Respiratory System Drugs Practice Questions

Q: Which of the following is a long-acting sympathomimetic used in bronchial asthma?

Salmeterol. **Explanation:** The question tests the classification of $\beta_2$-agonists based on their duration of action. **1. Why Salmeterol is Correct:** Salmeterol is a **Long-Acting Beta-2 Agonist (LABA)**. It possesses a long, lipophilic side chain that anchors the molecule into the cell membrane near the $\beta_2$ receptor, allowing it to repeatedly engage the receptor. This results in a prolonged duration of action (**>12 hours**). LABAs are used for the maintenance treatment of asthma and COPD but are **not** used for acute relief due to their slow onset of action. **2. Why the Other Options are Incorrect:** * **Salbutamol (Albuterol) & Terbutaline:** These are **Short-Acting Beta-2 Agonists (SABA)**. They have a rapid onset (5–15 mins) but a short duration of action (2–6 hours). They are the "rescue medications" of choice for acute bronchospasm. * **Bambuterol:** While Bambuterol is a long-acting prodrug of terbutaline (taken once daily), it is technically a **prodrug** and not the primary sympathomimetic molecule itself. In the context of standard pharmacological classification for NEET-PG, Salmeterol and Formoterol are the prototypical LABAs. **3. High-Yield Clinical Pearls for NEET-PG:** * **Formoterol vs. Salmeterol:** Formoterol is a LABA with a **fast onset**, making it unique as it can be used for both maintenance and "SMART" therapy (Single Maintenance and Reliever Therapy). Salmeterol has a slow onset. * **Black Box Warning:** LABAs should **never** be used as monotherapy in asthma (increased risk of asthma-related deaths); they must always be combined with an Inhaled Corticosteroid (ICS). * **Ultra-LABAs:** Indacaterol, Vilanterol, and Olodaterol have a 24-hour duration, used primarily in COPD. * **Side Effects:** Muscle tremors (most common), tachycardia, and hypokalemia.

Q: What is the mode of action of Sodium Cromoglycate?

Mast cell stabilization. **Explanation:** **Correct Answer: A. Mast cell stabilization** **Mechanism of Action:** Sodium Cromoglycate is a **mast cell stabilizer**. It acts by inhibiting the degranulation of sensitized mast cells that occurs after exposure to specific antigens. It prevents the release of inflammatory mediators such as histamine, leukotrienes (LTs), and chemotactic factors. The molecular mechanism involves the **blockade of delayed chloride channels** in the mast cell membrane, which prevents the calcium influx necessary for degranulation. **Why other options are incorrect:** * **B. Antihistaminic:** Sodium Cromoglycate does not block histamine receptors (H1 or H2) nor does it antagonize the effects of histamine once released. It only prevents histamine from being released in the first place. * **C. Anticholinergic:** It has no effect on muscarinic receptors. Anticholinergic drugs (like Ipratropium bromide) work by blocking M3 receptors to cause bronchodilation, whereas Cromoglycate is a prophylactic agent with no direct bronchodilatory action. **High-Yield Clinical Pearls for NEET-PG:** * **Prophylaxis Only:** It is ineffective in treating an acute attack of asthma (not a bronchodilator). It is used for the long-term prevention of bronchial asthma and exercise-induced bronchospasm. * **Route:** It is poorly absorbed orally; hence, it is administered via inhalation (as a fine powder or aerosol). * **Other Uses:** It is used topically for allergic rhinitis (nasal spray) and allergic conjunctivitis (eye drops). * **Nedocromil:** A related drug that is more potent and can also inhibit inflammatory cells like eosinophils and monocytes.

Q: All of the following statements about leukotriene modifiers in the management of bronchial asthma are true EXCEPT?

May be used for acute asthma. **Explanation** Leukotriene modifiers (LTRA) are essential maintenance therapies in asthma, but they have specific clinical limitations and associations that are frequently tested in NEET-PG. **1. Why Option A is the Correct Answer (The "Except" Statement):** Leukotriene modifiers (e.g., Montelukast, Zafirlukast) are **not indicated for acute asthma attacks**. They have a slow onset of action and are significantly less effective than inhaled $\beta_2$-agonists (SABA) for rapid bronchodilation. Their role is strictly limited to **prophylaxis** and chronic management of persistent asthma. **2. Analysis of Other Options:** * **Option B (Exercise-induced asthma):** LTRAs are effective in preventing exercise-induced bronchoconstriction. They are often preferred in pediatric patients or those who wish to avoid frequent inhaler use before physical activity. * **Option C (Zileuton):** This is a 5-lipoxygenase (5-LOX) inhibitor that prevents the synthesis of leukotrienes ($LTB_4, LTC_4, LTD_4, LTE_4$). While Montelukast blocks the receptor ($CysLT_1$), Zileuton is indeed classified as a leukotriene modifier. * **Option D (Churg-Strauss Syndrome):** The use of LTRAs (especially during corticosteroid tapering) is associated with the unmasking of **Eosinophilic Granulomatosis with Polyangiitis (Churg-Strauss Syndrome)**. This presents as eosinophilia, vasculitic rash, and pulmonary infiltrates. **Clinical Pearls for NEET-PG:** * **Aspirin-Induced Asthma:** LTRAs are the **drugs of choice** for Aspirin-Exacerbated Respiratory Disease (AERD). * **Metabolism:** Zafirlukast and Zileuton inhibit Cytochrome P450 enzymes (CYP3A4/1A2), potentially increasing Warfarin levels. **Montelukast** does not have these significant drug interactions. * **Neuropsychiatric effects:** The FDA has issued a boxed warning for Montelukast regarding serious mental health side effects (agitation, aggression, suicidal ideation).

Q: Omalizumab is used for which of the following conditions?

Asthma. **Explanation:** **Omalizumab** is a recombinant DNA-derived humanized monoclonal antibody specifically designed to target **Immunoglobulin E (IgE)**. **Why Asthma is correct:** The underlying mechanism of Omalizumab involves binding to the Fc portion of free circulating IgE. This prevents IgE from binding to its high-affinity receptors (FcεRI) on the surface of mast cells and basophils. By limiting the cross-linking of IgE, it inhibits the release of inflammatory mediators (like histamine and leukotrienes) that trigger an asthma attack. It is clinically indicated for **moderate-to-severe persistent allergic asthma** in patients who are inadequately controlled with inhaled corticosteroids. **Why other options are incorrect:** * **Ulcerative Colitis & Crohn’s Disease:** These are Inflammatory Bowel Diseases (IBD) primarily managed with TNF-alpha inhibitors (e.g., Infliximab, Adalimumab) or anti-integrin antibodies (e.g., Vedolizumab), not anti-IgE therapy. * **Psoriatic Arthritis:** This condition is typically treated with DMARDs or biologics targeting TNF-alpha, IL-17 (e.g., Secukinumab), or IL-12/23 (e.g., Ustekinumab). **High-Yield Clinical Pearls for NEET-PG:** * **Route:** Administered via **subcutaneous injection** every 2–4 weeks. * **Other Indications:** Also FDA-approved for **Chronic Spontaneous Urticaria (CSU)** and nasal polyps. * **Key Side Effect:** The most serious (though rare) side effect is **anaphylaxis**; patients should be monitored post-injection. * **Selection Criteria:** Before starting Omalizumab, a patient's **total serum IgE levels** must be measured to determine the appropriate dosage.

Q: Which of the following should be avoided in a patient with asthma?

NSAID. **Explanation:** The correct answer is **NSAIDs**. This is a high-yield concept in respiratory pharmacology known as **Aspirin-Exacerbated Respiratory Disease (AERD)** or Samter’s Triad (asthma, nasal polyps, and aspirin sensitivity). **Mechanism of Action:** NSAIDs inhibit the enzyme **Cyclooxygenase (COX)**. In susceptible asthmatic patients, blocking the COX pathway causes the metabolism of Arachidonic acid to shift toward the **Lipoxygenase (LOX) pathway**. This results in the overproduction of **Cysteinyl Leukotrienes (LTC4, LTD4, LTE4)**, which are potent bronchoconstrictors, leading to life-threatening bronchospasm. **Analysis of Incorrect Options:** * **B. Terbutaline:** This is a short-acting **$\beta_2$-agonist (SABA)**. It causes bronchodilation by increasing cAMP in bronchial smooth muscle and is a first-line treatment for acute asthma attacks. * **C. Theophylline:** A **Methylxanthine** that acts by inhibiting phosphodiesterase (PDE), leading to increased cAMP and bronchodilation. It is used as an add-on therapy in chronic asthma. * **D. Steroids:** Corticosteroids (e.g., Fluticasone, Prednisolone) are the **mainstay of asthma treatment**. They reduce airway inflammation and hyper-responsiveness. **NEET-PG High-Yield Pearls:** 1. **Safe Alternative:** If an asthmatic patient requires an analgesic, **Acetaminophen (Paracetamol)** is generally considered safe at low doses. 2. **Other Drugs to Avoid:** **Non-selective $\beta$-blockers** (e.g., Propranolol) are strictly contraindicated as they block $\beta_2$ receptors, causing bronchoconstriction. 3. **Leukotriene Antagonists:** Drugs like **Montelukast** and **Zafirlukast** work by blocking leukotriene receptors and are particularly effective in treating aspirin-induced asthma.

Q: Which of the following drugs inhibits histamine release?

Ketotifen. The correct answer is **Ketotifen**. **1. Why Ketotifen is correct:** Ketotifen is a second-generation H1-antihistamine [1] that possesses unique **mast cell stabilizing** properties. It acts by inhibiting the degranulation of mast cells, thereby preventing the release of histamine and other inflammatory mediators (like leukotrienes). It is primarily used in the prophylactic treatment of bronchial asthma and allergic rhinitis [1], [2]. Unlike acute bronchodilators, it does not reverse an ongoing attack but reduces airway hyperreactivity over time [1]. **2. Why the other options are incorrect:** * **D-tubocurarine, Morphine, and Suxamethonium:** These drugs are well-known **histamine liberators**. Instead of inhibiting release, they displace histamine from mast cells via a non-immunologic mechanism (direct action). * **D-tubocurarine:** A skeletal muscle relaxant that frequently causes hypotension and bronchospasm due to significant histamine release. * **Morphine:** An opioid analgesic that can cause itching, urticaria, and vasodilation through direct histamine release. * **Suxamethonium (Succinylcholine):** A depolarizing neuromuscular blocker that can also trigger histamine release, though usually to a lesser extent than tubocurarine. **3. NEET-PG High-Yield Pearls:** * **Mast Cell Stabilizers:** Other examples include **Sodium Cromoglycate** and **Nedocromil**. They are "preventers," not "relievers." * **Dual Action:** Ketotifen is unique because it is both a potent H1-receptor antagonist and a mast cell stabilizer. * **Drug of Choice (DOC):** For an acute anaphylactic reaction, the drug of choice is **Epinephrine (Adrenaline) 1:1000 IM**, not antihistamines, as it physiologically opposes histamine. * **Histamine Liberators Mnemonic:** "Many Drugs Can Release Histamine" (**M**orphine, **D**-tubocurarine, **C**hymotrypsin, **R**adiocontrast media, **H**ydralazine).

Q: Ipratropium bromide is contraindicated in which of the following conditions?

Urinary retention. **Explanation:** **Ipratropium bromide** is a short-acting muscarinic antagonist (SAMA). It works by blocking M3 receptors on smooth muscles, leading to bronchodilation and decreased secretions [3]. **Why Urinary Retention is the Correct Answer:** Muscarinic antagonists exert systemic anticholinergic effects. In the bladder, M3 receptors are responsible for the contraction of the **detrusor muscle** and relaxation of the sphincter to facilitate voiding. By blocking these receptors, Ipratropium can cause detrusor relaxation and increased sphincter tone, significantly worsening pre-existing **urinary retention** (especially in patients with Benign Prostatic Hyperplasia) [2], [4]. While Ipratropium is administered via inhalation to limit systemic absorption, enough can be absorbed to trigger these adverse effects in susceptible individuals. **Analysis of Incorrect Options:** * **A. Asthma:** This is a primary **indication**, not a contraindication [1]. Ipratropium is used as an adjunctive bronchodilator in acute asthma exacerbations. * **C. Hypertension:** Anticholinergics generally do not have a significant impact on blood pressure; they are more likely to cause tachycardia. It is not a contraindication. * **D. Peptic Ulcer:** Anticholinergics actually reduce gastric acid secretion (M1 blockade). While not a primary treatment for PUD today, they are certainly not contraindicated. **NEET-PG High-Yield Pearls:** * **Chemistry:** Ipratropium is a **quaternary ammonium compound**, meaning it is highly polar, does not cross the blood-brain barrier, and has poor systemic absorption compared to atropine [4]. * **Glaucoma Warning:** Use with caution in **narrow-angle glaucoma**, as it can increase intraocular pressure if the drug accidentally sprays into the eyes [2]. * **Drug of Choice:** Ipratropium/Tiotropium are the drugs of choice for **COPD** (more effective than beta-2 agonists in these patients) [1].

Q: A patient presents with dyspnea and bilateral diffuse wheezing on lung auscultation. Which medication would provide the fastest relief?

Salbutamol. **Explanation:** The clinical presentation of dyspnea and bilateral diffuse wheezing is characteristic of an acute bronchospasm (e.g., Asthma or COPD exacerbation). In such scenarios, the priority is a **Short-Acting Beta-2 Agonist (SABA)** to achieve rapid bronchodilation. **Why Salbutamol is correct:** Salbutamol (Albuterol) is the drug of choice for acute attacks. It acts by stimulating $\beta_2$ receptors in the bronchial smooth muscle, leading to increased cAMP and rapid relaxation. Its onset of action is **3–5 minutes**, making it the fastest-acting rescue medication among the options provided. **Analysis of Incorrect Options:** * **Salmeterol:** This is a **Long-Acting Beta-2 Agonist (LABA)**. While it has high affinity for $\beta_2$ receptors, it has a slow onset of action (approx. 15–20 minutes) and is used for maintenance therapy, not acute relief. * **Ipratropium Bromide:** An anticholinergic (SAMA) that blocks M3 receptors. While used in acute asthma/COPD, its onset is slower (15–30 minutes) than Salbutamol. It is typically used as an add-on therapy. * **Montelukast:** A Leukotriene Receptor Antagonist (LTRA). It is an oral medication used for **prophylaxis** and chronic management of asthma; it has no role in the immediate reversal of acute bronchospasm. **NEET-PG High-Yield Pearls:** * **Drug of Choice (DOC)** for acute asthma: Inhaled Salbutamol. * **DOC for Exercise-Induced Asthma:** Salbutamol (taken 15 mins prior). * **Side effects of SABAs:** Muscle tremors (most common), tachycardia, and hypokalemia (due to stimulation of Na+/K+ ATPase pump). * **Formoterol** is a unique LABA because it has a **fast onset** of action, similar to Salbutamol, but a long duration of action.

Q: All of the following are true about theophylline except?

It is the drug of choice for exercise-induced asthma.. Theophylline is a methylxanthine derivative once widely used for asthma but now relegated to a second or third-line role due to its narrow therapeutic index and side effect profile. **Explanation of the Correct Answer (Option B):** Theophylline is **not** the drug of choice for exercise-induced asthma. The preferred treatment for preventing exercise-induced bronchospasm is the use of **Short-Acting Beta-2 Agonists (SABA)** like Salbutamol, taken 15–30 minutes before exercise. Alternatively, Mast Cell Stabilizers (Cromolyn) or Leukotriene Receptor Antagonists (Montelukast) can be used. Theophylline has a slow onset of action and is unsuitable for the acute prevention or rescue required in exercise-induced symptoms. **Analysis of Other Options:** * **Option A:** Theophylline primarily works by **inhibiting Phosphodiesterase (PDE 3 and 4)**, leading to increased intracellular cAMP, which results in bronchodilation. It also acts as an **Adenosine receptor antagonist**. * **Option C:** It has a **narrow therapeutic index** (10–20 µg/ml). Levels above 20 µg/ml cause toxicity, necessitating **Therapeutic Drug Monitoring (TDM)** to ensure safety and efficacy. * **Option D:** As a methylxanthine (related to caffeine), it is a potent **CNS stimulant**. Toxic doses can lead to severe adverse effects, including intractable **seizures** and cardiac arrhythmias. **High-Yield Clinical Pearls for NEET-PG:** * **Metabolism:** It follows first-order kinetics at therapeutic doses but shifts to **zero-order kinetics** in overdose. * **Drug Interactions:** Its metabolism is **increased** by smoking and Phenytoin (enzyme inducers) and **decreased** by Erythromycin and Ciprofloxacin (enzyme inhibitors). * **Other uses:** Aminophylline (a soluble salt of theophylline) is sometimes used in apnea of prematurity.

Q: Which of the following drugs is NOT used in the management of acute asthma?

Montelukast. ### Explanation The management of **acute asthma exacerbations** requires drugs with a rapid onset of action to reverse bronchoconstriction and reduce airway inflammation immediately. **Why Montelukast is the correct answer:** Montelukast is a **Leukotriene Receptor Antagonist (LTRA)**. While it is highly effective for the **prophylaxis** and chronic management of asthma (especially aspirin-induced and exercise-induced asthma), it has a **slow onset of action** (taking hours to days for full effect). Therefore, it has no role in the emergency management of an acute attack where immediate bronchodilation is required. **Analysis of incorrect options:** * **Salbutamol (SABA):** The drug of choice for acute asthma. It acts on $\beta_2$ receptors to cause rapid bronchodilation within 5–15 minutes. * **Ipratropium (SAMA):** An anticholinergic that blocks M3 receptors. It is used as an add-on to Salbutamol in acute severe asthma (synergistic effect) to further reduce airflow obstruction. * **Hydrocortisone:** A systemic corticosteroid used in acute severe asthma to reduce airway inflammation and prevent late-phase responses. While it takes 4–6 hours to act, it is a standard component of acute management protocols. **High-Yield NEET-PG Pearls:** 1. **Drug of Choice (DOC) for Acute Asthma:** Inhaled Salbutamol (SABA). 2. **DOC for Chronic Maintenance:** Inhaled Corticosteroids (e.g., Fluticasone, Budesonide). 3. **DOC for Aspirin-Induced Asthma:** Montelukast/Zafirlukast. 4. **Zileuton:** A 5-Lipoxygenase inhibitor (different mechanism than Montelukast) also used for prophylaxis. 5. **Magnesium Sulfate:** Used intravenously in life-threatening asthma non-responsive to initial therapy.

Question 1

Which of the following is a long-acting sympathomimetic used in bronchial asthma?

Accepted Answer

Salmeterol

Answer

Salbutamol

Answer

Terbutaline

Answer

Bambuterol

Question 2

What is the mode of action of Sodium Cromoglycate?

Accepted Answer

Mast cell stabilization

Answer

Antihistaminic

Answer

Anticholinergic

Answer

None of the above

Question 3

All of the following statements about leukotriene modifiers in the management of bronchial asthma are true EXCEPT?

Accepted Answer

May be used for acute asthma

Answer

May be used for exercise-induced asthma

Answer

Zileuton is a leukotriene modifier

Answer

May uncover Churg-Strauss syndrome

Question 4

Omalizumab is used for which of the following conditions?

Accepted Answer

Asthma

Answer

Ulcerative colitis

Answer

Crohn disease

Answer

Psoriatic arthritis

Question 5

Which of the following should be avoided in a patient with asthma?

Accepted Answer

NSAID

Answer

Terbutaline

Answer

Theophylline

Answer

Steroids

Question 6

Which of the following drugs inhibits histamine release?

Accepted Answer

Ketotifen

Answer

D-tubocurarine

Answer

Morphine

Answer

Suxamethonium

Question 7

Ipratropium bromide is contraindicated in which of the following conditions?

Accepted Answer

Urinary retention

Answer

Asthma

Answer

Hypertension

Answer

Peptic ulcer

Question 8

A patient presents with dyspnea and bilateral diffuse wheezing on lung auscultation. Which medication would provide the fastest relief?

Accepted Answer

Salbutamol

Answer

Salmeterol

Answer

Ipratropium Bromide

Answer

Montelukast

Question 9

All of the following are true about theophylline except?

Accepted Answer

It is the drug of choice for exercise-induced asthma.

Answer

It acts by inhibiting phosphodiesterase enzyme.

Answer

Therapeutic drug monitoring is needed for theophylline.

Answer

It is a central nervous system stimulant and can lead to seizures.

Question 10

Which of the following drugs is NOT used in the management of acute asthma?

Accepted Answer

Montelukast

Answer

Salbutamol

Answer

Ipratropium

Answer

Hydrocortisone

Respiratory System Drugs — MCQs

Respiratory System Drugs — MCQs

On this page

Practice by Chapter

Want unlimited practice?