Emergency Pharmacology — MCQs

Emergency Pharmacology Indian Medical PG Practice Questions and MCQs

Question 21: A young man is prescribed parenteral antibiotics for a respiratory tract infection. He collapses immediately after receiving the first dose, presenting with tachycardia, wheezing, and a drop in blood pressure. What are the most appropriate immediate interventions for this situation?

A. Intravenous saline
B. Intravenous hydrocortisone
C. Subcutaneous epinephrine (Correct Answer)
D. Nebulized salbutamol

Explanation: ### Explanation **Diagnosis: Anaphylactic Shock** The clinical presentation of immediate collapse, hypotension (drop in BP), tachycardia, and bronchospasm (wheezing) following parenteral antibiotic administration is a classic case of **Type I Hypersensitivity (Anaphylaxis)**. **Why Epinephrine is the Correct Choice:** Epinephrine is the **drug of choice** and the only life-saving intervention in anaphylaxis. It acts as a physiological antagonist to the chemical mediators of allergy: * **α1 receptors:** Causes vasoconstriction, which increases peripheral vascular resistance and blood pressure, reducing mucosal edema. * **β1 receptors:** Increases cardiac output (positive inotropic and chronotropic effects). * **β2 receptors:** Causes bronchodilation and inhibits further mediator release from mast cells and basophils. **Analysis of Incorrect Options:** * **Intravenous Saline (A):** While important for volume expansion in shock, it is an *adjunct* therapy. It does not address the underlying bronchoconstriction or mast cell degranulation. * **Intravenous Hydrocortisone (B):** Steroids have a slow onset of action (4–6 hours). They are used to prevent **biphasic reactions** (delayed recurrence of symptoms) but are not effective for the acute, life-threatening phase. * **Nebulized Salbutamol (D):** This addresses bronchospasm only. It does not treat systemic hypotension or laryngeal edema. **NEET-PG High-Yield Pearls:** 1. **Route of Choice:** While the question mentions subcutaneous, the current **Gold Standard** recommendation for anaphylaxis is **Intramuscular (IM) Epinephrine** (1:1000) in the anterolateral thigh due to faster and more reliable absorption compared to the subcutaneous route. 2. **Dosage:** Adult dose is 0.3–0.5 mg (0.3–0.5 ml of 1:1000 solution). 3. **IV Epinephrine:** Reserved for patients with profound shock or those not responding to multiple IM doses; it must be diluted to 1:10,000 or 1:100,000 to prevent arrhythmias.

Question 22: Calcium gluconate is not indicated in the management of which of the following conditions during CPR?

A. Hypocalcemia
B. Hypokalemia (Correct Answer)
C. Hyperkalemia
D. Calcium antagonism

Explanation: **Explanation:** The correct answer is **Hypokalemia**. Calcium gluconate is used in emergency settings to stabilize the cardiac membrane; however, it has no therapeutic role in treating low potassium levels [1]. In fact, calcium administration does not affect potassium concentration itself but rather antagonizes the electrophysiological effects of potassium on the myocardium. **Why Hypokalemia is the correct answer:** In **Hypokalemia**, the resting membrane potential is already hyperpolarized, and the risk of arrhythmias (like U-waves or Torsades de Pointes) is managed by potassium replacement and magnesium [1], [2]. Calcium gluconate is not indicated and is not part of the ACLS protocol for hypokalemia. **Why the other options are incorrect:** * **Hypocalcemia:** Acute symptomatic hypocalcemia (e.g., post-thyroidectomy or during massive blood transfusion) can cause cardiac arrest or tetany. Calcium gluconate is the first-line treatment to restore ionized calcium levels. * **Hyperkalemia:** This is the most common indication for calcium in CPR. Calcium **stabilizes the cardiac myocyte membrane** by shifting the threshold potential, protecting the heart from life-threatening arrhythmias (like sine waves or VF) without actually lowering the serum potassium level [1]. * **Calcium Antagonism:** In cases of **Calcium Channel Blocker (CCB) overdose**, intravenous calcium is used as an antidote to overcome the competitive blockade of L-type calcium channels, improving myocardial contractility and blood pressure [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Calcium Gluconate vs. Chloride:** Calcium gluconate is preferred for peripheral lines because it is less caustic than Calcium chloride, which requires a central line to avoid tissue necrosis. * **Digoxin Toxicity:** Traditionally, calcium was avoided in digoxin toxicity ("Stone Heart" theory), though recent evidence suggests it may be used with extreme caution if hyperkalemia is life-threatening. * **Indications for Calcium in CPR:** Remember the triad: **Hyperkalemia, Hypocalcemia, and Hypermagnesemia** (or CCB overdose).

Question 23: What is the drug of choice in the management of a life-threatening allergic reaction?

A. Corticosteroids
B. Antihistamines
C. Adrenalin (Correct Answer)
D. Diazepam

Explanation: ### Explanation **Correct Answer: C. Adrenalin (Epinephrine)** In a life-threatening allergic reaction (Anaphylaxis), **Adrenalin** is the drug of choice because it acts as a **physiological antagonist** to histamine and other inflammatory mediators. It works through three critical mechanisms: 1. **Alpha-1 receptors:** Causes vasoconstriction, which increases blood pressure and reduces mucosal edema (laryngeal edema). 2. **Beta-1 receptors:** Exerts positive inotropic and chronotropic effects, improving cardiac output. 3. **Beta-2 receptors:** Induces potent bronchodilation and inhibits further mediator release from mast cells and basophils [1]. **Why other options are incorrect:** * **Corticosteroids (e.g., Hydrocortisone):** These have a slow onset of action (4–6 hours). They are used to prevent **biphasic reactions** (delayed recurrence of symptoms) but cannot treat the acute, life-threatening phase. * **Antihistamines (e.g., Cetirizine, Diphenhydramine):** These only block H1/H2 receptors. They help with skin symptoms (urticaria/itching) but do not reverse airway obstruction or hypotension. * **Diazepam:** This is a benzodiazepine used for seizures or anxiety; it has no role in managing anaphylaxis. **High-Yield Clinical Pearls for NEET-PG:** * **Route of Administration:** The preferred route in emergencies is **Intramuscular (IM)** in the anterolateral aspect of the thigh (vastus lateralis) due to rapid absorption. * **Concentration:** Use **1:1000** (1 mg/ml) for IM injection [1]. (Note: 1:10,000 is used for IV in cardiac arrest). * **Dose:** 0.5 mg for adults; 0.01 mg/kg for children. * **Mechanism:** It is the "Physiological Antagonist" of histamine (acting on different receptors to produce opposite effects).

Question 24: Oxygen as an emergency drug is contraindicated in which of the following conditions?

A. Anaphylaxis
B. Asthma
C. Hyperventilation (Correct Answer)
D. COPD

Explanation: **Explanation:** **1. Why Hyperventilation is the Correct Answer:** In acute hyperventilation (often associated with anxiety or panic attacks), the patient breathes rapidly and deeply, leading to the excessive "blowing off" of Carbon Dioxide ($CO_2$). This results in **Respiratory Alkalosis** and a decrease in the partial pressure of arterial $CO_2$ ($PaCO_2$). Administering supplemental oxygen is contraindicated because it does not address the underlying pathology and may further suppress the respiratory drive. The standard treatment is to increase the $CO_2$ levels (e.g., breathing into a paper bag or simple reassurance) to restore the acid-base balance. **2. Analysis of Incorrect Options:** * **Anaphylaxis (A):** This is a medical emergency where laryngeal edema and bronchospasm can cause severe hypoxia. High-flow oxygen is a critical supportive measure alongside Adrenaline. * **Asthma (B):** Acute severe asthma leads to ventilation-perfusion mismatch and hypoxia. Oxygen is indicated to maintain $SpO_2$ between 93-95%. * **COPD (D):** While excessive oxygen can cause CO2 retention in COPD patients (due to the loss of hypoxic drive), oxygen is **not contraindicated**. It must be administered cautiously (controlled oxygen therapy) using a Venturi mask to maintain a target $SpO_2$ of 88-92%. **3. NEET-PG High-Yield Pearls:** * **Hypoxic Drive:** In chronic CO2 retainers (like COPD), the respiratory center becomes insensitive to $CO_2$. Respiration is driven by low $O_2$ levels. Giving 100% $O_2$ can abolish this drive, leading to respiratory arrest. * **Oxygen Toxicity:** Prolonged use of 100% oxygen can lead to absorption atelectasis and Retinopathy of Prematurity (in neonates). * **Drug of Choice for Hyperventilation:** Reassurance and, if necessary, a benzodiazepine (e.g., Diazepam) to reduce anxiety.

Question 25: A patient who has undergone limb amputation is advised a stress test. What is the drug commonly used for this test?

A. Dopexamine
B. Dopamine
C. Dobutamine (Correct Answer)
D. Dipevefrine

Explanation: ### Explanation **Concept: Pharmacological Stress Testing** In patients who cannot perform physical exercise (e.g., due to limb amputation, severe arthritis, or neurological deficits), a **Pharmacological Stress Test** is performed to evaluate coronary artery disease. The goal is to increase myocardial oxygen demand to unmask areas of ischemia. **Why Dobutamine is the Correct Answer:** Dobutamine is a synthetic catecholamine and a potent **$\beta_1$-receptor agonist**. It has significant positive inotropic (contractility) and chronotropic (heart rate) effects. By increasing the heart rate and force of contraction, it mimics the cardiac stress of physical exercise. When combined with echocardiography (Dobutamine Stress Echo) or nuclear imaging, it helps identify wall motion abnormalities or perfusion defects. **Analysis of Incorrect Options:** * **A. Dopexamine:** A synthetic analog of dopamine with $\beta_2$ and dopaminergic activity. It is primarily used in low cardiac output states (e.g., post-cardiac surgery) but not for stress testing. * **B. Dopamine:** While it has $\beta_1$ effects, its significant $\alpha_1$ (vasoconstriction) and dopaminergic effects make it less ideal for controlled cardiac stressing compared to dobutamine. It is primarily used in cardiogenic shock. * **D. Dipivefrine:** A prodrug of epinephrine used topically in the treatment of open-angle glaucoma to reduce intraocular pressure. It has no role in cardiac stress testing. **High-Yield Clinical Pearls for NEET-PG:** * **Antidote:** If a patient develops severe arrhythmia or ischemia during a Dobutamine stress test, the drug of choice to reverse the effects is a short-acting $\beta$-blocker like **Esmolol**. * **Alternative:** For patients with contraindications to Dobutamine (e.g., severe tachyarrhythmias), **Adenosine** or **Dipyridamole** (coronary vasodilators) are used for nuclear stress tests. * **Contraindication:** Dobutamine should be avoided in patients with severe obstructive hypertrophic cardiomyopathy (HOCM).

Question 26: Which drug should NOT be used in a patient with hyperkalemia and no ECG findings?

A. Sodium bicarbonate
B. Calcium gluconate (Correct Answer)
C. Glucose with insulin
D. Resins

Explanation: ### Explanation The management of hyperkalemia is categorized into three goals: stabilizing the cardiac membrane, shifting potassium into cells, and removing potassium from the body. **Why Calcium Gluconate is the Correct Answer:** Calcium gluconate (or calcium chloride) is a **cardioprotective agent**. It antagonizes the membrane-excitability effects of hyperkalemia by stabilizing the resting membrane potential of cardiomyocytes. However, it **does not lower serum potassium levels**. Therefore, it is strictly indicated only when there are **ECG changes** (e.g., peaked T-waves, widened QRS) or severe hyperkalemia (>6.5 mEq/L). Using it in a patient with no ECG findings is unnecessary and provides no therapeutic benefit. **Analysis of Incorrect Options:** * **Glucose with Insulin (Option C):** This is the fastest way to shift potassium from the extracellular to the intracellular compartment (via stimulation of Na+/K+-ATPase pump). It is indicated regardless of ECG findings to lower serum levels. * **Sodium Bicarbonate (Option A):** It shifts potassium into cells by exchanging H+ for K+. It is particularly useful if the patient has underlying metabolic acidosis. * **Resins (Option B):** Cation-exchange resins (e.g., Kayexalate or Patiromer) bind potassium in the GI tract for excretion. These are used for definitive removal of potassium in stable patients. **NEET-PG High-Yield Pearls:** 1. **First-line for ECG changes:** Calcium gluconate (acts within 1-3 minutes; effect lasts 30-60 minutes). 2. **Fastest potassium shifter:** Insulin + Dextrose. 3. **Salbutamol (Nebulization):** Also shifts K+ intracellularly but should be used with caution in patients with tachycardia or CAD. 4. **Definitive Treatment:** Hemodialysis is the most effective method for potassium removal in refractory cases or renal failure.

Question 27: What is the drug of choice for anaphylactic shock?

A. Adrenaline (Correct Answer)
B. Antihistaminic
C. Corticosteroids
D. Epinephrine

Explanation: **Explanation:** **Adrenaline (Epinephrine)** is the drug of choice for anaphylactic shock [2] because it acts as a **physiological antagonist** to histamine and other inflammatory mediators. Its life-saving efficacy stems from its potent action on multiple receptors: [1], [2] * **$\alpha_1$ receptors:** Cause vasoconstriction, which increases peripheral vascular resistance to treat hypotension and reduces mucosal edema (laryngeal edema) [1], [2]. * **$\beta_1$ receptors:** Provide positive inotropic and chronotropic effects, improving cardiac output. * **$\beta_2$ receptors:** Induce bronchodilation and, crucially, **stabilize mast cells**, inhibiting further release of inflammatory mediators [1]. **Why other options are incorrect:** * **Antihistaminics (B):** These are considered **second-line** agents. They only block H1/H2 receptors and do not reverse life-threatening airway obstruction or hypotension. They have a slow onset of action. * **Corticosteroids (C):** These are used to prevent **biphasic reactions** (delayed recurrence of symptoms). They have a slow onset (4–6 hours) and are ineffective in the acute management of cardiovascular collapse. * **Epinephrine (D):** While Epinephrine is the same drug as Adrenaline, in many Indian medical examinations (including traditional NEET-PG patterns), **Adrenaline** is the preferred nomenclature used in standard textbooks like K.D. Tripathi. *Note: In clinical practice, they are synonymous.* **High-Yield Clinical Pearls for NEET-PG:** * **Route of Choice:** Intramuscular (IM) in the **anterolateral thigh** (Vastus lateralis) due to faster absorption and higher plasma levels compared to SC or IM deltoid [2]. * **Concentration:** **1:1000** (1 mg/ml) for IM; **1:10,000** (0.1 mg/ml) for IV [2]. * **Standard Dose:** 0.5 mg (0.5 ml of 1:1000) for adults; 0.01 mg/kg for children [2]. * **Mechanism:** Physiological antagonism.

Question 28: A patient is brought to the emergency department with signs suggesting opioid poisoning. What is the antidote of choice?

A. Flumazenil
B. Physostigmine
C. Naloxone (Correct Answer)
D. Atropine

Explanation: ***Naloxone***- **Naloxone** is the drug of choice for treating opioid poisoning, acting as a competitive antagonist at **mu**, kappa, and delta opioid receptors [1]. - It reverses the life-threatening effects of opioid overdose, primarily **respiratory depression** and **central nervous system depression**, within minutes of administration [3].*Flumazenil*- Flumazenil is the specific antagonist used to reverse the effects of **benzodiazepine overdose**, acting at the GABA-A receptor.- It is generally ineffective and not indicated for pure opioid toxicity.*Atropine*- Atropine is an **anticholinergic agent** used primarily in the treatment of symptomatic **bradycardia** and **organophosphate poisoning** [2].- It does not antagonize opioid receptors and has no direct role in reversing opioid-induced respiratory depression.*Physostigmine*- Physostigmine is a **reversible acetylcholinesterase inhibitor** used mainly for reversing severe central nervous system effects of **anticholinergic poisoning** (e.g., tricyclic antidepressants).- Increasing acetylcholine is irrelevant and potentially counterproductive in treating opioid-induced respiratory depression.

Question 29: What is the concentration of adrenaline used in the following route of administration?

A. 1:10,000 (Correct Answer)
B. 1:100
C. 1:1000
D. 1:100,000

Explanation: ***1:10,000*** - The image depicts **intraosseous (IO) infusion** being administered. For **IV/IO administration during cardiac arrest**, adrenaline is used in a **1:10,000 concentration** (0.1 mg/mL). - This is the standard concentration for resuscitation across all age groups (pediatric and adult) as per **PALS and ACLS guidelines**. - **Pediatric dose:** 0.01 mg/kg (0.1 mL/kg of 1:10,000 solution) IV/IO - **Adult dose:** 1 mg (10 mL of 1:10,000 solution) IV/IO - This concentration allows safe systemic delivery with appropriate cardiovascular effects during cardiac arrest. *1:1000* - The 1:1000 concentration (1 mg/mL) is used for **intramuscular (IM) injection** in the treatment of **anaphylaxis**. - **Dose:** 0.01 mg/kg IM (maximum 0.5 mg in adults, 0.3 mg in children) - This concentration is **too concentrated for direct IV/IO administration** and could cause severe hypertension, arrhythmias, and myocardial ischemia if given undiluted intravenously. *1:100* - A 1:100 concentration (10 mg/mL) is used for **topical application** or mixed with **local anesthetics** (e.g., lidocaine with epinephrine for local anesthesia). - This very high concentration is **never used for systemic administration** and would cause life-threatening cardiovascular complications if given IV/IO. *1:100,000* - The 1:100,000 concentration (0.01 mg/mL) is primarily used **mixed with local anesthetics** for prolonged local/regional anesthesia and hemostasis. - This concentration is **too dilute** for emergency resuscitation and is not the standard for IV/IO administration during cardiac arrest.

Question 30: A comatose person is brought to the hospital. On examination his respiratory rate is 8 / min with pulse rate of 75 bpm with BP of 110 / 70 mm Hg. His Pupils are shown below. Body temperature is 96°F. What is the probable diagnosis?

A. Opioid overdose (Correct Answer)
B. Uncal herniation
C. Pontine stroke
D. Metabolic encephalopathy

Explanation: ***Opioid overdose*** - The constellation of **pinpoint pupils** (as shown in the image), **respiratory depression** (rate 8/min), and **coma** is highly characteristic of opioid overdose. - While **hypothermia** (96°F) can be seen with opioid use, the critical findings are the miosis and severe hypoventilation. *Uncal herniation* - **Uncal herniation** typically presents with a **dilated pupil** on the side of the herniation due to compression of the oculomotor nerve (CN III). - It often involves neurological deficits like hemiparesis and decerebrate posturing, along with changes in consciousness. *Pontine stroke* - A **pontine stroke** can cause pinpoint pupils due to disruption of sympathetic pathways, but it is also commonly associated with severe neurological deficits like **quadriplegia**, locked-in syndrome, and distinct respiratory patterns (e.g., apneustic breathing). - The provided vital signs and pupil presentation are more classically aligned with opioid toxicity than an isolated pontine stroke. *Metabolic encephalopathy* - **Metabolic encephalopathy** usually presents with **reactive, but often small, pupils** or normal pupils. - It leads to a global depression of brain function but rarely causes pinpoint pupils or severe respiratory depression as the primary distinguishing features.

Practice by Chapter

Management of Anaphylaxis

Practice Questions

Drugs in Cardiac Arrest

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Status Epilepticus Management

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Acute Stroke Therapeutics

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Toxicological Emergencies

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Antidotes in Emergency Medicine

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Pain Management in Emergency

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Sedation and Paralysis in Emergency

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Drugs in Traumatic Emergencies

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Thrombolysis in Emergency Settings

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