Respiratory System Drugs Practice Questions

Q: In a child with exercise-induced asthma, which prophylactic measure is most appropriate?

Prophylaxis with mast cell stabilizers. **Explanation:** **Exercise-Induced Bronchoconstriction (EIB)** occurs due to the loss of heat and moisture from the airways during rapid breathing, leading to mast cell degranulation and the release of inflammatory mediators like histamine and leukotrienes. **Why Option B is Correct:** **Mast cell stabilizers** (e.g., Sodium Cromoglycate or Nedocromil) are the classic prophylactic agents for EIB. They work by stabilizing the mast cell membrane, preventing the release of bronchoconstrictive mediators triggered by exercise. When administered 10–20 minutes before physical activity, they effectively prevent symptoms without the systemic side effects of other drugs. **Why Other Options are Incorrect:** * **Option A (Steroids):** While Inhaled Corticosteroids (ICS) are the mainstay for *chronic* persistent asthma, they are not used as immediate "prophylaxis" right before exercise because they do not provide acute protection against EIB. * **Option C (Theophylline):** This is a weak bronchodilator with a narrow therapeutic index and significant side effects. It is not a first-line or preferred agent for exercise prophylaxis. * **Option D (Breathing exercises):** While helpful for general lung health, they cannot prevent the biochemical and physiological trigger of mast cell degranulation caused by exercise. **NEET-PG High-Yield Pearls:** * **Drug of Choice (DOC):** Short-Acting Beta-Agonists (**SABA**, e.g., Salbutamol) are currently considered the most effective first-line prophylaxis for EIB when used 5–15 minutes before exercise. * **Alternative/Classic Answer:** If SABA is not an option, **Mast Cell Stabilizers** are the preferred answer in traditional exam patterns. * **Non-Pharmacological Tip:** A thorough warm-up period and wearing a mask in cold weather can reduce the severity of EIB. * **Montelukast (LTRA):** Can also be used for EIB prophylaxis, especially in patients who do not want to use inhalers.

Q: Which of the following antihistamines can be used topically in allergic rhinitis?

Azelastine. **Explanation:** **Azelastine** is a second-generation H1-receptor antagonist specifically designed for **topical administration** (nasal spray or ophthalmic drops). In allergic rhinitis, its topical application provides a rapid onset of action (within 15–30 minutes) and achieves high local concentrations with minimal systemic absorption. Beyond its antihistaminic properties, it also inhibits mast cell degranulation and decreases the expression of adhesion molecules, making it highly effective for both seasonal and perennial allergic rhinitis. **Analysis of Incorrect Options:** * **Terfenadine (A):** This was the first non-sedating antihistamine but was **withdrawn globally** due to its potential to cause *Torsades de Pointes* (QT prolongation) when co-administered with CYP3A4 inhibitors (e.g., Ketoconazole, Erythromycin). It is a prodrug of Fexofenadine and is only available orally. * **Cetirizine (C):** A potent second-generation H1 blocker and a metabolite of Hydroxyzine. While highly effective, it is administered **orally** and is known for causing mild sedation in some patients compared to other second-generation agents. * **Fexofenadine (D):** The active metabolite of Terfenadine. It is considered the "most non-sedating" antihistamine. Like Cetirizine, it is administered **orally** and does not have a topical formulation for rhinitis. **High-Yield Clinical Pearls for NEET-PG:** * **Topical Antihistamines:** Apart from Azelastine, **Levocabastine** and **Olopatadine** are other agents used topically (nasal/ocular). * **Side Effect:** A common side effect of Azelastine nasal spray is a **bitter aftertaste** (dysgeusia). * **Drug of Choice:** For allergic rhinitis, intranasal corticosteroids are the first-line treatment, but topical antihistamines are preferred when rapid symptom relief is required. * **Safety:** Unlike Terfenadine and Astemizole, Fexofenadine and Cetirizine do not cause cardiotoxicity.

Q: Which one of the following is not recommended for the immediate treatment of acute severe asthma?

Salmeterol. **Explanation:** The management of acute severe asthma (status asthmaticus) requires **rapid-acting** bronchodilators and anti-inflammatory agents to reverse life-threatening airway obstruction. **Why Salmeterol is the correct answer:** Salmeterol is a **Long-Acting Beta-2 Agonist (LABA)**. It has a slow onset of action (approximately 15–30 minutes) and is strictly used for the long-term maintenance/prophylaxis of asthma. In an acute emergency, using a drug with a delayed onset is dangerous and ineffective. Therefore, LABAs (except Formoterol, which has a fast onset but is still not the primary choice for acute severe cases) are contraindicated for immediate rescue therapy. **Analysis of incorrect options:** * **Ipratropium (SAMA):** This is an inhaled anticholinergic used as an adjunct to SABA (Salbutamol) in acute severe asthma. It provides additional bronchodilation and reduces mucus secretion. * **Magnesium sulfate:** Administered intravenously, it acts as a smooth muscle relaxant by blocking calcium channels. It is recommended in patients who do not respond adequately to initial bolus nebulization. * **Hydrocortisone:** Systemic corticosteroids (IV Hydrocortisone or Methylprednisolone) are mainstay treatments to reduce airway inflammation and prevent late-phase responses. **NEET-PG High-Yield Pearls:** * **Drug of Choice (DOC)** for acute asthma: Inhaled **Salbutamol** (SABA). * **DOC for Prophylaxis:** Inhaled Corticosteroids (e.g., Fluticasone). * **Salmeterol vs. Formoterol:** Both are LABAs, but Formoterol has a fast onset (comparable to Salbutamol), whereas Salmeterol has a slow onset. * **SMART Therapy:** Refers to "Single Maintenance and Reliever Therapy" using a combination of Formoterol and Budesonide.

Q: An agitated and nervous 24-year-old woman has had severe wheezing and shortness of breath for 2 days. After receiving oxygen, steroids, and salbutamol (Ventolin) in the emergency room, her breathing improves. She is still wheezing and now feels tremulous and anxious with a pulse of 110/min and respirations 30/min. Arterial blood gases on oxygen reveal a pH of 7.40, PO2 340 mm Hg, PCO2 40 mm Hg, and bicarbonate of 24 mEq/L. She is hospitalized for further treatment. Which of the following treatments or medications should be avoided in her?

Sedatives. **Explanation:** The correct answer is **Sedatives (Option B)**. **Why Sedatives are Contraindicated:** The patient is presenting with a severe asthma exacerbation. Although she shows clinical improvement, her ABG reveals a **PCO2 of 40 mm Hg**. In a patient with tachypnea (respiratory rate of 30/min), one would expect a low PCO2 due to hyperventilation. A "normal" PCO2 in the setting of respiratory distress is an ominous sign indicating **respiratory muscle fatigue** and impending respiratory failure. Administering sedatives (like benzodiazepines) to an anxious patient with severe asthma is dangerous because they **depress the respiratory drive**. This can lead to hypoventilation, CO2 retention, and respiratory arrest. The patient's anxiety is likely a physiological response to hypoxia and the work of breathing, not a primary psychiatric issue. **Analysis of Incorrect Options:** * **Theophylline (Option A):** While no longer first-line due to a narrow therapeutic index, it is a bronchodilator that can be used in refractory cases. * **Corticosteroids (Option C):** These are the cornerstone of treatment for acute severe asthma to reduce airway inflammation. * **Sympathomimetic amines (Option D):** Drugs like Salbutamol (Beta-2 agonists) are the first-line treatment for bronchodilation. Her tremors and tachycardia are expected side effects of these medications. **NEET-PG High-Yield Pearls:** 1. **The "Normal" PCO2 Trap:** In acute asthma, a normal or rising PCO2 is a "red flag" indicating that the patient can no longer maintain the work of breathing. 2. **Drug of Choice:** Inhaled SABA (Salbutamol) is the DOC for acute relief; Systemic Corticosteroids are DOC for preventing relapse and reducing inflammation. 3. **Side Effects:** Beta-2 agonists commonly cause **hypokalemia, tremors, and tachycardia**.

Q: What is Tiotropium used for?

Treating asthma. **Explanation:** **Tiotropium** is a long-acting muscarinic antagonist (LAMA) that plays a crucial role in the management of obstructive airway diseases. **1. Why Option D is Correct:** Tiotropium works by competitively and reversibly inhibiting **M3 receptors** located on the smooth muscles of the bronchi. Blockade of these receptors prevents acetylcholine-induced bronchoconstriction, leading to prolonged **bronchodilation**. While traditionally the mainstay for COPD, Tiotropium is now frequently used as an "add-on" therapy in **bronchial asthma** (Step 4 or 5 of GINA guidelines) for patients not well-controlled on ICS-LABA combinations. Its long duration of action (24 hours) allows for once-daily dosing. **2. Why Other Options are Incorrect:** * **Options A & B:** Tiotropium is an anticholinergic. Anticholinergics actually *cause* urinary retention and decrease GI motility (potentially worsening ileus). Drugs used for these conditions are typically **cholinergics** (e.g., Bethanechol for urinary retention, Neostigmine for ileus). * **Option C:** Anticholinergics cause **xerostomia** (dry mouth) by blocking M3 receptors in salivary glands. Cholinergic agonists (e.g., Pilocarpine) are used to increase salivation. **3. NEET-PG High-Yield Pearls:** * **M3 Selectivity:** Tiotropium is kinetically selective; it dissociates very slowly from M3 and M1 receptors but rapidly from M2 receptors (which are autoreceptors that inhibit ACh release). This makes it more effective than Ipratropium. * **Delivery:** It is administered via inhalation (e.g., HandiHaler or Respimat) to minimize systemic side effects. * **Side Effects:** The most common side effect reported is **dry mouth**. * **Comparison:** Unlike Ipratropium (SAMA - Short-acting), Tiotropium is a **LAMA** (Long-acting).

Q: A patient with a known history of COPD is being treated with theophylline. Which of the following side effects is commonly observed due to the drug's inhibition of phosphodiesterase 4 (PDE4)?

Headache. **Explanation:** Theophylline is a methylxanthine derivative used in COPD and asthma. It has a multi-modal mechanism of action: non-selective inhibition of **phosphodiesterase (PDE) enzymes** (increasing cAMP), antagonism of **adenosine receptors**, and enhancement of **histone deacetylation**. **1. Why Headache is Correct:** Theophylline inhibits **PDE4**, the primary PDE isoform in airway smooth muscle and inflammatory cells. However, PDE4 is also found in the central nervous system and vascular smooth muscle. Inhibition of PDE4 leads to an accumulation of cAMP, which causes **vasodilation of cerebral blood vessels**. This vasodilation is the primary trigger for the common side effect of **headaches**. **2. Analysis of Incorrect Options:** * **B. Diuresis:** This is primarily caused by the **antagonism of Adenosine A1 receptors** in the kidneys, which increases glomerular filtration and inhibits sodium reabsorption. * **C. Cardiac Arrhythmias:** These occur at high serum concentrations due to **Adenosine A1 receptor antagonism** (which increases heart rate) and inhibition of **PDE3** (which increases cardiac contractility and heart rate). * **D. Epileptic Seizures:** These are a sign of severe toxicity and are largely attributed to the **antagonism of Adenosine A1 receptors** in the brain, which removes the natural inhibitory effect of adenosine on neuronal firing. **Clinical Pearls for NEET-PG:** * **Therapeutic Window:** Narrow (10–20 µg/ml). Monitoring is essential. * **Metabolism:** Metabolized by **CYP1A2**. Enzyme inhibitors like Ciprofloxacin or Erythromycin can precipitate toxicity. * **PDE4 Specificity:** While Theophylline is non-selective, **Roflumilast** is a selective PDE4 inhibitor used in COPD, also frequently causing headache and weight loss.

Q: Which of the following is not a bronchodilator?

Steroids. **Explanation:** The core concept in respiratory pharmacology is distinguishing between **bronchodilators** (which provide symptomatic relief by relaxing airway smooth muscle) and **anti-inflammatory agents** (which treat the underlying disease process). **Why Steroids are the correct answer:** Corticosteroids (e.g., Fluticasone, Prednisolone) are **not bronchodilators**. They do not cause immediate relaxation of the airway smooth muscle. Instead, they act as **anti-inflammatory agents** by inhibiting the recruitment of inflammatory cells, reducing mucosal edema, and decreasing capillary permeability. Their primary role is "control" rather than "rescue," and they take several hours to days to show clinical effects. **Why the other options are incorrect:** * **Beta-2 Agonists (e.g., Salbutamol, Salmeterol):** These are the most potent bronchodilators. They stimulate $\beta_2$ receptors, increasing intracellular cAMP, which leads to direct relaxation of bronchial smooth muscle. * **Methylxanthines (e.g., Theophylline, Aminophylline):** These act by inhibiting the enzyme phosphodiesterase (PDE), preventing the breakdown of cAMP, and by antagonizing adenosine receptors, resulting in bronchodilation. * **Anticholinergics (e.g., Ipratropium, Tiotropium):** These block $M_3$ muscarinic receptors in the bronchial smooth muscle, inhibiting the bronchoconstrictor effect of acetylcholine. **High-Yield Clinical Pearls for NEET-PG:** * **Synergy:** While steroids aren't bronchodilators, they **upregulate $\beta_2$ receptors**, making the airways more responsive to $\beta_2$ agonists. * **Drug of Choice (DOC):** In acute asthma attacks, the DOC is a **SABA** (Short-Acting Beta Agonist). For chronic maintenance of persistent asthma, the DOC is **Inhaled Corticosteroids (ICS)**. * **Side Effect:** A common side effect of ICS is oropharyngeal candidiasis; patients should be advised to rinse their mouth after use.

Q: Long-term use of which of the following drugs is most likely associated with the development of tremors?

Salbutamol. **Explanation:** **Salbutamol** is a short-acting **Beta-2 ($\beta_2$) agonist** used primarily as a bronchodilator in asthma and COPD. The development of tremors is the most common dose-related side effect of $\beta_2$ agonists. This occurs because $\beta_2$ receptors are present on the **skeletal muscle fibers**. Stimulation of these receptors causes an increase in the speed of muscle contraction and an imbalance in muscle spindle activity, leading to fine muscle tremors (typically in the hands). **Analysis of Incorrect Options:** * **Propofol (A):** An intravenous anesthetic agent. While it can rarely cause excitatory phenomena (myoclonus) during induction, it is not associated with chronic tremors. * **Betaxolol (C) & Timolol (D):** These are **Beta-blockers**. Betaxolol is $\beta_1$-selective, while Timolol is non-selective. Beta-blockers are actually used clinically to *treat* tremors (e.g., essential tremors or physiological tremors) by blocking the $\beta_2$ receptors on skeletal muscles. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism of Tremor:** Direct stimulation of $\beta_2$ receptors on skeletal muscles (not a CNS effect). * **Other Side Effects of Salbutamol:** Hypokalemia (due to $K^+$ shift into cells), tachycardia (direct $\beta_2$ and reflex $\beta_1$ stimulation), and hyperglycemia. * **Tolerance:** Continuous use of $\beta_2$ agonists can lead to **downregulation (tachyphylaxis)** of receptors, though tremors often diminish over time as the body adapts. * **Drug of Choice:** Salbutamol remains the drug of choice for acute episodes of bronchospasm (Rescue inhaler).

Question 1

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

Accepted Answer

Carbocisteine is a mucolytic agent with a free sulfhydryl group.

Answer

Dextromethorphan is an NMDA receptor antagonist that acts as a central antitussive.

Answer

Ambroxol is a mucolytic agent that causes depolymerization of mucopolysaccharides.

Answer

Baclofen is a peripheral-acting antitussive.

Question 2

In a child with exercise-induced asthma, which prophylactic measure is most appropriate?

Accepted Answer

Prophylaxis with mast cell stabilizers

Answer

Prophylaxis with steroids

Answer

Prophylaxis with theophylline

Answer

Breathing exercises

Question 3

Intranasal spray of budesonide is indicated in which of the following conditions?

Accepted Answer

Perennial vasomotor rhinitis

Answer

Acute sinusitis

Answer

Common cold

Answer

Epistaxis

Question 4

Which of the following antihistamines can be used topically in allergic rhinitis?

Accepted Answer

Azelastine

Answer

Terfenadine

Answer

Cetirizine

Answer

Fexofenadine

Question 5

Which one of the following is not recommended for the immediate treatment of acute severe asthma?

Accepted Answer

Salmeterol

Answer

Ipratropium

Answer

Magnesium sulfate

Answer

Hydrocortisone

Question 6

An agitated and nervous 24-year-old woman has had severe wheezing and shortness of breath for 2 days. After receiving oxygen, steroids, and salbutamol (Ventolin) in the emergency room, her breathing improves. She is still wheezing and now feels tremulous and anxious with a pulse of 110/min and respirations 30/min. Arterial blood gases on oxygen reveal a pH of 7.40, PO2 340 mm Hg, PCO2 40 mm Hg, and bicarbonate of 24 mEq/L. She is hospitalized for further treatment. Which of the following treatments or medications should be avoided in her?

Accepted Answer

Sedatives

Answer

Theophylline

Answer

Corticosteroids

Answer

Sympathomimetic amines

Question 7

What is Tiotropium used for?

Accepted Answer

Treating asthma

Answer

Treating urinary retention

Answer

Treating ileus

Answer

Increasing salivation

Question 8

A patient with a known history of COPD is being treated with theophylline. Which of the following side effects is commonly observed due to the drug's inhibition of phosphodiesterase 4 (PDE4)?

Accepted Answer

Headache

Answer

Diuresis

Answer

Cardiac arrhythmias

Answer

Epileptic seizures

Question 9

Which of the following is not a bronchodilator?

Accepted Answer

Steroids

Answer

Beta 2 agonists

Answer

Methylxanthines

Answer

Anticholinergics

Question 10

Long-term use of which of the following drugs is most likely associated with the development of tremors?

Accepted Answer

Salbutamol

Answer

Propofol

Answer

Betaxolol

Answer

Timolol

Respiratory System Drugs — MCQs

Respiratory System Drugs — MCQs

On this page

Practice by Chapter

Want unlimited practice?