Respiratory System Drugs — MCQs

Respiratory System Drugs Indian Medical PG Practice Questions and MCQs

Question 251: Assertion: Acetylcysteine is used to induce sputum for CBNAAT testing in patients suspected of having tuberculosis. Reason: Acetylcysteine acts as a mucolytic agent that helps to liquefy thick, viscous respiratory secretions, making it easier to obtain a sputum sample.

A. Assertion is false, Reason is false.
B. Assertion is true, Reason is true, but Reason is not the correct explanation for Assertion.
C. Assertion is true, Reason is true, and Reason is the correct explanation for Assertion. (Correct Answer)
D. Assertion is false, Reason is true.

Explanation: **Assertion is true, Reason is true, and Reason is the correct explanation for Assertion.** - **Acetylcysteine** is frequently used as a mucolytic agent to prepare sputum samples, especially when patients have difficulty producing adequate amounts for testing. - Its mechanism of action involves **breaking down disulfide bonds** in mucoproteins, which reduces the viscosity of sputum, making it easier to expectorate and process for tests like **CBNAAT**. *Assertion is false, Reason is false.* - This statement is incorrect because both the assertion and the reason are factually accurate regarding the use and mechanism of acetylcysteine in sputum induction. - **Acetylcysteine** is a well-established mucolytic, and sputum induction is a common practice for obtaining samples for tuberculosis diagnostics. *Assertion is true, Reason is true, but Reason is not the correct explanation for Assertion.* - This is incorrect because the reason directly explains *why* acetylcysteine is used for sputum induction for CBNAAT testing. - The mucolytic action of **acetylcysteine** is precisely what facilitates the easier collection of a quality sputum sample. *Assertion is false, Reason is true.* - This statement is incorrect as the assertion that acetylcysteine is used to induce sputum for CBNAAT is true. - The therapeutic use of **acetylcysteine** for sputum sample collection is a recognized clinical practice.

Question 252: How do antihistamines help in allergic rhinitis?

A. inhibit prostaglandin synthesis to relieve itching.
B. block histamine receptors to reduce symptoms. (Correct Answer)
C. reduce inflammation by blocking leukotrienes.
D. prevent the release of mast cell mediators.

Explanation: **Correct Answer: Block histamine receptors to reduce symptoms.** - Antihistamines work by competitively binding to **histamine H1 receptors**, preventing histamine from exerting its effects. - This action directly reduces symptoms such as **sneezing**, **itching**, and **rhinorrhea** (runny nose) associated with allergic reactions. - They act after histamine has been released by blocking its receptors on target tissues. *Incorrect: Inhibit prostaglandin synthesis to relieve itching.* - This mechanism of action is characteristic of **NSAIDs (non-steroidal anti-inflammatory drugs)**, which primarily target pain and inflammation, not the histamine-mediated symptoms of allergic rhinitis. - While prostaglandins can contribute to inflammation, antihistamines do not act on their synthesis. *Incorrect: Reduce inflammation by blocking leukotrienes.* - This mechanism describes the action of **leukotriene receptor antagonists** (e.g., Montelukast), which are used in asthma and allergic rhinitis but are distinct from antihistamines. - Leukotrienes are potent inflammatory mediators, and blocking them helps reduce inflammation and bronchoconstriction. *Incorrect: Prevent the release of mast cell mediators.* - This is the mechanism of **mast cell stabilizers** (e.g., cromolyn sodium), which prevent the degranulation of mast cells and the subsequent release of histamine and other inflammatory mediators. - Antihistamines act after histamine has already been released, not before.

Question 253: How do corticosteroids reduce symptoms of allergic rhinitis?

A. inhibit histamine release from mast cells.
B. decrease prostaglandin production.
C. block leukotriene receptors.
D. reduce inflammation by inhibiting phospholipase A2. (Correct Answer)

Explanation: ***reduce inflammation by inhibiting phospholipase A2*** - Corticosteroids exert their anti-inflammatory effects by inhibiting **phospholipase A2**, an enzyme crucial for releasing arachidonic acid from cell membranes. - This inhibition in turn prevents the synthesis of various inflammatory mediators, including **prostaglandins** and **leukotrienes**, thereby reducing the symptoms of allergic rhinitis. *inhibit histamine release from mast cells.* - While corticosteroids can stabilize mast cell membranes over time, their primary mechanism of action in allergic rhinitis is not the direct, immediate inhibition of **histamine release**. - **Antihistamines** are specifically designed to block the effects of histamine or reduce its release. *decrease prostaglandin production.* - Corticosteroids do decrease **prostaglandin production**, but this is a *downstream effect* of their inhibition of phospholipase A2, which is the more direct and overarching mechanism. - Non-steroidal anti-inflammatory drugs (NSAIDs) primarily inhibit **cyclooxygenase (COX) enzymes** to reduce prostaglandin synthesis. *block leukotriene receptors.* - Blocking **leukotriene receptors** is the mechanism of action for **leukotriene receptor antagonists** (e.g., montelukast), not corticosteroids. - Corticosteroids reduce the *production* of leukotrienes by inhibiting phospholipase A2, rather than directly blocking their receptors.

Question 254: Which beta-2 agonist bronchodilator is commonly used as a first-line therapy for managing acute asthma symptoms?

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

Explanation: ***Salbutamol*** - **Salbutamol** (also known as albuterol in some countries) is a **short-acting beta-2 agonist (SABA)** that provides rapid bronchodilation. - Its quick onset of action makes it ideal for the **first-line treatment of acute asthma symptoms** and exercise-induced bronchospasm. *Formoterol* - **Formoterol** is a **long-acting beta-2 agonist (LABA)** with a rapid onset of action, but it is typically used for **maintenance therapy** in combination with an inhaled corticosteroid, not as a rescue inhaler alone. - Using a LABA like formoterol as a monotherapy for acute symptoms without an inhaled steroid can be associated with increased risk of severe asthma exacerbations. *Salmeterol* - **Salmeterol** is another **long-acting beta-2 agonist (LABA)** that has a slower onset of action compared to salbutamol and formoterol. - It is used for **maintenance therapy** to prevent asthma symptoms and is not suitable for the immediate relief of acute asthma attacks. *Terbutaline* - **Terbutaline** is a **short-acting beta-2 agonist (SABA)** that can be used for acute asthma symptoms, similar to salbutamol. - However, **salbutamol** is generally the more commonly prescribed and widely recognized SABA for first-line acute asthma management in India.

Question 255: A patient with chronic obstructive pulmonary disease (COPD) is prescribed a phosphodiesterase-4 inhibitor to reduce the risk of exacerbations. Which drug is most likely being prescribed?

A. Theophylline
B. Salmeterol
C. Roflumilast (Correct Answer)
D. Ipratropium

Explanation: ***Roflumilast*** - **Roflumilast** is a selective **phosphodiesterase-4 (PDE-4) inhibitor** approved specifically for reducing the risk of exacerbations in patients with severe COPD associated with chronic bronchitis and a history of exacerbations. - Its mechanism of action involves increasing intracellular **cAMP**, leading to reduced inflammation and smooth muscle relaxation in the airways. *Theophylline* - Theophylline is a **non-selective phosphodiesterase inhibitor** with a narrow therapeutic index and significant side effects, making it a less preferred option for routine exacerbation prevention [1], [2]. - While it has bronchodilator and anti-inflammatory effects through PDE inhibition, it is not a selective PDE-4 inhibitor [1]. *Salmeterol* - **Salmeterol** is a **long-acting beta-2 agonist (LABA)**, which primarily acts by bronchodilation, not through phosphodiesterase inhibition [1]. - It works by stimulating beta-2 adrenergic receptors in the airways, leading to smooth muscle relaxation. *Ipratropium* - **Ipratropium** is a **short-acting muscarinic antagonist (SAMA)** that works by blocking muscarinic receptors in the airways, leading to bronchodilation [2]. - It does not exert its effects through phosphodiesterase inhibition.

Question 256: What are the advantages of using a long-acting beta-agonist (LABA) in combination with an inhaled corticosteroid for asthma management?

A. Reduces frequency of rescue inhaler use (Correct Answer)
B. May help in preventing long-term complications of asthma
C. May have local side effects
D. Minimizes systemic side effects compared to oral steroids

Explanation: ***Reduces frequency of rescue inhaler use*** - The combination of a LABA and an inhaled corticosteroid (ICS) provides both **bronchodilation** and **anti-inflammatory effects**, leading to better symptom control and reduced need for short-acting beta-agonists (SABAs). - LABAs provide **sustained bronchodilation**, preventing bronchoconstriction over a longer period, while the ICS addresses the underlying inflammation, together leading to a significant decrease in acute symptoms. *May help in preventing long-term complications of asthma* - While improved asthma control can mitigate the risk of some long-term complications, the primary direct advantage of this combination is **symptom management** and **exacerbation prevention**, not an explicit claim of preventing all long-term sequelae. - Long-term complications, such as **airway remodeling**, can still occur in severe or poorly controlled asthma despite combination therapy, although the risk is reduced. - This is a secondary benefit rather than a primary advantage of the combination. *Minimizes systemic side effects compared to oral steroids* - While this is true (inhaled therapy does have fewer systemic effects than oral corticosteroids), it is **not a specific advantage of the LABA/ICS combination** over using ICS alone. - This benefit applies to **all inhaled corticosteroids** regardless of whether they are combined with a LABA. - The question asks specifically about advantages of the **combination therapy**, not just advantages of using inhaled versus oral corticosteroids. *May have local side effects* - This statement is true, as both LABAs and ICS can cause local side effects (e.g., **oral candidiasis** with ICS, **tremor** with LABA), but it is a **disadvantage**, not an advantage. - The question asks for the advantages, and the presence of side effects, even if mild or local, is not an argument in favor of the therapy.

Question 257: In evaluating a new drug for asthma that targets muscle relaxation, which parameter would best indicate its efficacy during a clinical trial?

A. Decreased frequency of asthma attacks
B. Reduction in diurnal peak flow variability
C. Improved FEV1/FVC ratio (Correct Answer)
D. Lower serum IgE levels

Explanation: ***Improved FEV1/FVC ratio*** - A drug targeting muscle relaxation in asthma aims to reduce **bronchoconstriction**, thereby improving airflow. - The **FEV1/FVC ratio** is a direct measure of **airflow obstruction** and reversibility, making it a primary indicator of improved lung mechanics. *Decreased frequency of asthma attacks* - While a desirable outcome, this parameter is often influenced by multiple factors beyond immediate bronchodilation, such as long-term disease control and patient adherence. - It's a **clinical outcome** rather than a direct physiological measure of acute bronchodilatory efficacy. *Reduction in diurnal peak flow variability* - This parameter reflects the **stability of airway inflammation** and responsiveness over a 24-hour period, which is more relevant to long-term disease control and corticosteroid efficacy. - It is an important indicator of asthma control but not the most direct measure of acute **bronchodilator efficacy** from muscle relaxation. *Lower serum IgE levels* - Serum IgE levels are primarily associated with the **allergic component of asthma** and are targeted by therapies like anti-IgE antibodies (e.g., omalizumab). - A drug focused on muscle relaxation would not directly impact **IgE production** or levels.

Question 258: A 25-year-old male with a history of asthma uses an inhaler for quick relief of acute symptoms. Which of the following drugs is most likely to be in his inhaler?

A. Salmeterol
B. Ipratropium
C. Montelukast
D. Albuterol (Correct Answer)

Explanation: ***Albuterol*** - **Albuterol** is a **short-acting beta-2 adrenergic agonist (SABA)**, which is the cornerstone for **quick relief** of acute asthma symptoms due to its rapid onset of bronchodilation. - SABAs work by relaxing the **smooth muscle** surrounding the airways, thereby widening them and improving airflow. *Salmeterol* - **Salmeterol** is a **long-acting beta-2 adrenergic agonist (LABA)**, primarily used for **long-term control** and prevention of asthma symptoms, not for acute relief. - LABAs have a slower onset of action and provide bronchodilation for up to 12 hours, making them unsuitable for immediate symptom management. *Ipratropium* - **Ipratropium** is a **short-acting muscarinic antagonist (SAMA)**, which can be used as an alternative or adjunct to SABAs for acute asthma, especially in patients who cannot tolerate SABAs. - It works by blocking **acetylcholine's constrictive effects** on airways but is generally slower and less potent than SABAs for acute bronchodilation. *Montelukast* - **Montelukast** is a **leukotriene receptor antagonist** used for **long-term control** and prevention of asthma symptoms, particularly for exercise-induced asthma or aspirin-sensitive asthma. - It has a slower onset of action and is not effective for the immediate relief of acute asthma attacks.

Question 259: Which medication is considered the first-line treatment for long-term management of asthma?

A. Inhaled corticosteroids are the first-line treatment. (Correct Answer)
B. Combination therapy is the first-line treatment.
C. Long-acting beta agonists are the first-line treatment.
D. None of the options is the first-line treatment.

Explanation: ***Inhaled corticosteroids are the first-line treatment.*** - **Inhaled corticosteroids (ICS)** are the cornerstone of long-term asthma therapy due to their potent **anti-inflammatory effects** on the airways [1, 2]. - They reduce **airway hyperresponsiveness**, prevent exacerbations, and improve lung function by targeting the underlying inflammation of asthma [1].*Combination therapy is the first-line treatment.* - **Combination therapy**, typically involving an ICS and a **long-acting beta-agonist (LABA)**, is reserved for patients whose asthma is not well-controlled with ICS alone [1]. - While highly effective, it is a step-up therapy rather than the initial first-line approach for most newly diagnosed or mild asthmatics [1].*Long-acting beta agonists are the first-line treatment.* - **Long-acting beta-agonists (LABAs)** are bronchodilators that provide prolonged relief of bronchoconstriction but do not address airway inflammation [2]. - They should **never be used as monotherapy** in asthma due to the risk of masking inflammation and potentially increasing adverse events [1].*None of the options is the first-line treatment.* - This statement is incorrect as **inhaled corticosteroids** are indeed recognized as the primary first-line treatment for long-term asthma management [1, 2]. - Major asthma guidelines consistently recommend ICS as the initial and foundational therapy [1, 2].

Question 260: Which drug class is commonly used in the treatment of asthma to reduce inflammation in the airways?

A. Anticholinergics
B. Leukotriene modifiers
C. Corticosteroids (Correct Answer)
D. Beta-blockers

Explanation: ***Corticosteroids*** - **Inhaled corticosteroids** are the most effective anti-inflammatory medications for controlling persistent asthma. - They work by reducing the **synthesis of inflammatory mediators** and decreasing airway hyperresponsiveness. *Anticholinergics* - Primarily act as **bronchodilators** by blocking acetylcholine's effects on muscarinic receptors in the airways, leading to smooth muscle relaxation. - While they can improve airflow, their direct anti-inflammatory effect is **minimal** compared to corticosteroids. *Leukotriene modifiers* - These drugs block the action or synthesis of **leukotrienes**, which are inflammatory mediators involved in bronchoconstriction and airway inflammation. - They have anti-inflammatory properties but are generally considered **less potent** than inhaled corticosteroids for perennial asthma control. *Beta-blockers* - These medications can **worsen asthma symptoms** by blocking beta-2 adrenergic receptors in the airways, leading to bronchoconstriction. - They are specifically **contraindicated** in most asthmatic patients due to this risk.

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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