Respiratory System Drugs Practice Questions

Q: Vilanterol is FDA approved for the treatment of which condition?

COPD. **Explanation:** **Vilanterol** is an ultra-long-acting beta-2 agonist (uLABA) characterized by a rapid onset of action and a prolonged duration of effect (24 hours). 1. **Why COPD is correct:** Vilanterol is FDA-approved specifically for the maintenance treatment of airflow obstruction in patients with **Chronic Obstructive Pulmonary Disease (COPD)**, including chronic bronchitis and emphysema. It is typically used in fixed-dose combinations with long-acting muscarinic antagonists (LAMA) like Umeclidinium or inhaled corticosteroids (ICS) like Fluticasone furoate. 2. **Why Asthma is incorrect:** While Vilanterol is used in combination with Fluticasone furoate (Breo Ellipta) for asthma maintenance, **Vilanterol is NOT FDA-approved as a monotherapy for asthma.** In fact, the FDA maintains a "Black Box Warning" against using LABAs/uLABAs alone in asthma due to the increased risk of asthma-related death. In contrast, LABA monotherapy is acceptable and common in COPD management. 3. **Why "Both" is incorrect:** Because the question asks about the drug itself (Vilanterol), and its primary standalone indication and safety profile are rooted in COPD management, "COPD" is the most accurate answer for NEET-PG purposes. **High-Yield Clinical Pearls for NEET-PG:** * **Duration:** Vilanterol has a half-life that allows for **once-daily** dosing. * **Combinations:** * Vilanterol + Fluticasone furoate (ICS/LABA) * Vilanterol + Umeclidinium (LABA/LAMA) * Vilanterol + Umeclidinium + Fluticasone (Triple therapy - Trelegy Ellipta) * **Mechanism:** It works by increasing cyclic AMP, leading to relaxation of bronchial smooth muscle. * **Comparison:** Unlike Salmeterol (slow onset), Vilanterol has a **rapid onset** similar to Formoterol but lasts significantly longer.

Q: Which NMDA blocker is used as an antitussive?

Dextromethorphan. **Explanation:** **Dextromethorphan (Option B)** is the correct answer. It is the d-isomer of the codeine analog levorphanol. Unlike its l-isomer counterpart, it does not have significant analgesic or addictive properties [1]. Its primary mechanism as an antitussive involves increasing the cough threshold in the medulla. Crucially for this question, it acts as a **non-competitive NMDA receptor antagonist** [2], which contributes to its efficacy and also explains its potential for dissociative effects (hallucinations) when taken in high doses (abuse potential) [3]. **Analysis of Incorrect Options:** * **Pholcodeine (Option A):** This is a semi-synthetic opioid antitussive [2]. While it is more potent than codeine and has a longer duration of action, its primary mechanism is via opioid receptors in the cough center, not NMDA blockade. * **Diphenhydramine (Option B):** This is a first-generation H1-receptor antagonist. It is used as an adjuvant in cough syrups primarily for its sedative and anticholinergic (drying) properties [3], rather than a direct NMDA-mediated antitussive effect. * **Aprepitant (Option D):** This is a Neurokinin-1 (NK1) receptor antagonist used primarily as an antiemetic in chemotherapy-induced nausea and vomiting (CINV). It has no established role as a standard antitussive. **High-Yield Clinical Pearls for NEET-PG:** * **Safety Profile:** Unlike codeine, Dextromethorphan does not cause constipation or significant respiratory depression at therapeutic doses and has no ciliary inhibition [1]. * **Drug Interaction:** It can cause **Serotonin Syndrome** if co-administered with MAO inhibitors or SSRIs, as it inhibits serotonin reuptake. * **Metabolism:** It is metabolized by the enzyme **CYP2D6**. * **Clinical Note:** It is the most commonly used over-the-counter (OTC) cough suppressant worldwide [1].

Q: Which monoclonal antibody targets IL-5?

Mepolizumab. **Explanation:** **Mepolizumab** is a humanized monoclonal antibody that directly binds to and inhibits **Interleukin-5 (IL-5)** [1]. IL-5 is the primary cytokine responsible for the growth, differentiation, recruitment, and survival of eosinophils [1]. By neutralizing IL-5, Mepolizumab reduces eosinophilic inflammation, making it an effective "add-on" therapy for patients with severe eosinophilic asthma [1]. **Analysis of Incorrect Options:** * **Omalizumab:** This is a recombinant DNA-derived humanized IgG1 monoclonal antibody that binds selectively to **free IgE** in the blood and interstitial fluid [2]. It prevents IgE from binding to the high-affinity receptors (FcεRI) on mast cells and basophils, used primarily in severe allergic asthma [2]. * **Keliximab:** This is a monoclonal antibody that targets the **CD4 receptor** on T-lymphocytes. It was historically investigated for chronic asthma but is not a first-line treatment or a common IL-5 inhibitor. * **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 the Th2 response. **High-Yield Clinical Pearls for NEET-PG:** * **IL-5 Antagonists:** Remember the "Mep-Res-Ben" trio: **Mepolizumab** and **Reslizumab** target the IL-5 ligand itself, while **Benralizumab** targets the IL-5 receptor (IL-5Rα). * **Indication:** These drugs are specifically used for **Severe Eosinophilic Asthma** (refractory to inhaled corticosteroids) [1]. * **Dupilumab:** Another high-yield drug that targets the **IL-4 receptor alpha subunit**, effectively blocking both IL-4 and IL-13 signaling.

Q: What is the mechanism of action of theophylline in bronchial asthma?

Phosphodiesterase 4 inhibition. **Explanation:** **Mechanism of Action (Theophylline):** Theophylline is a methylxanthine derivative that primarily acts by **inhibiting the enzyme Phosphodiesterase (PDE)**, specifically the **PDE4** isoenzyme. * **The Concept:** PDE normally breaks down cyclic Adenosine Monophosphate (cAMP). By inhibiting PDE, theophylline increases intracellular cAMP levels in bronchial smooth muscle and inflammatory cells. Elevated cAMP leads to smooth muscle relaxation (bronchodilation) and suppresses the release of inflammatory mediators from mast cells and basophils. * **Additional Mechanism:** It also acts as an **Adenosine receptor antagonist** (A1 and A2 receptors), preventing adenosine-induced bronchoconstriction. **Analysis of Incorrect Options:** * **B. Beta2 agonism:** This is the mechanism for drugs like Salbutamol and Salmeterol, which stimulate adenylyl cyclase to increase cAMP directly. * **C. Anticholinergic action:** This describes Ipratropium and Tiotropium, which block M3 muscarinic receptors to prevent vagally-mediated bronchoconstriction. * **D. Inhibition of mucociliary clearance:** Theophylline actually **increases** mucociliary clearance, which helps in clearing secretions; inhibiting it would be detrimental in asthma. **High-Yield Clinical Pearls for NEET-PG:** 1. **Narrow Therapeutic Index:** Theophylline requires Therapeutic Drug Monitoring (TDM). The target range is **5–15 µg/ml**. 2. **Toxicity:** Toxicity presents as persistent vomiting, cardiac arrhythmias, and seizures. 3. **Histone Deacetylation:** In low doses, theophylline activates histone deacetylase (HDAC2), which enhances the anti-inflammatory effects of corticosteroids—a key synergy in COPD. 4. **Drug Interactions:** Enzyme inhibitors (Cimetidine, Erythromycin, Ciprofloxacin) increase theophylline levels, while enzyme inducers (Rifampicin, Phenytoin, Smoking) decrease them.

Q: In theophylline metabolism, drug interactions occur with all of the following except:

Tetracyclines. **Explanation:** Theophylline has a **narrow therapeutic index** (10-20 µg/ml) and is primarily metabolized by the hepatic **Cytochrome P450 (CYP1A2 and CYP3A4)** enzyme system. Consequently, its serum levels are highly sensitive to drugs that induce or inhibit these enzymes. **1. Why Tetracyclines is the correct answer:** Tetracyclines (like Doxycycline or Oxytetracycline) do not significantly inhibit or induce hepatic microsomal enzymes. Therefore, they do not alter the metabolism of theophylline. While some Macrolides (like Erythromycin) and Fluoroquinolones (like Ciprofloxacin) are notorious for increasing theophylline levels, **Tetracyclines are considered safe** in this regard. **2. Analysis of Incorrect Options:** * **Cimetidine:** A potent **enzyme inhibitor**. It inhibits CYP1A2 and CYP3A4, leading to decreased clearance of theophylline, which can result in theophylline toxicity (nausea, palpitations, seizures). * **Phenobarbitone:** A classic **enzyme inducer**. It increases the synthesis of microsomal enzymes, accelerating theophylline metabolism and potentially leading to sub-therapeutic levels and poor asthma control. * **Rifampicin:** A powerful **broad-spectrum enzyme inducer**. Similar to Phenobarbitone, it enhances the clearance of theophylline, necessitating a dosage increase. **High-Yield Clinical Pearls for NEET-PG:** * **Theophylline Toxicity:** Manifests as persistent vomiting, cardiac arrhythmias, and intractable seizures. * **Other Inhibitors (Increase levels):** Erythromycin, Ciprofloxacin, Oral Contraceptives, and Allopurinol. * **Other Inducers (Decrease levels):** Phenytoin, Carbamazepine, and **Smoking** (Polycyclic hydrocarbons induce CYP1A2). * **Mechanism:** Theophylline works by inhibiting Phosphodiesterase (PDE) and antagonizing Adenosine receptors.

Q: A 21-year-old woman with moderately severe asthma on three-drug treatment has elevated liver function tests thought to be caused by one of her medications. Which drug is causing this adverse effect?

Lipoxygenase inhibitor. **Explanation:** The correct answer is **Lipoxygenase inhibitor (Zileuton)**. **1. Why it is correct:** Zileuton is a selective inhibitor of 5-lipoxygenase (5-LOX), the enzyme responsible for converting arachidonic acid into leukotrienes. A well-documented and high-yield adverse effect of Zileuton is **hepatotoxicity**. It can cause a significant elevation in serum hepatic transaminases (ALT/AST), typically occurring within the first 2-3 months of therapy. Therefore, periodic liver function monitoring is mandatory for patients on this drug. **2. Why other options are incorrect:** * **Chromone agents (Cromolyn/Nedocromil):** These are mast cell stabilizers with an excellent safety profile. Their side effects are usually limited to local irritation (throat irritation or cough) and are not associated with liver injury. * **Leukotriene receptor antagonists (Montelukast/Zafirlukast):** While Zafirlukast has rare reports of hepatotoxicity, it is significantly less common than with Zileuton. Montelukast is generally considered safe for the liver. In the context of "three-drug treatment" and elevated LFTs, Zileuton is the classic pharmacological culprit. * **Methylxanthines (Theophylline):** These have a narrow therapeutic index, but toxicity typically manifests as GI upset, cardiac arrhythmias, or seizures, rather than primary hepatotoxicity. **Clinical Pearls for NEET-PG:** * **Zileuton:** Inhibits 5-LOX; causes hepatotoxicity; metabolized by CYP1A2 (increases levels of Theophylline and Warfarin). * **Montelukast/Zafirlukast:** Block CysLT1 receptors; used for aspirin-induced asthma and prophylaxis. * **Rule of Thumb:** If a question mentions asthma medications and liver enzymes, think **Zileuton**.

Q: Which monoclonal antibody is used in the management of asthma?

Omalizumab. **Omalizumab** is the correct answer because it is a recombinant DNA-derived humanized monoclonal antibody specifically designed for the management of moderate-to-severe persistent allergic asthma. [1] **Mechanism of Action:** Omalizumab binds selectively to **free circulating IgE**, forming complexes that prevent IgE from binding to its high-affinity receptors (FcεRI) on the surface of mast cells and basophils. This inhibits the release of inflammatory mediators (like histamine and leukotrienes) that trigger an asthma attack. It is typically indicated for patients whose symptoms are inadequately controlled by inhaled corticosteroids. [1] **Analysis of Incorrect Options:** * **Trastuzumab:** A monoclonal antibody against the **HER2/neu receptor**, used primarily in the treatment of HER2-positive breast cancer and gastric cancer. * **Muromonab (OKT3):** An anti-CD3 antibody used as an **immunosuppressant** to prevent acute rejection in organ transplantation. * **Alemtuzumab:** An anti-CD52 antibody used in the treatment of **Chronic Lymphocytic Leukemia (CLL)** and Multiple Sclerosis. **High-Yield Clinical Pearls for NEET-PG:** 1. **Route:** Administered via **subcutaneous injection** every 2–4 weeks. 2. **Other Biologicals in Asthma:** * **Anti-IL5:** Mepolizumab, Reslizumab (used for eosinophilic asthma). * **Anti-IL5 Receptor:** Benralizumab. * **Anti-IL4/IL13:** Dupilumab. 3. **Side Effect:** The most serious, though rare, side effect of Omalizumab is **anaphylaxis**; patients should be monitored post-injection.

Question 1

Vilanterol is FDA approved for the treatment of which condition?

Accepted Answer

COPD

Answer

Asthma

Answer

Both Asthma and COPD

Answer

None of the above

Question 2

Which NMDA blocker is used as an antitussive?

Accepted Answer

Dextromethorphan

Answer

Pholcodeine

Answer

Diphenhydramine

Answer

Aprepitant

Question 3

Which monoclonal antibody targets IL-5?

Accepted Answer

Mepolizumab

Answer

Omalizumab

Answer

Keliximab

Answer

Altrakincept

Question 4

What is the mechanism of action of theophylline in bronchial asthma?

Accepted Answer

Phosphodiesterase 4 inhibition

Answer

Beta2 agonism

Answer

Anticholinergic action

Answer

Inhibition of mucociliary clearance

Question 5

Which beta 2 agonist is not indicated for acute bronchial asthma?

Accepted Answer

Salmeterol

Answer

Salbutamol

Answer

Terbutaline

Answer

Methylxanthine

Question 6

In theophylline metabolism, drug interactions occur with all of the following except:

Accepted Answer

Tetracyclines

Answer

Cimetidine

Answer

Phenobarbitone

Answer

Rifampicin

Question 7

A 21-year-old woman with moderately severe asthma on three-drug treatment has elevated liver function tests thought to be caused by one of her medications. Which drug is causing this adverse effect?

Accepted Answer

Lipoxygenase inhibitor

Answer

Chromone agent

Answer

Leukotriene receptor antagonist

Answer

Methylxanthines

Question 8

Dr. Jones prescribes albuterol sulfate (Proventil) for a patient with newly diagnosed asthma. When teaching the patient about this drug, what adverse effect should the nurse explain is possible?

Accepted Answer

Nervousness

Answer

Nasal congestion

Answer

Lethargy

Answer

Hyperkalemia

Question 9

Which monoclonal antibody is used in the management of asthma?

Accepted Answer

Omalizumab

Answer

Trastuzumab

Answer

Muromonab

Answer

Alemtuzumab

Question 10

Which corticosteroid is administered via inhalation route?

Accepted Answer

Beclomethasone

Answer

Prednisolone

Answer

Dexamethasone

Answer

Hydrocortisone

Respiratory System Drugs — MCQs

Respiratory System Drugs — MCQs

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