 110/min and respirations 30/min. Arterial blood gases on oxygen reveal a pH of 7.40, PO2 340 mm Hg, PCO2 40 mm Hg, and bicarbonate of 24 mEq/L. She is hospitalized for further treatment. Which of the following treatments or medications should be avoided in her?

Q158Easy

What drug is used to prevent exercise-induced bronchial asthma?

Q159Medium

A 23-year-old man is experiencing a flare of his asthma. He is using his salbutamol inhaler more frequently than usual and despite increasing his inhaled steroids he is still short of breath. Previously, his asthma was considered mild with no severe exacerbations requiring oral steroids or hospitalization. With the current flare, he is experiencing recurrent episodes of bronchial obstruction, fever, malaise, and expectoration of brownish mucous plugs. On examination, there is bilateral wheezing. The heart, abdomen, neurologic, and skin exams are normal. A CXR reveals upper lobe pulmonary infiltrates; the eosinophil count is 3000/mL, and serum precipitating antibodies to Aspergillus are positive. Which of the following is the most likely diagnosis?

Q160Easy

What is Tiotropium used for?

Respiratory System Drugs Indian Medical PG Practice Questions and MCQs

Question 151: Which antibody is used in the treatment of asthma?

A. Omalizumab (Correct Answer)
B. Rituximab
C. Trastuzumab
D. Daclizumab

Explanation: **Explanation:** **Omalizumab** is the correct answer. It is a recombinant DNA-derived humanized monoclonal antibody that selectively binds to **free human Immunoglobulin E (IgE)** in the blood and interstitial fluid. By binding to the Fc portion of IgE, it prevents IgE from attaching to the high-affinity receptors (FcεRI) on the surface of mast cells and basophils. This inhibits the release of inflammatory mediators (like histamine and leukotrienes) that trigger an asthma attack. It is specifically indicated for patients with moderate-to-severe persistent allergic asthma who are inadequately controlled with inhaled corticosteroids. **Analysis of Incorrect Options:** * **Rituximab:** A chimeric monoclonal antibody against **CD20**, primarily found on the surface of B-cells. It is used in Non-Hodgkin Lymphoma, Chronic Lymphocytic Leukemia, and Rheumatoid Arthritis. * **Trastuzumab:** A monoclonal antibody against the **HER2/neu receptor**. It is used in the treatment of HER2-positive breast cancer and gastric cancer. * **Daclizumab:** An antibody against the **IL-2 receptor (CD25)**. It was historically used to prevent renal transplant rejection and in multiple sclerosis (though largely withdrawn due to hepatic toxicity). **High-Yield Clinical Pearls for NEET-PG:** * **Route:** Omalizumab is administered **subcutaneously** every 2–4 weeks. * **Other Biologicals in Asthma:** * **Mepolizumab, Reslizumab:** Anti-IL-5 antibodies (used for eosinophilic asthma). * **Benralizumab:** Anti-IL-5 receptor alpha antibody. * **Dupilumab:** Anti-IL-4 receptor alpha antibody (blocks both IL-4 and IL-13). * **Side Effect:** The most serious (though rare) side effect of Omalizumab is **anaphylaxis**, necessitating observation after administration.

Question 152: Intranasal spray of budesonide is indicated in which of the following conditions?

A. Acute sinusitis
B. Common cold
C. Perennial vasomotor rhinitis (Correct Answer)
D. Epistaxis

Explanation: **Budesonide** is a potent glucocorticoid with high first-pass metabolism, making it ideal for topical application via intranasal sprays. Its primary mechanism involves the inhibition of multiple inflammatory cells (mast cells, eosinophils, lymphocytes) and mediators (cytokines, leukotrienes), which reduces mucosal edema and airway hyperreactivity [1, 2].**Why Option C is Correct:** **Perennial vasomotor rhinitis** (and allergic rhinitis) is characterized by chronic inflammation of the nasal mucosa. Intranasal corticosteroids (INCS) like budesonide are the **first-line treatment** for these conditions because they effectively suppress the underlying inflammatory cascade, relieving symptoms of congestion, rhinorrhea, and sneezing [1].**Why Other Options are Incorrect:** * **A. Acute Sinusitis:** This is typically an acute bacterial or viral infection. While steroids may sometimes be used as an adjunct to reduce swelling, they are not the primary indication or definitive treatment.* **B. Common Cold:** This is a self-limiting viral infection. Budesonide does not provide symptomatic relief for the common cold and is not indicated.* **D. Epistaxis:** Intranasal steroids can actually **cause** epistaxis as a side effect due to mucosal drying and thinning; they are never used to treat it.**High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Intranasal steroids are the most effective long-term maintenance therapy for both seasonal and perennial allergic rhinitis.* **Onset of Action:** Unlike antihistamines, the peak effect of budesonide may take **3–7 days** of continuous use [1].* **Safety:** Budesonide has a high topical potency but low systemic bioavailability, minimizing the risk of systemic steroid side effects (like HPA axis suppression) at recommended doses [3].* **Side Effects:** Local irritation, dryness, and **septal perforation** (rare, usually due to improper spray technique) are key adverse effects to remember.

Question 153: The anticoagulant effect of warfarin is increased by all of the following EXCEPT?

A. Cimetidine
B. Phytonadione (Correct Answer)
C. Amiodarone
D. Phenylbutazone

Explanation: **Explanation:** The core concept here is the mechanism of action of **Warfarin**, which acts as a Vitamin K antagonist. It inhibits the enzyme **Vitamin K Epoxide Reductase (VKORC1)**, preventing the conversion of inactive Vitamin K epoxide to its active hydroquinone form. This, in turn, inhibits the synthesis of clotting factors II, VII, IX, and X. **Why Phytonadione is the correct answer:** **Phytonadione (Vitamin K1)** is the physiological antagonist to warfarin. By providing an exogenous source of Vitamin K, it bypasses the inhibition of VKORC1 and restores the synthesis of clotting factors. Therefore, it **decreases** (reverses) the anticoagulant effect of warfarin rather than increasing it. **Why the other options are incorrect:** * **Cimetidine & Amiodarone:** These are potent **Cytochrome P450 (CYP450) enzyme inhibitors**. Since warfarin is metabolized primarily by the liver (specifically CYP2C9), inhibiting these enzymes leads to decreased warfarin clearance, higher plasma levels, and an **increased** anticoagulant effect (increased PT/INR). * **Phenylbutazone:** This drug increases the effect of warfarin via two mechanisms: it is a CYP2C9 inhibitor and it **displaces warfarin from its plasma protein binding sites** (albumin), increasing the free, active fraction of the drug in the blood. **High-Yield Clinical Pearls for NEET-PG:** * **Warfarin Monitoring:** Monitored using **INR** (Target: 2.0–3.0). * **Antidote:** For immediate reversal, use **Fresh Frozen Plasma (FFP)** or Prothrombin Complex Concentrate (PCC). For non-emergency reversal, use **Phytonadione (Vitamin K1)**. * **Warfarin Skin Necrosis:** Occurs due to a rapid decline in Protein C (a natural anticoagulant) before the clotting factors are depleted. * **Enzyme Inducers (Decrease Warfarin effect):** Rifampicin, Phenytoin, Carbamazepine, and St. John’s Wort.

Question 154: Which of the following is an adverse effect of salmeterol?

A. Hyperkalemia
B. Seizures
C. Tremors (Correct Answer)
D. Interstitial nephritis

Explanation: **Explanation:** **Salmeterol** is a Long-Acting Beta-2 Agonist (LABA) used primarily for the maintenance treatment of asthma and COPD. **Why Tremors are the correct answer:** The most common side effect of Beta-2 agonists (both SABA and LABA) is **skeletal muscle tremors**. This occurs because Beta-2 receptors are present on the skeletal muscle fibers. Stimulation of these receptors causes an increase in the speed of muscle contraction and interferes with muscle spindle discharge, leading to fine tremors, typically involving the hands. **Analysis of Incorrect Options:** * **A. Hyperkalemia:** This is incorrect. Beta-2 agonists actually cause **Hypokalemia**. They stimulate the Na+/K+ ATPase pump, shifting potassium from the extracellular fluid into the cells. This property is why Salbutamol is used in the emergency management of hyperkalemia. * **B. Seizures:** While CNS stimulation can occur with high doses of sympathomimetics, seizures are not a characteristic side effect of selective Beta-2 agonists like Salmeterol. They are more commonly associated with Theophylline toxicity. * **C. Interstitial Nephritis:** This is an idiosyncratic inflammatory reaction of the kidneys, commonly associated with drugs like NSAIDs, Penicillins, and Diuretics, but not with bronchodilators. **NEET-PG High-Yield Pearls:** 1. **Tachycardia:** Beta-2 agonists can cause reflex tachycardia and direct stimulation of Beta-1 receptors in the heart at high doses. 2. **Tolerance:** Prolonged use of LABAs can lead to "downregulation" or desensitization of receptors; hence, they should always be used in combination with Inhaled Corticosteroids (ICS) in asthma. 3. **Metabolic effects:** They can cause hyperglycemia and hypomagnesemia.

Question 155: Which of the following antihistamines can be used topically in allergic rhinitis?

A. Terfenadine
B. Azelastine (Correct Answer)
C. Cetirizine
D. Fexofenadine

Explanation: **Explanation:** **Azelastine** is a second-generation H1-receptor antagonist specifically designed for **topical administration** (nasal spray or ophthalmic drops). In allergic rhinitis, its topical application provides a rapid onset of action (within 15–30 minutes) and achieves high local concentrations with minimal systemic absorption. Beyond its antihistaminic properties, it also inhibits mast cell degranulation and decreases the expression of adhesion molecules, making it highly effective for both seasonal and perennial allergic rhinitis. **Analysis of Incorrect Options:** * **Terfenadine (A):** This was the first non-sedating antihistamine but was **withdrawn globally** due to its potential to cause *Torsades de Pointes* (QT prolongation) when co-administered with CYP3A4 inhibitors (e.g., Ketoconazole, Erythromycin). It is a prodrug of Fexofenadine and is only available orally. * **Cetirizine (C):** A potent second-generation H1 blocker and a metabolite of Hydroxyzine. While highly effective, it is administered **orally** and is known for causing mild sedation in some patients compared to other second-generation agents. * **Fexofenadine (D):** The active metabolite of Terfenadine. It is considered the "most non-sedating" antihistamine. Like Cetirizine, it is administered **orally** and does not have a topical formulation for rhinitis. **High-Yield Clinical Pearls for NEET-PG:** * **Topical Antihistamines:** Apart from Azelastine, **Levocabastine** and **Olopatadine** are other agents used topically (nasal/ocular). * **Side Effect:** A common side effect of Azelastine nasal spray is a **bitter aftertaste** (dysgeusia). * **Drug of Choice:** For allergic rhinitis, intranasal corticosteroids are the first-line treatment, but topical antihistamines are preferred when rapid symptom relief is required. * **Safety:** Unlike Terfenadine and Astemizole, Fexofenadine and Cetirizine do not cause cardiotoxicity.

Question 156: Which one of the following is not recommended for the immediate treatment of acute severe asthma?

A. Ipratropium
B. Magnesium sulfate
C. Hydrocortisone
D. Salmeterol (Correct Answer)

Explanation: **Explanation:** The management of acute severe asthma (status asthmaticus) requires **rapid-acting** bronchodilators and anti-inflammatory agents to reverse life-threatening airway obstruction. **Why Salmeterol is the correct answer:** Salmeterol is a **Long-Acting Beta-2 Agonist (LABA)**. It has a slow onset of action (approximately 15–30 minutes) and is strictly used for the long-term maintenance/prophylaxis of asthma. In an acute emergency, using a drug with a delayed onset is dangerous and ineffective. Therefore, LABAs (except Formoterol, which has a fast onset but is still not the primary choice for acute severe cases) are contraindicated for immediate rescue therapy. **Analysis of incorrect options:** * **Ipratropium (SAMA):** This is an inhaled anticholinergic used as an adjunct to SABA (Salbutamol) in acute severe asthma. It provides additional bronchodilation and reduces mucus secretion. * **Magnesium sulfate:** Administered intravenously, it acts as a smooth muscle relaxant by blocking calcium channels. It is recommended in patients who do not respond adequately to initial bolus nebulization. * **Hydrocortisone:** Systemic corticosteroids (IV Hydrocortisone or Methylprednisolone) are mainstay treatments to reduce airway inflammation and prevent late-phase responses. **NEET-PG High-Yield Pearls:** * **Drug of Choice (DOC)** for acute asthma: Inhaled **Salbutamol** (SABA). * **DOC for Prophylaxis:** Inhaled Corticosteroids (e.g., Fluticasone). * **Salmeterol vs. Formoterol:** Both are LABAs, but Formoterol has a fast onset (comparable to Salbutamol), whereas Salmeterol has a slow onset. * **SMART Therapy:** Refers to "Single Maintenance and Reliever Therapy" using a combination of Formoterol and Budesonide.

Question 157: An agitated and nervous 24-year-old woman has had severe wheezing and shortness of breath for 2 days. After receiving oxygen, steroids, and salbutamol (Ventolin) in the emergency room, her breathing improves. She is still wheezing and now feels tremulous and anxious with a pulse of 110/min and respirations 30/min. Arterial blood gases on oxygen reveal a pH of 7.40, PO2 340 mm Hg, PCO2 40 mm Hg, and bicarbonate of 24 mEq/L. She is hospitalized for further treatment. Which of the following treatments or medications should be avoided in her?

A. Theophylline
B. Sedatives (Correct Answer)
C. Corticosteroids
D. Sympathomimetic amines

Explanation: **Explanation:** The correct answer is **Sedatives (Option B)**. **Why Sedatives are Contraindicated:** The patient is presenting with a severe asthma exacerbation. Although she shows clinical improvement, her ABG reveals a **PCO2 of 40 mm Hg**. In a patient with tachypnea (respiratory rate of 30/min), one would expect a low PCO2 due to hyperventilation. A "normal" PCO2 in the setting of respiratory distress is an ominous sign indicating **respiratory muscle fatigue** and impending respiratory failure. Administering sedatives (like benzodiazepines) to an anxious patient with severe asthma is dangerous because they **depress the respiratory drive**. This can lead to hypoventilation, CO2 retention, and respiratory arrest. The patient's anxiety is likely a physiological response to hypoxia and the work of breathing, not a primary psychiatric issue. **Analysis of Incorrect Options:** * **Theophylline (Option A):** While no longer first-line due to a narrow therapeutic index, it is a bronchodilator that can be used in refractory cases. * **Corticosteroids (Option C):** These are the cornerstone of treatment for acute severe asthma to reduce airway inflammation. * **Sympathomimetic amines (Option D):** Drugs like Salbutamol (Beta-2 agonists) are the first-line treatment for bronchodilation. Her tremors and tachycardia are expected side effects of these medications. **NEET-PG High-Yield Pearls:** 1. **The "Normal" PCO2 Trap:** In acute asthma, a normal or rising PCO2 is a "red flag" indicating that the patient can no longer maintain the work of breathing. 2. **Drug of Choice:** Inhaled SABA (Salbutamol) is the DOC for acute relief; Systemic Corticosteroids are DOC for preventing relapse and reducing inflammation. 3. **Side Effects:** Beta-2 agonists commonly cause **hypokalemia, tremors, and tachycardia**.

Question 158: What drug is used to prevent exercise-induced bronchial asthma?

A. Sodium cromoglycate (Correct Answer)
B. Ipratropium bromide
C. Terbutaline
D. Epinephrine

Explanation: **Explanation:** **Sodium cromoglycate** is the drug of choice for the prevention of exercise-induced bronchospasm (EIB). It belongs to the class of **Mast Cell Stabilizers**. Its mechanism involves inhibiting the degranulation of sensitized mast cells by blocking chloride channels, thereby preventing the release of inflammatory mediators like histamine and leukotrienes. Since it does not possess direct bronchodilatory properties, it must be administered prophylactically (usually 10–15 minutes before exercise) to be effective. **Analysis of Incorrect Options:** * **Ipratropium bromide:** An anticholinergic (LAMA/SAMA) used primarily in COPD and as an add-on in acute asthma. It is not the first-line choice for preventing exercise-induced symptoms. * **Terbutaline:** A short-acting beta-2 agonist (SABA). While SABAs can be used to *treat* acute bronchospasm or prevent EIB, Sodium cromoglycate is the classic textbook answer for specific prophylaxis in this context due to its unique mechanism of preventing mediator release. * **Epinephrine:** A non-selective alpha and beta-adrenergic agonist used primarily in emergency management of anaphylaxis or status asthmaticus, not for routine exercise prophylaxis. **NEET-PG High-Yield Pearls:** * **Route of Administration:** Sodium cromoglycate is not absorbed orally; it is administered via inhalation (metered-dose inhaler or dry powder). * **Clinical Use:** It is effective for **prophylaxis only**; it has no role in treating an ongoing acute asthma attack. * **Other Indications:** It is also used in allergic rhinitis and allergic conjunctivitis (topical) and systemic mastocytosis (oral). * **Rule of Thumb:** For NEET-PG, if the question asks for a drug to *prevent* exercise-induced asthma, look for Mast Cell Stabilizers (Cromoglycate/Nedocromil) or Leukotriene Antagonists (Montelukast).

Question 159: A 23-year-old man is experiencing a flare of his asthma. He is using his salbutamol inhaler more frequently than usual and despite increasing his inhaled steroids he is still short of breath. Previously, his asthma was considered mild with no severe exacerbations requiring oral steroids or hospitalization. With the current flare, he is experiencing recurrent episodes of bronchial obstruction, fever, malaise, and expectoration of brownish mucous plugs. On examination, there is bilateral wheezing. The heart, abdomen, neurologic, and skin exams are normal. A CXR reveals upper lobe pulmonary infiltrates; the eosinophil count is 3000/mL, and serum precipitating antibodies to Aspergillus are positive. Which of the following is the most likely diagnosis?

A. Ascaris infestation
B. Allergic bronchopulmonary aspergillosis (Correct Answer)
C. Churg-Strauss allergic granulomatosis
D. Loeffler syndrome

Explanation: ### **Explanation** The clinical presentation is classic for **Allergic Bronchopulmonary Aspergillosis (ABPA)**. ABPA is a hypersensitivity reaction (Type I and Type III) to *Aspergillus fumigatus* colonizing the airways of patients with asthma or cystic fibrosis. **Why Option B is Correct:** The diagnosis of ABPA is confirmed by the following "high-yield" constellation of findings present in this patient: 1. **Pre-existing Asthma:** Worsening symptoms despite standard therapy. 2. **Clinical Clues:** Fever, malaise, and the pathognomonic **brownish mucous plugs**. 3. **Laboratory Findings:** Marked peripheral **eosinophilia** (>1000/mL) and positive **serum precipitating antibodies** (IgG) to *Aspergillus*. 4. **Radiology:** Recurrent pulmonary infiltrates (often upper lobes) and potentially "finger-in-glove" shadows (mucoid impaction). **Why the Other Options are Incorrect:** * **A. Ascaris infestation:** While it causes eosinophilia and lung infiltrates (Löffler syndrome), it does not typically present with brownish mucous plugs or specific *Aspergillus* antibodies. * **C. Churg-Strauss (EGPA):** This is a systemic vasculitis. While it involves asthma and eosinophilia, it usually presents with **p-ANCA positivity** and multi-organ involvement (e.g., mononeuritis multiplex, skin nodules, or renal issues), which are absent here. * **D. Loeffler syndrome:** A transient, self-limiting pulmonary eosinophilia usually due to parasites. It lacks the chronic asthmatic complications and specific fungal markers seen in ABPA. ### **NEET-PG High-Yield Pearls** * **Drug of Choice:** Oral **Corticosteroids** (to reduce inflammation) + **Itraconazole** (to reduce fungal burden). * **Diagnostic Gold Standard:** Elevated **Total Serum IgE** (>1000 IU/mL) is the most characteristic laboratory finding. * **Radiology:** Central bronchiectasis on HRCT is a hallmark of advanced ABPA. * **Key Association:** Always suspect ABPA in an asthmatic patient with "recurrent pneumonia" or "difficult-to-treat" asthma.

Question 160: What is Tiotropium used for?

A. Treating urinary retention
B. Treating ileus
C. Increasing salivation
D. Treating asthma (Correct Answer)

Explanation: **Explanation:** **Tiotropium** is a long-acting muscarinic antagonist (LAMA) that plays a crucial role in the management of obstructive airway diseases. **1. Why Option D is Correct:** Tiotropium works by competitively and reversibly inhibiting **M3 receptors** located on the smooth muscles of the bronchi. Blockade of these receptors prevents acetylcholine-induced bronchoconstriction, leading to prolonged **bronchodilation**. While traditionally the mainstay for COPD, Tiotropium is now frequently used as an "add-on" therapy in **bronchial asthma** (Step 4 or 5 of GINA guidelines) for patients not well-controlled on ICS-LABA combinations. Its long duration of action (24 hours) allows for once-daily dosing. **2. Why Other Options are Incorrect:** * **Options A & B:** Tiotropium is an anticholinergic. Anticholinergics actually *cause* urinary retention and decrease GI motility (potentially worsening ileus). Drugs used for these conditions are typically **cholinergics** (e.g., Bethanechol for urinary retention, Neostigmine for ileus). * **Option C:** Anticholinergics cause **xerostomia** (dry mouth) by blocking M3 receptors in salivary glands. Cholinergic agonists (e.g., Pilocarpine) are used to increase salivation. **3. NEET-PG High-Yield Pearls:** * **M3 Selectivity:** Tiotropium is kinetically selective; it dissociates very slowly from M3 and M1 receptors but rapidly from M2 receptors (which are autoreceptors that inhibit ACh release). This makes it more effective than Ipratropium. * **Delivery:** It is administered via inhalation (e.g., HandiHaler or Respimat) to minimize systemic side effects. * **Side Effects:** The most common side effect reported is **dry mouth**. * **Comparison:** Unlike Ipratropium (SAMA - Short-acting), Tiotropium is a **LAMA** (Long-acting).

Practice by Chapter

Bronchodilators

Practice Questions

Corticosteroids in Respiratory Disorders

Practice Questions

Anti-inflammatory Respiratory Agents

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Mast Cell Stabilizers

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Leukotriene Modifiers

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Antitussives and Expectorants

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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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