Respiratory System Drugs — MCQs

Respiratory System Drugs Indian Medical PG Practice Questions and MCQs

Question 41: Bromhexine acts by:

A. Central opioid agonism
B. Muscarine receptor antagonism
C. Depolymerisation of mucopolysaccharides (Correct Answer)
D. MAO inhibitor

Explanation: **Explanation:** **Bromhexine** is a potent **mucolytic agent** derived from the alkaloid vasicine. Its primary mechanism of action involves the **depolymerisation of mucopolysaccharides** within the bronchial secretions. It stimulates the release of lysosomal enzymes that break down the network of glycoprotein fibers in sputum. This process reduces the viscosity (thickness) of the mucus, making it thinner and easier to expectorate (clear from the airways). Additionally, it increases the permeability of the blood-bronchial barrier, enhancing the penetration of certain antibiotics like Amoxicillin or Erythromycin into the sputum. **Analysis of Incorrect Options:** * **A. Central opioid agonism:** This is the mechanism for **antitussives** like Codeine and Pholcodine, which suppress the cough reflex in the medulla. * **B. Muscarine receptor antagonism:** This describes **anticholinergics** (e.g., Ipratropium bromide), which cause bronchodilation and reduce secretions but do not depolymerize mucus. * **D. MAO inhibitor:** These drugs (e.g., Selegiline) are used in psychiatry and Parkinson’s disease; they have no role in respiratory mucus clearance. **High-Yield Clinical Pearls for NEET-PG:** * **Ambroxol** is the active metabolite of Bromhexine and shares the same mechanism. * **Acetylcysteine**, another mucolytic, works differently by breaking **disulfide bonds** in mucoproteins. * Bromhexine is contraindicated in patients with **gastric ulcers** as it may disrupt the gastric mucosal barrier. * It is often used as an adjuvant in chronic bronchitis, emphysema, and bronchiectasis.

Question 42: Which drug is NOT used in the management of severe persistent asthma?

A. Short-acting beta-2 agonist
B. Oral corticosteroids (Correct Answer)
C. Long-acting beta-2 agonist
D. Inhaled high-dose steroids

Explanation: **Explanation:** The management of **Severe Persistent Asthma** (Step 4 and 5 of GINA guidelines) focuses on achieving control using high-dose inhaled therapies and add-on controllers. **Why Oral Corticosteroids (OCS) is the correct answer:** While OCS are used to manage **acute exacerbations** of asthma, they are **not** recommended for the routine, long-term management of severe persistent asthma if other options are available. Due to significant systemic side effects (Cushingoid features, osteoporosis, hyperglycemia), OCS are considered a "last resort" (Step 5) only when the patient remains uncontrolled despite high-dose ICS-LABA and biologics. In the context of standard maintenance therapy options listed, it is the least preferred long-term intervention. **Analysis of Incorrect Options:** * **Short-acting beta-2 agonist (SABA):** These (e.g., Salbutamol) are the "reliever" medications used across all stages of asthma for immediate symptom relief. * **Long-acting beta-2 agonist (LABA):** Drugs like Salmeterol or Formoterol are the preferred "add-on" therapy to inhaled steroids in persistent asthma to provide 12–24 hour bronchodilation. * **Inhaled high-dose steroids (ICS):** High-dose ICS (e.g., Fluticasone) is the cornerstone of maintenance therapy for severe persistent asthma to reduce airway inflammation. **High-Yield NEET-PG Pearls:** * **Drug of Choice (Acute Attack):** SABA (Inhaled Salbutamol). * **Drug of Choice (Prophylaxis/Maintenance):** Inhaled Corticosteroids (ICS). * **Black Box Warning:** LABAs should **never** be used as monotherapy in asthma (increased risk of asthma-related death); they must always be combined with an ICS. * **New GINA Update:** Low-dose ICS-Formoterol is now the preferred reliever (SMART therapy) across most stages to reduce exacerbation risk.

Question 43: What is the recommended treatment for ventilator-associated pneumonia (VAP) caused by multidrug-resistant Acinetobacter baumannii?

A. Quinupristin and dalfopristin
B. Colistin (Correct Answer)
C. Lavendamycin
D. Tedizolid

Explanation: **Explanation:** **Correct Answer: B. Colistin** Multidrug-resistant (MDR) *Acinetobacter baumannii* is a significant cause of Ventilator-Associated Pneumonia (VAP) in ICU settings. It is often resistant to carbapenems, leaving **Polymyxins (Colistin/Polymyxin E and Polymyxin B)** as the mainstay of "salvage therapy." Colistin acts as a cationic detergent that disrupts the bacterial outer membrane. Due to its narrow therapeutic index, it is primarily reserved for life-threatening infections caused by Gram-negative "superbugs" like *Acinetobacter*, *Pseudomonas*, and *Klebsiella*. **Analysis of Incorrect Options:** * **A. Quinupristin and dalfopristin:** This streptogramin combination is active against Gram-positive cocci, specifically Vancomycin-resistant *Enterococcus faecium* (VRE) and MRSA. It has no activity against Gram-negative organisms like *Acinetobacter*. * **C. Lavendamycin:** This is an experimental antitumor antibiotic. It is not used in clinical practice for the treatment of pneumonia or bacterial infections. * **D. Tedizolid:** This is a second-generation oxazolidinone (similar to Linezolid). It is used for acute bacterial skin and skin structure infections (ABSSSI) caused by Gram-positive bacteria (MRSA). It is ineffective against Gram-negative pathogens. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice for MDR Acinetobacter:** Colistin or Polymyxin B (often in combination with Tigecycline or Minocycline). * **Colistin Toxicity:** The major dose-limiting toxicities are **Nephrotoxicity** (Acute Tubular Necrosis) and **Neurotoxicity** (paresthesia, muscle weakness, or neuromuscular blockade). * **Administration:** Colistin is administered as a prodrug, **Colistimethate sodium (CMS)**, for systemic use to reduce local toxicity. * **The "ESCAPE" Pathogens:** *Acinetobacter* is part of the ESCAPE group (*Enterococcus, Staphylococcus, Clostridium, Acinetobacter, Pseudomonas, Enterobacteriaceae*) known for high antibiotic resistance.

Question 44: Which of the following drugs have an anti-inflammatory action on the airways?

A. Fluticasone (Correct Answer)
B. Ipratropium bromide
C. Budesonide
D. Terbutaline

Explanation: **Explanation:** The management of bronchial asthma and COPD involves two main categories of drugs: **Controllers** (Anti-inflammatory) and **Relievers** (Bronchodilators). **Correct Answer: A. Fluticasone** Fluticasone is a potent **Inhaled Corticosteroid (ICS)**. Corticosteroids are the most effective anti-inflammatory agents for the airways. They work by inhibiting the recruitment of inflammatory cells (eosinophils, T-lymphocytes) and suppressing the synthesis of pro-inflammatory cytokines (IL-4, IL-5). Note: While **C. Budesonide** is also an ICS and possesses anti-inflammatory properties, in single-choice questions, Fluticasone is often prioritized due to its higher topical potency and lower systemic bioavailability. **Analysis of Incorrect Options:** * **B. Ipratropium bromide:** This is a **Short-Acting Muscarinic Antagonist (SAMA)**. It acts as a bronchodilator by blocking M3 receptors on bronchial smooth muscle, reducing vagal tone. It has no significant anti-inflammatory action. * **D. Terbutaline:** This is a **Short-Acting Beta-2 Agonist (SABA)**. It provides rapid symptomatic relief by increasing intracellular cAMP, leading to bronchodilation, but it does not treat the underlying airway inflammation. **High-Yield NEET-PG Pearls:** * **Mechanism of Action:** Steroids act via cytoplasmic receptors to alter gene transcription (transactivation of anti-inflammatory genes and transrepression of pro-inflammatory genes like NF-κB). * **Side Effects:** The most common local side effects of ICS are **Oropharyngeal Candidiasis** (prevented by using a spacer and rinsing the mouth) and **Dysphonia**. * **Drug of Choice:** ICS are the first-line maintenance therapy for persistent asthma. * **Ciclesonide:** A "prodrug" steroid activated only in the lungs by esterases, minimizing local side effects like hoarseness.

Question 45: All of the following antihistamines can be used topically except?

A. Ketotifen
B. Levocetirizine (Correct Answer)
C. Olopatadine
D. Astemizole

Explanation: The question tests your knowledge of the routes of administration for various H1-antihistamines. While many antihistamines are available for systemic use, only a specific subset is formulated for topical application (ophthalmic or nasal) [1]. **Why Levocetirizine is the correct answer:** **Levocetirizine** is a second-generation H1-antihistamine (the active R-enantiomer of Cetirizine). It is exclusively administered **systemically** (oral tablets or syrups) for allergic rhinitis and chronic urticaria. It does not currently have a commercially available topical (eye drop or nasal spray) formulation. **Analysis of Incorrect Options:** * **Ketotifen:** This is a dual-action drug (H1-antihistamine + mast cell stabilizer). It is widely used **topically** as ophthalmic drops for allergic conjunctivitis [1]. * **Olopatadine:** A highly effective second-generation antihistamine and mast cell stabilizer. It is a gold-standard **topical** agent used in both ophthalmic drops (for itching) and nasal sprays (for allergic rhinitis). * **Astemizole:** While Astemizole was primarily an oral drug, it was withdrawn globally due to cardiotoxicity (QT prolongation/Torsades de pointes). However, in the context of pharmacological classification, it is historically distinct from the newer topical-specific agents like Olopatadine or Azelastine. *Note: In many MCQ banks, if Azelastine or Levocetirizine is present, the focus is on the "available formulation." **High-Yield Clinical Pearls for NEET-PG:** * **Topical Antihistamines (Ophthalmic/Nasal):** Azelastine, Olopatadine, Ketotifen, Epinastine, and Lemedastine [1]. * **Azelastine** is unique as it is available as both a nasal spray and eye drops [1]. * **Mast Cell Stabilizers:** Sodium Cromoglycate and Nedocromil are also used topically but lack the immediate antihistaminic effect of Olopatadine. * **Second-generation antihistamines** are preferred over first-generation because they are non-sedating and lack anticholinergic side effects.

Question 46: What is the mechanism of action of zileuton?

A. Inhibits production of IgE
B. Inhibits Lipoxygenase (Correct Answer)
C. Inhibits Cyclooxygenase
D. Inhibits activity of mast cells

Explanation: **Explanation:** **Mechanism of Action:** Zileuton is a specific and reversible inhibitor of **5-lipoxygenase (5-LOX)**, the enzyme responsible for converting arachidonic acid into leukotrienes (LTB4, LTC4, LTD4, and LTE4). By inhibiting this enzyme, zileuton prevents the synthesis of these potent inflammatory mediators, which are known to cause bronchoconstriction, increased mucus secretion, and mucosal edema in asthma patients. **Analysis of Options:** * **Option A (IgE Inhibition):** This describes the mechanism of **Omalizumab**, a monoclonal antibody that binds to free IgE, preventing it from binding to mast cells. * **Option C (COX Inhibition):** This is the mechanism of **NSAIDs** (like Aspirin). Inhibiting COX can actually worsen asthma in some patients (Aspirin-Exacerbated Respiratory Disease) by shunting arachidonic acid toward the LOX pathway. * **Option D (Mast Cell Stabilization):** This describes drugs like **Sodium Cromoglycate** and **Nedocromil**, which prevent the degranulation of mast cells. **High-Yield Clinical Pearls for NEET-PG:** * **Classification:** Zileuton is a *Leukotriene Synthesis Inhibitor*, whereas Montelukast and Zafirlukast are *Leukotriene Receptor Antagonists (LTRAs)* that block the CysLT1 receptor. * **Adverse Effect:** The most significant side effect of Zileuton is **hepatotoxicity** (elevation of liver enzymes); therefore, periodic liver function tests (LFTs) are mandatory. * **Drug Interactions:** It is a microsomal enzyme inhibitor and can increase the plasma levels of **Theophylline** and **Warfarin**. * **Indication:** It is used for the prophylactic treatment of chronic asthma (not for acute attacks).

Question 47: All are side effects of salbutamol EXCEPT:

A. Palpitation
B. Muscle tremors
C. Sedation (Correct Answer)
D. Throat irritation

Explanation: Salbutamol is a **Short-Acting Beta-2 (β2) Agonist (SABA)** used primarily as a bronchodilator [1]. Its side effect profile is a direct result of its sympathomimetic action on β-receptors located throughout the body. **Why Sedation is the Correct Answer:** Salbutamol acts as a **Central Nervous System (CNS) stimulant**, not a depressant. It can cause restlessness, anxiety, and insomnia. Therefore, **sedation** is not a side effect; in fact, the drug has the opposite effect on the level of consciousness. **Analysis of Other Options:** * **Palpitation:** Although Salbutamol is β2-selective, at therapeutic or high doses, it causes peripheral vasodilation (leading to reflex tachycardia) and can have some cross-reactivity with **β1-receptors** in the heart, causing palpitations. * **Muscle Tremors:** This is the **most common side effect**. It occurs due to the direct stimulation of β2-receptors located in the skeletal muscles. * **Throat Irritation:** Since Salbutamol is frequently administered via Metered-Dose Inhalers (MDI) or dry powder inhalers [1], the local deposition of the drug particles can cause mechanical irritation of the pharynx, leading to a cough or sore throat. **High-Yield Clinical Pearls for NEET-PG:** * **Hypokalemia:** Salbutamol promotes the entry of potassium into cells (via Na+/K+ ATPase pump stimulation). This is a high-yield metabolic side effect often used therapeutically to treat hyperkalemia. * **Hyperglycemia:** β2-stimulation increases glycogenolysis, which can lead to elevated blood sugar levels. * **Tolerance:** Overuse of SABA can lead to the "downregulation" of β-receptors.

Question 48: Which of the following drugs used for bronchial asthma can lead to hoarseness of voice?

A. Theophylline
B. Ciclesonide (Correct Answer)
C. Umeclidinium
D. Zafirlukast

Explanation: **Explanation:** The correct answer is **Ciclesonide**. **1. Why Ciclesonide is correct:** Ciclesonide is an **Inhaled Corticosteroid (ICS)**. Local side effects of ICS occur due to the deposition of the drug in the oropharynx. The most common side effects include **oropharyngeal candidiasis (thrush)** and **dysphonia (hoarseness of voice)**. Hoarseness occurs because the steroid causes local myopathy of the laryngeal muscles (vocal cord adductor muscles). *Note:* Ciclesonide is a **prodrug** activated by esterases in the bronchial epithelium. While it is designed to minimize systemic side effects, it can still cause local irritation or hoarseness if not used with a spacer or if the mouth is not rinsed after inhalation. **2. Why the other options are incorrect:** * **A. Theophylline:** A methylxanthine (phosphodiesterase inhibitor). Its side effects are primarily systemic, such as GI upset, tachycardia, tremors, and seizures at toxic levels, but it does not cause hoarseness. * **C. Umeclidinium:** A Long-Acting Muscarinic Antagonist (LAMA). Common side effects include dry mouth, urinary retention, and blurred vision (anticholinergic effects), but not hoarseness. * **D. Zafirlukast:** A Leukotriene Receptor Antagonist (LTRA) administered orally. It is associated with Churg-Strauss syndrome and hepatotoxicity, but since it is not inhaled, it has no local effect on the larynx. **3. NEET-PG High-Yield Pearls:** * **Prevention:** To reduce the risk of hoarseness and oral thrush, patients should be advised to use a **spacer** and **rinse their mouth** with water after every ICS dose. * **Ciclesonide Advantage:** Because it is a prodrug activated in the lungs, it has a lower incidence of oropharyngeal candidiasis compared to Fluticasone or Beclomethasone. * **Drug of Choice:** ICS are the "Controller" drugs of choice for all steps of persistent asthma.

Question 49: Which of the following is not a recommended treatment for acute severe bronchial asthma?

A. Salbutamol
B. Terbutaline
C. Salmeterol (Correct Answer)
D. Methyl xanthine

Explanation: **Explanation:** The management of **acute severe asthma (Status Asthmaticus)** requires drugs with a rapid onset of action to reverse life-threatening bronchospasm immediately. **Why Salmeterol is the correct answer:** Salmeterol is a **Long-Acting Beta-2 Agonist (LABA)**. While it has high lipid solubility and a long duration of action (12+ hours), it has a **slow onset of action** (approx. 15–20 minutes). In an acute emergency, immediate bronchodilation is required; using a slow-acting drug like Salmeterol can delay critical treatment and lead to clinical deterioration. Therefore, LABAs are used for maintenance/prophylaxis, never for acute relief. **Analysis of incorrect options:** * **Salbutamol & Terbutaline:** These are **Short-Acting Beta-2 Agonists (SABA)**. They are the first-line "rescue" medications because they have a rapid onset (2–5 minutes) and effectively relax airway smooth muscle during an attack. * **Methylxanthines:** While no longer first-line due to a narrow therapeutic index, intravenous **Aminophylline** or **Theophylline** can be used as adjunctive therapy in refractory cases of acute severe asthma that do not respond to SABAs and corticosteroids. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice (DOC)** for acute asthma: Inhaled SABA (Salbutamol). * **Formoterol Paradox:** Unlike Salmeterol, Formoterol is a LABA with a **fast onset**, making it the only LABA recommended for both maintenance and reliever therapy (SMART therapy). * **Treatment components for Acute Severe Asthma:** Oxygen, high-dose SABA (nebulized), systemic corticosteroids (Hydrocortisone/Prednisolone), and Ipratropium bromide. * **Magnesium Sulfate (IV):** Used in severe cases not responding to initial nebulization.

Question 50: Which of the following is NOT a side effect of inhaled corticosteroids?

A. Adrenal suppression
B. Cataract
C. Osteoporosis
D. Hypoglycemia (Correct Answer)

Explanation: **Explanation:** Inhaled Corticosteroids (ICS), such as Budesonide and Fluticasone, are the mainstay of chronic asthma management. While they are designed for local action, a small fraction undergoes systemic absorption via the lungs or the gastrointestinal tract (if swallowed). **Why Hypoglycemia is the correct answer:** Glucocorticoids are "diabetogenic" hormones. They stimulate gluconeogenesis and decrease peripheral glucose uptake, leading to **Hyperglycemia**, not hypoglycemia. Therefore, hypoglycemia is not a side effect of corticosteroid therapy. **Analysis of Incorrect Options:** * **Adrenal Suppression (A):** High doses of ICS can suppress the Hypothalamic-Pituitary-Adrenal (HPA) axis through negative feedback, leading to secondary adrenal insufficiency. * **Cataract (B) & Glaucoma:** Systemic absorption of steroids can lead to increased intraocular pressure and the formation of posterior subcapsular cataracts. * **Osteoporosis (C):** Steroids inhibit osteoblast activity and decrease calcium absorption, leading to decreased bone mineral density and increased fracture risk over long-term use. **High-Yield Clinical Pearls for NEET-PG:** * **Most Common Local Side Effect:** Oropharyngeal Candidiasis (Thrush) and Hoarseness of voice (Dysphonia). * **Prevention:** Patients should be advised to **rinse their mouth with water** after each use or use a **spacer** device to minimize local deposition. * **Growth:** In children, high-dose ICS may cause a temporary reduction in growth velocity, though final adult height is generally unaffected. * **Ciclesonide:** A "prodrug" activated only in the lungs by esterases, which significantly reduces the risk of local side effects like thrush.

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

Practice Questions

Pulmonary Surfactants

Practice Questions

Drugs for Pulmonary Hypertension

Practice Questions

Oxygen Therapy

Practice Questions

Want unlimited practice?

Get full access to all questions, explanations, and performance tracking.

Start For Free