Emergency Pharmacology Practice Questions

Q: What is the recommended dose of diphtheria antitoxin for severe cases of diphtheria?

80,000 to 120,000 IU. ***80,000 to 120,000 IU*** - For **severe cases** of diphtheria, especially those with extensive pseudomembrane formation (involving larynx, extensive pharyngeal/tonsillar involvement, or "bull neck" appearance) or systemic toxicity, a high dose of **diphtheria antitoxin (DAT)** ranging from **80,000 to 120,000 IU** is recommended. - This high dose is necessary to neutralize the large amount of circulating toxin and prevent life-threatening complications such as **myocarditis**, **neuropathy**, and **respiratory obstruction**. - The antitoxin should be administered as early as possible, ideally after a **test dose** to check for hypersensitivity [1], and is given **intravenously** for rapid effect in severe cases. *20,000 to 40,000 IU* - This dose range is typically reserved for **mild cases** of pharyngeal or tonsillar diphtheria without extensive membrane formation or systemic involvement. - Administering this dose in a severe case would be **insufficient** to neutralize the toxin load, potentially leading to fatal complications. *40,000 to 60,000 IU* - This is the recommended range for **moderate cases** of nasopharyngeal or more extensive pharyngeal diphtheria. - While higher than mild case dosing, it remains inadequate for severe presentations with extensive membrane or systemic toxicity. *60,000 to 80,000 IU* - This intermediate dose might be considered for **moderately severe cases**, but falls short of the recommended dosing for truly severe diphtheria. - Severe cases with laryngeal involvement, bull neck, or signs of toxemia require higher doses to ensure adequate toxin neutralization.

Q: What is the drug of choice (DOC) for a scorpion sting bite?

Prazosin. ***Prazosin*** - **Prazosin** is an **alpha-1 adrenergic antagonist** that effectively counteracts the symptoms of scorpion envenomation, particularly **autonomic hyperactivity** like hypertension and tachycardia. - It works by blocking the effects of norepinephrine released by the scorpion venom, helping to stabilize vital signs and reduce cardiovascular complications. *EDTA* - **EDTA (ethylenediaminetetraacetic acid)** is a **chelating agent** primarily used to treat **heavy metal poisoning**, such as lead or mercury. - It binds to metal ions, forming a stable complex that can then be excreted from the body; it has no role in scorpion envenomation. *Neostigmine* - **Neostigmine** is an **acetylcholinesterase inhibitor** used to treat conditions like myasthenia gravis or to reverse the effects of neuromuscular blocking agents. - It increases acetylcholine levels at the neuromuscular junction; it is not indicated for the management of scorpion stings. *N-acetylcysteine* - **N-acetylcysteine (NAC)** is primarily used as an **antidote for acetaminophen overdose** and as a mucolytic agent in respiratory conditions. - It replenishes glutathione stores, helping to detoxify harmful metabolites; it has no direct role in treating scorpion venom effects.

Q: What is the best drug for control of acute esophageal variceal bleeding?

Octreotide. ***Octreotide*** - **Octreotide** is a somatostatin analog that causes **splanchnic vasoconstriction**, reducing portal venous inflow and pressure, which is crucial in controlling **esophageal variceal bleeding**. - Its mechanism involves inhibiting the release of **vasodilatory hormones** like glucagon, leading to a decrease in portal pressure without significant systemic side effects. *Vasopressin* - **Vasopressin** is a potent vasoconstrictor that can reduce portal pressure but has significant systemic side effects such as **myocardial ischemia** and **bowel ischemia** due to widespread vasoconstriction. - It is generally no longer considered the first-line pharmacological treatment for variceal bleeding due to its **adverse effect profile**. *GnRH* - **GnRH** (Gonadotropin-releasing hormone) plays a role in regulating the reproductive system by controlling the release of FSH and LH from the pituitary. - It has **no direct role** in the management or control of esophageal bleeding. *Propranolol* - **Propranolol** is a non-selective beta-blocker primarily used for **prophylaxis** of variceal bleeding by reducing portal pressure chronically. - It works by reducing cardiac output and causing splanchnic vasoconstriction, but it is **not used for acute control** of active bleeding.

Q: Oximes are contraindicated in which type of poisoning?

Carbamate poisoning. ***Carbamate poisoning*** - Oximes are generally **not recommended** (and sometimes considered contraindicated) in carbamate poisoning - Carbamates cause **reversible carbamylation** of acetylcholinesterase that spontaneously reverses within **minutes to hours** [1, 4] - Since the enzyme-carbamate bond breaks down spontaneously, oxime reactivation provides **no additional benefit** - Some evidence suggests oximes may be **harmful in specific carbamate poisonings** (e.g., carbaryl), though the mechanism is debated - **Clinical principle:** The spontaneous reactivation makes oxime therapy unnecessary and potentially risky [3] *Organophosphate poisoning* - Oximes (e.g., **pralidoxime, obidoxime**) are the **primary antidotes** for organophosphate poisoning - They **reactivate acetylcholinesterase** by breaking the phosphate-enzyme bond before "aging" occurs [4] - Must be administered **early** (within 24-48 hours) before the enzyme-organophosphate complex undergoes aging (becomes irreversible) - Reverses **nicotinic and muscarinic** symptoms of cholinergic crisis [3] *Methanol poisoning* - Treatment involves **fomepizole** (first-line) or **ethanol** to competitively inhibit alcohol dehydrogenase [2] - This prevents conversion of methanol to toxic metabolites (formaldehyde and formic acid) - **Hemodialysis** for severe cases and acidosis correction - Oximes have **no role** in alcohol poisoning management *Cyanide poisoning* - Treated with **hydroxocobalamin** (binds cyanide to form cyanocobalamin), **sodium thiosulfate** (converts cyanide to thiocyanate), or **sodium nitrite** (forms methemoglobin) - Oximes are **not indicated** and have no mechanism of action against cyanide toxicity

Q: In the context of neonatal resuscitation, naloxone would be indicated for a child whose mother is taking which of the following substances?

Methadone. ***Methadone*** - Methadone is a **long-acting opioid** used in opioid maintenance therapy. - A neonate born to a mother on methadone may experience **respiratory depression** due to in utero opioid exposure. - Naloxone is an **opioid antagonist** and may be used in severe cases of neonatal respiratory depression from opioid exposure, though careful titration is needed to avoid precipitating acute withdrawal syndrome. *Amphetamine* - Amphetamine is a **stimulant**, not an opioid. - Naloxone is ineffective for amphetamine toxicity. - Neonatal exposure presents with **irritability**, **tachycardia**, and **poor feeding**, not opioid-related respiratory depression. *Cocaine* - Cocaine is a **stimulant** and does not respond to naloxone. - Infants exposed to cocaine may exhibit **irritability**, **jitteriness**, **poor feeding**, and **cardiovascular instability**. - These effects are not mediated by opioid receptors. *Phencyclidine (PCP)* - PCP is a **dissociative anesthetic**, not an opioid. - Naloxone has no role in PCP toxicity. - Overdose may cause **behavioral disturbances**, **nystagmus**, **hypertension**, and **seizures**.

Q: Which drug is the specific antidote for organophosphorus poisoning?

Pralidoxime (PAM). ***Pralidoxime (PAM)*** - **Pralidoxime (PAM)** reactivates the enzyme **acetylcholinesterase** by detaching the organophosphate from the enzyme's active site. - It is most effective when administered early, ideally within a few hours of exposure, to prevent **aging** of the enzyme-inhibitor complex. *EDTA* - **EDTA** (ethylenediaminetetraacetic acid) is a chelating agent primarily used in the treatment of **heavy metal poisoning**, such as lead poisoning. - It is not effective against organophosphorus compounds, which act by inhibiting acetylcholinesterase. *BAL* - **BAL** (British Anti-Lewisite, or dimercaprol) is another chelating agent used to treat poisoning by **heavy metals** such as arsenic, mercury, and gold. - It does not have a mechanism of action that addresses the enzyme inhibition caused by organophosphates. *Atropine* - **Atropine** is used in organophosphorus poisoning, but it is not a specific antidote as it does not address the cause of poisoning. - It acts to counteract the **muscarinic effects** of excessive acetylcholine, such as bradycardia, bronchospasm, and excessive secretions, but does not reactivate acetylcholinesterase.

Q: 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?

Glycerol. ***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**.

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

Phentolamine. ***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**.

Q: Which of the following is considered a universal antidote?

Activated charcoal. ***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 1

Which of the following statements about epinephrine is false?

Accepted Answer

Routine use of high dose epinephrine during resuscitation is indicated

Answer

It improves coronary perfusion pressure and myocardial blood flow

Answer

Has potent alpha and beta stimulating properties

Answer

Increases cerebral blood flow during CPR

Question 2

What is the recommended dose of diphtheria antitoxin for severe cases of diphtheria?

Accepted Answer

80,000 to 120,000 IU

Answer

20,000 to 40,000 IU

Answer

60,000 to 80,000 IU

Answer

40,000 to 60,000 IU

Question 3

What is the drug of choice (DOC) for a scorpion sting bite?

Accepted Answer

Prazosin

Answer

EDTA

Answer

Neostigmine

Answer

N-acetylcysteine

Question 4

What is the best drug for control of acute esophageal variceal bleeding?

Accepted Answer

Octreotide

Answer

Vasopressin

Answer

GnRH

Answer

Propranolol

Question 5

Oximes are contraindicated in which type of poisoning?

Accepted Answer

Carbamate poisoning

Answer

Organophosphate poisoning

Answer

Methanol poisoning

Answer

Cyanide poisoning

Question 6

In the context of neonatal resuscitation, naloxone would be indicated for a child whose mother is taking which of the following substances?

Accepted Answer

Methadone

Answer

Cocaine

Answer

Amphetamine

Answer

Phenylcyclidine (PCP)

Question 7

Which drug is the specific antidote for organophosphorus poisoning?

Accepted Answer

Pralidoxime (PAM)

Answer

EDTA

Answer

BAL

Answer

Atropine

Question 8

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?

Accepted Answer

Glycerol

Answer

Latanoprost

Answer

Dorzolamide

Answer

Acetazolamide

Question 9

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

Accepted Answer

Phentolamine

Answer

Dantrolene sodium

Answer

Yohimbine

Answer

Amitriptyline

Question 10

Which of the following is considered a universal antidote?

Accepted Answer

Activated charcoal

Answer

Magnesium oxide

Answer

Tannic acid

Answer

Sodium sulphate

Emergency Pharmacology — MCQs

Emergency Pharmacology — MCQs

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