Respiratory System Drugs Practice Questions

Q: FDA approved the use of modafinil as an adjunct in which of the following conditions?

Sleep apnea. **Explanation:** **Modafinil** is a non-amphetamine wakefulness-promoting agent. While its exact mechanism is not fully elucidated, it is believed to inhibit dopamine reuptake and increase hypothalamic levels of orexin and histamine, leading to increased alertness. **Why Sleep Apnea is the Correct Answer:** The FDA has specifically approved modafinil as an **adjunctive (add-on) therapy** for **Obstructive Sleep Apnea (OSA)**. In these patients, modafinil is used to treat residual excessive daytime sleepiness (EDS) that persists despite optimal treatment of the underlying airway obstruction with Continuous Positive Airway Pressure (CPAP). It does not treat the cause of apnea but improves the patient's quality of life and alertness. **Analysis of Incorrect Options:** * **B. Narcolepsy:** While modafinil is a **first-line treatment** for narcolepsy, the question specifically asks for its use as an **adjunct**. In narcolepsy, it is typically used as primary monotherapy for daytime somnolence. * **C. Depression with lethargy:** Modafinil is sometimes used "off-label" to treat fatigue associated with depression or multiple sclerosis, but it is not FDA-approved for this indication. * **D. Tourette's syndrome:** Modafinil has no role in Tourette’s; in fact, stimulants can sometimes exacerbate tics. **High-Yield Clinical Pearls for NEET-PG:** * **FDA Approved Indications:** Narcolepsy, Shift Work Sleep Disorder, and Adjunct in OSA. * **Side Effects:** Headache (most common), nausea, and nervousness. Rarely, it can cause serious skin reactions like **Stevens-Johnson Syndrome (SJS)**. * **Advantage over Amphetamines:** It has a lower potential for abuse, less peripheral sympathomimetic stimulation (less tachycardia/hypertension), and less "rebound" hypersomnolence. * **Armodafinil:** The R-enantiomer of modafinil with a longer half-life.

Q: Which humanized monoclonal antibody binds IgE to prevent its binding to the high-affinity IgE receptor, thereby blocking IgE-mediated allergic response and inflammation in bronchial asthma?

Omalizumab. **Explanation:** **Omalizumab** is a recombinant DNA-derived humanized monoclonal antibody specifically designed for the management of moderate-to-severe persistent allergic asthma. **Mechanism of Action:** Omalizumab binds selectively to the **Fc region of free circulating IgE**. By doing so, it prevents IgE from binding to the high-affinity IgE receptors (**FcεRI**) located on the surface of mast cells and basophils. This prevents the cross-linking of IgE by allergens, thereby inhibiting the release of inflammatory mediators (histamine, leukotrienes) that cause bronchoconstriction and airway inflammation. It also downregulates the expression of FcεRI receptors over time. **Analysis of Incorrect Options:** * **Palivizumab (A):** A monoclonal antibody directed against the **F protein of Respiratory Syncytial Virus (RSV)**. It is used for the prevention of RSV infections in high-risk infants. * **Natalizumab (B):** An anti-integrin antibody that binds to **α4-integrin**. It is used in the treatment of Multiple Sclerosis and Crohn’s disease by preventing leukocyte migration into tissues. * **Etilizumab (D):** This is not a standard drug used in respiratory pharmacology; it is likely a distractor. **High-Yield Clinical Pearls for NEET-PG:** * **Route:** Administered **Subcutaneously** every 2–4 weeks. * **Indication:** Step 5 or 6 of GINA guidelines for patients with high serum IgE levels not controlled by high-dose ICS + LABA. * **Side Effect:** The most serious (though rare) side effect is **anaphylaxis**; patients should be monitored post-injection. * **Other Biologicals in Asthma:** * **Mepolizumab/Reslizumab:** Anti-IL-5 (for eosinophilic asthma). * **Benralizumab:** Anti-IL-5 Receptor alpha. * **Dupilumab:** Anti-IL-4 Receptor alpha (inhibits IL-4 and IL-13).

Q: Zafirlukast used in asthmatic patients acts by?

Leukotriene receptor blockage. **Explanation:** **Correct Answer: C. Leukotriene receptor blockage** Zafirlukast and Montelukast are **selective and competitive antagonists** of the **CysLT1 receptor** (Cysteinyl Leukotriene receptor 1). In asthma, leukotrienes (LTC4, LTD4, and LTE4) are potent bronchoconstrictors and mediators of inflammation. By blocking these receptors, Zafirlukast prevents airway edema, smooth muscle contraction, and the inflammatory response, making it an effective "controller" medication for prophylaxis. **Analysis of Incorrect Options:** * **A. Phosphodiesterase (PDE) inhibition:** This is the mechanism of **Theophylline** (non-selective PDE inhibitor) and **Roflumilast** (selective PDE4 inhibitor). These drugs increase intracellular cAMP, leading to bronchodilation. * **B. Endothelium receptor blockage:** This likely refers to Endothelin receptor antagonists like **Bosentan**, which are used in the treatment of Pulmonary Arterial Hypertension (PAH), not bronchial asthma. * **D. Lipoxygenase inhibitor:** This refers to **Zileuton**, which inhibits the 5-Lipoxygenase (5-LOX) enzyme, thereby preventing the *synthesis* of leukotrienes rather than blocking their receptors. **High-Yield Clinical Pearls for NEET-PG:** * **Indications:** Used for chronic asthma prophylaxis and aspirin-induced asthma. They are **not** effective for acute asthma attacks. * **Montelukast vs. Zafirlukast:** Montelukast is preferred as it is taken once daily and does not inhibit CYP enzymes. * **Side Effects:** Zafirlukast can cause a rare elevation in liver enzymes and is associated with **Churg-Strauss syndrome** (eosinophilic granulomatosis with polyangiitis) upon withdrawal of systemic steroids. * **Drug Interaction:** Zafirlukast inhibits CYP2C9 and CYP3A4, potentially increasing Warfarin levels.

Q: Which opioid analgesic is used in the treatment of cough?

Codeine. **Explanation:** **Codeine** is the correct answer because it is a prototypical **opioid antitussive**. It acts centrally by suppressing the cough center in the medulla oblongata. It is highly effective for dry, non-productive coughs at sub-analgesic doses. While it carries a risk of constipation and mild sedation, it remains the gold standard against which other antitussives are compared. **Analysis of Options:** * **Noscapine (Option A):** While used as an antitussive, it is an alkaloid derived from opium but is **non-narcotic/non-opioid** in nature. It does not have analgesic or addicting properties and acts by suppressing the cough reflex without affecting the CNS like opioids. * **Dextromethorphan (Option B):** This is a synthetic derivative of morphine (the d-isomer of levorphanol). However, it is classified as a **non-opioid antitussive** because it does not act on opioid receptors (it acts on NMDA and sigma receptors) and lacks analgesic or addictive potential. * **Meperidine (Option D):** Also known as Pethidine, this is a potent opioid analgesic used for acute pain and shivering. It has **no significant antitussive activity** and is not used in respiratory medicine. **High-Yield Clinical Pearls for NEET-PG:** * **Codeine** is contraindicated in children under 12 years (and up to 18 years post-tonsillectomy) due to the risk of ultra-rapid metabolism to morphine, leading to fatal respiratory depression. * **Pholcodine** is another opioid antitussive with a longer duration of action than codeine. * **Benzonatate** is a peripherally acting antitussive that works by anesthetizing stretch receptors in the lungs. * For a productive cough, antitussives are generally avoided; **expectorants** (e.g., Guaifenesin) or **mucolytics** (e.g., Bromhexine, Acetylcysteine) are preferred.

Q: Which oral and topical drug is used for nasal decongestion?

Phenylephrine. **Explanation:** **Phenylephrine** is the correct answer because it is a selective **$\alpha_1$-adrenergic agonist**. Its primary mechanism of action involves stimulating $\alpha_1$ receptors on the vascular smooth muscle of the nasal mucosa, leading to **vasoconstriction**. This reduces mucosal edema and nasal stuffiness. It is unique among the options as it is available in both **topical** (nasal drops/sprays) and **oral** formulations (often found in multi-symptom cold medicines). **Analysis of Incorrect Options:** * **Histamine:** This is a mediator of inflammation and allergy. It causes vasodilation and increased capillary permeability, which actually *worsens* nasal congestion and causes rhinorrhea. * **Methoxamine:** While it is a selective $\alpha_1$ agonist, it is primarily used parenterally to treat hypotension during anesthesia. It is not used clinically as a nasal decongestant. * **Dopamine:** This is a catecholamine used in emergency settings for cardiogenic shock or acute heart failure. It acts on $D_1$, $\beta_1$, and $\alpha_1$ receptors (at high doses) but has no role in treating nasal congestion. **High-Yield Clinical Pearls for NEET-PG:** * **Rhinitis Medicamentosa:** Prolonged use of topical decongestants (usually >3–5 days) like Phenylephrine or Oxymetazoline can lead to **rebound congestion** due to down-regulation of receptors. * **Systemic Effects:** Oral Phenylephrine should be used with caution in patients with **Hypertension** and **Benign Prostatic Hyperplasia (BPH)**, as $\alpha_1$ stimulation can increase blood pressure and urinary retention. * **Other Decongestants:** **Pseudoephedrine** is another common oral decongestant, but it is a non-selective sympathomimetic.

Q: Megaloblastic anemia may be caused by all of the following except?

Long term aspirin intake. Megaloblastic anemia is characterized by impaired DNA synthesis, leading to the presence of large, nucleated red blood cell precursors (megaloblasts) in the bone marrow [1]. **Why Long-term Aspirin is the Correct Answer:** Aspirin (Acetylsalicylic acid) is a non-steroidal anti-inflammatory drug (NSAID) that inhibits cyclooxygenase (COX) enzymes. While chronic aspirin use is associated with **Iron Deficiency Anemia** (due to occult gastrointestinal bleeding), it does not interfere with DNA synthesis or folate/B12 metabolism. Therefore, it does not cause megaloblastic anemia. **Analysis of Incorrect Options:** * **Vitamin B12 & Folic Acid Deficiency:** These are the most common causes [3]. B12 and Folate are essential co-factors for DNA synthesis [2]. Deficiency leads to "nuclear-cytoplasmic asynchrony," where the nucleus matures slower than the cytoplasm. * **Dilantin (Phenytoin) Toxicity:** Phenytoin is a notorious cause of drug-induced megaloblastic anemia. It interferes with folate metabolism by inhibiting the intestinal enzyme (folate conjugase) required for folate absorption and by increasing folate catabolism. **NEET-PG High-Yield Pearls:** * **Drug-Induced Megaloblastic Anemia (Mnemonic: "M-P-S-T"):** * **M**ethotrexate (Dihydrofolate reductase inhibitor) * **P**henytoin/Pyrimethamine * **S**ulfa drugs (Trimethoprim) * **T**rimethoprim * **Zidovudine (AZT):** A common cause of macrocytosis (increased MCV) without necessarily causing full megaloblastic changes. * **Nitrous Oxide:** Can cause acute megaloblastic anemia by oxidizing the cobalt atom in Vitamin B12, rendering it inactive.

Q: Which of the following antiasthma drugs is not a bronchodilator?

Sodium cromoglycate. **Explanation:** The management of bronchial asthma involves two main categories of drugs: **Bronchodilators** (which provide symptomatic relief by relaxing airway smooth muscle) and **Anti-inflammatory agents/Mast cell stabilizers** (which prevent attacks but do not reverse bronchoconstriction). **Why Sodium Cromoglycate is the correct answer:** Sodium cromoglycate is a **Mast Cell Stabilizer**. It works by inhibiting the degranulation of mast cells triggered by IgE-antigen interactions, thereby preventing the release of inflammatory mediators like histamine and leukotrienes. It is used for **prophylaxis** only; it has no direct relaxant effect on bronchial smooth muscle and is, therefore, **not a bronchodilator**. It is ineffective during an acute attack of asthma. **Analysis of Incorrect Options:** * **A. Ipratropium bromide:** An **Anticholinergic (Muscarinic antagonist)**. It blocks M3 receptors in the bronchial smooth muscle, leading to bronchodilation. It is particularly useful in COPD and as an adjunct in acute asthma. * **B. Theophylline:** A **Methylxanthine**. It causes bronchodilation by inhibiting the enzyme phosphodiesterase (PDE), leading to increased levels of cAMP, and by antagonizing adenosine receptors. * **D. Formoterol:** A **Long-Acting Beta-2 Agonist (LABA)**. It stimulates $\beta_2$ receptors, increasing cAMP and causing potent bronchodilation. **NEET-PG High-Yield Pearls:** * **Drug of choice for Acute Asthma:** Salbutamol (SABA). * **Drug of choice for Exercise-induced Asthma:** Cromolyn sodium (if taken prophylactic) or Salbutamol. * **Nedocromil:** Another mast cell stabilizer similar to Sodium cromoglycate but with better efficacy in reducing bronchial hyperreactivity. * **Side effect of Sodium cromoglycate:** Throat irritation, cough, and rarely, bronchospasm (paradoxical).

Question 1

FDA approved the use of modafinil as an adjunct in which of the following conditions?

Accepted Answer

Sleep apnea

Answer

Narcolepsy

Answer

Depression with lethargy

Answer

Tourette's syndrome

Question 2

Which humanized monoclonal antibody binds IgE to prevent its binding to the high-affinity IgE receptor, thereby blocking IgE-mediated allergic response and inflammation in bronchial asthma?

Accepted Answer

Omalizumab

Answer

Palivizumab

Answer

Natalizumab

Answer

Etilizumab

Question 3

Zafirlukast used in asthmatic patients acts by?

Accepted Answer

Leukotriene receptor blockage

Answer

Phosphodiesterase inhibition

Answer

Endothelium receptor blockage

Answer

Lipoxygenase inhibitor

Question 4

Which opioid analgesic is used in the treatment of cough?

Accepted Answer

Codeine

Answer

Noscapine

Answer

Dextromethorphan

Answer

Meperidine

Question 5

Which of the following is very effective in the management of acute exacerbation of asthma and status asthmaticus?

Accepted Answer

None of the above

Answer

Beclomethasone

Answer

Budesonide

Answer

Ciclesonide

Question 6

Which oral and topical drug is used for nasal decongestion?

Accepted Answer

Phenylephrine

Answer

Histamine

Answer

Methoxamine

Answer

Dopamine

Question 7

In a patient experiencing an acute exacerbation of asthma, salbutamol was administered with no improvement. Subsequent treatment with intravenous corticosteroids and aminophylline led to clinical improvement. What is the primary mechanism of action of corticosteroids in managing acute asthma?

Accepted Answer

Corticosteroids increase bronchial responsiveness to bronchodilators like salbutamol.

Answer

Corticosteroids provide direct bronchodilation, particularly when used in conjunction with xanthines.

Answer

Corticosteroids indirectly enhance the effects of xanthines by acting on adenosine receptors.

Answer

Corticosteroids improve mucociliary clearance, contributing to symptom relief.

Question 8

A diabetic female on isoniazid and rifampicin for tuberculosis developed deep vein thrombosis. She was started on warfarin. Her prothrombin time is not raised. What should be the next step in management?

Accepted Answer

Use low molecular weight heparin

Answer

Increase the dose of warfarin

Answer

Replace warfarin with acenocoumarol

Answer

Switch ethambutol for rifampicin

Question 9

Megaloblastic anemia may be caused by all of the following except?

Accepted Answer

Long term aspirin intake

Answer

Dilantin toxicity

Answer

Vitamin B12 deficiency

Answer

Folic acid deficiency

Question 10

Which of the following antiasthma drugs is not a bronchodilator?

Accepted Answer

Sodium cromoglycate

Answer

Ipratropium bromide

Answer

Theophylline

Answer

Formoterol

Respiratory System Drugs — MCQs

Respiratory System Drugs — MCQs

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