Respiratory System Drugs Practice Questions

Q: Which drug used in bronchial asthma requires therapeutic drug monitoring?

Theophylline. **Explanation:** **Theophylline** is the correct answer because it has a **narrow therapeutic index** (10–20 µg/mL). Therapeutic Drug Monitoring (TDM) is essential because its metabolism is highly variable and follows saturation kinetics at higher doses. Small increases in dose can lead to disproportionate rises in plasma concentration, resulting in severe toxicity (seizures, arrhythmias, and persistent vomiting). Furthermore, its clearance is affected by numerous factors like smoking, liver disease, and drugs that inhibit or induce CYP1A2 enzymes. **Why other options are incorrect:** * **Cromoglycate:** This is a mast cell stabilizer used prophylactically. It is poorly absorbed systemically and is usually administered via inhalation, making systemic toxicity and the need for TDM non-existent. * **Salmeterol:** A Long-Acting Beta-2 Agonist (LABA) used via inhalation. It has a wide safety margin, and its effects are monitored clinically (peak flow/symptoms) rather than by plasma levels. * **Terbutaline:** A Short-Acting Beta-2 Agonist (SABA). While it can be given systemically in emergencies, it does not require TDM as its side effects (tremors, tachycardia) are easily monitored clinically. **High-Yield Clinical Pearls for NEET-PG:** * **Therapeutic Range:** 10–20 µg/mL (Bronchodilation); >20 µg/mL (Toxicity). * **Mechanism:** Inhibits Phosphodiesterase (PDE III & IV), increasing cAMP; also acts as an Adenosine receptor antagonist. * **Drug Interactions:** Cimetidine, Erythromycin, and Ciprofloxacin **increase** theophylline levels (enzyme inhibitors), while Phenytoin and Rifampicin **decrease** them (enzyme inducers). * **Antidote for Toxicity:** There is no specific pharmacological antagonist; management involves gastric lavage, activated charcoal, and hemodialysis in severe cases.

Q: What is the therapeutic blood range of theophylline in micrograms per liter?

10-20. **Explanation:** Theophylline is a methylxanthine derivative used in the treatment of bronchial asthma and COPD. It works primarily by inhibiting phosphodiesterase (PDE), leading to increased cAMP levels, and by antagonizing adenosine receptors, resulting in bronchodilation. **1. Why Option D (10-20 µg/mL) is Correct:** Theophylline has a **narrow therapeutic index**, meaning the margin between a therapeutic dose and a toxic dose is very small. The established therapeutic range for optimal bronchodilation with minimal side effects is **10-20 µg/mL** (or mg/L). * *Note:* Recent guidelines often suggest a lower range (5-15 µg/mL) to further reduce toxicity, but 10-20 µg/mL remains the standard "textbook" answer for competitive exams like NEET-PG. **2. Why Other Options are Incorrect:** * **0-5 µg/mL (Option A):** This concentration is sub-therapeutic; it is generally insufficient to produce significant bronchodilation. * **15-25 µg/mL (Option C):** While there is an overlap, concentrations above 20 µg/mL are associated with a high incidence of toxicity. **3. High-Yield Clinical Pearls for NEET-PG:** * **Toxicity Profile:** * **>20 µg/mL:** GI upset (nausea, vomiting), restlessness, and insomnia. * **>30 µg/mL:** Serious toxicities including **cardiac arrhythmias** and **intractable seizures** (theophylline-induced seizures are often resistant to standard anticonvulsants). * **Metabolism:** It follows **First-order kinetics** at therapeutic levels but shifts to **Zero-order kinetics** at higher concentrations (saturation kinetics). * **Drug Interactions:** * *Levels increased by:* Enzyme inhibitors like Cimetidine, Erythromycin, and Ciprofloxacin. * *Levels decreased by:* Enzyme inducers like Phenytoin, Rifampicin, and smoking. * **Mechanism:** Non-selective PDE inhibition and Adenosine (A1/A2) receptor antagonism.

Q: Which of the following drugs can be administered by the subcutaneous route?

Terbutaline. **Explanation:** **Terbutaline** is a selective $\beta_2$-agonist used primarily in the management of asthma and COPD. It is unique among the options because it is the only $\beta_2$-agonist available in the United States and India for **subcutaneous (SC) administration**. 1. **Why Terbutaline is correct:** While most $\beta_2$-agonists are administered via inhalation to minimize systemic side effects, Terbutaline can be given subcutaneously (0.25 mg) in emergency settings, such as **Status Asthmaticus**, when inhaled therapy is not feasible or effective. It is also used off-label as a tocolytic to inhibit premature uterine contractions. 2. **Why other options are incorrect:** * **Albuterol (Salbutamol):** Though the most common SABA, it is administered via inhalation (MDI/nebulization) or orally. In emergencies, it can be given intravenously (IV) in some regions, but not SC. * **Metaproterenol (Orciprenaline):** This is a less selective $\beta$-agonist available in oral and inhaled forms. It is rarely used now due to significant $\beta_1$ cardiac side effects. * **Pirbuterol:** This is an inhaled selective $\beta_2$-agonist with a chemical structure similar to Albuterol, available only as a breath-actuated aerosol. **High-Yield Clinical Pearls for NEET-PG:** * **Emergency Use:** SC Terbutaline is indicated when a patient has severe bronchospasm and is unable to move enough air to utilize a nebulizer or MDI. * **Tocolysis:** Terbutaline relaxes uterine smooth muscle; however, its use is limited to 48–72 hours due to risks of maternal pulmonary edema and tachycardia. * **Side Effects:** Systemic administration (SC/Oral) significantly increases the risk of skeletal muscle tremors (most common), hypokalemia, and palpitations.

Q: Which of the following constituents of commonly used metered dose inhalers in bronchial asthma is also an air pollutant dangerous to the Earth's stratosphere?

Fluorocarbons. **Explanation:** **Correct Option: A. Fluorocarbons** Metered-dose inhalers (MDIs) traditionally used **Chlorofluorocarbons (CFCs)** as propellants to deliver medication into the lungs. While effective for drug delivery, CFCs are potent air pollutants. When released, they migrate to the stratosphere where ultraviolet radiation causes them to release chlorine atoms. These atoms catalyze the breakdown of the **ozone layer**, leading to environmental damage. Due to the Montreal Protocol, CFC-propelled MDIs have been largely phased out and replaced by **Hydrofluoroalkanes (HFAs)**, which do not deplete the ozone layer. **Analysis of Incorrect Options:** * **B. Salbutamol:** This is a short-acting beta-2 agonist (SABA) used as the active pharmacological agent (bronchodilator) in the inhaler [1]. It is a medication, not an atmospheric pollutant. * **C. Ozone:** While ozone is the substance being *depleted* in the stratosphere by fluorocarbons, it is not a constituent of an MDI. Ground-level ozone is a pollutant (smog), but it is not used in medical inhalers. * **D. Oxygen:** Oxygen is a natural atmospheric gas and is often used in emergency management of asthma, but it is not a propellant in MDIs and does not damage the stratosphere. **High-Yield Clinical Pearls for NEET-PG:** * **Propellant Shift:** Modern MDIs use **HFA (Hydrofluoroalkane)**. HFAs produce a slower, warmer, and softer spray compared to CFCs, which reduces the "cold-freon effect" (where the cold spray causes the patient to stop inhaling). * **Technique:** The most common error in MDI use is poor hand-breath coordination. Using a **spacer** device can mitigate this and increase lung deposition while decreasing oropharyngeal side effects (like candidiasis with steroids). * **Dry Powder Inhalers (DPIs):** These are breath-actuated and do not require propellants, making them more environmentally friendly than MDIs.

Q: A woman taking cetirizine for allergic rhinitis complains of excessive sleepiness. Which of the following is the best alternative with minimal sedative effect?

Fexofenadine. ***Fexofenadine***- It is a second-generation H1 antihistamine that has the **lowest lipophilicity** and is actively transported out of the central nervous system (CNS) by the **P-glycoprotein** pump.- This mechanism results in **minimal to virtually no sedative effects**, making it the best non-sedating alternative to cetirizine.*Hydroxyzine*- This is a first-generation H1 antihistamine that easily crosses the **blood-brain barrier** (BBB).- It is known for its significant **sedative** and **anxiolytic properties**, and would worsen the patient's complaint of excessive sleepiness.*Diphenhydramine*- As a highly lipophilic, first-generation antihistamine, it exhibits profound CNS penetration and causes profound **drowsiness** and cognitive impairment.- It also possesses potent **anticholinergic effects**, which contribute significantly to various side effects but not lack of sedation.*Promethazine*- This drug is a first-generation antihistamine known for its **strong antiemetic** and highly **sedative** properties.- It is structurally related to phenothiazine antipsychotics and would likely cause **more severe sleepiness** than cetirizine.

Q: Benralizumab acts on which receptor?

IL 5. ***IL 5***- Benralizumab is a monoclonal antibody that specifically targets the **alpha subunit (IL-5Rα) of the Interleukin-5 Receptor** [1].- By blocking this receptor, it facilitates the depletion of **eosinophils** via **antibody-dependent cell-mediated cytotoxicity (ADCC)**, crucial for treating severe eosinophilic asthma [1].*IL4*- IL-4 is a key mediator of **Type 2 inflammation** often targeted by drugs like **Dupilumab**, which inhibits both IL-4 and **IL-13 signaling**.- Targeting IL-4 is generally aimed at reducing IgE production and overall Th2 response, a different mechanism than the eosinophil depletion mechanism of Benralizumab.*IL1*- IL-1 is a potent **pro-inflammatory cytokine** primarily associated with **autoinflammatory diseases** and targeted by agents like **Anakinra** (IL-1 receptor antagonist).- It is not the primary or specific therapeutic target in severe eosinophilic asthma, which involves Th2 mechanisms and eosinophil recruitment.*TNF alpha*- **TNF-alpha** is a major systemic inflammatory cytokine targeted by biological agents like **Infliximab** and **Etanercept** used in conditions such as **Rheumatoid Arthritis** and **Crohn’s disease**.- While inflammation is involved in asthma, TNF-alpha antagonists are not the standard specific treatment for severe eosinophilic asthma.

Q: The image given below shows a portable battery device called ultrasonic nebulizer for salbutamol delivery. All are correct about the device except:

Advantage of using all anti-asthma formulations. ***Advantage of using all anti-asthma formulations*** **(CORRECT - This is the EXCEPTION/False statement)** - Ultrasonic nebulizers are typically **not suitable for all anti-asthma formulations**, particularly those containing **proteins or suspensions**, as the high-frequency vibrations can **denature or alter their efficacy**. - Medications like **cromolyn sodium, budesonide (suspension), and dornase alfa** are generally not recommended for use with ultrasonic nebulizers due to potential degradation. - This is a **major limitation** of ultrasonic nebulizers compared to jet nebulizers. *Operates on piezoelectric crystal vibrations* **(True statement)** - Ultrasonic nebulizers **use a piezoelectric crystal** to convert electrical energy into **high-frequency ultrasonic waves (1-3 MHz)**. - These waves cause the medication solution to **vibrate at a high frequency**, creating an aerosol of fine droplets (1-5 μm). *Little patient coordination required* **(True statement)** - Nebulizers, including ultrasonic types, deliver medication over a **longer period (5-15 minutes)**, allowing patients to simply **breathe normally through a mouthpiece or mask**. - This design is particularly beneficial for patients who have difficulty with the **coordinated inspiration and actuation** required for metered-dose inhalers (MDIs). *Quiet and portable* **(True statement)** - Ultrasonic nebulizers are generally **quieter** than jet nebulizers, as they do not rely on a compressor to generate airflow. - Their **compact size and often battery-operated design** make them highly portable, facilitating use outside the home.

Q: Which of the following instructions is not given if a second puff is required from this device?

Wash mouth between two puffs. ***Wash mouth between two puffs*** - Washing the mouth is typically recommended *after* the final dose of certain inhaled medications (especially **corticosteroids**) to prevent oral candidiasis (thrush), not *between* puffs of the same medication. - Doing so between puffs would be inconvenient and unnecessary for optimal drug delivery, especially for bronchodilators where quick repeated dosing is often required. *Wait for one minute before taking the second puff* - This is a standard instruction for metered-dose inhalers (MDIs) to allow the first dose to take effect and to ensure proper delivery of the second dose by allowing the propellant to reset and the airways to potentially open further. - It ensures that the medication from the first puff has time to reach the lungs before the second puff is administered. *Shake again* - Shaking the inhaler before each puff is crucial to ensure that the medication is **evenly mixed** with the propellant. - This guarantees that a consistent and accurate dose of medication is delivered with every actuation, even for subsequent puffs. *Keep mouth piece dry* - Keeping the mouthpiece dry is important for **hygiene** and to prevent blockages or malfunction. - Moisture could potentially affect the aerosolization process or lead to bacterial growth.

Q: Consider the following steps for using a metered dose inhaler (MDI) : I. Incline the head backward to minimize oropharyngeal deposition II. Remove the cap and shake the inhaler III. Breathe out gently and place the mouthpiece into the mouth IV. Hold the breath for 10 seconds V. Simultaneously, begin a slow deep inspiration, depress the canister and continue to inhale Which one of the following is the correct sequence of using MDI?

II, III, I, V, IV. ***II, III, I, V, IV*** - The correct sequence for using an MDI starts with **preparing the inhaler** (shaking it and removing the cap), followed by **proper positioning** and **breathing technique** to maximize drug delivery. - After preparing and positioning, the patient should inhale deeply while actuating the device, then **hold their breath** to allow for drug deposition. - **Note:** In standard MDI technique, the head should be in a **neutral or slightly upright position**, not inclined backward. Inclining the head backward would actually **increase** oropharyngeal deposition, contrary to what step I suggests. However, given the options provided in this question, this is the correct sequence. *III, II, I, V, IV* - This sequence incorrectly places **removing the cap and shaking the inhaler** (II) after beginning to breathe out and placing the mouthpiece (III), which means the inhaler isn't properly prepared before use. - The MDI needs to be shaken well before each use to ensure the medication is evenly distributed and delivered at the correct dose. *II, I, IV, III, V* - This sequence incorrectly places **holding the breath for 10 seconds** (IV) before placing the mouthpiece into the mouth and inhaling (III and V). - The breath hold should occur *after* inhalation to maximize drug deposition in the lungs. *III, I, II, IV, V* - This sequence places **removing the cap and shaking the inhaler** (II) very late, after preparing to breathe and inclining the head, which is incorrect. - The inhaler must be properly shaken *before* it is placed in the mouth and activated to ensure proper medication delivery.

Q: Which of the following is a centrally acting non-opioid antitussive?

Dextromethorphan. ***Dextromethorphan*** - **Dextromethorphan** is a **centrally acting non-opioid antitussive** that suppresses the cough reflex by acting on the cough center in the medulla oblongata [1], [2]. - It is an **NMDA receptor antagonist** and a **sigma-1 receptor agonist**, which are the primary mechanisms responsible for its antitussive effects [2]. - Unlike opioid antitussives (codeine, hydrocodone), it does **not bind significantly to opioid receptors** at therapeutic doses and therefore lacks addiction potential, respiratory depression, and other opioid side effects [1], [3]. - It is a synthetic morphine analog (dextro-isomer) but is pharmacologically distinct from opioids [1]. *Ambroxol* - **Ambroxol** is a **mucolytic agent** that helps to thin and clear mucus from the respiratory tract. - It works by stimulating serous gland secretion and breaking down mucopolysaccharide fibers, which is different from suppressing the cough reflex centrally. *Guaifenesin* - **Guaifenesin** is an **expectorant** that increases the volume and reduces the viscosity of respiratory tract secretions. - This action helps to make coughs more productive, rather than directly suppressing the cough reflex. *Diphenhydramine* - **Diphenhydramine** is a first-generation **antihistamine** with significant sedative and anticholinergic properties. - While it has some antitussive effects, these are primarily due to its anticholinergic actions causing drying of respiratory secretions and its sedative properties, rather than direct central action on the cough center.

Question 1

Which drug used in bronchial asthma requires therapeutic drug monitoring?

Accepted Answer

Theophylline

Answer

Cromoglycate

Answer

Salmeterol

Answer

Terbutaline

Question 2

What is the therapeutic blood range of theophylline in micrograms per liter?

Accepted Answer

10-20

Answer

0-5

Answer

15-25

Question 3

Which of the following drugs can be administered by the subcutaneous route?

Accepted Answer

Terbutaline

Answer

Albuterol

Answer

Metaproterenol

Answer

Pirbuterol

Question 4

Which of the following constituents of commonly used metered dose inhalers in bronchial asthma is also an air pollutant dangerous to the Earth's stratosphere?

Accepted Answer

Fluorocarbons

Answer

Salbutamol

Answer

Ozone

Answer

Oxygen

Question 5

A woman taking cetirizine for allergic rhinitis complains of excessive sleepiness. Which of the following is the best alternative with minimal sedative effect?

Accepted Answer

Fexofenadine

Answer

Promethazine

Answer

Diphenhydramine

Answer

Hydroxyzine

Question 6

Benralizumab acts on which receptor?

Accepted Answer

IL 5

Answer

IL1

Answer

IL4

Answer

TNF alpha

Question 7

The image given below shows a portable battery device called ultrasonic nebulizer for salbutamol delivery. All are correct about the device except:

Accepted Answer

Advantage of using all anti-asthma formulations

Answer

Operates on piezoelectric crystal vibrations

Answer

Little patient coordination required

Answer

Quiet and portable

Question 8

Which of the following instructions is not given if a second puff is required from this device?

Accepted Answer

Wash mouth between two puffs

Answer

Wait for one minute before taking the second puff

Answer

Shake again

Answer

Keep mouth piece dry

Question 9

Consider the following steps for using a metered dose inhaler (MDI) :
I. Incline the head backward to minimize oropharyngeal deposition
II. Remove the cap and shake the inhaler
III. Breathe out gently and place the mouthpiece into the mouth
IV. Hold the breath for 10 seconds
V. Simultaneously, begin a slow deep inspiration, depress the canister and continue to inhale

Which one of the following is the correct sequence of using MDI?

Accepted Answer

II, III, I, V, IV

Answer

III, II, I, V, IV

Answer

II, I, IV, III, V

Answer

III, I, II, IV, V

Question 10

Which of the following is a centrally acting non-opioid antitussive?

Accepted Answer

Dextromethorphan

Answer

Ambroxol

Answer

Guaifenesin

Answer

Diphenhydramine

Respiratory System Drugs — MCQs

Respiratory System Drugs — MCQs

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