Respiratory System Drugs Practice Questions

Q: A machinery worker in a factory presents with profuse rhinorrhea and sneezing. Which of the following is the most appropriate medication for symptomatic relief?

Cetirizine. **Explanation:** The patient is presenting with symptoms of allergic rhinitis (rhinorrhea and sneezing). The key clinical consideration in this question is the patient’s occupation: a **machinery worker**. **Why Cetirizine is correct:** Cetirizine is a **second-generation H1 antihistamine**. Unlike first-generation agents, second-generation antihistamines are highly selective for peripheral H1 receptors and have poor lipid solubility, meaning they do not cross the blood-brain barrier significantly. Consequently, they are **non-sedating** and do not impair psychomotor performance. For a machinery worker, avoiding sedation is critical to prevent workplace accidents. **Why the other options are incorrect:** * **Diphenhydramine, Promethazine, and Hydroxyzine** are all **first-generation H1 antihistamines**. These drugs are highly lipophilic and readily cross the blood-brain barrier. They cause significant sedation, drowsiness, and impairment of cognitive/motor functions. * **Promethazine** is particularly known for its strong sedative and anti-emetic properties. * **Hydroxyzine** is often used for its anxiolytic and antipruritic effects but is highly sedating. **High-Yield NEET-PG Pearls:** * **Second-generation antihistamines:** Cetirizine, Loratadine, Fexofenadine, Desloratadine, and Azelastine. * **Fexofenadine** is considered the least sedating of all antihistamines (the "purest" non-sedating agent). * **Cetirizine** is a metabolite of Hydroxyzine; while generally non-sedating, it may cause mild drowsiness in a small percentage of patients compared to Fexofenadine. * **Contraindication:** First-generation antihistamines should be avoided in pilots, drivers, and machinery operators.

Q: Which of the following is a lipoxygenase inhibitor?

Zileuton. **Explanation:** The correct answer is **Zileuton**. This question tests your knowledge of the leukotriene pathway in the management of bronchial asthma. **1. Why Zileuton is correct:** Leukotrienes are potent bronchoconstrictors derived from arachidonic acid via the **5-Lipoxygenase (5-LOX)** enzyme pathway. **Zileuton** is a specific inhibitor of the 5-LOX enzyme. By blocking this enzyme, it prevents the synthesis of all leukotrienes (LTB4, LTC4, LTD4, and LTE4), thereby reducing airway inflammation and bronchospasm. **2. Why other options are incorrect:** * **Montelukast:** This is a **Leukotriene Receptor Antagonist (LTRA)**. It does not inhibit the enzyme; instead, it selectively blocks the **CysLT1 receptor**, preventing the action of cysteinyl leukotrienes (LTC4, LTD4, LTE4). * **Thromboxanes:** These are eicosanoids produced via the **Cyclooxygenase (COX)** pathway, not the lipoxygenase pathway. They primarily mediate platelet aggregation and vasoconstriction. * **Sodium cromoglycate:** This is a **Mast Cell Stabilizer**. It works by preventing the degranulation of mast cells and the subsequent release of inflammatory mediators like histamine; it has no direct effect on the lipoxygenase enzyme. **Clinical Pearls for NEET-PG:** * **Hepatotoxicity:** Zileuton is known to cause a rise in liver enzymes; therefore, periodic **Liver Function Tests (LFTs)** are mandatory. * **Aspirin-Exacerbated Respiratory Disease (AERD):** Leukotriene modifiers (both Zileuton and Montelukast) are particularly effective in patients with the "Samter’s Triad" (Asthma, Aspirin sensitivity, and Nasal polyps). * **Churg-Strauss Syndrome:** Be aware of the rare association between LTRA (Montelukast/Zafirlukast) use and the development of this systemic vasculitis.

Q: What is the advantage of salmeterol over salbutamol?

Longer duration of action. **Explanation:** The primary pharmacological difference between Salmeterol and Salbutamol lies in their **pharmacokinetics**, specifically their duration of action. **1. Why "Longer duration of action" 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 $\beta_2$-adrenoceptor. This allows the active head of the drug to repeatedly engage with the receptor site, resulting in a prolonged bronchodilatory effect lasting **12 hours or more**. In contrast, Salbutamol is a **Short-Acting Beta-2 Agonist (SABA)** with a duration of only 4–6 hours. **2. Why other options are incorrect:** * **Shorter duration of action:** This describes Salbutamol (SABA), which is used for "rescue" relief of acute symptoms. * **More potency:** While their binding affinities differ, "potency" is not the clinically defining advantage. The therapeutic choice is based on the *timing* of the effect. * **Lesser cardiac effects:** Both drugs are $\beta_2$-selective but can cause tachycardia and tremors at high doses due to some $\beta_1$ cross-reactivity or reflex mechanisms. Salmeterol does not inherently possess a significantly safer cardiac profile than Salbutamol. **Clinical Pearls for NEET-PG:** * **Onset of Action:** Salbutamol acts within 5 minutes (ideal for acute attacks). Salmeterol has a **slow onset** (15–20 mins) and should **never** be used for acute relief. * **Black Box Warning:** LABAs (Salmeterol/Formoterol) should generally not be used as monotherapy in asthma; they must be combined with an **Inhaled Corticosteroid (ICS)** to reduce the risk of asthma-related mortality. * **Formoterol Exception:** Unlike Salmeterol, Formoterol is a LABA that has a **fast onset** of action.

Q: What are the complications of inhalational steroid use?

Oral candidiasis. **Explanation:** Inhalational corticosteroids (ICS), such as Budesonide and Fluticasone, are the mainstay for long-term management of bronchial asthma. The primary advantage of the inhalational route is that it delivers the drug directly to the target site (airway), minimizing systemic absorption and associated side effects. **Why Oral Candidiasis is the Correct Answer:** When using a Metered-Dose Inhaler (MDI), a significant portion of the drug (approx. 80-90%) deposits in the oropharynx. Steroids cause local immunosuppression in the oral mucosa, which facilitates the overgrowth of opportunistic fungi, most commonly *Candida albicans*. This results in **Oral Candidiasis (Thrush)**. Another common local side effect is **Dysphonia** (hoarseness of voice) due to myopathy of the laryngeal muscles. **Analysis of Incorrect Options:** * **A & C (Cushing’s Syndrome & Decreased ACTH):** These are features of systemic corticosteroid toxicity. While high doses of potent ICS can theoretically cause some adrenal suppression, they rarely cause full-blown Cushingoid features or significant ACTH suppression at standard therapeutic doses. * **D (Systemic Complications):** The inhalational route is specifically designed to avoid systemic complications like osteoporosis, hyperglycemia, and growth retardation, which are common with oral or parenteral steroids. **High-Yield Clinical Pearls for NEET-PG:** * **Prevention:** Patients should be advised to **rinse their mouth with water and spit** after every use of an ICS to remove oropharyngeal deposits. * **Spacers:** Using a spacer device with an MDI reduces oropharyngeal deposition and increases lung delivery, further decreasing the risk of candidiasis. * **Ciclesonide:** This is a **prodrug** activated by esterases in the lungs; it has minimal activity in the oropharynx, significantly reducing the risk of local side effects.

Q: A 28-year-old female with a known history of asthma, currently prescribed inhalational salbutamol, budesonide, and salmeterol, presents with dyspnea. Her peak expiratory flow (PEF) shows mild improvement. Zafirlukast has been added to her treatment regimen. What is the mechanism of action of zafirlukast?

Inhibition of the actions of LTC4, LTD4. ### Explanation **1. Mechanism of Action (Correct Answer: B)** Zafirlukast and Montelukast are **selective CysLT₁ receptor antagonists**. In asthma, cysteinyl leukotrienes (LTC4, LTD4, and LTE4) are potent bronchoconstrictors that also increase mucus secretion and airway edema. By competitively blocking the CysLT₁ receptor, zafirlukast inhibits the **actions** of these leukotrienes, leading to bronchodilation and reduced airway inflammation. **2. Analysis of Incorrect Options** * **Option A:** LTB4 is primarily a chemoattractant for neutrophils. While it plays a role in inflammation, CysLT₁ antagonists do not target LTB4 receptors. * **Option C:** This describes the mechanism of **Zileuton**, which is a 5-Lipoxygenase (5-LOX) inhibitor. Zileuton prevents the *synthesis* (formation) of leukotrienes, whereas zafirlukast blocks their *receptors*. * **Option D:** This describes the mechanism of **Mast Cell Stabilizers** (e.g., Sodium Cromoglicate), which prevent the degranulation and release of various mediators, including leukotrienes. **3. NEET-PG High-Yield Clinical Pearls** * **Indications:** Used for prophylactic treatment of chronic asthma and aspirin-induced asthma (AIA). They are **not** used for acute attacks. * **Metabolism:** Zafirlukast is an inhibitor of CYP2C9 and CYP3A4; it can increase the serum levels of **Warfarin**, leading to increased prothrombin time. * **Side Effects:** Generally well-tolerated, but rarely associated with **Churg-Strauss syndrome** (eosinophilic granulomatosis with polyangiitis) when systemic steroids are tapered. * **Administration:** Montelukast is taken once daily (usually at night), while Zafirlukast is taken twice daily.

Q: All of the following drugs are useful in the treatment of a patient with acute bronchial asthma EXCEPT?

Montelukast. ### Explanation The management of **acute bronchial asthma** focuses on rapid reversal of airway obstruction and reduction of inflammation. **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 (Option B):** A Short-Acting Beta-2 Agonist (SABA). It is the **drug of choice** for acute asthma due to its rapid onset (2–5 minutes) of bronchodilation via cAMP stimulation. * **Ipratropium (Option A):** A Short-Acting Muscarinic Antagonist (SAMA). It is used as an adjunct to SABAs in acute severe asthma to provide additional bronchodilation by blocking vagal-mediated bronchoconstriction. * **Hydrocortisone (Option D):** A systemic corticosteroid. It is used in acute attacks to reduce airway inflammation and upregulate beta-receptors. While it takes 4–6 hours to act, it is vital for preventing relapse and managing "status asthmaticus." **Clinical Pearls for NEET-PG:** * **Drug of Choice (Acute):** Inhaled Salbutamol. * **Drug of Choice (Prophylaxis/Chronic):** Inhaled Corticosteroids (e.g., Fluticasone). * **Aspirin-Induced Asthma:** LTRAs (Montelukast/Zafirlukast) are the preferred treatment. * **Magnesium Sulfate:** Used intravenously in life-threatening asthma non-responsive to initial therapy.

Q: Methylxanthines exert the following action(s) at cellular/molecular level:

All of the above. **Explanation:** Methylxanthines (such as **Theophylline** and **Aminophylline**) are bronchodilators that work through multiple synergistic mechanisms at the cellular level: 1. **Inhibition of Phosphodiesterase (PDE):** Methylxanthines non-selectively inhibit PDE enzymes (primarily PDE3 and PDE4). This prevents the degradation of cyclic AMP (cAMP), leading to increased intracellular cAMP levels. In bronchial smooth muscle, this results in relaxation and bronchodilation. 2. **Antagonism of Adenosine:** Adenosine acts on A1 and A2 receptors to cause bronchoconstriction and histamine release from mast cells. Methylxanthines act as competitive antagonists at adenosine receptors, thereby preventing these effects. 3. **Intracellular Release of Ca²⁺:** At higher concentrations, methylxanthines promote the release of calcium from the sarcoplasmic reticulum in skeletal and cardiac muscles. This explains their positive inotropic effect on the heart and improved contractility of the diaphragm (useful in COPD). Since all three mechanisms are characteristic of methylxanthines, **Option D** is the correct answer. **High-Yield Clinical Pearls for NEET-PG:** * **Therapeutic Window:** Theophylline has a narrow therapeutic index (10–20 µg/ml). Monitoring is essential to avoid toxicity (seizures, arrhythmias). * **Metabolism:** It is metabolized by **CYP1A2**. Enzyme inducers (Rifampicin, Smoking) decrease its levels, while inhibitors (Ciprofloxacin, Erythromycin) increase levels, leading to toxicity. * **Additional Action:** They also enhance **Histone Deacetylation**, which helps reverse corticosteroid resistance in COPD and asthma patients.

Q: Which of the following is the primary bronchodilator used in the management of COPD?

Anticholinergics. **Explanation:** In Chronic Obstructive Pulmonary Disease (COPD), the primary reversible component of airway obstruction is **vagal-mediated cholinergic tone**. Unlike asthma, where inflammation is the driver, COPD is characterized by increased parasympathetic activity leading to bronchoconstriction. **1. Why Anticholinergics are Correct:** Anticholinergics (Muscarinic antagonists) like **Ipratropium (SAMA)** and **Tiotropium (LAMA)** are considered the first-line bronchodilators in COPD. They work by blocking M3 receptors on bronchial smooth muscle, thereby inhibiting the bronchoconstrictor effect of acetylcholine. Tiotropium is particularly favored due to its long duration of action and selectivity for M3 receptors. **2. Why Incorrect Options are Wrong:** * **Antiadrenergic agents:** These (e.g., Beta-blockers) would cause bronchoconstriction and worsen COPD symptoms. * **Cholinergic agents:** These (e.g., Methacholine) stimulate muscarinic receptors, causing profound bronchoconstriction and mucus secretion, which is contraindicated in COPD. * **Alpha agonists:** These primarily cause vasoconstriction (alpha-1) or inhibit norepinephrine release (alpha-2). They have no significant role in bronchodilation; **Beta-2 agonists** (not alpha) are the adrenergic agents used for bronchodilation. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice (DOC):** For symptomatic relief in COPD, LAMAs (Tiotropium) are generally superior to LABAs. * **Combination Therapy:** In advanced COPD, a combination of LAMA + LABA is more effective than monotherapy. * **Side Effects:** The most common side effect of inhaled anticholinergics is **dry mouth**. Use with caution in patients with narrow-angle glaucoma or prostatic hyperplasia. * **Asthma vs. COPD:** While Beta-2 agonists are the mainstay for Asthma, Anticholinergics are the mainstay for COPD.

Question 1

A machinery worker in a factory presents with profuse rhinorrhea and sneezing. Which of the following is the most appropriate medication for symptomatic relief?

Accepted Answer

Cetirizine

Answer

Diphenhydramine

Answer

Promethazine

Answer

Hydroxyzine

Question 2

Which of the following is a lipoxygenase inhibitor?

Accepted Answer

Zileuton

Answer

Montelukast

Answer

Thromboxanes

Answer

Sodium cromoglycate

Question 3

What is the advantage of salmeterol over salbutamol?

Accepted Answer

Longer duration of action

Answer

Shorter duration of action

Answer

More potency

Answer

Lesser cardiac effects

Question 4

What are the complications of inhalational steroid use?

Accepted Answer

Oral candidiasis

Answer

Cushing's syndrome

Answer

Decreased ACTH

Answer

Systemic complications

Question 5

A 28-year-old female with a known history of asthma, currently prescribed inhalational salbutamol, budesonide, and salmeterol, presents with dyspnea. Her peak expiratory flow (PEF) shows mild improvement. Zafirlukast has been added to her treatment regimen. What is the mechanism of action of zafirlukast?

Accepted Answer

Inhibition of the actions of LTC4, LTD4

Answer

Inhibition of the actions of LTB4

Answer

Inhibition of the formation of LTC4, LTD4

Answer

Inhibition of the release of leukotrienes from mast cells

Question 6

Which of the following H1 blockers has high anticholinergic activity?

Accepted Answer

Chlorpheniramine

Answer

Cetirizine

Answer

Fexofenadine

Answer

Astemizole

Question 7

What is the drug of choice for Type 1 Brittle asthma?

Accepted Answer

Subcutaneous terbutaline

Answer

Subcutaneous salbutamol

Answer

Subcutaneous adrenaline

Answer

Subcutaneous mometasone

Question 8

All of the following drugs are useful in the treatment of a patient with acute bronchial asthma EXCEPT?

Accepted Answer

Montelukast

Answer

Ipratropium

Answer

Salbutamol

Answer

Hydrocortisone

Question 9

Methylxanthines exert the following action(s) at cellular/molecular level:

Accepted Answer

All of the above

Answer

Intracellular release of Ca2+

Answer

Inhibition of phosphodiesterase

Answer

Antagonism of adenosine

Question 10

Which of the following is the primary bronchodilator used in the management of COPD?

Accepted Answer

Anticholinergics

Answer

Antiadrenergic agents

Answer

Cholinergic agents

Answer

Alpha agonists

Respiratory System Drugs — MCQs

Respiratory System Drugs — MCQs

On this page

Practice by Chapter

Want unlimited practice?