Respiratory System Drugs

Respiratory System Drugs Indian Medical PG Question 1: Drug not used in pulmonary hypertension is:

• A. Endothelin receptor antagonist
• B. Prostacyclin
• C. Alpha blocker (Correct Answer)
• D. Calcium channel blocker

Respiratory System Drugs Explanation: ***Alpha blocker*** - Alpha-blockers primarily cause **systemic vasodilation** [1] and are not indicated for the specific pulmonary vascular remodeling and vasoconstriction seen in pulmonary hypertension. [2] - Their use could lead to an undesirable drop in **systemic blood pressure** [3] without adequately addressing the pulmonary arterial pressure. *Calcium channel blocker* - **Calcium channel blockers** (namely **dihydropyridines** like nifedipine and amlodipine) are used in a small subset of pulmonary hypertension patients who are **vasoreactive** on acute testing. - They work by relaxing pulmonary arterial smooth muscle, reducing **pulmonary vascular resistance**. *Endothelin receptor antagonist* - **Endothelin receptor antagonists** (e.g., bosentan, ambrisentan) block the effects of **endothelin-1**, a potent vasoconstrictor and smooth muscle proliferator involved in pulmonary hypertension. - They improve hemodynamics, exercise capacity, and clinical outcomes by preventing **vasoconstriction** and **vascular remodeling**. *Prostacyclin* - **Prostacyclin analogs** (e.g., epoprostenol, treprostinil) are potent **vasodilators** and inhibitors of platelet aggregation. - They are highly effective in treating severe pulmonary hypertension by relaxing pulmonary arteries and preventing **thrombosis**.

Respiratory System Drugs Indian Medical PG Question 2: A 60-year-old with COPD develops tremor after a medication. Which medication is most likely responsible?

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

Respiratory System Drugs Explanation: ***Salmeterol*** - Salmeterol is a **long-acting beta-2 agonist (LABA)** commonly used in COPD [1]. Beta-2 agonists can cause **tremor** due to stimulation of skeletal muscle beta-2 receptors [2]. - This side effect is dose-dependent and more common with higher doses or in sensitive individuals. *Montelukast* - Montelukast is a **leukotriene receptor antagonist** used in asthma and allergic rhinitis, not typically a primary agent for COPD, and does not commonly cause tremor. - Its mechanism of action involves blocking leukotriene D4 receptors, which are not directly linked to muscle tremor. *Ipratropium* - Ipratropium is a **short-acting muscarinic antagonist (SAMA)** used in COPD. Its primary side effects are typically anticholinergic, such as dry mouth or blurred vision [3]. - Tremor is not a common or expected side effect of ipratropium as it does not act on beta-adrenergic receptors. *Fluticasone* - Fluticasone is an **inhaled corticosteroid (ICS)** used in COPD, often in combination with LABAs [1]. While systemic corticosteroids can cause tremor, the inhaled form has minimal systemic absorption. - **Inhaled corticosteroids** are primarily associated with local side effects like oral candidiasis or dysphonia.

Respiratory System Drugs Indian Medical PG Question 3: Under the Stepwise Approach to the management of Bronchial Asthma, which one of the following is the correct initial treatment at Step 1 for a patient diagnosed with Asthma?

• A. Low dose inhaled corticosteroid plus leukotriene antagonist
• B. Low dose inhaled corticosteroid only (Correct Answer)
• C. Low dose inhaled corticosteroid plus long acting anti-muscarinic agents
• D. Low dose inhaled corticosteroid plus oral corticosteroid

Respiratory System Drugs Explanation: ***Low dose inhaled corticosteroid only*** - For newly diagnosed asthma patients requiring daily controller therapy (Step 1 or 2 as per GINA 2021+), a **low-dose inhaled corticosteroid (ICS)** is the recommended initial monotherapy [1]. - ICS addresses the underlying inflammation in asthma, which is crucial even in mild persistent cases. *Low dose inhaled corticosteroid plus leukotriene antagonist* - This combination is typically considered at **higher steps** (e.g., Step 3 or 4) if control is not achieved with low-dose ICS alone or if there are specific indications like **aspirin-exacerbated respiratory disease** [1]. - Initiating with two controller medications at Step 1 is generally not recommended as per guideline. *Low dose inhaled corticosteroid plus long acting anti-muscarinic agents* - **Long-acting muscarinic antagonists (LAMAs)** are primarily used in **severe asthma** that remains uncontrolled despite ICS/LABA therapy, usually at Step 4 or 5. - They are not considered a first-line addition to ICS at Step 1. *Low dose inhaled corticosteroid plus oral corticosteroid* - **Oral corticosteroids** are reserved for asthma **exacerbations** or very severe, uncontrolled asthma, used for short periods due to significant systemic side effects [1]. - They are never used as initial daily maintenance therapy at Step 1 due to their high side effect profile.

Respiratory System Drugs Indian Medical PG Question 4: What is an atypical side effect of montelukast?

• A. Goodpasture syndrome
• B. Membranous glomerulonephritis
• C. Bronchial asthma
• D. Churg-Strauss syndrome (Correct Answer)

Respiratory System Drugs Explanation: ***Churg-Strauss syndrome*** - The apparent development of **Churg-Strauss syndrome** (eosinophilic granulomatosis with polyangiitis) has been reported in patients treated with montelukast, although it is believed to be related more to the unmasking of the disease rather than a direct drug effect. - This typically occurs when **corticosteroids** are tapered or withdrawn as montelukast takes over, revealing the underlying vasculitis. *Goodpasture syndrome* - **Goodpasture syndrome** is an autoimmune disease causing rapidly progressive glomerulonephritis and pulmonary hemorrhage, characterized by anti-glomerular basement membrane (GBM) antibodies. - There is no established association between montelukast use and the development of Goodpasture syndrome. *Membranous glomerulonephritis* - **Membranous glomerulonephritis** is a common cause of nephrotic syndrome, characterized by immune complex deposition on the glomerular basement membrane. - This condition is not typically linked to the use of montelukast. *Bronchial asthma* - **Bronchial asthma** is the condition montelukast is used to treat, acting as a leukotriene receptor antagonist to reduce inflammation and bronchoconstriction. - It is a primary indication for the drug, not a side effect.

Respiratory System Drugs Indian Medical PG Question 5: A patient comes with a history of asthma and sinusitis. On looking into his medical records, you notice this has been attributed to Samter’s triad. Which drug should be avoided in this patient due to its potential to exacerbate respiratory symptoms?

• A. Cotrimoxazole
• B. Co-amoxiclav
• C. Chloramphenicol
• D. Aspirin (Correct Answer)

Respiratory System Drugs Explanation: ***Aspirin (Correct Answer)*** - Samter's triad, or **aspirin-exacerbated respiratory disease (AERD)**, is characterized by **asthma**, **nasal polyps with chronic rhinosinusitis**, and a severe reaction to **aspirin** and other **NSAIDs**. - **Aspirin** inhibits COX-1, leading to an overproduction of **leukotrienes**, which causes bronchoconstriction and exacerbates respiratory symptoms in susceptible individuals. - This is the drug that **must be avoided** in patients with Samter's triad. *Cotrimoxazole (Incorrect)* - **Cotrimoxazole** (trimethoprim-sulfamethoxazole) is an antibiotic not directly involved in the cyclooxygenase pathway. - While allergic reactions can occur, it is **not specifically contraindicated** in Samter's triad. *Co-amoxiclav (Incorrect)* - **Co-amoxiclav** (amoxicillin/clavulanic acid) is a penicillin-class antibiotic, and its mechanism of action does not involve prostaglandin synthesis. - It does not pose a specific risk for exacerbating respiratory symptoms in patients with **Samter's triad**. *Chloramphenicol (Incorrect)* - **Chloramphenicol** is an antibiotic that inhibits bacterial protein synthesis and is not associated with the pathogenesis of Samter's triad. - It does not impact the **cyclooxygenase or lipoxygenase pathways** that are central to AERD.

Respiratory System Drugs Flashcard 1 of 5

Question: _____ and Nedocromil prevent mast cell degranulation (used for asthma prophylaxis)

Answer: Cromolyn sodium

Respiratory System Drugs Flashcard 2 of 5

Question: First Aid Pharmacology: Respiratory _____ is a synthetic codeine analog that is used clinically as an anti-tussive

Answer: Dextromethorphan

Respiratory System Drugs Flashcard 3 of 5

Question: What is the ideal drug management of mild persistent asthma?_____

Answer: As needed SABA + low dose ICS + daily low dose ICS

Respiratory System Drugs Flashcard 4 of 5

Question: What is recommended as regular therapy for the prevention of symptoms of exercise-induced asthma?_____

Answer: Inhaled corticosteroids

Respiratory System Drugs Flashcard 5 of 5

Question: Ipratropium and tiotropium primarily affect the _____ (organ) via inhibition of M3 muscarinic receptors

Answer: lungs