Emergency Pharmacology — MCQs

Emergency Pharmacology Indian Medical PG Practice Questions and MCQs

Question 91: Which of the following drugs is safe to use in a patient with a history of sulfa allergy presenting with an acute attack of angle-closure glaucoma?

A. Latanoprost
B. Dorzolamide
C. Glycerol (Correct Answer)
D. Acetazolamide

Explanation: ***Glycerol*** - **Glycerol** is an osmotic diuretic that reduces intraocular pressure (IOP) by drawing water out of the eye into the bloodstream, making it a safe choice in patients with sulfa allergy. - It does not contain a sulfa moiety, thus posing no risk of allergic reaction in individuals with **sulfa hypersensitivity**. - Osmotic agents like glycerol work rapidly and are the cornerstone of emergency management for **acute angle-closure glaucoma**. *Acetazolamide* - **Acetazolamide** is a **carbonic anhydrase inhibitor** (CAI) with a sulfa chemical structure, making it contraindicated in patients with a history of sulfa allergy. - Its use in a sulfa-allergic patient could precipitate a severe **hypersensitivity reaction**, ranging from rash to anaphylaxis. *Dorzolamide* - **Dorzolamide** is also a **carbonic anhydrase inhibitor** (CAI) and contains a **sulfa group**, rendering it unsafe for patients with a known sulfa allergy. - Topical CAIs like dorzolamide can still cause systemic absorption and trigger allergic reactions in sensitive individuals. *Latanoprost* - **Latanoprost** is a prostaglandin analog that does not contain sulfa, but it is **contraindicated in acute angle-closure glaucoma**. - Prostaglandin analogs can cause **miosis, anterior chamber inflammation**, and increased uveoscleral outflow, which may **worsen angle closure** and exacerbate pupillary block. - While safe from an allergy standpoint, it is inappropriate for the acute emergency setting and is reserved for **chronic open-angle glaucoma**.

Question 92: What is the best initial pharmacotherapy management option for a 30-year-old male who presents to the emergency department with palpitations, has a regular broad complex tachycardia on ECG, and is haemodynamically stable if DC cardioversion is not available?

A. IV verapamil
B. IV amiodarone
C. IV procainamide (Correct Answer)
D. IV adenosine

Explanation: ***IV procainamide*** - **Procainamide** is a Class Ia antiarrhythmic drug and is an effective initial pharmacotherapy for **stable broad complex tachycardia (BCT)** if direct current cardioversion (DCC) is not immediately available - It works by blocking sodium and some potassium channels, prolonging the **action potential duration** and **effective refractory period**, which helps terminate re-entrant rhythms and slow conduction - Particularly useful when the origin of BCT (ventricular vs. supraventricular with aberrancy) is uncertain *IV amiodarone* - **Amiodarone** is a Class III antiarrhythmic drug that is effective for both supraventricular and ventricular arrhythmias - It is also an acceptable option for stable BCT and is preferred by some guidelines, though it has a **slower onset of action** compared to procainamide - May be preferred in patients with structural heart disease or heart failure *IV verapamil* - **Verapamil** is a non-dihydropyridine **calcium channel blocker** that primarily slows AV nodal conduction - It is **contraindicated** in broad complex tachycardia (BCT) of uncertain or ventricular origin because it can worsen hypotension and precipitate ventricular fibrillation - Can cause hemodynamic collapse in ventricular tachycardia or pre-excitation syndromes (e.g., Wolff-Parkinson-White syndrome) *IV adenosine* - **Adenosine** is primarily used for the acute termination of **supraventricular tachycardias (SVTs)**, especially those involving the AV node - It is **contraindicated** in broad complex tachycardia as it can lead to hemodynamic collapse or ventricular fibrillation, particularly if the BCT is due to **ventricular tachycardia** - May cause paradoxical acceleration in **Wolff-Parkinson-White syndrome** with antegrade conduction down an accessory pathway

Question 93: Which drug is used as adjunctive therapy in acute severe asthma when conventional treatments are insufficient?

A. Magnesium sulfate (Correct Answer)
B. Anti-leukotriene
C. Cromolyn sodium
D. Cyclosporine

Explanation: ***Magnesium sulfate*** - **Magnesium sulfate** is an **adjunctive bronchodilator** in severe acute asthma, particularly when conventional therapies like beta-agonists and corticosteroids are insufficient. - It works by acting as a **calcium channel antagonist**, leading to **smooth muscle relaxation** and bronchodilation. *Cromolyn sodium* - **Cromolyn sodium** is a **mast cell stabilizer** used for asthma prevention, not acute severe exacerbations. - It works by preventing the release of inflammatory mediators and is used as a **controller medication** in mild persistent asthma. *Anti-leukotriene* - **Anti-leukotrienes** (e.g., montelukast) are **maintenance therapies** for chronic asthma and are not indicated for acute severe asthma exacerbations. - They primarily reduce airway inflammation and bronchoconstriction over time, but their effect is too slow for acute relief. *Cyclosporine* - **Cyclosporine** is an **immunosuppressant** used in severe, refractory asthma unresponsive to standard treatments, but it is not a first-line adjunctive therapy for acute exacerbations. - Its use is limited due to significant **side effects** and requires careful monitoring.

Question 94: Which of the following is not used in the treatment of organophosphorus poisoning?

A. Pralidoxime
B. Atropine
C. Activated charcoal
D. Naltrexone (Correct Answer)

Explanation: ***Naltrexone*** - **Naltrexone** is an **opioid receptor antagonist** primarily used in the management of **alcohol and opioid dependence**; it has no role in treating organophosphorus poisoning. - Its mechanism of action involves blocking opioid receptors, which is unrelated to the cholinergic crisis seen in organophosphorus toxicity. *Pralidoxime* - **Pralidoxime** is a **cholinesterase reactivator** that works by removing organophosphate molecules from acetylcholinesterase, thereby regenerating the enzyme and reversing nicotinic effects. - It is particularly effective if administered early in the course of poisoning, before **"aging"** of the enzyme occurs. *Atropine* - **Atropine** is a **muscarinic acetylcholine receptor antagonist** used to block the muscarinic effects of organophosphorus poisoning, such as **bronchospasm**, **bradycardia**, and **secretions**. - It does not reactivate cholinesterase or reverse nicotinic effects (e.g., muscle weakness), but it is crucial for managing life-threatening muscarinic symptoms. *Activated charcoal* - **Activated charcoal** is used for **gastrointestinal decontamination** in cases of oral organophosphorus ingestion. - It works by **adsorbing** the poison in the gastrointestinal tract, preventing its absorption into the systemic circulation.

Question 95: A 15-year-old girl with type 1 diabetes is brought to the emergency department complaining of dizziness. Laboratory findings include severe hyperglycemia, ketoacidosis, and a blood pH of 7.15. To achieve rapid control of severe ketoacidosis, which of the following is the most appropriate drug?

A. NPH insulin
B. Tolbutamide
C. Ultralente insulin
D. Regular insulin (Correct Answer)

Explanation: ***Regular insulin*** - **Regular insulin** is a **short-acting insulin** that can be administered intravenously, allowing for rapid onset and precise titration, which is crucial for managing severe **ketoacidosis**. - Intravenous regular insulin is the cornerstone of **diabetic ketoacidosis (DKA)** treatment, as it quickly lowers blood glucose and suppresses ketogenesis. *NPH insulin* - **NPH (Neutral Protamine Hagedorn) insulin** is an **intermediate-acting insulin** and is not suitable for the rapid control required in DKA. - Its delayed onset and prolonged duration make it inappropriate for acute emergency management of severe hyperglycemia and ketoacidosis. *Tolbutamide* - **Tolbutamide** is an oral sulfonylurea used to stimulate insulin secretion in patients with **type 2 diabetes** who still have some pancreatic beta-cell function. - It is ineffective in **type 1 diabetes** where there is an absolute insulin deficiency, and it does not provide rapid insulin action for DKA. *Ultralente insulin* - **Ultralente insulin** is a **long-acting insulin** that is no longer widely used and has a very slow onset and prolonged duration of action. - It is unsuitable for the acute management of severe ketoacidosis, which requires rapid and titratable insulin delivery.

Question 96: What is the drug of choice for managing a hypertensive crisis due to tyramine ingestion, commonly referred to as a cheese reaction?

A. Dantrolene sodium
B. Phentolamine (Correct Answer)
C. Yohimbine
D. Amitriptyline

Explanation: ***Phentolamine*** - **Phentolamine** is an **alpha-adrenergic blocker** that rapidly reverses the potent **vasoconstriction** and **hypertension** caused by excess catecholamines released due to tyramine. [2] - Its quick onset of action and short duration make it ideal for emergent control of **hypertensive crisis** from tyramine. *Amitriptyline* - **Amitriptyline** is a **tricyclic antidepressant** that primarily affects serotonin and norepinephrine reuptake and can *cause* **hypertensive crisis** when combined with MAOIs, rather than treating it. [1] - It has no role in the acute management of a **tyramine-induced hypertensive crisis**. *Dantrolene sodium* - **Dantrolene sodium** is a **muscle relaxant** used to treat **malignant hyperthermia** and neuroleptic malignant syndrome, by acting on **ryanodine receptors** to decrease intracellular calcium. - It is not indicated for the management of acute **hypertensive crisis** or **tyramine reactions**. *Yohimbine* - **Yohimbine** is an **alpha-2 adrenergic antagonist** that can increase **sympathetic activity** and potentially worsen a **hypertensive crisis**. - It is generally contraindicated in hypertensive patients and would exacerbate, not alleviate, a **tyramine-induced pressor response**.

Question 97: Which of the following is the most appropriate treatment for severe nicotine poisoning?

A. Neostigmine
B. Atropine (Correct Answer)
C. Phentolamine
D. Trimethaphan

Explanation: ***Atropine*** - **Atropine** is the most appropriate pharmacological treatment among the options for managing the **muscarinic symptoms** of severe nicotine poisoning, as it acts as a **competitive antagonist** at muscarinic acetylcholine receptors [1]. - Nicotine initially stimulates and then paralyzes nicotinic acetylcholine receptors at autonomic ganglia and neuromuscular junctions, leading to a biphasic toxidrome with both muscarinic and nicotinic effects [1]. - Severe cases often present with prominent **cholinergic overdrive** (bradycardia, excessive salivation, bronchorrhea, bronchospasm) that responds to atropine. - **Note:** Overall management of severe nicotine poisoning primarily involves **supportive care** (airway management, mechanical ventilation), with atropine used for symptomatic relief of muscarinic effects. *Neostigmine* - **Neostigmine** is an **acetylcholinesterase inhibitor** that increases acetylcholine levels at the synapse. - This would exacerbate the cholinergic effects of nicotine poisoning and is therefore contraindicated. *Phentolamine* - **Phentolamine** is an **alpha-adrenergic blocker** used to treat hypertensive crises, particularly those caused by catecholamine release. - While nicotine can cause initial sympathetic stimulation and catecholamine release, phentolamine does not address the primary cholinergic toxicity of severe nicotine poisoning. *Trimethaphan* - **Trimethaphan** is a **ganglionic blocker** that can block both sympathetic and parasympathetic ganglia at nicotinic receptors [2]. - While theoretically it might prevent some nicotinic effects, it is obsolete and rarely used due to its non-selective nature and potential for severe hypotension and other side effects, making it unsuitable compared to supportive care and targeted atropine therapy [2].

Question 98: Which of the following is considered a universal antidote?

A. Activated charcoal (Correct Answer)
B. Magnesium oxide
C. Tannic acid
D. Sodium sulphate

Explanation: ***Activated charcoal*** - It is often referred to as a **"universal antidote"** (though this term is outdated in modern toxicology) because it can adsorb a wide range of toxins and drugs, preventing their absorption from the gastrointestinal tract. - Its large surface area allows it to bind to many organic and inorganic compounds, making it effective in various poisonings. - **Limitations:** Does NOT work for alcohols, heavy metals (iron, lithium), corrosive substances, or hydrocarbons. - Most widely used gastrointestinal decontaminant in acute poisoning management. *Magnesium oxide* - This is an antacid and laxative, primarily used to neutralize **stomach acid** or relieve **constipation**. - It does not have broad adsorptive properties for a wide range of poisons. - Historically was part of the "universal antidote" mixture (now abandoned). *Tannic acid* - Historically used as an antidote for heavy metal poisoning and alkaloid poisoning, tannic acid is now considered **toxic and ineffective** for most poisonings. - Its use is largely abandoned due to hepatotoxicity and limited efficacy. - Was also part of the historical "universal antidote" mixture. *Sodium sulphate* - This is a **saline laxative** used to induce bowel movements (cathartic agent). - It does not act as an antidote by binding or neutralizing poisons in a widespread manner. - May be used alongside activated charcoal in some poisoning protocols to enhance elimination.

Question 99: A 70-year-old man develops pneumonia and septicemia, and subsequently experiences renal failure with a blood pressure of 70/50 mmHg. Which drug should be used to maintain blood pressure?

A. Adrenaline
B. Ephedrine
C. Phenylephrine
D. Norepinephrine (Correct Answer)

Explanation: ***Norepinephrine*** - **Norepinephrine** is the first-line vasopressor recommended for treating **septic shock** with hypotension unresponsive to fluid resuscitation, as it potently increases **mean arterial pressure** without excessive tachycardia. - It primarily acts on **alpha-1 adrenergic receptors** to cause vasoconstriction, thereby increasing systemic vascular resistance and blood pressure, which is crucial in stabilizing a patient with **sepsis and renal failure**. *Adrenaline* - **Adrenaline (epinephrine)** is a potent vasopressor but is generally reserved for septic shock unresponsive to norepinephrine or in cases of **cardiac arrest** due to its potential for increased arrhythmias and splanchnic vasoconstriction. - While it raises blood pressure, its broader **beta-adrenergic effects** can lead to undesirable side effects such as tachycardia and increased myocardial oxygen demand. *Ephedrine* - **Ephedrine** is an indirect sympathomimetic that releases stored norepinephrine, providing both alpha and beta effects, but its use in severe septic shock is limited by its **weaker and less predictable pressor effect** compared to direct-acting catecholamines. - It has a slower onset and longer duration of action, making it less suitable for rapid titration and precise blood pressure control in an acute, unstable condition like **septic shock**. *Phenylephrine* - **Phenylephrine** is a pure alpha-1 agonist that causes significant vasoconstriction and increases blood pressure, but its use in septic shock is generally discouraged due to its potential to cause **reflex bradycardia** and a higher risk of reducing **cardiac output**. - While it effectively raises blood pressure, its lack of direct inotropic effects and potential for reducing perfusion to vital organs make it a less optimal choice compared to norepinephrine in **septicemia-induced hypotension**.

Question 100: What is the antidote used in cases of heparin overdose?

A. Phylloquinone
B. Ticlopidine
C. Clopidogrel
D. Protamine sulfate (Correct Answer)

Explanation: ***Protamine sulfate*** - **Protamine sulfate** is the specific antidote for **unfractionated heparin (UFH)** overdose. - It works by forming a stable **ionically-bonded complex** with heparin, neutralizing its anticoagulant effects. - For **low molecular weight heparin (LMWH)**, protamine provides only **partial reversal** (~60% neutralization). *Phylloquinone* - **Phylloquinone** (Vitamin K1) is the antidote specifically used to reverse the effects of **warfarin** overdose. - Warfarin exerts its anticoagulant effect by inhibiting **vitamin K-dependent clotting factors** (II, VII, IX, X), while phylloquinone helps restore their synthesis. *Ticlopidine* - **Ticlopidine** is an **antiplatelet agent** that irreversibly inhibits the **P2Y12 ADP receptor** on platelets, preventing platelet aggregation. - It is not an antidote for any anticoagulant overdose but rather a medication used to prevent thrombosis. - **No specific antidote exists** for ticlopidine overdose. *Clopidogrel* - **Clopidogrel** is another **antiplatelet agent** similar to ticlopidine, irreversibly blocking the **P2Y12 ADP receptor**. - Like ticlopidine, it is used to prevent blood clots, not reverse the effects of heparin. - Platelet transfusion may be considered in severe bleeding from clopidogrel.

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