Respiratory System Drugs — MCQs

Respiratory System Drugs Indian Medical PG Practice Questions and MCQs

Question 141: All of the following drugs can be given in status asthmaticus except?

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

Explanation: **Explanation:** The core concept in managing **Status Asthmaticus** (Acute Severe Asthma) is the need for **rapid-acting** bronchodilation and anti-inflammatory action to reverse life-threatening airway obstruction. [1] **Why Salmeterol is the correct answer:** Salmeterol is a **Long-Acting Beta-2 Agonist (LABA)**. While it is highly effective for maintenance therapy and prophylaxis, it has a **slow onset of action** (approximately 15–20 minutes) [3]. In an emergency like status asthmaticus, drugs must work almost instantly. Using a slow-acting drug like Salmeterol in an acute crisis can delay necessary treatment and lead to fatal outcomes. Therefore, it is contraindicated for acute symptom 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 of action (within 1–5 minutes) when given via inhalation or nebulization [1]. In severe cases, they can also be administered parenterally. * **Hydrocortisone:** Systemic corticosteroids are a cornerstone in status asthmaticus management [2]. While they don't cause immediate bronchodilation, they reduce airway inflammation and, crucially, **upregulate beta-receptors**, making the patient more responsive to SABA therapy [4]. **High-Yield Clinical Pearls for NEET-PG:** * **Formoterol Exception:** Unlike Salmeterol, Formoterol is a LABA with a **fast onset of action**, allowing it to be used for both maintenance and rescue (SMART therapy). * **Drug of Choice:** Nebulized Salbutamol (SABA) + Ipratropium bromide (SAMA) is the initial treatment of choice for acute severe asthma. * **Magnesium Sulfate:** IV Magnesium sulfate is used as an add-on in refractory status asthmaticus for its smooth muscle relaxant properties.

Question 142: What is the optimal particle size for aerosol therapy?

A. 0.5-1 µm
B. 1-5 µm (Correct Answer)
C. 5-10 µm
D. 10-15 µm

Explanation: The effectiveness of aerosol therapy depends on the **Mass Median Aerodynamic Diameter (MMAD)** of the particles, which determines where they deposit in the respiratory tract. ### Why 1–5 µm is Correct For a drug to be clinically effective in conditions like asthma or COPD, it must reach the **lower airways (bronchi and bronchioles)**. Particles sized **1–5 µm** are ideal because they are small enough to bypass the upper airway but heavy enough to settle in the smaller airways via **sedimentation**. This range ensures maximum deposition in the target site for bronchodilators and inhaled corticosteroids. ### Analysis of Incorrect Options * **5–10 µm (Option C) & 10–15 µm (Option D):** These particles are too large. Due to **inertial impaction**, they hit the back of the throat (oropharynx) and are swallowed rather than inhaled. This increases systemic side effects (e.g., oral candidiasis with steroids) and decreases therapeutic efficacy. * **0.5–1 µm (Option A):** These particles are too light. They behave like a gas and remain suspended in the air. Instead of settling on the airway mucosa, they are typically **exhaled** out before deposition can occur. ### NEET-PG High-Yield Pearls * **Deposition Mechanisms:** * >10 µm: Oropharyngeal deposition (Impaction). * 1–5 µm: Small airways (Sedimentation). * <0.1 µm: Alveoli (Diffusion/Brownian motion). * **Clinical Tip:** To maximize the deposition of 1–5 µm particles, patients are advised to take a **slow, deep breath** followed by a **10-second breath-hold**. * **Spacers:** These devices help by filtering out larger particles (>10 µm), reducing oropharyngeal deposition and improving delivery to the lungs.

Question 143: In which GOLD group is Roflumilast indicated for the management of COPD?

A. Group A
B. Group B
C. Group C
D. Group D (Correct Answer)

Explanation: **Explanation:** **Roflumilast** is a selective, long-acting inhibitor of the enzyme **Phosphodiesterase-4 (PDE4)**. By inhibiting PDE4, it increases intracellular cAMP levels in inflammatory cells, leading to potent anti-inflammatory effects specifically in the airways. **Why Group D is correct:** According to the **GOLD (Global Initiative for Chronic Obstructive Lung Disease)** guidelines, Roflumilast is specifically indicated for patients in **Group D** (High risk, high symptom burden). It is used as an add-on therapy for patients with **severe to very severe airflow obstruction (FEV1 < 50% predicted)**, chronic bronchitis, and a history of frequent exacerbations despite being on optimal long-acting bronchodilator therapy (LABA + LAMA or LABA + ICS). **Why other options are incorrect:** * **Group A (Low risk, low symptoms):** Managed primarily with a single bronchodilator (SABA or LABA/LAMA) as needed. * **Group B (Low risk, high symptoms):** Managed with long-acting bronchodilators (LABA or LAMA). * **Group C (High risk, low symptoms):** Managed primarily with a LAMA to prevent exacerbations. Roflumilast is not a first-line or second-line choice here as symptoms are low. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Selective PDE4 inhibition → ↑ cAMP → ↓ Inflammation. It is **not** a bronchodilator. * **Primary Indication:** Reduction of exacerbations in patients with **Chronic Bronchitis** phenotype and FEV1 < 50%. * **Side Effects:** Significant weight loss (monitor weight), diarrhea, nausea, and **neuropsychiatric effects** (insomnia, anxiety, and depression/suicidal ideation). * **Metabolism:** Metabolized by CYP3A4 and CYP1A2; use caution with inhibitors/inducers of these enzymes.

Question 144: Which of the following drugs does not act by blocking GP 2b/3a receptors?

A. Eptifibatide
B. Abciximab
C. Tirofiban
D. Clopidogrel (Correct Answer)

Explanation: **Explanation:** The question tests your knowledge of antiplatelet drug mechanisms. The correct answer is **Clopidogrel** because it belongs to a different class of antiplatelets. **1. Why Clopidogrel is the correct answer:** Clopidogrel is a **P2Y12 receptor antagonist**. It works by irreversibly blocking the ADP (Adenosine Diphosphate) receptor on the platelet surface. This prevents the activation of the GP IIb/IIIa receptor complex, thereby inhibiting platelet aggregation. It does not bind to the GP IIb/IIIa receptor itself. **2. Why the other options are incorrect:** Options A, B, and C are all direct **Glycoprotein (GP) IIb/IIIa inhibitors**. These drugs block the "final common pathway" of platelet aggregation by preventing the binding of fibrinogen to the GP IIb/IIIa receptors. * **Abciximab:** A chimeric monoclonal antibody fragment. It is non-competitive and has a long biological half-life. * **Eptifibatide:** A synthetic cyclic peptide derived from rattlesnake venom (Barbourin). It is a reversible inhibitor. * **Tirofiban:** A non-peptide, small-molecule reversible inhibitor. **3. NEET-PG High-Yield Pearls:** * **GP IIb/IIIa Inhibitors:** Used primarily in Acute Coronary Syndrome (ACS) and during Percutaneous Coronary Intervention (PCI). * **Abciximab Side Effect:** Can cause profound thrombocytopenia; monitoring platelet counts is essential. * **Clopidogrel Metabolism:** It is a **prodrug** activated by the hepatic enzyme **CYP2C19**. Patients with a genetic deficiency of this enzyme or those taking Omeprazole (a CYP2C19 inhibitor) may show reduced clinical efficacy. * **Aspirin:** Acts by irreversibly inhibiting COX-1, reducing Thromboxane A2 (TXA2) synthesis.

Question 145: All of the following statements regarding sodium cromoglycate are true EXCEPT:

A. Used in the management of acute bronchial asthma (Correct Answer)
B. Inhibits degranulation of mast cells
C. It is not a bronchodilator
D. Administered via the inhalational route

Explanation: ### Explanation **Sodium Cromoglycate** is a **mast cell stabilizer** used primarily in the prophylactic management of bronchial asthma. **1. Why Option A is the Correct Answer (The False Statement):** Sodium cromoglycate is **ineffective in acute bronchial asthma**. It does not possess any intrinsic bronchodilatory or anti-inflammatory activity once the mediators have already been released. It acts by preventing the release of mediators (prophylaxis) rather than reversing their effects. In an acute attack, rapid-acting bronchodilators like Salbutamol (SABA) are the drugs of choice. **2. Analysis of Other Options:** * **Option B (Inhibits degranulation):** This is the primary mechanism of action. It stabilizes the mast cell membrane by inhibiting the trigger-induced influx of calcium, thereby preventing the release of histamine, leukotrienes, and other inflammatory mediators. * **Option C (Not a bronchodilator):** Unlike beta-2 agonists or theophylline, cromoglycate has no direct action on bronchial smooth muscle tone. It only prevents bronchoconstriction triggered by allergens or exercise. * **Option D (Inhalational route):** Sodium cromoglycate is highly polar and poorly absorbed from the GI tract. Therefore, it must be administered via inhalation (as a microfine powder via Rotahaler or as an aerosol) to act locally on the bronchial mucosa. **3. High-Yield Clinical Pearls for NEET-PG:** * **Indications:** Prophylaxis of bronchial asthma, allergic rhinitis (nasal spray), and allergic conjunctivitis (eye drops). * **Exercise-Induced Asthma:** It is particularly effective when taken 10–15 minutes before exercise. * **Adverse Effects:** Generally safe, but may cause throat irritation, cough, or rare bronchospasm (prevented by pre-administering a bronchodilator). * **Rule of Thumb:** Remember that mast cell stabilizers are "preventers," not "relievers."

Question 146: Which anti-IgE monoclonal antibody is used in the management of bronchial asthma?

A. Mepolizumab
B. Omalizumab (Correct Answer)
C. Keliximab
D. Altrakincept

Explanation: **Explanation:** **Omalizumab** is a recombinant DNA-derived humanized monoclonal antibody that specifically binds to **free circulating IgE** in the blood and interstitial fluid. By binding to the Fc portion of the IgE antibody, it prevents IgE from attaching to the high-affinity receptors (FcεRI) on the surface of mast cells and basophils. This prevents the subsequent release of inflammatory mediators (histamine, leukotrienes) that trigger an asthma attack. It is clinically indicated for patients with moderate-to-severe persistent allergic asthma who are inadequately controlled with inhaled corticosteroids. **Analysis of Incorrect Options:** * **Mepolizumab:** This is a monoclonal antibody against **Interleukin-5 (IL-5)**. It is used in the management of severe eosinophilic asthma by reducing eosinophil production and survival. * **Keliximab:** This is a monoclonal antibody directed against the **CD4 receptor** on T-lymphocytes. While it was studied for asthma, it is not a standard clinical treatment for the condition. * **Altrakincept:** This is a recombinant soluble **IL-4 receptor** (not a monoclonal antibody). It acts as a decoy receptor to neutralize IL-4, thereby inhibiting Th2-mediated inflammation. **High-Yield Clinical Pearls for NEET-PG:** * **Route:** Omalizumab is administered **subcutaneously** every 2–4 weeks. * **Dosing:** The dose is determined by the patient’s baseline serum IgE levels and body weight. * **Black Box Warning:** It carries a risk of **anaphylaxis**; therefore, patients must be monitored for a period after injection. * **Other Monoclonals:** Remember **Reslizumab** (Anti-IL-5) and **Dupilumab** (Anti-IL-4 receptor alpha subunit).

Question 147: What is the primary action of glucocorticoids in bronchial asthma?

A. Act as potent bronchodilators
B. Reduce airway inflammation (Correct Answer)
C. Inhibit degranulation of mast cells
D. Block the action of humoral mediators

Explanation: **Explanation:** **Why Option B is Correct:** Glucocorticoids are the most effective **anti-inflammatory** agents used in asthma. Their primary action is to suppress the underlying airway inflammation by inhibiting the recruitment and activation of inflammatory cells (eosinophils, T-lymphocytes, and macrophages). At a molecular level, they bind to cytoplasmic receptors, translocate to the nucleus, and decrease the transcription of pro-inflammatory cytokines (IL-4, IL-5, TNF-α) while increasing the expression of anti-inflammatory proteins. This leads to reduced mucosal edema and decreased airway hyper-responsiveness. **Analysis of Incorrect Options:** * **Option A:** Glucocorticoids are **not bronchodilators**. They do not have a direct effect on airway smooth muscle relaxation and are therefore ineffective for the immediate relief of an acute asthma attack (rescue therapy). * **Option C:** While they have some inhibitory effects on inflammatory cells, **Mast Cell Stabilizers** (like Sodium Cromoglicate) are specifically known for preventing mast cell degranulation. * **Option D:** While steroids reduce the production of mediators (like prostaglandins and leukotrienes via Phospholipase A2 inhibition), they do not "block" the action of humoral mediators at the receptor level; that is the role of drugs like **Leukotriene Receptor Antagonists (LTRAs)**. **NEET-PG High-Yield Pearls:** * **Synergistic Effect:** Glucocorticoids "prime" the lungs by upregulating **β2-receptors**, making the airways more responsive to β2-agonists. * **Drug of Choice:** Inhaled Corticosteroids (ICS) like Budesonide or 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 of voice** (dysphonia). Patients should be advised to rinse their mouth after use.

Question 148: All of the following glucocorticoids can be given by inhalation EXCEPT?

A. Dexamethasone (Correct Answer)
B. Beclomethasone
C. Budesonide
D. Fluticasone

Explanation: **Explanation:** The correct answer is **Dexamethasone**. **Why Dexamethasone is the correct answer:** Glucocorticoids used in the management of bronchial asthma and COPD are categorized into **Inhaled Corticosteroids (ICS)** and **Systemic Corticosteroids**. Dexamethasone is a highly potent, long-acting systemic glucocorticoid. It lacks the specific pharmacokinetic properties required for effective inhalation, such as high first-pass metabolism and high topical-to-systemic potency ratio. If inhaled, it would be absorbed systemically in significant amounts, leading to severe side effects (Cushingoid features, HPA axis suppression) without providing the localized benefit required for airway inflammation. **Why the other options are incorrect:** * **Beclomethasone dipropionate:** A classic ICS. It is a prodrug converted by esterases in the lungs to its active form, ensuring localized action. * **Budesonide:** A widely used ICS with high topical potency and significant first-pass metabolism in the liver, which minimizes systemic toxicity if swallowed. * **Fluticasone propionate:** Known for its high affinity for glucocorticoid receptors and near-zero oral bioavailability, making it one of the most effective and safe inhaled options. **High-Yield Clinical Pearls for NEET-PG:** * **Ciclesonide** is a "soft drug" (prodrug) activated only by bronchial esterases, further reducing the risk of oropharyngeal candidiasis. * **Flunisolide** and **Mometasone** are other examples of inhaled steroids. * **Side Effects of ICS:** The most common local side effects are **Oropharyngeal Candidiasis** (thrush) and **Hoarseness of voice** (dysphonia). These can be prevented by using a spacer or rinsing the mouth with water after inhalation. * **Systemic Steroids in Asthma:** Reserved for acute severe asthma (Status Asthmaticus) or severe persistent asthma (e.g., Hydrocortisone IV or Prednisolone orally).

Question 149: Which enzyme is inhibited by caffeine?

A. Monoamine oxidase
B. Alcohol dehydrogenase
C. Phosphodiesterase (Correct Answer)
D. Cytochromo P 450

Explanation: **Explanation:** **Caffeine** belongs to the **Methylxanthine** class of drugs (along with theophylline and theobromine). Its primary mechanism of action involves the **non-selective inhibition of the enzyme Phosphodiesterase (PDE)**. 1. **Why Phosphodiesterase is correct:** PDE is responsible for the degradation of cyclic nucleotides (cAMP and cGMP). By inhibiting PDE, caffeine prevents the breakdown of **cAMP**, leading to increased intracellular levels of this second messenger. In the respiratory system, elevated cAMP causes bronchodilation and inhibits the release of inflammatory mediators. Additionally, caffeine acts as an **adenosine receptor antagonist** ($A_1$ and $A_2$ receptors), which further contributes to its CNS stimulant and bronchodilatory effects. 2. **Why other options are incorrect:** * **Monoamine oxidase (MAO):** This enzyme breaks down catecholamines (epinephrine, norepinephrine). While caffeine increases catecholamine release, it does not inhibit MAO. * **Alcohol dehydrogenase:** This is the primary enzyme for ethanol metabolism; caffeine has no inhibitory effect here. * **Cytochrome P450:** Caffeine is actually a **substrate** for CYP1A2, not a primary inhibitor. In fact, other drugs (like ciprofloxacin) inhibit CYP1A2, leading to caffeine toxicity. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Caffeine citrate is the DOC for **Apnea of Prematurity** due to its wider therapeutic index and longer half-life compared to theophylline. * **Therapeutic Range:** Theophylline has a narrow therapeutic window (10–20 µg/ml); caffeine is safer. * **Adverse Effects:** High doses can cause tachycardia, restlessness, and increased gastric acid secretion.

Question 150: All of the following are true about antitussives and mucolytics, except:

A. Dextromethorphan is an NMDA receptor antagonist that acts as a central antitussive.
B. Ambroxol is a mucolytic agent that causes depolymerization of mucopolysaccharides.
C. Carbocisteine is a mucolytic agent with a free sulfhydryl group. (Correct Answer)
D. Baclofen is a peripheral-acting antitussive.

Explanation: **Explanation:** The correct answer is **C** because it contains a factual error regarding the chemical structure of the drug. 1. **Why Option C is the correct answer (The False Statement):** While both **Acetylcysteine** and **Carbocisteine** are mucolytics, only Acetylcysteine contains a **free sulfhydryl (-SH) group**. This group directly breaks the disulfide bonds in mucoproteins to liquefy mucus. In contrast, **Carbocisteine** has its sulfhydryl group "blocked" (carboxymethylated). It works by altering the synthesis of bronchial secretions (increasing sialomucins and decreasing fucomucins), making it a **mucoregulatory** agent rather than a direct-acting mucolytic. 2. **Analysis of Other Options:** * **Option A:** Dextromethorphan is a d-isomer of the codeine analog levorphanol. It acts centrally on the cough center and is an **NMDA receptor antagonist**. It lacks analgesic or addictive properties, making it a preferred non-opioid antitussive. * **Option B:** Ambroxol (a metabolite of Bromhexine) acts by **depolymerizing mucopolysaccharides** and stimulating surfactant production, which reduces mucus viscosity. * **Option C (Correction):** Baclofen is a GABA-B agonist. While primarily a muscle relaxant, it acts as a **centrally acting antitussive** (not peripheral) by inhibiting the cough reflex arc, often used in refractory cases. *Note: The question asks for the "except" (false) statement; while D is technically inaccurate regarding the site of action, C is the more classically tested biochemical distinction in pharmacology.* **High-Yield Clinical Pearls for NEET-PG:** * **Acetylcysteine** is also the specific antidote for **Paracetamol (Acetaminophen) poisoning** as it replenishes glutathione stores. * **Benzonatate** is a unique **peripheral-acting antitussive** that anesthetizes stretch receptors in the lungs. * **Guaifenesin** is the most commonly used **expectorant** (increases airway fluid volume).

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

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