Drug Toxicity and Overdose — MCQs
Which of the following is the recommended treatment for iron poisoning in a 4-year-old child?
A farmer presented with confusion, increased salivation, fasciculations, miosis, tachycardia and hypertension. Poison that can cause these manifestations:
Which drug is the specific antidote for organophosphorus poisoning?
Which of the following diuretics is contraindicated in Hepatic coma?
A patient presented to the emergency department with an overdose of a drug, exhibiting increased salivation and increased bronchial secretions. On examination, the blood pressure was 88/60 mmHg, and the RBC cholinesterase level was reduced to 50% of normal. What should be the treatment for this individual?
A female, Lalita, aged 26 years takes 100 tablets of paracetamol. Treatment of choice is:
All are features of organophosphorus poisoning, except:
What is the treatment of choice for Lalita, a 26-year-old female who accidentally took 100 tablets of paracetamol?
Ulipristal acetate (progesterone receptor modulator) should not be prescribed as emergency contraceptive in women with
Which drug is least likely to cause exanthematous skin eruptions?
Drug Toxicity and Overdose Indian Medical PG Practice Questions and MCQs
Question 1: Which of the following is the recommended treatment for iron poisoning in a 4-year-old child?
- A. Blood transfusion
- B. Stomach lavage
- C. Observation and supportive care
- D. Deferoxamine IV at a dose of 15 mg/kg/hour (Correct Answer)
Explanation: ***Deferoxamine IV at a dose of 15 mg/kg/hour*** - **Deferoxamine** is a chelating agent specifically used to bind free iron, forming a complex that can be excreted renally. - An intravenous infusion at 15 mg/kg/hour is the recommended dose for severe iron poisoning, particularly when serum iron levels are high or symptoms indicate significant toxicity. *Stomach lavage* - **Stomach lavage** is generally not recommended for iron poisoning due to the risk of pushing iron tablets further into the intestine, potential for perforation, and limited efficacy in removing large, unabsorbed iron tablets. - Iron tablets are often **large** and **poorly soluble**, making lavage ineffective for complete removal. *Blood transfusion* - **Blood transfusion** is not a primary treatment for iron poisoning because iron toxicity is due to free iron in the body, not a deficiency that would be corrected by transfused blood. - It would only be considered in cases of severe anemia or significant blood loss, which are not direct treatments for iron overload. *Observation and supportive care* - While supportive care is crucial in managing complications of iron poisoning, **observation alone is insufficient** for moderate to severe cases of iron poisoning. - Significant iron overdose requires active intervention to prevent systemic toxicity, organ damage, and potentially fatal outcomes.
Question 2: A farmer presented with confusion, increased salivation, fasciculations, miosis, tachycardia and hypertension. Poison that can cause these manifestations:
- A. Arsenic
- B. Opium
- C. Dhatura
- D. OPC (Correct Answer)
Explanation: ***OPC*** - The combination of **confusion**, increased salivation, **fasciculations**, **miosis**, and **tachycardia/hypertension** points towards **organophosphate poisoning (OPC)** due to excessive cholinergic stimulation. - Farmers are at high risk for OPC due to exposure to **pesticides**. *Arsenic* - **Arsenic poisoning** typically causes severe gastrointestinal symptoms such as vomiting, diarrhea, and abdominal pain, along with **garlic breath** and **neuropathy**. - It does not commonly present with prominent salivation, fasciculations, or miosis. *Opium* - **Opioid overdose** characteristically leads to **CNS depression**, **respiratory depression**, **pinpoint pupils (miosis)**, and **bradycardia** and **hypotension**. - It does not cause increased salivation, fasciculations, or tachycardia. *Dhatura* - **Dhatura poisoning** is characterized by **anticholinergic symptoms** such as **dry mouth**, dilated pupils (mydriasis), blurred vision, warm dry skin, **tachycardia**, and **agitation/delirium**. - It would not cause increased salivation, fasciculations, or miosis.
Question 3: Which drug is the specific antidote for organophosphorus poisoning?
- A. EDTA
- B. BAL
- C. Atropine
- D. Pralidoxime (PAM) (Correct Answer)
Explanation: ***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.
Question 4: Which of the following diuretics is contraindicated in Hepatic coma?
- A. Bumetanide
- B. Furosemide
- C. Acetazolamide (Correct Answer)
- D. Spironolactone
Explanation: ***Acetazolamide*** - **Acetazolamide** inhibits carbonic anhydrase, leading to increased bicarbonate excretion and metabolic acidosis. In patients with **hepatic coma**, this can worsen the condition by impairing the liver's ability to convert ammonia to urea, leading to increased levels of **ionized ammonia** that can cross the blood-brain barrier. - The resulting **metabolic acidosis** can also interfere with the kidney's response to ammonia, further exacerbating the **hepatic encephalopathy**. *Bumetanide* - **Bumetanide** is a loop diuretic that acts on the **thick ascending limb of the loop of Henle** to inhibit sodium, potassium, and chloride reabsorption. - It does not directly exacerbate **hepatic encephalopathy** through metabolic acidosis in the same way as acetazolamide. *Furosemide* - **Furosemide** is a loop diuretic similar to bumetanide, acting on the **thick ascending limb** to promote diuresis. - While aggressive diuresis with furosemide in critical patients can sometimes lead to **volume depletion** and electrolyte imbalances that may indirectly affect liver function, it does not directly worsen **hepatic coma** by altering systemic acid-base balance and ammonia detoxification like acetazolamide. *Spironolactone* - **Spironolactone** is an **aldosterone antagonist** and a potassium-sparing diuretic, commonly used in liver cirrhosis with ascites. - It does not directly cause **metabolic acidosis** or increase ionized ammonia levels; in fact, by improving fluid balance, it can sometimes help manage complications of liver disease.
Question 5: A patient presented to the emergency department with an overdose of a drug, exhibiting increased salivation and increased bronchial secretions. On examination, the blood pressure was 88/60 mmHg, and the RBC cholinesterase level was reduced to 50% of normal. What should be the treatment for this individual?
- A. Atropine (Correct Answer)
- B. Physostigmine
- C. Flumazenil
- D. Neostigmine
Explanation: ***Atropine*** - The patient exhibits symptoms of **cholinergic crisis** (increased salivation, bronchial secretions, hypotension) and reduced RBC esterase, strongly indicative of **organophosphate poisoning**. - **Atropine** is the primary antidote, as it competitively blocks muscarinic acetylcholine receptors, reversing the parasympathetic effects. *Neostigmine* - **Neostigmine** is an **acetylcholinesterase inhibitor**, meaning it would worsen the cholinergic crisis by increasing acetylcholine levels further. - It is used in conditions like **myasthenia gravis** to improve muscle strength, not in organophosphate poisoning. *Flumazenil* - **Flumazenil** is an **antagonist of benzodiazepine receptors** and is used to reverse benzodiazepine overdose. - It has no role in treating organophosphate poisoning or cholinergic symptoms. *Physostigmine* - **Physostigmine** is also an **acetylcholinesterase inhibitor** that can cross the blood-brain barrier. - While it has some ophthalmic uses, it would exacerbate the cholinergic symptoms of organophosphate poisoning due to increased acetylcholine.
Question 6: A female, Lalita, aged 26 years takes 100 tablets of paracetamol. Treatment of choice is:
- A. Lavage with charcoal
- B. Dialysis
- C. Alkaline diuresis
- D. Acetylcysteine (Correct Answer)
Explanation: ***Acetylcysteine*** - **Acetylcysteine** is the **antidote of choice** for paracetamol (acetaminophen) overdose, replenishing **glutathione stores** and detoxifying toxic paracetamol metabolites. - Early administration (within 8 hours of ingestion) is crucial for preventing **hepatic damage**, as it inhibits the binding of the toxic metabolite **NAPQI** to liver proteins. *Lavage with charcoal* - **Gastric lavage** and **activated charcoal** are primarily used for **decontamination** in the early stages (within 1-2 hours) of acute overdose, to prevent absorption. - Given the ingestion of **100 tablets**, a significant amount of paracetamol has likely already been absorbed, making these less effective as the sole treatment. *Dialysis* - **Dialysis** is generally reserved for severe cases of paracetamol overdose complicated by **acute liver failure** or other severe organ dysfunction, which requires elimination of paracetamol and its metabolites from the blood. - It is not the **first-line treatment** for acute paracetamol overdose itself, but rather a supportive measure for complications. *Alkaline diuresis* - **Alkaline diuresis** is sometimes used to enhance the elimination of **acidic drugs** like salicylates (aspirin) from the body. - Paracetamol is primarily metabolized by the liver into glucuronide and sulfate conjugates, which are then excreted, and its elimination is not significantly enhanced by **alkaline diuresis**.
Question 7: All are features of organophosphorus poisoning, except:
- A. Lacrimation
- B. Bradycardia
- C. Sweating
- D. Mydriasis (Correct Answer)
Explanation: ***Mydriasis*** - Organophosphorus poisoning leads to excessive **acetylcholine** activity, causing **miosis** (pinpoint pupils), not mydriasis. - Mydriasis would indicate **anticholinergic** effects, which are opposite to the symptoms of organophosphorus poisoning. *Lacrimation* - Excess **acetylcholine** stimulates **muscarinic receptors** in lacrimal glands, leading to excessive tear production. - This is a classic "SLUDGE" symptom (Salivation, Lacrimation, Urination, Defecation, Gastric upset, Emesis). *Bradycardia* - Increased **acetylcholine** activity at cardiac muscarinic receptors (M2 receptors) slows the heart rate, causing **bradycardia**. - This is a common and potentially dangerous cardiovascular effect of organophosphorus poisoning. *Sweating* - **Acetylcholine** acts on muscarinic receptors in secretory glands, including sweat glands, causing profuse **sweating**. - This is another characteristic cholinergic symptom due to widespread autonomic overstimulation.
Question 8: What is the treatment of choice for Lalita, a 26-year-old female who accidentally took 100 tablets of paracetamol?
- A. Acetyl cysteine (Correct Answer)
- B. Gastric lavage
- C. Hemodialysis
- D. Alkaline diuresis
Explanation: ***Acetyl cysteine*** - **Acetyl cysteine** is the **antidote** of choice for paracetamol (acetaminophen) overdose. - It works by replenishing **glutathione stores**, which are essential for detoxifying the toxic metabolite of paracetamol, **N-acetyl-p-benzoquinone imine (NAPQI)**. *Gastric lavage* - **Gastric lavage** is generally not recommended for paracetamol overdose unless performed within **1 hour** of ingestion, and even then, its effectiveness is limited. - It carries risks such as aspiration and esophageal injury, making it less favorable than activated charcoal. *Hemodialysis* - **Hemodialysis** is generally reserved for severe cases of paracetamol overdose with life-threatening complications like **severe metabolic acidosis** or **renal failure**, and when acetyl cysteine treatment is delayed or ineffective. - Paracetamol itself is dialyzable, but hemodialysis is not the primary treatment for uncomplicated overdose. *Alkaline diuresis* - **Alkaline diuresis** is a treatment used for overdoses of **weak acids**, such as salicylates or phenobarbital, to enhance their renal excretion. - Paracetamol is not a weak acid, so alkaline diuresis would not be effective in eliminating it from the body.
Question 9: Ulipristal acetate (progesterone receptor modulator) should not be prescribed as emergency contraceptive in women with
- A. liver dysfunction (Correct Answer)
- B. glaucoma
- C. coagulopathy
- D. kidney failure
Explanation: ***Correct: liver dysfunction*** - **Ulipristal acetate** is extensively metabolized in the **liver** by the CYP450 enzyme system, predominantly CYP3A4. - In individuals with **severe hepatic impairment**, the metabolism of ulipristal acetate can be impaired, leading to increased plasma concentrations and potential adverse effects. - **Severe liver dysfunction** is a documented contraindication in product labeling. *Incorrect: glaucoma* - There is **no known contraindication** for ulipristal acetate use in individuals with **glaucoma**. - Its mechanism of action primarily involves progesterone receptors and does not directly impact intraocular pressure. *Incorrect: coagulopathy* - Ulipristal acetate does **not significantly affect blood coagulation** parameters or platelet function. - It is not contraindicated in individuals with **coagulopathy**, unlike some estrogen-containing contraceptives. *Incorrect: kidney failure* - While urinary excretion of ulipristal acetate metabolites occurs, the **primary elimination pathway is fecal** (approximately 90%). - **Kidney failure** is not considered a contraindication, and dose adjustments are generally not required.
Question 10: Which drug is least likely to cause exanthematous skin eruptions?
- A. Phenytoin
- B. Ampicillin
- C. Phenylbutazone
- D. Hydrocortisone (Correct Answer)
Explanation: ***Hydrocortisone*** - **Corticosteroids** like hydrocortisone are **anti-inflammatory** and immunosuppressive agents. - They are commonly used to **treat allergic reactions** and skin eruptions, making them highly unlikely to cause exanthematous eruptions themselves. *Phenytoin* - **Anticonvulsant** medications like phenytoin are frequently associated with various **drug-induced skin reactions**, including exanthematous eruptions. - It is a common cause of **drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome**, which manifests with a widespread rash. *Ampicillin* - **Antibiotics**, particularly **aminopenicillins** like ampicillin, are well-known triggers for **maculopapular rashes** and other exanthematous eruptions. - The incidence of ampicillin-induced rash is notably higher, especially in patients with **viral infections** like infectious mononucleosis. *Phenylbutazone* - This **non-steroidal anti-inflammatory drug (NSAID)** has a documented history of causing severe cutaneous adverse reactions, including **exanthematous eruptions**. - Due to its potential for serious side effects, such as **aplastic anemia** and severe skin reactions, its use is now highly restricted.
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