Respiratory System Drugs Practice Questions

Q: Beta-agonists in asthma act by which of the following mechanisms, except?

Decrease inflammation. ### Explanation **Mechanism of Action:** Beta-2 ($\beta_2$) agonists (like Salbutamol and Salmeterol) act by stimulating $\beta_2$ receptors on bronchial smooth muscle. This activates the enzyme **adenylyl cyclase**, increasing intracellular **cAMP** levels. Elevated cAMP leads to the activation of Protein Kinase A, which causes smooth muscle relaxation and potent **bronchodilatation**. **Why "Decrease inflammation" is the correct answer:** While $\beta_2$ agonists are excellent bronchodilators, they have **no significant anti-inflammatory effect**. They do not inhibit the late-phase inflammatory response or reduce airway hyper-responsiveness over time. In asthma management, inflammation is primarily addressed by **Corticosteroids**, not $\beta_2$ agonists. **Analysis of Incorrect Options:** * **Option A (Cause bronchodilatation):** This is the primary physiological effect of $\beta_2$ agonists. They are the most potent bronchodilators available. * **Option B (Abort an acute attack):** Short-Acting Beta-Agonists (SABAs) like Salbutamol have a rapid onset of action (2–5 minutes), making them the "rescue" drugs of choice to abort acute bronchospasm. * **Option D (All of the above):** Incorrect, as the drugs lack anti-inflammatory properties. **NEET-PG High-Yield Pearls:** * **Drug of Choice (DOC):** SABAs are the DOC for acute asthma attacks and exercise-induced bronchospasm. * **Side Effects:** Muscle tremors (most common, due to $\beta_2$ stimulation in skeletal muscles), tachycardia (due to $\beta_1$ cross-reactivity), and **hypokalemia** (due to K+ shifting into cells). * **Tolerance:** Prolonged use can lead to "tachyphylaxis" due to the down-regulation of $\beta_2$ receptors. * **LABAs:** Salmeterol and Formoterol are Long-Acting Beta-Agonists used for maintenance, never as monotherapy (always combined with inhaled steroids).

Q: What is the mechanism of action of Montelukast?

Inhibition of leukotriene production. **Explanation:** **Mechanism of Action:** Montelukast is a **Leukotriene Receptor Antagonist (LTRA)**. Specifically, it works by competitively and selectively inhibiting the **CysLT1 receptor**. By blocking this receptor, it prevents the actions of cysteinyl leukotrienes (LTC4, LTD4, and LTE4), which are potent inflammatory mediators. This leads to a reduction in bronchoconstriction, airway edema, and mucus secretion, making it effective in the management of bronchial asthma. **Analysis of Options:** * **Option A (Correct):** By blocking the receptor, Montelukast effectively inhibits the physiological effects of leukotriene production in the airways. (Note: While Zileuton inhibits the *synthesis* via 5-LOX, LTRAs like Montelukast are clinically categorized under the umbrella of leukotriene modifiers/inhibitors). * **Option B:** Alpha-receptor inhibitors (e.g., Prazosin) are used for hypertension or BPH, not for asthma. * **Option C:** Beta-2 agonists (e.g., Salbutamol, Salmeterol) act by stimulating receptors to increase cAMP, causing direct bronchodilation. * **Option D:** Phosphodiesterase (PDE) inhibition is the mechanism for **Theophylline** (non-selective) or **Roflumilast** (PDE-4 selective). **High-Yield Clinical Pearls for NEET-PG:** 1. **Churg-Strauss Syndrome:** A rare but high-yield association; patients switching from oral steroids to Montelukast may unmask this systemic vasculitis. 2. **Aspirin-Induced Asthma:** LTRAs are the **drugs of choice** for Aspirin-Exacerbated Respiratory Disease (AERD). 3. **Exercise-Induced Bronchospasm:** Montelukast is effective for prophylaxis in these patients. 4. **Neuropsychiatric Side Effects:** The FDA has issued a boxed warning for Montelukast regarding serious mental health side effects (e.g., agitation, aggression, suicidal ideation).

Q: A 55-year-old female who is taking propranolol for the management of a cardiovascular disease experiences an acute asthmatic attack. Which of the following drugs would be most appropriate to manage this asthmatic attack?

Ipratropium bromide. **Explanation:** The core clinical challenge in this scenario is **Beta-blocker induced bronchospasm**. Propranolol is a non-selective beta-blocker that inhibits $\beta_2$ receptors in the bronchial smooth muscle, leading to bronchoconstriction. **1. Why Ipratropium Bromide is the correct answer:** In patients taking beta-blockers, $\beta_2$ agonists (like Salbutamol) are often ineffective because the receptors are competitively occupied/blocked by the drug. Therefore, the preferred alternative for acute relief is an **Anticholinergic (Muscarinic antagonist)** like **Ipratropium bromide**. It works by blocking M3 receptors, inhibiting the parasympathetic-mediated bronchoconstriction, which remains an open pathway for bronchodilation despite beta-blockade. **2. Why other options are incorrect:** * **Salbutamol:** As a $\beta_2$ agonist, its action is directly antagonized by Propranolol. It will fail to provide rapid relief in this specific patient. * **Cromolyn sodium:** This is a mast cell stabilizer used for **prophylaxis** (prevention) of asthma. It has no role in managing an acute attack as it does not cause bronchodilation. * **Beclomethasone:** This is an inhaled corticosteroid used for **long-term control** of airway inflammation. It has a slow onset of action and is not used for acute "rescue" therapy. **Clinical Pearls for NEET-PG:** * **Drug of Choice (DOC):** For acute asthma in patients on beta-blockers, the DOC is **Ipratropium bromide**. * **Mechanism:** Ipratropium is a quaternary ammonium compound; it is poorly absorbed systemically, leading to fewer side effects (like tachycardia) compared to atropine. * **Contraindication:** Non-selective beta-blockers (Propranolol, Nadolol, Timolol) are strictly contraindicated in asthmatics. If a beta-blocker is mandatory, cardioselective agents (e.g., Metoprolol, Atenolol) are preferred, though still used with caution.

Q: Reslizumab is used in which of the following conditions?

Asthma. **Explanation:** **Reslizumab** is a humanized monoclonal antibody specifically designed to target and neutralize **Interleukin-5 (IL-5)**. IL-5 is the primary cytokine responsible for the growth, differentiation, recruitment, and activation of eosinophils. By binding to IL-5, Reslizumab prevents it from interacting with its receptor on the eosinophil surface, thereby reducing blood and tissue eosinophilia. It is FDA-approved as an add-on maintenance treatment for patients with **severe eosinophilic asthma** who are not adequately controlled on standard therapies. **Analysis of Options:** * **Option A (Psoriasis):** Psoriasis is typically treated with biologics targeting TNF-α (Infliximab), IL-17 (Secukinumab), or IL-23 (Ustekinumab). * **Option B (RSV infection):** The monoclonal antibody used for the prevention of Respiratory Syncytial Virus (RSV) in high-risk infants is **Palivizumab** (targets the RSV F protein). * **Option D (Crohn’s disease):** Management involves biologics targeting TNF-α (Adalimumab) or integrins (Vedolizumab). **High-Yield Clinical Pearls for NEET-PG:** * **Anti-IL-5 Agents:** Remember the trio—**Reslizumab, Mepolizumab** (both target IL-5 ligand), and **Benralizumab** (targets the IL-5 receptor alpha). * **Route of Administration:** Unlike Mepolizumab (subcutaneous), Reslizumab is administered via **intravenous (IV) infusion**. * **Black Box Warning:** Reslizumab carries a risk of **anaphylaxis**; patients must be monitored closely during and after infusion. * **Omalizumab:** Another high-yield asthma biologic that targets **IgE** (used in allergic asthma).

Q: Which of the following antitussives is present in opium but has no analgesic or addicting properties?

Noscapine. **Explanation:** **Noscapine** is a benzylisoquinoline alkaloid naturally found in **opium**. Unlike morphine or codeine, it does not act on opioid receptors ($\mu$, $\delta$, or $\kappa$). Consequently, it is completely devoid of analgesic, euphoric, or addicting properties. It acts as a potent antitussive by suppressing the cough reflex through non-opioid mechanisms. It is particularly useful in spasmodic cough, though it may occasionally release histamine, causing bronchoconstriction in asthmatics. **Analysis of Incorrect Options:** * **Codeine (Methylmorphine):** This is the "gold standard" antitussive. While it is an opium alkaloid, it acts on $\mu$-opioid receptors, leading to side effects like constipation, respiratory depression, and a potential for addiction/abuse. * **Pholcodeine:** A semi-synthetic derivative of morphine. While it has negligible analgesic properties and is less addicting than codeine, it is **not** naturally present in opium; it is synthesized. * **Ethylmorphine:** Similar to codeine, it is a semi-synthetic opioid with significant sedative and potential addictive properties. **High-Yield NEET-PG Pearls:** * **Noscapine** is also known as "Narcotine," but this is a misnomer as it lacks narcotic effects. * **Dextromethorphan** is another common non-analgesic antitussive, but it is a synthetic derivative, not an opium alkaloid. * **Benzonatate** is a peripherally acting antitussive that works by anesthetizing stretch receptors in the lungs. * **Contraindication:** Avoid Noscapine and other cough suppressants in productive coughs, as they can lead to sputum retention and secondary infections.

Q: A child on $\beta_2$ agonists for treatment of bronchial asthma may exhibit all of the following features EXCEPT:

Hypoglycemia. $\beta_2$ agonists (e.g., Salbutamol, Terbutaline) act by stimulating $\beta_2$ receptors, which are primarily coupled to the $G_s$ protein-adenylyl cyclase pathway. **Explanation of the Correct Answer:** **B. Hypoglycemia:** This is the correct answer because $\beta_2$ agonists actually cause **Hyperglycemia**, not hypoglycemia. Stimulation of $\beta_2$ receptors in the liver and skeletal muscles promotes **glycogenolysis** (breakdown of glycogen to glucose) and **gluconeogenesis**. Additionally, they can stimulate glucagon release, further raising blood glucose levels. **Explanation of Incorrect Options:** * **A. Tremors:** This is the most common side effect. It occurs due to direct stimulation of $\beta_2$ receptors in the **skeletal muscles** (specifically the muscle spindles), leading to rhythmic contractions. * **C. Hypokalemia:** $\beta_2$ stimulation activates the **Na⁺/K⁺-ATPase pump**, causing an inward shift of potassium from the extracellular fluid into the cells (primarily skeletal muscle). This is why salbutamol nebulization is used as an emergency treatment for hyperkalemia. * **D. Bronchodilation:** This is the primary therapeutic effect. Stimulation of $\beta_2$ receptors on bronchial smooth muscle increases intracellular cAMP, leading to muscle relaxation. **NEET-PG High-Yield Pearls:** * **Muscle Tremors** are the dose-limiting side effect of oral $\beta_2$ agonists. * **Tachycardia** can occur via two mechanisms: direct stimulation of cardiac $\beta_2$ receptors and reflex tachycardia due to peripheral vasodilation ($\beta_2$ effect on blood vessels). * **Tolerance (Tachyphylaxis):** Prolonged use leads to down-regulation (internalization) of $\beta_2$ receptors. * **Drug of choice** for acute asthma exacerbations: Inhaled short-acting $\beta_2$ agonists (SABA).

Q: A highway truck driver presents with profuse rhinorrhea and sneezing. Which of the following drugs would you prescribe?

Cetirizine. The core clinical consideration in this question is the patient’s occupation: a **highway truck driver**. This requires a medication that treats allergic rhinitis without causing sedation or psychomotor impairment, which could lead to road accidents. **1. Why Cetirizine is correct:** Cetirizine is a **Second-Generation Antihistamine (SGA)**. Unlike first-generation drugs, SGAs have poor lipid solubility and high affinity for P-glycoprotein efflux pumps, preventing them from crossing the blood-brain barrier (BBB) in significant amounts. Consequently, they are "non-sedating" and do not interfere with tasks requiring high alertness, making them the drug of choice for drivers, pilots, and heavy machinery operators [1, 2]. **2. Why the other options are incorrect:** * **Pheniramine, Promethazine, and Dimenhydrinate** are all **First-Generation Antihistamines**. These drugs are highly lipophilic and readily cross the BBB, causing significant sedation, drowsiness, and impaired concentration [1, 2]. * **Promethazine** is particularly potent and is often used for its sedative and anti-emetic properties [1, 2]. * **Dimenhydrinate** is primarily used for motion sickness and is highly sedating [2]. * Prescribing any of these to a truck driver would be a safety hazard [1, 2]. **3. NEET-PG High-Yield Pearls:** * **Second-Generation Antihistamines:** Include Cetirizine, Loratadine, Fexofenadine, and Desloratadine. * **Fexofenadine** is considered the least sedating (truly non-sedating) among the SGAs because it does not cross the BBB at all. * **Azelastine** is a topical (nasal spray) SGA often used for rapid relief of allergic rhinitis. * **Side Effects:** First-generation drugs also cause **anti-cholinergic side effects** (dry mouth, blurred vision, urinary retention), which are largely absent in second-generation drugs.

Question 1

Beta-agonists in asthma act by which of the following mechanisms, except?

Accepted Answer

Decrease inflammation

Answer

Cause bronchodilatation

Answer

Abort an acute attack

Answer

All of the above

Question 2

What is the mechanism of action of Montelukast?

Accepted Answer

Inhibition of leukotriene production

Answer

Inhibits alpha receptors

Answer

Beta receptor agonist

Answer

Phosphodiesterase inhibition

Question 3

A 55-year-old female who is taking propranolol for the management of a cardiovascular disease experiences an acute asthmatic attack. Which of the following drugs would be most appropriate to manage this asthmatic attack?

Accepted Answer

Ipratropium bromide

Answer

Cromolyn sodium

Answer

Salbutamol

Answer

Beclomethasone

Question 4

Reslizumab is used in which of the following conditions?

Accepted Answer

Asthma

Answer

Psoriasis

Answer

RSV infection

Answer

Crohn's disease

Question 5

Which of the following antitussives is present in opium but has no analgesic or addicting properties?

Accepted Answer

Noscapine

Answer

Codeine

Answer

Pholcodeine

Answer

Ethylmorphine

Question 6

Which of the following drugs is a second-generation antihistamine?

Accepted Answer

Loratadine

Answer

Promethazine

Answer

Diphenhydramine

Answer

Doxylamine

Question 7

Which of the following anti-asthma drugs is not indicated for oral administration in pregnancy?

Accepted Answer

Ipratropium bromide

Answer

Salbutamol

Answer

Prednisolone

Answer

Theophylline

Question 8

A child on $\beta_2$ agonists for treatment of bronchial asthma may exhibit all of the following features EXCEPT:

Accepted Answer

Hypoglycemia

Answer

Tremors

Answer

Hypokalemia

Answer

Bronchodilation

Question 9

The second phase of bronchial asthma can be prevented by which of the following classes of drugs?

Accepted Answer

Corticosteroids

Answer

Beta-2 agonists

Answer

Xanthine derivatives

Answer

Anticholinergics

Question 10

A highway truck driver presents with profuse rhinorrhea and sneezing. Which of the following drugs would you prescribe?

Accepted Answer

Cetirizine

Answer

Pheniramine

Answer

Promethazine

Answer

Dimenhydrinate

Respiratory System Drugs — MCQs

Respiratory System Drugs — MCQs

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